SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES ? NUMBER 2
Field and Laboratory Investigations
of Meteorites from Victoria Land
and the Thiel Mountains Region, Antarctica,
1982-1983 and 1983-1984
Ursula B. Marvin
and Glenn J. MacPherson
EDITORS
SMITHSONIAN INSTITUTION PRESS
Washington, D.C.
1989
MAR 0 a 1989
ABSTRACT
Marvin, Ursula B., and Glenn J. MacPherson, editors. Field and Laboratory Investigations
of Meteorites from Victoria Land and the Thiel Mountains Region, Antarctica, 1982-1983 and
1983-1984. Smithsonian Contributions to the Earth Sciences, number 28, 146 pages,
frontispiece, 86 figures, 14 tables, 1989.?This monograph describes the meteorite collecting
activities of the United States Antarctic Search for Meteorites (ANSMET) expeditions of the
1982-1983 and 1983-1984 field seasons. Descriptions and classifications are given of most
specimens collected during the 1982-1983 season and some of those collected in the 1983-1984
season. Articles are included reviewing topics such as Antarctic achondrites, carbonaceous
chondrites, meteorite weathering under polar conditions, trace element contents of Antarctic
meteorites in comparison with those found elsewhere, and the meteorite pairing problem. One
chapter describes the crystalline fabric of the ice surrounding a meteorite discovered emerging
at the surface. The Appendix lists all ANSMET specimens classified as of June 1984, in
numerical order for each locality and by meteorite class. The Appendix also includes a tentative
list of paired specimens.
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is
recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: Aerial
view of Ulawun Volcano, New Britain.
Library of Congress Cataloging in Publication Data
Field and laboratory investigations of meteorites from Victoria Land and the Thiel Mountains Region, Antarctica,
1982-1983 and 1983-1984.
(Smithsonian contributions to the earth sciences ; no. 28)
"This monograph describes the meteorite collecting activities of the United States Antarctic Search for Meteorites
(ANSMET) expeditions of the 1982-1983 and 1983-1984 field seasons"?P.
Bibliography: p.
1. Meteorites?Antarctic regions?Victoria Land. 2. Meteorites?Antarctic regions?Thiel Mountains Re-
gion. I. Marvin, Ursula B. II. MacPherson, Glenn J. III. Series.
QE1.S227 no. 28 550s 88-600361
[QB755.5.A6] [523.5'1]
Contents
Page
1. EDITOR'S INTRODUCTION, by Ursula B. Marvin and Glenn J. MacPherson ... 1
2. THE 1982-1983 ANTARCTIC SEARCH FOR METEORITES (ANSMET) FIELD
PROGRAM, by William A. Cassidy 5
3. THE EXPEDITION TO THE THIEL MOUNTAINS AND PECORA ESCARPMENT,
1982-1983, by John W. Schutt 9
4. EXTENSION OF THE ALLAN HILLS TRIANGULATION NETWORK SYSTEM,
by John O. Annexstad and Kristine M. Annexstad 17
5. THE FIELD SEASON IN VICTORIA LAND, 1983-1984, by Robert F. Fudali and
John W. Schutt 23
6. DESCRIPTIONS OF STONY METEORITES, by Brian Mason, Glenn J. MacPherson,
Roberta Score, Carol Schwarz, and Jeremy S. Delaney 29
7. DESCRIPTIONS OF SOME ANTARCTIC IRON METEORITES, by Roy S. Clarke, Jr.. 61
8. OVERVIEW OF SOME ACHONDRTTE GROUPS, by Jeremy S. Delaney and
Martin Prinz 65
9. ANTARCTIC CARBONACEOUS CHONDRITES: NEW OPPORTUNITIES FOR
RESEARCH, by Harry Y. McSween, Jr 81
10. THE EMERGING METEORITE: CRYSTALLINE STRUCTURE OF THE ENCLOSING
ICE, by Anthony J. Gow and William A. Cassidy 87
11. SIGNIFICANCE OF TERRESTRIAL WEATHERING EFFECTS IN ANTARCTIC
METEORITES, by James L. Gooding 93
12. TRACE ELEMENT VARIATIONS BETWEEN ANTARCTIC (VICTORIA LAND) AND
NON-ANTARCTIC METEORITES, by Michael E. Lipschutz 99
13. PAIRING OF METEORITES FROM VICTORIA LAND AND THE THIEL MOUNTAINS,
ANTARCTICA, by Edward R.D. Scott 103
14. METEORITE DISTRIBUTIONS AT THE ALLAN HILLS MAIN ICEFIELD AND THE
PAIRING PROBLEM, by Ursula B. Marvin 113
APPENDIX: Tables of ANSMET Meteorites 121
HI
2 cm
FRONTISPIECE.?The emerging meteorite, ALH82102. Left: The meteorite sitting in its enclosing ice after the
block had been sawn in half. Right: A thin section of the enclosing ice shown in cross-polarized light. Flattened,
horizontal ice crystals curve upwards toward the mold of the meteorite at top left of the photo. (Both photographs
are at the same scale.)
Field and Laboratory Investigations
of Meteorites from Victoria Land
and the Thiel Mountains Region, Antarctica,
1982-1983 and 1983-1984
1. Editors' Introduction
Ursula B. Marvin and Glenn J. MacPherson
This is the fourth publication in the Smithsonian Con-
tributions to the Earth Sciences series to present the results of
the yearly United States Antarctic Search for Meteorites
(ANSMET) expeditions to Antarctica. This issue describes the
1982-1983 and 1983-1984 field seasons in Victoria Land (at
about 76?77/S, 159?E) and in the Thiel Mountains region,
which lies nearer the South Pole at about 85?86'S, 90?W
(Figure 1-1). It includes chapters describing and classifying the
meteorites collected in these two seasons, and giving overviews
of topics such as the range and character of Antarctic
achondrites and carbonaceous chondrites, studies of meteorite
weathering under polar conditions, and discussions of the
difficult problem of pairing?identifying which specimens are
fragments from the same meteorite fall. The first meteorite
caught in the act of emerging at the surface of the ice is
described, as is the crystalline fabric of the ice surrounding it.
Appendix Table A lists all meteorites classified through June
1984 in numerical order for each locality; Appendix Table B
lists specimens in consecutive order by meteorite class; and
Appendix Table C lists those groups of paired specimens that
are generally agreed upon at the present time. Paired groups
should always be regarded as tentative because new analyses
may identify specimens that do not belong to a group or
additional specimens that do.
The numbers and main categories of meteorite specimens
collected in the 1982-1983 and 1983-1984 seasons are listed
Ursula B. Marvin, Smithsonian Astrophysical Observatory, Mail Stop
52, 60 Garden Street, Cambridge, Massachusetts 02138. Glenn J.
MacPherson, Department of Mineral Sciences, National Museum of
Natural History, Smithsonian Institution, Washington, D.C. 20560.
in Table 1-1. Total numbers and aggregate weights of
specimens of each meteorite class are given in Appendix Table
B. The aggregate weights are of interest because of the inherent
intractability of the pairing problem. We are unlikely ever to
obtain secure counts of the number of falls of each meteorite
class represented on the Antarctic stranding surfaces, and so
we cannot compare numbers of Antarctic falls with those in
the rest of the world. We can, however, obtain aggregate
weights and, allowing for the vagaries of discovery, gain a
general idea of how relative proportions of meteorite classes
in the Antarctic collections compare with those found
elsewhere.
The system for naming Antarctic meteorites was changed
in 1982 by the dropping of a letter (A, for example) to designate
the collecting expedition. When the system was originally
adopted, some members of the Nomenclature Committee
looked forward optimistically to a time when two or more
expeditions, from different countries or organizations, might
visit an area such as the Allan Hills during the same season.
They foresaw the need for a letter (A, B, C) to identify each
one. Hence, letters and numbers in a name such as ALHA76001
were chosen to indicate place, expedition, year, and specimen
number: ALH (Allan Hills), A (Expedition A), 76 (1976), 001
(Specimen 1). In practice, however, meteoriticists viewed the
expedition letter as incomprehensible and unnecessary. It has
been dropped for all meteorites collected after the 1981 season;
thus, the first Allan Hills specimen of 1982 was ALH82001.
The ANSMET program is governed by an interagency
agreement between the National Science Foundation, the
Smithsonian Institution, and the National Aeronautics and
1
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 1-1.?Numbers of classified meteorite specimens collected in the
1982-1983 and 1983-1984 (in parentheses) seasons.
Locality Ordinary Carbonaceouschondrites chondrites Achondrites Irons
Allan Hills
Elephant Moraine
Pecora Escarpment
Thiel Mountains*
Taylor Glacier
Inland Forts
39 (77)
16(183)
25
14
1
4(3)
(3)
1
2(3)
1(15)
3
2
(3)
*Thiel Mountains includes specimens collected at the Davies and Moulton
Escarpments.
Space Administration. At the request of the scientific
community, procedures (based on those used for lunar samples)
were adopted for collecting specimens by sterile techniques
and keeping them frozen until they are processed in
nitrogen-filled cabinets at the Johnson Space Center at
Houston. Details of the field and laboratory procedures are
outlined in the first publication in this series (Marvin and
Mason, 1980). In order to distribute research samples quickly
and widely, all newly classified specimens are described in the
Antarctic Meteorite Newsletters; these are mailed, on request,
to investigators throughout the world. Any scientist wishing
to obtain samples may submit a request, describing the
proposed research and the numbers, weights, and types of
samples required, to the Meteorite Working Group, a
committee with a rotating membership responsible for
monitoring the program and allocating samples. Requests for
the Antarctic Meteorite Newsletter or for research materials
should be addressed to the Secretary, Meteorite Working
Group, Lunar and Planetary Institute, 3303 NASA Road 1,
Houston, Texas 77058.
The Antarctic Meteorite Working Group meets twice each
year, usually in April and September. Each issue of the
newsletter publishes dates of meetings and deadlines for
requests. Sample requests are welcome from all qualified
scientists and are considered on the basis of their merit
regardless of whether a scientist is funded for meteorite
research. The allocation of Antarctic meteorite samples does
not in any way commit a funding agency to support the
proposed research.
For references on Antarctic meteorites, see the earlier
publications in this series (Marvin and Mason, 1980, 1982,
1984) and the computerized lists of publications from the
Antarctic Meteorite Bibliography, which may be obtained on
request from the Lunar and Planetary Institute, 3303 NASA
Road 1, Houston, Texas 77058. The Antarctic Meteorite
Bibliography references articles in Meteoritics, in the annual
proceedings of the Lunar and Planetary Science conferences
at Houston, the symposia on Antarctic Meteorites held by the
National Institute of Polar Research in Tokyo, and numerous
other sources.
Libraries of polished thin sections are maintained in
Washington, D.C., Houston, and Tokyo for the use of visitors
who wish to make microscopic examinations. To obtain
meteorite samples collected by parties sponsored by the
Japanese Antarctic Research Expeditions, or to use the thin
section library in Tokyo, contact Dr. Keizo Yanai, Curator, at
the National Institute of Polar Research, 9-10 Kaga 1-chome,
Itabashi-ku, Tokyo 173, Japan. To use the thin section library
at the Johnson Space Center at Houston, contact the Secretary
of the Meteorite Working Group at the address given above.
To use the thin section library at the National Museum of
Natural History, Smithsonian Institution, Washington, D.C.
20560, contact Roy S. Clarke, Jr., Curator.
Literature Cited
Marvin, Ursula B., and Brian Mason, editors
1980. Catalog of Antarctic Meteorites, 1977-1978. Smithsonian Con-
tributions to the Earth Sciences, 23: 50 pages.
1982. Catalog of Meteorites from Victoria Land, Antarctica, 1978-1980.
Smithsonian Contributions to the Earth Sciences, 24: 97 pages.
1984. Field and Laboratory Investigations of Meteorites from Victoria
Land, Antarctica. Smithsonian Contributions to the Earth Sciences,
26: 138 pages.
NUMBER 28
Yamato M_ts
Belgica
2
Ellsworth Mts
Purgatory Peak (Dry Valleys)
t. Baldr
Man Hills
eckling Peak
lephant Moraine
McMurdo Station
Granite Harbor
Antarctica
KEY
Continental Boundary
Ice Shelf Border
Major Glaciers
Meteorite Find
180
500 km
FIGURE 1-1.?Outline map of Antarctica showing sites of meteorite finds. Chance discoveries of four meteorites
were made before deliberate searches began in 1973: Adelie Land, 1912, by Douglas Mawson; Lazarev, 1961,
by a Soviet Union field party; Thiel Mountains, 1962, and Neptune Mountains, 1964, by U.S. field teams. The
first concentration of different types of meteorites was found in 1969 on a blue icefield near the Yamato
Mountains by Japanese scientists, who have since found thousands of specimens in the regions of the Yamato
and Belgica mountains. ANSMET teams, working out of McMurdo Station, have found about 2000 specimens
at the Allan Hills and other sites from Darwin Camp to Elephant Moraine and in the Thiel Mountains region.
Individual meteorites have been found near Purgatory Peak, at Inland Forts in the Wright Dry Valley, and on
the Taylor Glacier. These last two sites lie a short distance south of Purgatory Peak, too close to be distinguished
on this map.
2. The 1982-1983 Antarctic Search for Meteorites
(ANSMET) Field Program
William A. C as sidy
Introduction
During December 1982 and January 1983, the ANSMET
program fielded three teams. One made reconnaissance
searches in the Thiel Mountains (85?15'S, 91?00/W)-Pecora
Escarpment (85?38'S, 68?42AW) area to locate previously
unknown stranding surfaces (see Chapter 3). The second team
carried out systematic searches and made meteorite recoveries
at known concentration sites such as the Allan Hills (76?43'S,
159?40'E) and Elephant Moraine (76?11'S, lSJ^O'E). The
third team remeasured and extended a previously set triangula-
tion grid at the Allan Hills (see Chapter 4). The bilateral
collecting effort was designed to insure recoveries this season
and in future years. The Allan Hills party collected meteorites,
as had been expected, and the reconnaissance party located new
stranding surfaces, as had been hoped.
The Allan Hills-Elephant Moraine Excursion
Members of this group were Vagn F. Buchwald of the
Instituttet for Metallaere Danmarks Tekniske Hojskole at
Lyngby, Denmark, Tony Meunier of the United States
Geological Survey at Reston, Virginia, Carl Thompson, an
alpinist from Methuen, New Zealand, and the writer. Three of
us set out by helicopter for the Middle Western Icefield
(76?50'S, 158?26'E) where the lunar meteorite, ALHA81005,
had been found the year before. Because of a lack of surface
landmarks, however, we were unable to identify that icefield
with certainty and landed, instead, at the Allan Hills Far
Western Icefield (16?54'S, lSV^l'E). This site is beyond the
permitted limit for helicopter flights, but, at the time, we were
unsure of our location. When we landed, the helicopter
crewman hopped out and picked up a small meteorite, thereby
establishing it as a site where meteorites could be found. (We
believe he actually first saw the meteorite from the air and
directed the pilot down to a landing alongside the specimen.)
We had about half of our camp supplies with us and would
William A. Cassidy, Department of Geology and Planetary Science,
University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
have been able to stay, but we could not establish radio
communications with McMurdo Station, and so we had to
return, leaving our equipment and supplies at the site. Two
days later we had another opportunity, and this time we
succeeded in making radio contact with McMurdo and were
allowed to stay.
Vagn Buchwald remained in McMurdo temporarily and
traveled as a passenger on a helicopter run to the head of the
Taylor Glacier. Walking around the landing site, he was both
startled and highly pleased to pick up a meteorite he found
lying on the glacier ice. Thus, the field season for this group
began with two accidental discoveries. Meanwhile, at the Far
Western Icefield we were finding that our accidental discovery
there had placed us on a very large area of exposed ice with
many meteorite specimens scattered on its surface.
The Far Western Icefield is a large, roughly W-shaped patch
of ice about 75 km west of Allan Hills (Figure 2-1). Satellite
photos show no areas of exposed ice farther west than this
one. This site has a significant advantage in common with the
Near and Middle Western Icefields, in that there is no source
of terrestrial rocks upstream of it. Therefore, any rock found
on its surface must be a meteorite. It appears to lie generally
upstream of the Allan Hills Main Icefield. If so, any meteorites
falling onto this surface, or being exposed here by ice ablation,
should be transported to the Main Icefield over a period of
time that would be measured by the horizontal flow rate of the
ice. One would expect specimens recovered here to have
younger terrestrial ages than those located closer to the Allan
Hills barrier; one would expect also a more sparse distribution
of specimens this far from the Allan Hills (cf. Whillans and
Cassidy, 1983).
In the several weeks available we could not cover the entire
surface of this large patch of bare ice, so we concentrated on
its southeastern end and the central exposure near our campsite.
We recovered 45 specimens in all, establishing the Far Western
Icefield as a productive meteorite stranding surface. Among
the specimens recovered was a walnut-sized meteorite "caught
in the act" of weathering out of the underlying ice: a minor
part of the meteorite was already exposed, but most of it was
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 2-1.?Landsat photomap showing our field traverses, all meteorite stranding surfaces mentioned in this
article, and the locations of six reference points determined by satellite Doppler positioning. (Illustration taken
from 1972 NASA ERTS image E-l 128-28293-7, near infra-red band.)
embedded in the ice. The significance of this occurrence and
our treatment of the sample are described by Gow and Cassidy
(Chapter 10).
The Far Western Icefield is so far from the Transantarctic
Mountains that the only visible peak is Mt. Brooke in the
Convoy Range, and this can be seen only from certain vantage
points. Mapping of ice exposures and meteorite specimens is
a problem here because reference points cannot be established
by triangulation, and fixed points cannot be established because
the ice is moving. Fortunately we had arranged the loan of two
Magnavox model MX 1502 geoceivers from the U.S. Bureau
of Land Management; one was with the Thiel Mountains party
and we had the other. With these instruments we were able to
locate five points to use as references for mapping our
meteorite finds. All of the five will be valuable as reference
points for future finds, and three of them are precise enough
to be useful in measuring ice flow vectors in this part of the
East Antarctic Ice Sheet (see Table 2-1).
After using all the time we originally planned to devote to
systematic searching on the Middle Western Icefield, we
traversed eastward to John Annexstad's camp at the Main
Icefield. Carl Thompson's snowmobile was running on only
one cylinder at that time, so Tony Meunier and I each had to
draw three loaded Nansen sledges behind our snowmobiles.
We noticed very little difference between pulling two and
pulling three sledges, and it is now a routine procedure to draw
three sledges behind one snowmobile whenever that arrange-
ment seems most convenient.
NUMBER 28
TABLE 2-1.?Best determinations of six geoceiver stations used in mapping meteorite finds. Locations and
elevations of six stations were determined using satellite Doppler positioning procedures. Raw data determined
in the field were refined later, using standardized computer programs for this purpose to arrive at the
post-processed data given here. Stations 0100-0104 are located at the Far Western Allan Hills Icefield, and
Station 0105 was located at our campsite at Elephant Moraine (Figure 2-1).
Station Number
0100
0101
0102
0103*
0104*
0105f
Latitude S
76?54'09.520"
76?57'46.861"
76?59'27.417"
77?02'50.954"
77?02'24.614"
76?17'34.910"
Longitude E
157?01'26.511"
156?54'40.164"
156?53'46.806"
157? 11'00.270"
157?15'33.896"
157?20'04.944"
Elevation (m)
2117.54
2145.01
2190.95
2163.50
2142.87
2022.33
Estimated error (in m)
1.5
2
2
5-10
5-10
10
*Reference oscillator frequency offset was abnormally high but stable; data are good but a larger error is
assigned.
f Broadcast solution (e.g., field data) not post-processed. Latitude and Longitude are referenced to the Naval
Weapons Laboratory 10D system (Jenkins and Leroy, 1979).
Carl had a replacement machine waiting for him at John's
camp, and we were joined there by Vagn Buchwald. We left
for Elephant Moraine two days later, as a party of four. The
traverse to a campsite at the far end of Elephant Moraine took
exactly 11 hours, including about an hour of searching for the
feature once we had arrived within a few miles of where we
knew it to be.
During a week at Elephant Moraine, we collected 18
specimens and left the site, confident that more fragments will
be recovered there in the future. High winds had prevented any
but rather random reconnaissance searches, and, in areas where
random searches give good recovery rates, systematic search-
ing has always yielded many more specimens. During our one
day of relatively good weather at Elephant Moraine we
accomplished a round trip of 120 km, on which we visited
some of the extensive ice exposures due west of Elephant
Moraine (see photomap, Figure 2-1), and an isolated exposure
to the northwest. Random-path searching at the latter site
yielded two meteorites. As our four snowmobiles had covered
a cumulative distance of 64 km, this seemed to be a low rate
of discovery.
Because the weather had been consistently poor, and it was
getting late in the season, we decided to return to the Allan
Hills at the first opportunity. This came on 19 January. At 3:00
P.M. that day the wind dropped to 15 knots, so we broke camp
and left by 7:00 P.M. The return to Annexstad's camp took only
seven-and-one-half hours, despite steadily rising winds. These,
combined with cold temperatures due to the lower sun angle
during the night, stressed us more than I would have preferred,
but the trip was made without incident. We were interested to
find that we could easily follow our outward tracks made a
week earlier, not because they were pressed into the snow but
because they were now standing up several centimeters in
relief, having offered some resistance to the erosive effects of
the wind during the intervening week.
Results and Discussion
During the 1982-1983 field season unforeseen circum-
stances played a larger part in our results than in earlier years.
Initially we landed at the wrong ice exposure west of the Allan
Hills and discovered a previously unsuspected meteorite
stranding surface. We had visited this site briefly by helicopter
during the 1977-1978 season but had not found meteorites.
We probably never would have returned to it had it not been
for this lucky accident. Unforeseen also, however, was the
spate of days with high winds, which greatly reduced our
operating efficiency and turned our planned days of systematic
searching at Elephant Moraine into days of reconnaissance
trips, mostly near our field camp. In retrospect, these two
circumstances may have offset one another.
Finally, by sheer coincidence we were able to borrow
geoceivers for the very field season during which a put-in by
mistake at an unplanned location left us at a site where we
could benefit most from having a geoceiver orientation
capability. If the effects of the first two factors offset each
other, then this one gave us a distinct advantage.
The Whillans and Cassidy (1983) model for forming
meteorite concentrations at a barrier such as the Allan Hills
describes three mechanisms that may operate simultaneously:
the direct fall of meteorites onto an exposed ice ablation
surface, weathering out of meteorites that fell upstream and
were transported at various depths to the ice ablation surface,
and, once they emerged on that surface, ice-flow crowding of
both sets of specimens toward the barrier. Given a constant
infall rate of meteorites through time, and equal age for all
parts of an ablation surface (and, for the moment, disregarding
the crowding effect), all parts of the ablation surface should
have a constant density of meteorites that fell directly onto
that surface. Similarly, if ancient ice is being exposed by
ablation close to the barrier at the same rate that less ancient
ice is being exposed farther from the barrier, then the
contribution of transported meteorites also should be constant.
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Thus, any gradient in frequency of occurrence of meteorites
on different parts of an ablation surface could be attributable
only to the crowding effect, and this effect should act to
increase the frequency of meteorite occurrences toward the
barrier. Is such an increase observed? Because pairing
estimates are so uncertain, it is difficult to judge in quantitative
terms whether or not a regular increase in numbers of
meteorites does occur as one traverses eastward from the Far
Western Ice Field, over the Middle Western and Near Western
Icefields, to the Main Icefield at the foot of the Allan Hills.
Qualitatively, however, I can see no such variation, except
within the Main Icefield itself. There, the frequency of
meteorite occurrences is much higher on the ultimate
downstream section of the ablation surface, below the step
feature and closer to the barrier, than it is above the step feature.
This suggests the possibility that the three icefields to the west
actually are not located on a direct flowline toward the
stranding surface at the Main Icefield. Future remeasurements
of our geoceiver stations at the Far Western Icefield should
help to resolve this question, since the ice will have moved in
the interval.
Literature Cited
Jenkins, R.E., and C.F. Leroy
1979. "Broadcast" versus "Precise" Ephemeris-Apples and Oranges.
Proceedings of the Second International Geodetic Symposium on
Satellite Doppler Positioning (Austin, Texas, Jan 1979). Austin:
University of Texas Press.
Whillans, I.M., and W.A. Cassidy
1983. Catch a Falling Star: Meteorites and Old Ice. Science, 222:55-57.
3. The Expedition to the Thiel Mountains
and Pecora Escarpment, 1982-1983
John W. Schutt
Reconnaissance by C-130 Hercules
Two weeks of waiting in McMurdo at the end of the
1981-1982 season for aircraft availability and flying weather
were over. William Cassidy and I were aboard a ski-equipped
C-130 Hercules approaching the Thiel Mountains for a
bird's-eye view of icefields selected as having a good
probability of significant meteorite concentrations. Cassidy had
looked at hundreds of aerial photographs of the Transantarctic
Mountains, searching for expanses of ice with characteristics
similar to those with known meteorite concentrations in
southern Victoria Land. In West Antarctica, several areas in
the Thiel Mountains region and at the Pecora Escarpment, 160
km to the east, appeared favorable (Figure 3-1). Two fragments
of a pallasite had been found on blue ice in the Thiel Mountains
in 1961 (Ford and Tabor, 1971). Could they signify a large
meteorite concentration?
As the plane flew low over the Davies Escarpment we could
see ice gleaming below. We passed over the precipitous Bermel
Escarpment for a look at the icefields along the eastern side
of the Thiel Mountains and then on to the Moulton Escarpment.
Our excitement grew as we viewed these icefields. They did
indeed have features in common with the concentration sites
at the Allan Hills, Elephant Moraine, and Reckling Moraine.
The aircraft turned from the Thiel Mountains, heading eastward
for the Pecora Escarpment. Our excitement peaked as we
circled low over these icefields and they, too, looked
promising. Before leaving Antarctica we made plans to return
to the Thiel Mountains and Pecora Escarpment for a
reconnaissance traverse the following field season.
The Thiel Mountains-Pecora Escarpment Field Season
The field party of 1982-1983 consisted of Richard Crane,
of the United States Navy, Urs Krahenbuhl, of the University
of Bern, Switzerland, Louis Rancitelli, of Battelle Memorial
Institute at Columbus, Ohio, and the writer. Our party spent
John W. Schutt, Department of Geology and Planetary Sciences,
University of Pittsburgh, Pittsburgh, Pennsylvania, 15260.
thirty-five days in the field traveling roughly 1250 km on
snowmobiles.
On 13 December 1982 we flew over the Thiel Mountains
area to locate a landing site and to off-load equipment and
drums of snowmobile fuel. We landed at 85?07'S, 88?02'W,
approximately 23 km east of the Ford Massif. Two days later
we flew a second mission to drop fuel at two points along our
intended route and to put our party into the field.
Our first objective was a search of the icefields east of Mt.
Walcott and Mt. Wrather in the southern Thiel Mountains,
where the pallasite had been found (Figure 3-2). We discovered
no meteorites there. We then proceeded to the Pecora
Escarpment, a traverse of nearly 200 km requiring three days.
The Pecora Escarpment is a rocky mountainside, approxi-
mately 23 km long. It trends SW-NE and forms an absolute
barrier to ice flow. Roughly 125 square km of ice is exposed
upstream (Figure 3-3). Several less extensive icefields associ-
ated with ice escarpments are present within a radius of about
50 km. Upon arriving at the Pecora Escarpment we found snow
from recent storms covering a considerable area of the icefield.
Nevertheless, we began finding meteorites there soon after
beginning our search. Two days of high katabatic winds
interrupted our reconnaissance, but the winds removed much
of the snow and allowed us to search more effectively. We
found meteorites in greater numbers as we worked our way
toward the southwest end of the Pecora Escarpment. Many of
the specimens lay upstream of the rock barrier, as would be
expected. However, many others were found on ice that appears
to be downstream of the absolute barrier to ice flow; this has
not yet been explained. From the icefields in the immediate
vicinity of the Pecora Escarpment, we recovered 32 meteorite
specimens and took one sample of ice to be used for age
determination and ice chemistry studies. Because time did not
allow for both thorough searching and collection, we left at
least 50 meteorites in the field to be picked up in future seasons.
We did not explore ice patches outside the immediate vicinity
of the Pecora Escarpment, where we hope that additional
meteorites will be found.
Once we had determined that a significant meteorite
10 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
LOCATION DIAGRAM
30? WEST 0? EAST 30?
60? 60?
90?
120 120?
150? WEST 180? EAST 150?
FIGURE 3-1.?Location of the Thiel Mountains-Pecora Escarpment Region,
West Antarctica.
concentration existed at the Pecora Escarpment and that
systematic searching would be required there, we resumed our
reconnaissance traverse. Our next objective was the Davies
Escarpment, 160 km to the west. We followed our outward
trail back for a distance, then broke off and headed for Lewis
Nunatak, near the southern end of the Davies Escarpment.
Extending southward from the Thiel Mountains nearly 55 km,
the Davies Escarpment presents no absolute barrier to ice flow.
Ice cliffs and heavily crevassed areas are common along its
length with only a couple of small, isolated rock exposures.
Blue ice areas are of limited extent there and are present only
at the base of the escarpment (Figure 3-4).
Upon reaching the Davies Escarpment we found consider-
able snow on the icefields; however, there was sufficient
exposure to determine the extent of any meteorite concentra-
tions. Our search of icefields along the Davies Escarpment
yielded seven meteorite specimens. We found no meteorites
on the small ice patches near Lewis Nunatak, but we picked
up one specimen on the ice approximately 8 km SSW of Lewis
Nunatak and six specimens during a thorough search of the
largest and northernmost icefield. We concluded that large
meteorite concentrations are not present in the vicinity of the
Davies Escarpment.
Proceeding from the Davies Escarpment, we traversed to the
Moulton Escarpment, an isolated nunatak 15 km west of the
Ford Massif. This east-west trending escarpment is approxi-
mately 20 km in length. A bedrock ridge standing above the
ice cap forms an apparent absolute barrier to ice flow along 7
km of the escarpment. At least seven distinct bouldery,
ice-cored moraines, with no exposed bedrock, are situated
below the escarpment (Figure 3-5).
Conventional thought on meteorite concentrations dictates
that the icefields upstream of a bedrock barrier should have the
greatest potential as stranding surfaces. Our first search
upstream at the Moulton Escarpment resulted in no meteorite
finds. A search of the second most likely area, 6 km east of
Chastain Peak, produced only one specimen. After our
successes at the Pecora and Davies escarpments, we had felt
confident of success at the Moulton Escarpment as well, and
were disappointed by the absence of any concentrations. We
expected the ice downstream of the bedrock to lack meteorites,
and we probably would not have visited that area except that
we had to cross it to reach our air drop of fuel. On the last trip
to the drop site, we spotted a small meteorite, distinguished
by its anomalous shape, lying amongst the abundant dark-gray
and black terrestrial rocks. We returned the next day in better
weather and lighting conditions. We found no additional
specimens at the easternmost ice-cored moraine, but, as we
moved southward past the moraine, we found nine meteorites
concentrated in a small area between the moraine and the
escarpment (Figure 3-6). We recovered a total of 11 meteorite
specimens from the Moulton Escarpment icefields.
Our party found three new meteorite concentration sites and
recovered a total of 50 specimens as a result of reconnaissance
searches of the Pecora, Davies, and Moulton escarpments.
Forty-two of the specimens are classified as ordinary
chondrites, seven as achondrites, and one as a carbonaceous
chondrite (see Table 3-1).
The meteorite concentration at the Moulton Escarpment is
unusual in that all meteorites, except one, were located on ice
that is apparently downstream of an absolute barrier to ice flow.
We also found meteorites on what may be downstream ice at
the Pecora Escarpment. The discovery of these "unusual"
concentrations, which contradict previous experience and
TABLE 3-1.?Classification of meteorite specimens recovered from the Thiel
Mountains/Pecora Escarpment region, 1982-1983. (See Antarctic Meteorite
Newsletter, 6(2), 7(1), 7(2).)
Location
Pecora
Escarpment
Davies
Escarpment
Moulton
Escarpment
Total
Ordinary
chondrite
26
6
10
42
Classification
Carbonaceous
chondrite
1
0
0
1
Achondrite
5
1
1
7
Total
32
7
11
50
NUMBER 28 11
FIGURE 3-2.?Route of the 1982-1983 reconnaissance traverse in the Thiel Mountains-Pecora Escarpment region.
FIGURE 3-3.?Camp near the base of Mount Wrather, Thiel Mountains.
12 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 3-4.?Aerial view looking southward over Pecora Escarpment. The large icefield, covering about 125
square km upstream (south) of the barrier yielded an abundance of meteorite specimens (dots), but specimens
were also found on smaller icefields downstream of the Escarpment in the vicinity of Ludlow Rock and west
of Damschroder Rock.
conventional thought on the concentration mechanism, have
increased the prospects for finding concentrations in areas that
previously would not have been searched.
NOTE: A Magnavox MX-1502 Satellite Surveyor, on loan
from the U.S. Bureau of Land Management, was used to
determine the geodetic positions of several meteorites (Figure
3-7) at the Pecora Escarpment. Doppler base stations were
established on Lulow Rock at the Pecora Escarpment and at
Chastain Peak (Figure 3-8) at the Moulton Escarpment. These
data have been used by the U.S.G.S. to improve the WGS-72
survey net in Antarctica.
Literature Cited
Antarctic Meteorite Newsletter, 6(2), August 1983.
Antarctic Meteorite Newsletter, 7(1), February 1984.
Antarctic Meteorite Newsletter, 7(2), July 1984.
Ford, A.B., and R.W. Tabor
1971. The Thiel Mountains Pallasite. United States Geological Survey
Professional Paper, 750-D. Washington, D.C.: United States
Government Printing Office.
NUMBER 28 13
FIGURE 3-5.?Aerial view looking southward along the Da vies Escarpment (right center). Dots indicate locations
of the seven meteorite specimens found in this area: six on the northernmost icefields at the foot of the
Escarpment, and one about 8 km SSW of Lewis Nunatak.
14 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 3-6.?Aerial view looking southward over the Moulton Escarpment with Chastain Peak near the eastern end.
NUMBER 28 15
;,.-?*#***?
FIGURE 3-7.?Satellite surveying of meteorite locations at the Pecora Escarpment.
FIGURE 3-8.?Satellite surveying at Chastain Peak survey point in the Moulton Escarpment.
4. Extension of the Allan Hills Triangulation
Network System
John O. Annexstad and Kristine M. Annexstad
The Allan Hills Icefield was spanned by a triangulation
network of 20 stations in 1978 (Nishio and Annexstad, 1979).
Station locations in relation to the Allan Hills and its associated
icefields are shown in Figure 4-1. The network crosses the
region of highest meteorite concentration represented by the
dotted area. The stations were resurveyed in 1979 and 1981
and the results showed that ice movement was generally from
west to east, it decreased in velocity as the Allan Hills were
approached, and the ice surface ablated at an average rate of
about 5 cm per year (Nishio and Annexstad, 1980; Annexstad,
1983; Schultz and Annexstad, 1984).
During the 1982/1983 austral summer field season the
authors extended the original triangulation network from the
Allan Hills Main Icefield to the Near Western Icefield (Figure
4-2) and attempted to locate station positions with an
astronomical theodolite. Inclement weather forced an early end
to the field season and frustrated attempts to accurately survey
the newly established stations.
The network as it now appears is shown in Figure 4-3
extending in a westerly direction from the baseline (Stations 1
and 2). Stations 25 to 38 were added to the original line. Station
numbers are not sequential because the strain flower (Stations
21-24) was established after the initial survey of the original
network (Stations 1-20).
Ablation was measured at each station of the original
network prior to installing the line extension. This measure-
ment consists of obtaining the distance to 0.1 cm from the top
of the pole to the surface of the ice. An east side and west side
reading is taken at each station and the measurements averaged,
because the ice surface can be quite uneven near the base of
the poles.
Table 4-1 lists the annual rates of ablation from 1978 to
1982 with the four year average and standard deviation (from
Annexstad, 1983). From this table it can be seen that the rate
of ablation varies from year to year and from station to station.
John O. Annexstad, NASA Johnson Space Center, Houston, Texas
77058. Kristine M. Annexstad, Frank Welch and Associates, Dallas,
Texas 75205.
Although sublimation plays an important part in the process
of ablation, Annexstad (1983) has shown that the abrasive
action of blowing ice crystals is also a contributing factor.
The network was extended from Station 20 to the visible
part of the Near Western Icefield as determined by binocular
observations. The eastern portion of the Near Western Icefield,
as viewed from Station 20, is a small ice patch about 1 km
wide situated below the crest of a rather prominent firn field.
Therefore, the extension line was constructed as two legs, one
leg from Station 20 and one leg about a kilometer south of
Station 20, each of which intercepted one edge of the visible
portion of the eastern section of the Near Western Icefield.
Stations 20-36 (even numbered) were positioned about 1.5
km apart unless a closer spacing was needed for visual contact.
Each station was placed so that a lower numbered and a higher
numbered station were visible with binoculars.
Stations 25 to 37 were positioned along a line 1 km to the
south of the even-numbered leg. Each individual station was
placed as close as possible to a point on the perpendicular
bisecting the line between two even-numbered stations and
visible from a lower and higher numbered station on the same
leg. This method of positioning ensures that the surveyor at
each station has clear visibility of at least three other stations.
Each station consists of a 3 m bamboo pole placed into a 7.5
cm diameter hole drilled 70-100 cm deep in the ice or firn.
The base of the pole is wrapped in a layer of fiberglass
insulation to decrease ablation effects from conduction and to
ease pole removal for the survey. The poles were numbered
appropriately and a red trail flag attached 2-3 centimeters
below the top. Measurements were taken of the depth of the
hole and the height of the pole from the surface.
Figure 4-4 shows one of us (KMA) using a fiberglass-bodied
drill to establish one of the stations. The drill is operated by
hand and the operator is protected from the prevailing winds
by a snowmobile-mounted, triangularly shaped windbreak. The
fiberglass-bodied drill is considerably easier to use than the
steel SIPRE drill, formerly used on this project, but its lack of
weight requires some downward pressure by the operator.
Numerous attempts were made to establish station positions
17
18 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
-TfX'S
EASTERN ANTARCTIC
ICE SHEET
\ BLUE id, ' '***''
ANTARCTIC METEORITE DISCOVERY AREA
FIGURE 4-1.?The original triangulation network across the Allan Hills Main Icefield.
and distances from known points by triangulation survey
methods. A Wild T-2 theodolite and the triangular windbreak
pictured in Figure 4-4 were used in these attempts. Unfortu-
nately, the Antarctic weather did not cooperate and only two
stations (20 and 19) were successfully occupied. It should be
noted that conditions varied between whiteouts and severe
blowing snow, which made theodolite observations all but
impossible in this area. The network extension is constructed
primarily in firn so that even moderate winds will obscure the
survey targets with blowing snow.
The distances between Stations 20-38, shown in Figure 4-1,
are snowmobile odometer readings, because the triangulation
NUMBER 28 19
ALLAN HILLS ICEFIELD
\
North
Battlements
Nunatak
Main
Near
Western
Middle
Western oo
, 10 km
FIGURE 4-2.?The four icefields lying west of the Allan Hills.
survey was not completed. These distances are subject to the
errors due to surface undulations of the firn and the notorious
inaccuracies of snowmobile odometers.
Although a precise determination of position and movement
of the stations must await future surveys, some visual
observations of surface conditions were noted at the Near
Western Icefield. A wave-like step feature at the eastern edge
of the Near Western Icefield is the most prominent topographic
feature. This step feature resembles the one in the immediate
vicinity of the Allan Hills that Yanai et al. (1978) described
as a monocline. On the eastern slope of the step the blue ice
has reached the surface and the high winds in that area keep it
free of snow. The ice surface is interlaced with small crevasses
and tensional cracks, which are common features in blue ice
areas. The general alignment of the crevasses is with the long
axis perpendicular to a northeast ice flow direction. The
crevasse patterns indicate that the surface ice in this vicinity
will bypass the Allan Hills Main Icefield, which lies to the east.
20 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 4-3.?The triangulation network with recent extensions: the strain flower (Stations 21 to 24) and the
southwest extension (Stations 25-38).
In a description of the four icefields that are upstream of the
Allan Hills, Schutt et al. (1983) suggested that they are all
interconnected and part of the main Allan Hills Icefield. The
locations of these ice fields are shown in Figure 4-2 relative
to the Allan Hills and Battlements Nunatak (Annexstad, 1983).
The assumption that the four icefields are interconnected may
be a premature guess if the direction of motion indicated by
crevasse alignment at the Near Western Icefield is correct. If
the icefields are interconnected, it should follow that surface
crevasse patterns should indicate an easterly flow direction,
toward the Allan Hills. A positive determination of the
direction of flow and its velocity must await further survey
data. Until those data are available it does appear that the
meteorite concentration areas in the main Allan Hills Icefield
represent the convergence of a diverse set of flow patterns
emanating from a number of widely spaced sources.
Literature Cited
Annexstad, J. O.
1983. Meteorite Concentrations and Glaciological Parameters in the Allan
Hills Icefield, Victoria Land, Antarctica. Doctoral dissertation,
Doktor der Naturwissenschaft, Johannes Gutenberg Universitat,
Mainz, Federal Republic of Germany.
Nishio, F., and J. O. Annexstad
1979. Glaciological Survey in the Bare Ice Area near the Allan Hills in
Victoria Land, Antarctica. Memoirs of the National Institute of Polar
Research (Japan), special issue, 15:13-23.
1980. Studies on the Ice Flow in the Bare Ice Area near the Allan Hills
in Victoria Land, Antarctica. Memoirs of the National Institute of
Polar Research (Japan), special issue, 17:1?13.
Schultz, L., and J. O. Annexstad
1984. Ablation and Ice Movement at the Allan Hills Main Icefield between
1978 and 1981. In U.B. Marvin and B. Mason, editors, Field and
Laboratory Investigations of Meteorites from Victoria Land,
Antarctica. Smithsonian Contributions to the Earth Sciences,
26:17-22.
Schutt, J.W., W.A. Cassidy, G. Crozaz, R.F. Fudali, and U.B. Marvin
1983. Results of Meteorite Search and Recovery Activities in the Vicinity
of the Allan Hills, Antarctica, Dec. 1981-Jan. 1982. In R.L. Oliver,
P.R. James, and J.B. Jago, editors, Antarctic Earth Science.
Canberra: Australian Academy of Science.
Yanai, K., W.A. Cassidy, M. Funaki, and B.P. Glass
1978. Meteorite Recoveries in Antarctica During Field Season 1977-78.
Proceedings of the 9th Lunar and Planetary Science Conference,
pages 977-987.
NUMBER 28 21
TABLE 4-1.?Rates of ablation (-) and accumulation (+) measured in centimeters per year at survey stations
on the Allan Hills Icefield.
Station
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1978-1979
-2.2
-2.3
-1.1
-1.7
-2.6
-3.8
-4.3
-6.6
-5.7
-4.5
-5.7
-7.2
-5.8
-4.3
-5.4
-4.7
-3.2
-1.8
-6.5
-5.8
-6.1
-0.5
1979-1980
+ 1.8
-0.9
-2.1
-2.5
-2.8
-1.7
-2.0
-3.7
-2.7
-2.9
-6.5
-2.6
-2.1
-0.1
-3.5
-4.2
-1.1
-1.3
-2.6
-1.4
-3.0
-3.7
1980-1981
-2.0
+ 18.1
+ 1.4
-2.8
+ 2.6
-1.9
-3.3
-5.7
-5.8
-5.1
-6.2
-4.3
-4.9
-1.6
-2.9
-3.5
-2.0
-1.7
-4.9
-2.8
-5.6
-4.8
1981-1982
+ 2.8
-2.9
-0.1
-3.2
-0.4
-1.3
-4.7
-0.2
-7.1
-2.4
-5.8
-4.8
-4.2
-1.8
-7.2
-5.7
-2.5
+ 0.4
+ 5.1
-8.4
-3.3
-5.6
1978-1982
Average ? Std. Dev.
+ 0.1+2.6
+ 3.0?10.1
-0.5 ?1.5
-2.6 + 0.6
-0.8 ?2.5
-2.211.1
-3.6 ?1.2
-4.0 ?2.8
-5.3 ?1.9
-3.7 ?1.3
- 6.0 ? 0.4
-4.7 ?1.9
-4.2 ?1.6
-2.0 ?1.7
-4.8 ?2.0
-4.5 ?0.9
-2.2 ?0.9
-1.1 ?1.0
-2.2 ?5.1
-4.6 ?3.1
-4.5 ?1.6
- 4.8 ? 0.8
22 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 4-4.?Kristine Annexstad drilling a station hole with the fiberglass-bodied drill. The triangular
windshield is attached to the snowmobile.
5. The Field Season in Victoria Land, 1983-1984
Robert F. Fudali and John W. Schutt
The 1983-1984 season marked the eighth consecutive year
of Antarctic Search for Meteorites fieldwork on the South Polar
Plateau. This ANSMET team was the largest single field party
to date, consisting of eight people equipped with eight
steel-cleated snowmobiles and 12 Nansen sleds. The team was
led by William A. Cassidy of the University of Pittsburgh.
Other participants were A.C. Hitch, of Ferndale, Washington,
K. Nishiizumi, of the University of California at San Diego,
Paul Pellas, of the Museum of Natural History in Paris, Ludolf
Schultz, Max Planck Institute for Chemistry in Mainz, West
Germany, Paul Sipiera, Harper College, Illinois, and the
authors.
Despite some annoying equipment malfunctions involving
the snowmobiles, Nansen sleds, and field radios, and two
potentially serious mishaps caused by a parachute that failed
to open during a fuel drop at Elephant Moraine, plus a bad
tent fire late in the season, our overall accomplishments rank
with the best of those of previous seasons. Our provisional field
count of meteorites, meteorite fragments, and possible
meteorites was 367, and 40 to 50 more small fragments were
not bagged individually. One iron meteorite was found in the
Wright Valley by a member of George Demon's University
of Maine field party and turned over to us at the end of the
season.
For the first time, many of the meteorite find locations were
determined using a theodolite and an electronic distance
measuring device. These locations were also determined
absolutely, with accuracy on the order of a few meters, by tying
them to geoceiver stations positioned at Elephant Moraine and
the Far Western Icefield the previous season by satellite
doppler tracking. This surveying equipment was also used to
emplace a series of survey stations between the Far Western
Icefield and the Main Icefield in the Allan Hills region. These
stations were tied to the previously established triangulation
network on the Main Icefield and to the geoceiver stations on
the Far Western Icefield. Gravity measurements were made at
Robert F. Fudali, Department of Mineral Sciences, National Museum
of Natural History, Smithsonian Institution, Washington, D.C. 20560.
John W. Schutt, Department of Geology and Planetary Sciences,
University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
all these stations and tied to the previous gravity measurements
over the triangulation network (Fudali, 1982). The gravity data
are now sufficient to give us a general idea of the depth and
configuration of the ice/bedrock interface out to a distance of
70 km WSW of the Allan Hills. Finally, we collected large
blocks of ice from five icefields, using a power chain saw, for
a number of isotopic studies that we hope will lead to a better
understanding of the ice ages and ice dynamics in the collecting
areas.
Our original plan called for a Hercules C-130 put-in of our
party at the Far Western Icefield, 70 km WSW of the Allan
Hills, which we would search systematically and then move
to the Mid and Near Western Icefields for similar work. The
four separate blue icefields WSW of the Allan Hills have been
described in some detail by Fudali and Schutt (1984) and are
shown in Figure 4-2 (Chapter 4). However, C-130 reconnais-
sance flights were unable to find a suitable landing site
anywhere in the vicinity of the Far Western Field. The only
suitable landing site we found was in the vicinity of Griffin
and Outpost Nunataks, which held no promise of meteorites.
Under those circumstances, we decided to revise our plans and
devote a major effort to systematically searching Elephant
Moraine and its adjacent blue ice fields, and then to traverse
overland to the ice fields west of Allan Hill (Figure 5-1).
To find a suitable landing site for a ski-equipped C-130 on
the South Polar Plateau is an interesting task. The preferred
test is to drive the C-130 onto the snowfield under flying power
and observe the effects of this maneuver, both on the aircraft
and on the snow surface. Those of us who participated in such
reconnaissance flights can attest to the adrenalin-pumping
nature of such maneuvers. We commend C-130 Commander
Brian Rich and his crew for their competence and their "cool."
On 9 and 10 December, two C-130 flights put in our party,
equipment, and supplies, 60 km north of Elephant Moraine
(Figure 5-2). Strong katabatic winds made overland travel
difficult and, indeed, kept us tentbound at the landing site for
two days. We reached the moraine (Figure 5-3) on the morning
of 15 December.
We spent 13 days at Elephant Moraine, systematically
searching the blue ice fields, east, west, and south of the
moraine with snowmobile sweeps. We also spent considerable
23
24 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
* >
FIGURE 5-1.?Camps and route of the season's snowmobile traverse that logged 1250 km in 45 days.
time searching, on foot, within the moraine. Meteorites do
occur in the moraine and can be distinguished from the
terrestrial rock litter (Figure 5-4), but the bulk of the meteorites
were recovered from the blue ice surfaces, and it is questionable
whether persistent moraine searches on foot is a time-effective
way to recover Antarctic meteorites. We continued to find
meteorites on blue ice until the day we left and there are surely
additional meteorites on the icefields there. A total of 207 field
numbers were issued at Elephant Moraine, with provisional
field identifications as shown in Table 5-1.
On 26 December, a C-130 air drop at the moraine provided
us with a spectacular cratering experiment. One of the three
pallets failed to deploy its parachute and four 55-gallon drums
of fuel impacted the snow with undiminished velocity. All
NUMBER 28 25
FIGURE 5-2.?Unloading a ski-equipped C-130 Hercules near Griffin and
Outpost Nunataks.
FIGURE 5-3.?The southern part of Elephant Moraine, looking south.
four drums were breached by the impact but we managed to
salvage three of the four with minimal fuel loss. The fourth
drum provided us with 55 gallons of fuel-soaked snow in which
to burn our trash before breaking camp.
Elephant Moraine is an interesting feature that deserves
further study. It is unrelated to any bedrock outcrop and
consists of a complexly configured ice ridge littered with a thin
surface veneer of rocks of diverse sizes and types. Similar
moraines elsewhere in Antarctica have been assumed to signal
the presence of bedrock at shallow depth beneath them. The
meteorite concentration provides indirect evidence of a
subsurface, partial barrier to ice movement, but we have no
direct information on this postulated barrier.
The weather during the 15-28 December period was almost
entirely dominated by temperatures well below freezing and
strong katabatic winds. Nevertheless, on several occasions
liquid water was observed on the lee and sunny side of rock
surfaces in the moraine (Figure 5-5). Almost all Antarctic
meteorites show some weathering effects and many are badly
oxidized. Meteorite weathering has generally been regarded
as an extremely slow process on the Polar Plateau, character-
ized by only infrequent contact with liquid water on warm,
sunny, windless days. Our observations at Elephant Moraine
suggest that liquid water may be a more pervasive weathering
agent than previously supposed.
We departed Elephant Moraine on 29 December (Figure
5-6) and proceeded to the camp site of the 1982-1983 season
on the Far Western Icefield. Aside from the partial disintegra-
tion of one Nansen sled, carrying two 55-gallon drums of fuel,
this leg was made in two days without significant incident.
We did not intend to collect meteorites systematically at the
Far Western Icefield, as the field season was drawing to a close
and we had much else still to do. We were primarily interested
in collecting ice samples for isotopic studies, especially from
the site of a meteorite found embedded in the ice last year (see
Chapter 10), and in tying together the geoceiver stations
emplaced the previous season with a view toward extending
ground-surveyed stations from the Far Western Field all the
way to the Allan Hills network. At the expense of leaving a
number of observed but uncollected meteorites on the ice, we
achieved these goals. We could not, however, resist collecting
a few meteorites, including 76 individual fragments of a
carbonaceous chondrite (Figures 5-7 and 5-8) that Paul Pellas
caught sight of as we were proceeding toward the ice-
embedded meteorite site. These fragments appeared to be
entirely fresh and were scattered on both ice and snow surfaces,
leading us to believe we might be collecting a very recent fall.
26A1 measurements have subsequently shown this supposition
to be incorrect (W.A. Cassidy, personal communication).
On 6 January we broke camp and proceeded to the Middle
Western Icefield, putting in survey and gravity stations along
the way. We intended to systematically and thoroughly sweep
that entire icefield for meteorites but were hampered by high
winds during virtually our entire nine-day stay. In fact high
winds kept us tentbound for seven straight days. Nevertheless,
we did manage to collect a few meteorites and extend the
survey and gravity stations half way to the Near Western
Icefield before leaving for the Main Icefield.
On 14 January a bad tent fire resulted in burns to Paul
Sipiera's hands and face. He was evacuated by helicopter
within two hours and, upon landing at McMurdo, was put
directly on a C-130 flight to New Zealand. The same helicopter
returned Paul Pellas and Ludolf Schutz to McMurdo, leaving
five of us in the field.
On 16 January we moved camp for the last time, extending
survey and gravity stations to the Near Western Icefield and
then traversing directly to the Main Icefield for our final few
days. On the 17th a three-man crew from the British
Broadcasting Corporation joined us for several days of filming
and thereby severely curtailed our collecting activities. In just
a few hours of searching, however, we found 29 meteorites
on ice surfaces that have been searched and researched in past
26 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 5-4.?Small iron meteorite (dark and shiny) found among the rocks
of Elephant Moraine.
:??
FIGURE 5-5.?Liquid water and icicle on the sun-facing side of a boulder in
Elephant Moraine.
FIGURE 5-7.?Paul Pellas and the first three carbonaceous chondrite fragments
found at the northernmost extension of a small strewnfield containing a total
of 56 fragments (see also Figure 5-8).
seasons. This probably reflects the fact that snow cover was
remarkable for its virtual absence on the Main Icefield, in
contrast to previous seasons. A few meteorites were also
incidentally picked up by a two-person party working to extend
the survey stations from the Near Western Field to the
triangulation network on the Main Field.
On 21 January, meteorites, ice blocks, and three team
members were flown to McMurdo. Three days later the last
two people were returned safely, bringing to a close what was
arguably the most ambitious ANSMET field season to date.
Our snowmobile odometers logged over 1250 km during 45
days on the Polar Plateau. In addition to the large number of
meteorites returned from five separate locations, an ice
sampling program was carried out, and survey and gravity
stations now extend from exposed bedrock at Allan Hills to the
Far Western Icefield.
Literature Cited
Fudali, Robert F.
1982. Gravity Measurements across the Allan Hills Main Meteorite
Collecting Area. Antarctic Journal of the United States, XVIII,
5:58-60.
Fudali, Robert F., and John W. Schutt
1984. The Field Season in Victoria Land, 1981-1982. In U.B. Marvin and
B. Mason, editors, Field and Laboratory Investigations of Meteorites
from Victoria Land, Antarctica. Smithsonian Contributions to the
Earth Sciences, 26:9-16.
FIGURE 5-6.?ANSMET on the move.
NUMBER 28 27
Table 5-1.?Tentative classification of meteorite specimens found at Elephant Moraine and the
Allan Hills icefields during the 1983-1984 season.
Specimens
Ordinary
chondrites
Carbonaceous
chondrites
Acondrites
Stony-Irons
Irons
Possible
meteorites
Total
Elephant
Moraine
179
4
12
1
3
8
207
Allan
Hills
Far West
7
76
83
Icefield
Allan
Hills
Mid West
31
2
2
35
Allan
Hills
Near West
13
13
Allan
Hills
Main
29
29
Total
259
82
14
1
3
8
367
2128
2126-5 through 56
2120
2126-4
I? 2126-1, 2,3
pinnacles
FIGURE 5-8.?Sketch map of carbonaceous chondrite strewnfield of 56
fragments (field numbers 2126-1 to 2126-56) on the Allan Hills Far Western
Icefield. Numbers 2120 and 2128 are other types of meteorites in the same area.
6. Descriptions of Stony Meteorites
Brian Mason, Glenn J. MacPherson, Roberta Score,
Carol Schwarz, and Jeremy S. Delaney
This chapter provides descriptions of some of the individual
meteorite specimens collected during the 1982-1983 and
1983-1984 field seasons. The descriptions are based largely
on those published in the Antarctic Meteorite Newsletter, with
additional information as available. Also included here are
previously unpublished data on small specimens of special
interest from the 1978-1979 and 1981-1982 field seasons.
The Appendix contains a complete list of Antarctic meteorites
recovered to date, along with their type, weathering grade,
mass, etc. Specimens weighing less than 100 grams that do
not show distinctive features are listed in the Appendix, but
are not described in the text.
Descriptions are arranged according to meteorite classifica-
tion. Within the chondrites the specimens are grouped
according to the Van Schmus and Wood (1967) classification,
and the descriptions follow the order of increasing petrographic
type.
The letter-number designations concur with guidelines
recommended by the Committee on Nomenclature of the
Meteoritical Society; each carries the following information:
location, e.g., ALH (Allan Hills); expedition and year, e.g.,
A81 (Expedition A, 1981); sample number, xxx (e.g., 213).
After 1981 the "A" preceding the year was dropped. The
original weight of the specimen is given to the nearest gram
(nearest 0.1 gram for specimens weighing less than 100 grams).
Chondrites
CLASS C2
FIGURES 6-1,6-2
ALHA81312 (0.7 g).?This small specimen (1.0 x 0.8 x 0.5
cm) was tentatively identified as a carbonaceous chondrite
from its exterior features, and this has been confirmed by
Brian Mason and Glenn J. MacPherson, Department of Mineral
Sciences, National Museum of Natural History, Smithsonian Institu-
tion, Washington, D.C. 20560. Roberta Score and Carol Schwarz,
North?op-Houston, Johnson Space Center, Houston, Texas, 77058.
Jeremy S. Delaney, Department of Mineral Sciences, American
Museum of Natural History, New York, N.Y. 10024.
examination of the thin section. The section shows several
small chondrules (maximum diameter 0.5 mm) and numerous
colorless mineral grains in a translucent brown to opaque black
matrix. McSween (personal communication) reports the
following modal analysis of this section (vol. %): matrix, 60.3;
monomineralic grains, 14.1; chondrules and plplymineralic
fragments, 22.8; inclusions, 2.8. Microprobe analyses show the
following wide ranges in composition for olivine and
pyroxene: olivine, Fa135, with a mean of Fa6; pyroxene
generally close to clinoenstatite in composition, but individual
grains range up to Fs31. Small refractory (spinel-rich)
inclusions are present, some of which contain pleochroic (deep
blue to colorless) hibonite.
ALH82100 (24.3 g).?Patches of fusion crust are preserved
mainly on one side of this small stone (3.5 x 3.5 x 2.5 cm).
Small submillimeter inclusions are visible on the exposed
interior surfaces. The stone is unfractured and one face has a
rough texture from weathering. The thin section shows
numerous small colorless grains (up to 0.3 mm) and irregular
aggregates (up to 0.6 mm, and mainly of olivine), and sparse
chondrules, in a black matrix that is translucent brown in
thinned areas. A few small spinel- and perovskite-bearing
refractory inclusions and spherules are present. Trace amounts
of nickel-iron and troilite occur as widely dispersed minute
grains. Microprobe analyses show olivine compositions in the
range Fa147, but most grains are iron-poor and the mean
composition is Fa5; pyroxene is rare, and only two grains of
clinoenstatite (Fs^) were analyzed. McSween (personal
communication) reports the following modal analysis of this
section (vol.%): matrix, 77.1; monomineralic grains, 7.5;
chondrules and polymineralic fragments, 13.9; inclusions, 1.5.
ALH82131 (1.0 g).?One small patch of blistery fusion crust
remains on this tiny specimen (1 x 1 x 0.5 cm). The exposed
underlying surface is black with a greenish tinge. The interior
is black and contains many submillimeter-size white inclu-
sions. A green weathering rind extends approximately 1 mm
into the stone. The very small thin section shows a single
chondrule in a black (brown on thin edges) opaque matrix.
Microprobe analyses show that the matrix has the composition
29
30 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
ALH 83016 ,0
*?*% "
FIGURE 6-1.?C2 chondrites; note the blistery fusion crust on ALH83016.
characteristic of C2 chondrites. Clasts and inclusions are
largely replaced by green to brown phyllosilicate material.
Olivine in the chondrule is almost pure forsterite (FeO 0.3%;
CaO 0.3%-0.4%).
ALH83016 (4.1 g).?A brown to black fusion crust covers
part of this small stone (3 x 2 x 0.8 cm). The interior is black
with abundant irregular white inclusions and some chondrules.
The thin section shows a few poorly defined chondrules up to
1.8 mm across, consisting of granular or barred olivine with
minor polysynthetically twinned clinopyroxene. A few small
spinel-rich inclusions are present. The bulk of the meteorite
consists of translucent brown to opaque black matrix. Scattered
through the matrix are colorless, birefringent grains, mostly
olivine, up to 0.3 mm but usually less than 0.1 mm across.
Trace amounts of nickel-iron and sulfides are dispersed
throughout the section as minute grains. Well-preserved fusion
crust rims part of the section. Microprobe analyses show that
olivine varies widely in composition, ranging from Fa^ to
Fa30 (with a mean of Fan); it also has a notable chromium
content, 0.1-0.5 weight percent Cr2O3. Pyroxene is generally
close to clinoenstatite in composition. McSween (personal
communication) reports the following modal analysis of this
section (vol.%): matrix, 65.6; monomineralic grains, 7.1;
chondrules and polymineralic fragments, 22.6; inclusions, 3.7.
ALH83100 (2293 g).?Since the initial description of this
stone, many other specimens have been paired with it (e.g., see
Antarctic Meteorite Newsletter, 8(2), and the cumulative
weight for 55 pieces is 2293 g. ALH83100 itself is an angular
fragment, and is so highly fractured that several pieces fell off
during handling. The surface is dull black with a few barely
discernible clasts or chondrules. White "evaporite" deposits are
present locally; these are apparently weathering products
formed in the Antarctic, but they only became visible in the
receiving laboratory as water in the interior of the meteorite
worked its way to the surface carrying soluble salts along with
it. The thin section shows a large number of clasts (up to 1
NUMBER 28 31
FIGURE 6-2.?Photomicrographs of thin sections of C2 chondrites (each field of view is 3 x 2 mm): a,
ALHA81312; b, ALH83100; c, EET83226; d, EET83250. Irregular aggregates, grains, and rare chondrules,
mainly of olivine (white to gray) in translucent to opaque matrix (black).
mm across) and mineral grains, and a few chondrules, in a dark
matrix. A little (about 1%) sulfide is present as minute grains,
some of which are concentrated at the margins of chondrules.
Nickel-iron occurs in trace amounts, some as small spherules.
The clasts, inclusions, and most of the mineral grains consist
of phyllosilicate and, in many places, calcite, that are probably
alteration products of the original phases. Microprobe analyses
shows that a few preserved primary grains are forsteritic
olivine.
ALH83102 (1786 g).?This meteorite consists of 20 or
more pieces; only two of the larger pieces have been examined
to date. Both pieces are extensively fractured and extremely
friable. Small patches of fusion crust are present. White
evaporite deposits (see above) are present on both interior and
exterior surfaces. Small white inclusions are visible in a
greenish black to black matrix that locally shows signs of heavy
oxidation. The thin sections show that the two fragments are
identical. Both are intensely altered, with the matrix, inclu-
sions, and chondrules being almost completely replaced by
iron-rich phyllosilicates, calcite, and iron oxides. The matrix
is opaque and black except where the sections are unusually
thin. Olivine grains are sporadically preserved, with composi-
tions that are mostly Fa^, although some range up to Fa42.
One small spinel-rich refractory spherule was found, in which
the spinel is nearly pure MgAl2O4. No other primary phases
were found in this spherule.
This meteorite can confidently be paired with ALH83100,
because of the identical and unusual petrographic features of
both specimens and because of their geographic proximity on
the ice field where they were found (see Chapter 5).
EET83224 (8.6 g).?A dull and fractured fusion crust covers
about one-quarter of this small specimen (2.5 x 2.5 x 1.5 cm).
32 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Some of the uncrusted surface is jet black, but in places it has
weathered to a brown color. Chondrules and small irregular
white inclusions are visible in the jet black interior. The thin
section shows a few chondrules (up to 0.8 mm in diameter),
small (0.1 mm or less), colorless, and birefringent grains
(mostly olivine), and what appear to be chondrule or clast
fragments, all in a transparent brown to opaque black matrix.
Chondrules consist mostly of granular olivine, but a few have
minor polysynthetically twinned clinopyroxene as well. A few
small spinel-bearing refractory inclusions are present. Acces-
sory nickel-iron and trace amounts of sulfide are dispersed
throughout the section as minute grains. Microprobe analyses
gave the following compositions: olivine ranges from Fa0 2 to
Fa41, with a mean of Fag; pyroxene is generally near enstatite
in composition (FeO 0.4%-1.0%). McSween (personal commu-
nication) reports the following modal analysis of this section
(vol.%): matrix, 63.8; monomineralic grains, 12.4; chondrules
and polymineralic fragments, 21.3; inclusions, 2.5.
EET83226 (33.1 g).?No fusion crust remains on this
angular fragment (4 x 2.5 x 3 cm). The exposed surface is jet
black with a granular texture and shows abundant chondrules
and inclusions. The thin section shows abundant small
chondrules, averaging about 0.3 mm in diameter, and numerous
mineral aggregates and mineral grains, set in a moderate
amount of dark brown to black opaque matrix. Chondrule types
include granular and barred olivine, some of which contain
pale brown and partly devitrified glass. Accessory amounts of
finely dispersed nickel-iron and sulfide are present. Microprobe
analyses show that much of the olivine is near forsterite in
composition, but occasional iron-rich grains are present (the
overall range is Fao5.69, with a mean of Fa12). Pyroxene grains
are rare; their composition range is Fs0 ^Q. McSween (personal
communication) reports the following modal analysis of this
section (vol.%): matrix, 39.6; monomineralic grains, 14.5;
chondrules and polymineralic fragments, 36.1; inclusions, 9.8.
EET83250 (11.5 g).?This specimen broke into many
fragments during transport from Antarctica. Both fusion crust
and white evaporite deposits cover much of the exterior
surface. Interior surfaces are black and speckled with white
inclusions. In thin section only a few chondrules and chondrule
fragments are seen; the bulk of the meteorite consists of brown
to black semi-opaque matrix, enclosing numerous small (0.1
mm and less), colorless, birefringent grains, mostly olivine. A
few small spinel-rich inclusions are present. The matrix also
contains trace amounts of finely dispersed nickel-iron and
sulfides. Well-preserved fusion crust rims part of the section.
Microprobe analyses show most of the olivine is close to
forsterite in composition, with a few iron-rich grains (the range
is FaQ 3_22, with a mean of Fa4). Pyroxene grains are rare; their
composition range is Fs2.14. McSween (personal communica-
tion) reports the following modal analysis of this section
(vol.%): matrix, 71.2; monomineralic grains, 14.5; chondrules
and polymineralic fragments, 12.1; inclusions, 2.2.
CLASS C3
FIGURES 6-3,6-4
ALHA81258 (1.1 g).?This small stone (1 x 1 x 0.5 cm) is
mostly covered by vesicular black fusion crust; chondrules are
visible on interior surfaces. The thin section shows numerous
chondrules up to 2 mm across and irregular crystalline
aggregates up to 3 mm in maximum dimension, set in a minor
amount of dark brown to black semi-opaque matrix. The
chondrules and aggregates consist mainly of granular olivine
with minor amounts of polysynthetically twinned pyroxene.
Trace amounts of nickel-iron are present as minute grains.
Sulfide is present in small amounts, finely dispersed through-
out the matrix and sometimes concentrated in chondrule rims.
Microprobe analyses of chondrule olivines show a wide
composition range: Fa^g, mean Fan; the matrix appears to
consist largely of fine-grained iron-rich olivine, Fa40.60.
Pyroxene in the chondrules is clinoenstatite, mostly near Fs15
but with occasional Fe-rich grains. The meteorite is a C3V
chondrite, very similar to ALHA81003; the possibility of
pairing should be considered.
ALH82101 (29.1 g).?The exterior surfaces of this stone (3
x 2.7 x 2.7 cm) are mostly covered with a shiny, blistery fusion
crust. Broken surfaces reveal a gray-beige interior with an
outer, 1 mm thick, discontinuous weathering rind. The matrix
is fine-grained, with metal and a few white to gray inclusions
being visible. The thin section shows an aggregate of small
chondrules (average diameter -0.5 mm), chondrule fragments,
and mineral grains set in an extremely fine-grained, translucent
tan to yellow-brown matrix. The chondrules show a wide
variety of textures; in barred olivine chondrules the material
interstitial to the bars is pale brown isotropic glass. Minor
amounts of nickel-iron and sulfide are present, as small grains
FIGURE 6-3.?C3 chondrite ALH82101.
NUMBER 28 33
FIGURE 6-4.?Photomicrographs of thin sections of C3 chondrites (each field of view is 3 x 2 mm), a,
ALHA81258; b, ALH82101. Note the textural differences between ALHA81258 (C3V) and ALH82101 (C3O).
within some chondrules and also concentrated around their
margins. Numerous small refractory inclusions are present;
identified phases include melilite, deep pink spinel, and
colorless hibonite. Microprobe analyses of olivine show a wide
composition range: Fa^Q, with a mean of Fa22; only a few
grains of pyroxene were found, having a composition range
of FsM0. The meteorite is classified as a C3 chondrite of the
Ornans subtype; it is possibly paired with ALHA77003.
Wieler et al. (1985) have reported abundances and isotopic
compositions of He, Ne, and Ar in ALH82101.
CLASS H3
FIGURE 6-5
ALH82110 (39.3 g).?Fusion crust totally covers this small
stone (4.5 x 2.5 x 2.0 cm). Chipping has exposed a weathered
interior with some obvious inclusions. The thin section shows
a close-packed aggregate of chondrules and chondrule
fragments in a minor amount of opaque matrix. Nickel-iron
grains are abundant in the matrix, sometimes concentrated in
chondrule rims; troilite is present in lesser amount. A wide
variety of chondrules is present, ranging up to 2 mm in
diameter; the most common types are porphyritic and granular
olivine and olivine-pyroxene. Microprobe analyses show the
following wide composition ranges in olivine and pyroxene:
olivine, Fa^.^, with a mean of Fa14 (% mean deviation of FeO
is 52; see Dodd et al., 1967, for definition of % mean
deviation); pyroxene, Fs3_2g, with a mean of Fs13 (% mean
deviation of FeO is 48).
PCA82520 (22.7 g).?Dull black fusion crust covers 80%
of the surface of this pyramidal stone (3 x 2 x 1.5 cm), the
remainder being covered with a shiny reddish brown crust.
Extensive weathering has given the matrix a yellowish to
reddish brown color, but some metal is nonetheless preserved.
The thin section shows a close-packed aggregate of chondrules
(up to 1.5 mm in diameter), chondrule fragments, and a few
clasts, with interstitial nickel-iron and troilite and a relatively
small amount of dark matrix. A considerable variety of
chondrules is present, the majority being granular or porphyri-
tic olivine types with transparent to turbid interstitial glass;
other types include fine-grained pyroxene, medium-grained
olivine plus polysynthetically twinned clinopyroxene, and
barred olivine. Brown limonitic staining pervades the section.
FIGURE 6-5.?Photomicrograph of thin section of H3 chondrite ALH82110
(field of view is 3 x 2 mm). A closely packed aggregate of chondrules, irregular
fragments, and mineral grains is set in a minor amount of dark matrix.
34 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Microprobe analyses show olivine mainly in the range Fa15.22,
but one clast has olivine Fa6; the mean composition is Fa17
(% mean deviation of FeO is 27). Pyroxene ranges in
composition from Fs2 to Fs19 with a mean of Fs 14 (% mean
deviation of FeO is 24).
CLASS L3
FIGURES 6-6,6-7
ALHA78013 (4.1 g), 78186 (3.1 g), 78236 (14.4 g), 78238
(9.8 g), 78243 (1.9 g), 81145 (21.1 g), 81156 (19.7 g), 81162
(59.4 g), 81190 (48.3 g), 81191 (30.4 g), 81214 (4.4 g), 81229
(40.0 g), 81243 (15.0 g), 81259 (9.9 g), 81272 (22.9 g), 81280
(54.9 g), 81292 (12.9 g), 81299 (0.5 g).?Examination of thin
sections and microprobe analyses of the minerals in these
meteorites show that they are essentially identical to ALHA77011,
and can confidently be paired with it E.R.D. Scott (personal
communication) has also examined the sections and supports
this interpretation.
ALHA78046 (70.0 g).?Thin section examination shows
that this stone consists almost entirely of a close-packed
aggregate of chondrules and chondrule fragments; most of the
interstitial material consists of nickel-iron and troilite grains,
in places forming rims on the chondrules. Weathering is
extensive, with limonitic staining and small areas of brown
limonite throughout the section. Chondrules range from 0.3 to
3.6 mm in diameter; a variety of types is present, the most
common being granular and porphyritic olivine and olivine-
pyroxene. Microprobe analyses show considerable variability
in mineral compositions. Olivine compositions range from Fa8
to Fa^, with a mean of Fa19 (% mean deviation of FeO is 20).
Pyroxene compositions range from Fs8 to Fs20, with a mean
of Fs16. The % mean deviation of FeO in olivine is much lower
than that for olivine in the ALHA77011 group, suggesting that
this meteorite is more equilibrated and hence different from
the 77011 group.
ALHA78133 (59.9 g).?Thin section examination shows
that this stone is largely made up of chondrules and chondrule
fragments set in a minor amount of dark matrix. Nickel-iron
and troilite are present in subequal amounts, dispersed through
the matrix as small grains and sometimes forming rims on the
chondrules. A moderate amount of weathering is indicated by
brown limonitic staining throughout the matrix. Chondrules
range in diameter from 0.3 to 1.5 mm; types seen include
porphyritic olivine and olivine-pyroxene, granular olivine and
olivine-pyroxene, devitrified glass, and radiating pyroxene.
Microprobe analyses show olivine ranging in composition from
Fat to FaM with a mean of Fa16 (% mean deviation of FeO is
52); pyroxene ranges in composition from FSj to Fs16 with a
mean of Fs8 (% mean deviation of FeO is 69). In mineral
composition this meteorite is similar to those in the ALHA
77011 group, but E.R.D. Scott (personal communication) states
FlGURE 6-6.?L3 chondrites.
that it appears to lack the graphite-magnetite intergrowths
characteristic of that group.
ALH83010 (395 g).?A black iridescent fusion crust is
present on one side of this meteorite fragment (10.5 x 8 x 2
cm). The other surfaces are dark greenish gray with iridescent
reddish brown areas. Numerous chondrules (1-4 mm in
diameter) and large clasts (the largest is 1.0 x 0.5 cm) are
visible on the exposed interior surfaces. The stone is extremely
coherent. The interior consists of dark matrix with numerous
millimeter-sized, gray to yellowish colored chondrules. Nickel-
iron is clearly visible. The thin section shows sharply defined
chondrules up to 2.5 mm in diameter, many of which contain
clear brown isotropic glass. Pyroxene is mostly monoclinic and
has a composition range of Fs2_2g. Olivine compositions are in
the range Fa4.31. Metal (two phases present) is subequal with
troilite in abundance. There are well-defined sulfide rims
around many chondrules. Chromite is accessory and is
NUMBER 28 35
FIGURE 6-7.?Photomicrographs of thin section of L3 chondrites (each field of view is 3 x 2 mm): a,
ALHA78046; b, ALHA78133; c, EET82601; d, EET83213. A closely packed aggregate of chondrules, irregular
fragments, and mineral grains set in dark matrix.
generally very fine-grained.
EET82601 (149 g).?This angular to subrounded specimen
is covered with patchy remnants of fusion crust. Chondrules
1-4 mm in diameter are visible on the surfaces where fusion
crust is missing. The interior is very dark with weathered,
millimeter-sized chondrules visible. The thin section shows a
close-packed aggregate of chondrules, ranging up to 1.5 mm
in maximum dimension. A variety of types is present, the
most common being granular olivine and olivine-pyroxene,
porphyritic olivine and olivine-pyroxene, and cryptocrystalline
pyroxene. The small amount of matrix is fine-grained and
opaque, and contains a few grains of nickel-iron and troilite.
The meteorite is considerably weathered, with brown limonitic
staining throughout the section. Olivine and pyroxene show
the following wide ranges of compositions: olivine, Fa2 to
Fa39, with a mean of Fa^ (% mean deviation of FeO is 36);
pyroxene, Fst to Fs35, with a mean of Fs13 (% mean deviation
of FeO is 45).
EET83213 (2727 g).?A dull, fractured fusion crust covers
most of this stone (16 x 15 x 7 cm); evaporite deposits are
present on several surfaces. The interior is greenish gray with
numerous white, cream, and darker gray inclusions or
chondrules. Some metal is present. The thin section shows
sharply defined chondrules up to 3 mm in diameter set in a
brown matrix. Isotropic clear brown glass is preserved in some
chondrules. Moderate limonitic staining is locally present,
indicating mild to moderate weathering. Monoclinic pyroxene
is very common, with a composition range of Fs3.26. Olivine
36 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
ranges in composition from Fa13 to FajQ. Minor metal and
troilite are present in subequal amounts; two metal phases are
present, locally in plessitic intergrowths.
This meteorite is very similar in texture and mineral
compositions to EET82601, and the possibility of pairing
should be considered.
CLASS LL3
FIGURE 6-8
TIL82408 (80.1 g).?A polygonally fractured, black fusion
crust coats much of this stone (4.5 x 4 x 2.5 cm). Areas without
fusion crust are somewhat friable. The meteorite is clast-rich,
with a very dark gray to black matrix. Oxidation is evenly
distributed throughout the interior. The thin section shows a
close-packed aggregate of chondrules and chondrule frag-
ments, up to 4 mm across. The matrix is black and opaque,
much of it forming rims to the chondrules; the matrix contains
much sulfide and a little nickel-iron (largely weathered to
limonite). A wide variety of chondrule types is present,
including porphyritic olivine and olivine-pyroxene, granular
olivine and olivine-pyroxene, barred olivine, and fine-grained
pyroxene. Some of the chondrules preserve clear, isotropic,
interstitial glass. Microprobe analyses show the following wide
ranges of compositions for olivine and pyroxene: olivine,
Faj_29, with a mean of Fa15 (% mean deviation of FeO is 41);
pyroxene, Fs2_21, with a mean of Fs9. The highly variable
compositions of olivine and pyroxene and the presence of
isotropic glass indicate type 3, and the small amount of
nickel-iron suggests the LL group; the meteorite is thus
tentatively classified as an LL3 chondrite.
Wieler et al. (1985) have reported abundances and isotopic
compositions of He, Ne, and Ar in TIL82408.
CLASS C4
FIGURES 6-9, 6-10
ALH82135 (12.1 g).?Black fusion crust covers most of
this triangular-shaped stone (3 x 2.5 x 1 cm). Freshly broken
surfaces expose a dark bluish gray matrix with signs of some
oxidation. In thin section the meteorite consists largely of
finely granular olivine (grains ranging up to 0.1 mm), minor
pyroxene, plagioclase, and opaques. A few relatively coarse-
grained olivine chondrules are present. Microprobe analyses
give the following compositions: olivine, Fa27 (a few grains
are more iron-rich); pyroxene, Fs25; plagioclase, An20_75. This
meteorite is similiar to Karoonda and PC A82500 in texture and
mineral compositions.
Wieler et al. (1985) have reported abundances and isotopic
compositions of He, Ne, and Ar in ALH82135. Scott (1985)
has discussed its petrology.
PCA82500 (90.9 g).?This specimen (7 x 5 x 2.8 cm) has
a very unusual external appearance. It is extremely fragmented
and has numerous rounded cavities, some of which extend
through the thickness of the specimen to give it a "swiss
cheese" appearance. The cavities were filled with ice and snow
when the meteorite was found. Several patches of fusion crust
are present. The exterior surfaces vary in color from dark gray
to lighter gray and yellowish gray, the lighter colors being
characteristic of the less weathered areas. Inclusions (chon-
drules?) are exposed on those portions of the exterior surface
that lack fusion crust. White evaporite deposits and yellow-
colored weathering residues are abundant on interior surfaces;
the white material is an unusual nickel-rich magnesium sulfate
(J. Gooding, personal communication, 1986). In spite of the
weathering and evaporite deposits, the interior surfaces reveal
a fine-grained matrix with minute metal flecks and a few
FIGURE 6-8.?Photomicrograph of thin section of LL3 chondrite TIL82408
(field of view is 3 x 2 mm). Chondrules, chondrule fragments, irregular
fragments, and mineral grains are set in a dark matrix. FIGURE 6-9.?C4 chondrite PCA82500.
NUMBER 28 37
FIGURE 6-10.?Photomicrographs of thin section of C4 chondrites (each field of view is 3 x 2 mm): a,
ALH82135; b, PCA82500. In ALH82135, sparse chondrules are set in a matrix consisting largely of fine-grained
olivine. In PCA82500, the lower left area shows a segment of a large (3.6 mm diameter) chondrule.
yellowish dots of oxidation. The thin section contains a single
porphyritic olivine chondrule, diameter 3.6 mm, in an
aggregate of turbid anhedral olivine grains averaging 0.1 mm.
Small amounts of troilite and nickel-iron are present, the metal
being largely weathered to brown limonite. Microprobe
analyses show a uniform olivine composition of Fa31, and
variable plagioclase in the range An^ to An^. No pyroxene
was found. This meteorite was classified in the Antarctic
Meteorite Newsletter, 6(2), as an LL6 chondrite, but has since
been recognized as a C4 chondrite that is very similar to
Karoonda (Scott, 1985).
Wieler efal. (1985) have reported abundances and isotopic
compositions of He, Ne, and Ar in PCA 82500. Scott (1985)
concludes that Karoonda, PCA 82500, Yamato 6903, and
Mulga (West) are very similar and may have come from the
same body.
CLASS E4
FIGURE 6-11
ALHA81189 (2.6 g).?No fusion crust remains on this
fractured reddish brown stone (2 x 1.5 x 0.5 cm). The thin
section shows an aggregate of chondrules, chondrule frag-
ments, and mineral grains set in an opaque matrix. The
chondrules range up to 0.9 mm in diameter; most of them
consist of granular pyroxene (sometimes with a little olivine),
but a few are made up of nickel-iron and troilite. The matrix
consists largely of nickel-iron and troilite, with a considerable
amount of secondary limonite. Microprobe analyses show that
the pyroxene is close to MgSiO3 in composition (FeO
0.5%-4.5%, with a mean of 1.9%; A12O3 0.02%-2.4%, mean
0.7%; CaO 0.1%-0.7%, mean 0.3%; TiO2 0%-0.13%, mean
0.08%; MnO 0.07%-0.22%, mean 0.15%). Most of the olivine
grains are close to Mg2Si04 in composition (FeO 0.7%-6.4%).
One grain of a silica polymorph was analyzed. The metal
contains approximately 2.5% Si. Because some of the pyroxene
is polysynthetically twinned clinoenstatite, the meteorite is
tentatively classified as an E4 chondrite.
ALH82132 (5.9 g).?No fusion crust remains on this
iridescent, reddish brown, highly oxidized stone (2x2x1
cm). A thin coating of evaporite deposits are present on some
of the extensively weathered interior surfaces. Thin section
examination shows that chondrules are relatively abundant but
small, ranging up to 0.6 mm in diameter. Most of them consist
of pyroxene, but some are made up almost entirely of
nickel-iron and troilite. The matrix consists largely of granular
pyroxene, with lesser amounts of nickel-iron and sulfides, a
little plagioclase and a silica polymorph. The meteorite is
considerably weathered, with brown limonitic staining through-
out the section. Microprobe analyses show that the pyroxene
is almost pure MgSiO3 (FeO 0.06%-0.7%, mean 0.3%; A12O3
0-0.3%, mean 0.04%; CaO 0.02%-0.6%, mean 0.16%; TiO2
and MnO each less than 0.05%). Plagioclase is almost pure
albite (CaO 0.2%, K2O 0.11%). The meteorite is an enstatite
chondrite and, since some of the pyroxene is polysynthetically
twinned clinoenstatite, it is classified as an E4 chondrite.
E.R.D. Scott (personal communication) has examined the
thin sections of the E4 chondrites from the Allan Hills, and
comments that 81189 and 82132 are definitely not paired,
82132 appearing more equilibrated than 81189; 81189 does
resemble 77156 and 77295, and may tentatively be paired with
them.
PCA82518 (21.9 g).?The fusion crust coating this stone
(3 x 2.5 x 2 cm) is shiny, iridescent, and ranges in color from
orange-red to brown to black. The exterior is dotted with
numerous vugs that are lined with fusion crust. Exposed
interior surfaces reveal a dark brown matrix with abundant
chondrules (as large as 3 mm in diameter) and metal. Thin
38 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 6-11.?Photomicrographs of thin sections of E4 chondrites (each field
of view is 3 x 2 mm): a, ALHA81189; b, ALH82132; c, PCA82518. All three
sections show chondrules, chondrule fragments, and mineral grains (mainly
clinoenstatite) in an opaque matrix consisting largely of nichel-iron and troilite.
section examination shows that the chondrules are abundant
but generally small, ranging from 0.3 to 0.9 mm in diameter;
they consist of granular or fine-grained pyroxene. The matrix
consists largely of granular pyroxene, with lesser amounts of
nickel-iron and sulfides, and a little plagioclase. The meteorite
is considerably weathered, with brown limonitic staining
throughout the section. Microprobe analyses show that the
pyroxene is almost pure MgSiO3 (FeO 0.2%-0.8%, mean
0.5%; A12O3 0.07%-0.7%, mean 0.5%; CaO 0.04%-0.7%,
mean 0.2%; TiO2 and MnO each less than 0.1%). Plagioclase
is almost pure albite (K2O 0.6%, CaO less than 0.1%). One
grain of forsteritic olivine was analyzed. The meteorite is an
enstatite chondrite and, since part of the pyroxene is
polysynthetically twinned clinoenstatite, it is classified as E4.
CLASS H4
FIGURES 6-12,6-13
ALHA78051 (119 g).?In thin section this stone is seen to
consist of numerous chondrules, up to 1.5 mm in diameter, set
in finely granular matrix of olivine, pyroxene, nickel-iron, and
troilite. Moderate weathering is indicated by brown limonitic
staining concentrated around metal grains. Well-preserved
fusion crust borders one edge of the section. Microprobe
analyses show olivine to be uniformly Fa18 in composition; the
pyroxene composition is somewhat variable, Fs15.lg.
ALH82126 (139 g).?This stone (7 x 4 x 2.5 cm) was
completely covered with dull brown fusion crust. Chipping
revealed some inclusions in the heavily weathered interior. The
thin section shows numerous chondrules, up to 2 mm in
diameter, in a granular groundmass of olivine and pyroxene,
with minor nickel-iron and lesser amounts of troilite. Brown
limonitic staining pervades the section. Remnants of fusion
crust are present on one edge. Microprobe analyses give the
following compositions: olivine, Fa18; pyroxene is somewhat
variable, Fs14.18.
EET82602 (1824 g).? An extremely thin, black fusion crust
completely covers the regmaglypted surface of this meteorite
NUMBER 28 39
(10 x 14 x 8 cm). The stone broke along a pre-existing fracture,
exposing both weathered and unweathered material. The
material exposed is orange-brown with abundant visible metal
(this may not be representative of the entire specimen).
Chondritic structure is well developed in thin section, with
chondrules ranging up to 1.5 mm in diameter. A variety of
chondrule types is present, including porphyritic and barred
olivine (with turbid, devitrified glass between the olivine
crystals), granular olivine, olivine-pyroxene, and fine-grained
pyroxene. Some of the pyroxene is polysynthetically twinned
clinobronzite. The chondrules are set in a fine-grained granular
groundmass of olivine and pyroxene, with minor amounts of
nickel-iron and troilite. Brown limonitic staining pervades the
section, and veinlets of red-brown limonite are present.
Microprobe analyses give the following compositions: olivine,
Fa19; pyroxene, Fs16.
EET82609 (325 g).?This stone (7.5 x 5 x 3.5 cm) is angular
with rounded corners. Brownish black fusion crust or remnant
fusion crust covers the entire specimen. The interior has a dark
matrix with reddish brown oxidation disseminated throughout.
The thin section shows a close-packed aggregate of small
chondrules, ranging up to 0.6 mm in diameter, set in a granular
groundmass consisting largely of olivine and pyroxene, with
minor amounts of nickel-iron and troilite. Some of the
pyroxene is polysynthetically twinned clinobronzite. Brown
limonitic staining pervades the section. Microprobe analyses
give the following compositions: olivine, Fa18; pyroxene Fs17
(the pyroxene is somewhat variable in composition).
EET83207 (1238 g).?A black to reddish brown fusion crust
covers this oblong meteorite (15 x 7.5 x 6 cm ). Several deep
fractures penetrate the interior, one splitting the stone almost
in half. The interior is mostly dark reddish brown, although
small areas of less-weathered yellowish matrix are still present.
The thin section shows well-defined chondrules up to 2 mm
in diameter. Microcrystalline structure is preserved in some
chondrules , but glass is devitrified. Olivine is uniformly Fa18
in composition. Monoclinic pyroxene (Fs16_18) is common.
Two metal phases are present, and tetrataenite (Ni 55%) is also
present locally. Troilite is subordinate to metal in abundance.
Chromite is accessory. This meteorite was originally classified
as H4-5 in the Antarctic Meteorite Newsletter, 8(1).
EET83211 (542 g).?A weathered, polygonally fractured
fusion crust covers 75% of this meteorite fragment (10 x 7 3.5
cm). The surface is iridescent in places, and a minor amount
of evaporite deposit is present. The interior of the stone is also
very fractured; broken surfaces are reddish brown and quite
smooth. The interior is extremely weathered, but some metal
is nonetheless visible. The thin section shows sharply defined
chondrules up to approximately 0.6 mm in diameter in a
microcrystalline groundmass. Metal is abundant and exceeds
troilite in amount. Intense limonitic staining, together with
hematite veins, indicate heavy weathering. The olivine
composition is relatively uniform, Fa18.20. Pyroxene is
commonly monoclinic, with a narrow composition range of
FIGURE 6-12.?H4 chondrites.
Fs1620. Some very fine-grained plagioclase (An12Or5) was
found.
PCA82511 (149 g).?Flow marks are apparent in the
iridescent brown to black fusion crust on the top surface (as
oriented on the ice) of this stone (5.5 x 6 x 3.5 cm). The bottom
surface shows several fractures and the fusion crust is
extensively weathered, having an orange tinge. The interior
that was exposed by chipping may not be representative of the
entire stone; it is heavily weathered with only small areas of
unweathered light gray material. In thin section, chondrules are
abundant and well-developed. A variety of types is present, the
commonest being porphyritic olivine, porphyritic olivine-
pyroxene, and radiating pyroxene. Much of the pyroxene is
polysynthetically-twinned clinobronzite. The matrix consists
of fine-grained olivine and pyroxene, with minor amounts of
nickel-iron and troilite; it is heavily stained with limonite.
Well-preserved fusion crust is present along one edge of the
section. Microprobe analyses give the following compositions:
40 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 6-13.?Photomicrographs of thin sections of H4 chondrites (each field of view is 3 x 2 mm): a,
PCA82524; b, PCA82511. Although both contain numerous well-defined chondrules, some chondrule margins
tend to merge with the granular matrix.
olivine, Fa17; pyroxene, Fs15.
PCA82524 (113 g).?A black fusion crust covers most of
this cuboidal stone (5 x 4 x 3.5 mm). Chipping exposed a
continuous weathering rind, light gray matrix and numerous
small light and dark inclusions. In thin section chondrules are
abundant and well-developed, ranging up to 1.2 mm in
diameter; a variety of types is present, including barred olivine,
granular and porphyritic olivine-pyroxene, and fine-grained
pyroxene. Some of the pyroxene is polysynthetically twinned
clinobronzite. The groundmass consists largely of fine-grained
olivine and pyroxene, with minor amounts of nickel-iron and
troilite. A minor degree of weathering is indicated by brown
limonitic staining around metal grains. Microprobe analyses
give the following compositions: olivine, Falg; pyroxene, Fs16.
CLASS L4
FIGURES 6-14,6-15
ALH83001 (1568 g).?Shallow regmaglypts are present on
this fusion-crusted stone (17.5 x 9 x 6.5 cm). Most of the
interior that has been exposed by chipping is weathered, but it
may not be representative of the entire stone. The less
weathered material is medium gray and contains chondrules.
The thin section shows sharply defined chondrules up to 2.5
mm in diameter, in which original brown glass is now turbid
and birefringent. Metal (mostly one-phase) and troilite are
subequal in amount. Light to moderate limonitic staining
indicates mild weathering. Olivine composition is somewhat
variable, Fa23.28. Monoclinic pyroxene is abundant, and has a
composition range of Fs20_32.
PCA82514 (129 g).?A dull black fusion crust is present
on one surface of this stone (6 x 3 x 3 cm), the other surfaces
having weathered to reddish brown. The interior is medium
gray and shows dark and light inclusions. A partial weathering
rind was exposed when the stone was chipped. In thin section
chondrules are abundant and well-developed, ranging up to 2
mm in diameter; a variety of types is present, including
porphyritic olivine, porphyritic olivine-pyroxene, barred oli-
vine, and fine-grained olivine and pyroxene. Much of the
pyroxene is polysynthetically-twinned clinobronzite. The
matrix consists of fine-grained olivine and pyroxene, with
coarser grains of nickel-iron and troilite. Brown limonitic
staining surrounds the metal grains. Microprobe analyses give
the following compositions: olivine, Fa23; pyroxene somewhat
variable, Fs^^, mean Fs18.
The following four specimens are L4 chondrites from the
Thiel Mountains that are possibly paired. All are very similar
in their textures, mineral compositions, and degree of
weathering. The thin sections all show a close-packed
aggregate of chondrules, up to 3 mm in diameter, in a minor
amount of granular groundmass that consists of olivine,
pyroxene and minor amounts of nickel-iron and troilite. Brown
limonitic staining pervades the sections. Microprobe analyses
give the following compositions: olivine Fa^.^; pyroxene is
somewhat variable, with a mean of Fs20_21.
TIL82404 (321 g).?This stone (7 x 7.5 x 3 cm) is partly
covered with brownish black fusion crust; many inclusions are
visible in areas devoid of crust. Chipping has exposed a dark
gray matrix that is inclusion- and metal-rich, with evenly
distributed oxidation.
TIL82406 (152 g).?This stone (5.5 x 5.0 x 3.5 cm) is
angular with subrounded edges, and most of it is covered with
dull black fusion crust. The dark gray interior shows numerous
inclusions, and oxidation is evenly scattered throughout.
NUMBER 28 41
TIL82407 (220 g).?This is an angular oblong stone (9.5 x
4.5 x 3 cm) with three flat sides, completely covered with
brownish black fusion crust. Abundant oxidation haloes are
obvious on the surface. Most of the interior has weathered to
a deep reddish brown, but fresh material is dark gray.
TIL82411 (179 g).?This meteorite (6.5 x 4.5 x 3 cm) is
covered with slightly weathered fusion crust. No fractures are
present. The interior is dark and slightly weathered, and
contains abundant chondrules 1-2 mm in diameter.
FIGURE 6-14.?L4 chondrites.
TYR82700 (892 g).?Black to brown fusion crust covers
60% of this stone (10 x 8.5 x 7 cm). Other surfaces are brown
with light inclusions. A white evaporite deposit dots the
surface. The interior is extensively oxidized. The thin section
shows a close-packed aggregate of chondrules and chondrule
fragments, set in a minor amount of granular matrix. A variety
of chondrule types is present, including granular olivine,
porphyritic olivine, porphyritic olivine-pyroxene, barred oli-
vine, and radiating fibrous pyroxene. Much of the pyroxene is
polysynthetically twinned clinobronzite. Minor amounts of
nickel-iron and troilite are present, interstitial to the chondrules.
Minor weathering is indicated by brown limonitic staining
around metal grains. Microprobe analyses give the following
compositions: olivine, Fa^; pyroxene somewhat variable,
Fs15_23, mean Fs18.
CLASS H5
FIGURES 6-16,6-17
ALHA81161 (122 g).?This stone (6.5 x 4 x 2.8 cm) has
thin fusion crust on one side. It is extremely fractured and
brown to iridescent brown. Chipping exposed a totally
weathered interior.
ALHA81183 (104 g).?Dull fusion crust covers most of this
stone (6 x 3.5 x 3 cm); areas without fusion crust have an
iridescent red-brown color. Several fractures penetrate the
interior, which has a deep reddish brown color.
ALHA81295 (105 g).?Some very thin fusion crust is
preserved on one surface of this meteorite (7 x 4.5 x 2 cm).
The surface color is iridescent reddish brown. Many fractures
penetrate the interior, which is extensively weathered.
ALH82102 (48 g).?This stone was found weathering out
of the ice in the Far Western Icefield. It was collected in situ
inside of a large block of encasing ice (see Frontispiece). The
ice block was sent to an ice coring lab in New Hampshire and
determined to be original (not refrozen) ice; see Chapter 10.
The dull black, polygonally fractured fusion crust of the
meteorite contains many centimeter-size oxidation haloes that
are orange-red. One fracture surface is reddish brown. The
interior of the meteorite is uniformly very weathered.
ALH82103 (2529 g).?A slightly weathered fusion crust
covers nearly all of this meteorite (14 x 11 x 9 cm).
Regmaglypts occur on several faces. Surfaces without fusion
42 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 6-15.?Photomicrographs of thin sections of L4 chondrites (each field of view is 3 x 2 mm): a, TIL82406;
b, PCA82514. Chondritic structure is prominent, but some chondrules show partial integration with the granular
matrix.
crust show a 1-2 mm thick weathering rind, but a few small
clasts are visible. The interior consists of gray matrix dotted
with oxidation.
ALH82122 (142 g).?A thin fusion crust covers this
rectangular meteorite (4.5 x 4 x 2.5 cm). The interior is light
to dark gray with oxidation haloes around metal grains.
EET82603 (8210 g).?This large stone (18 x 19 x 14 cm)
is almost completely covered with a black, polygonally
fractured fusion crust. White evaporite deposits occur on four
of the six sides of the meteorite and are quite thick in some
places. As in the cases of other Antarctic meteorites having
evaporite deposits (see description for ALH83100), the
deposits on EET82603 formed while the sample was drying
in the gaseous nitrogen atmosphere of the storage cabinets in
Houston. Chipping of the meteorite revealed that a weathering
rind is also present. The interior matrix is gray with large areas
having a dark gray to deep reddish brown color. Extensive
weathering has occurred along internal cracks.
EET82604 (1570 g).?A thin black fusion crust coats most
of this blocky meteorite (11 x 11x8.5c m). The stone broke
along a pre-existing fracture, exposing mostly weathered
material, though metal is still obvious, as is a small amount
of less-weathered material.
EET83200 (778 g).?This angular chondrite (10 x 8 x 5
cm) is covered with weathered black fusion crust that is pitted
with oxidation. Row lines are present on part of one surface.
The stone is broken, and the exposed surface is weathered to
a shiny dark brown. The interior is a dark reddish brown with
a small band of relatively unweathered material. This meteorite
was originally classified H4-5 in the Antarctic Meteorite
Newsletter, 8(1).
EET83203 (545 g).?No fusion crust remains on this smooth
reddish brown chondrite (6.5 x 7.5 x 6 cm). Several deep
parallel fractures penetrate the interior, which is reddish brown
with some areas less weathered than others. Metal flecks are
visible.
EET83208 (263 g).?This meteorite (11 x 5.5 x 3 cm) is
totally covered by a smooth black fusion crust. Several
penetrating fractures and a number of regmaglypts are present.
The stone broke in half along a fracture, and the interior is
extensively weathered. Further chipping has revealed a
less-weathered dark interior.
TIL82409 (230 g).?A black to slightly weathered fusion
crust covers nearly all the meteorite (6.5 x 4.5 x 4.5 cm). The
interior has a yellowish tinge and large dark haloes from
weathering.
In thin section, all of the H5 chondrites show a generally
well-developed chondritic structure with a variety of chondrule
types, including granular olivine, porphyritic olivine, porphyri-
tic olivine-pyroxene, barred olivine, and fine-grained pyroxene.
Chondrule margins may be somewhat diffuse, tending to merge
with the granular groundmass. The latter consists largely of
olivine and pyroxene, with minor amounts of 2-phase
nickel-iron, troilite, and chromite; minute grains of sodic
plagioclase can sometimes be detected. The compositions of
the olivine (Fa1649) and pyroxene (Fs14.17) are uniform within
the individual specimens.
CLASS L5
FIGURES 6-18,6-19
ALH82104 (398 g).?This stone (6 x 6 x 6 cm) is mostly
covered with a thin black fusion crust. The exposed underlying
FIGURE 6-16.?H5 chondrites. Note the flow lines on the fusion crust of EET83200.
FIGURE 6-17.?Photomicrographs of thin sections of H5 chondrites (each field of view is 3 x 2 mm): a, EET82603; b,
TTL82409. Chondritic structure is well-developed, but chondrule margins tend to merge with the granular groundmass.
44 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
surfaces are brown and rough in texture. The interior is made
up of light gray matrix with rounded and irregular inclusions.
A few oxidation haloes and a continuous weathering rind are
present.
PCA82504 (3093 g).?Fusion crust covers 80% of the
surface of this meteorite (18x 12x9cm), and is dotted with
oxidation. Areas not covered with fusion crust are somewhat
weathered but still reveal a grayish matrix. The interior is gray,
contains small inclusions, and is dotted with oxidation haloes.
PCA82505 (3085 g).?Patches of fusion crust remain on
this meteorite (16 x 11 x 11 cm). Exposed underlying surfaces
are generally reddish brown, with lighter colored inclusions
evident. A major fracture divides the stone in half. The interior
is dark with reddish oxidation.
PCA82510 (254 g).?Some of the blackish brown fusion
crust has been plucked off, exposing the clast-rich interior of
this stone (6.5 x 4.5 x 4 cm). The matrix is medium gray and
loaded with inclusions, both rounded and irregular. The stone
is amazingly fresh; minor pockets of oxidation are present, but
they are the exception.
PCA82513 (239 g).?One face of this stone (6 x 5 x 4 cm)
is rounded and smooth, with a shiny black to weathered fusion
crust. The other faces have a dull fractured fusion crust that is
slightly blistery in places. Flow lines are present. The interior
is light gray with occasional dark gray inclusions or
chondrules. Metal flecks are visible, and are commonly
surrounded by oxidation haloes. A discontinuous weathering
rind is present.
PCA82519 (125 g).?A dull brownish black fusion crust
covers 80% of this meteorite fragment (4x6x3 cm).
Oxidation is evenly disseminated throughout the interior.
Unweathered matrix is dark gray and inclusion-rich.
TIL82400 (220 g).?This meteorite (8 x 5 x 5 cm) has only
a few remnant patches of fusion crust. The exposed underlying
meteorite is friable, has a rough texture and reddish brown
color, and shows numerous gray-green chondrules (1-3 mm
1 cm
FIGURE 6-18.?L5 chondrites.
NUMBER 28 45
FIGURE 6-19.?Photomicrographs of thin section of L5 chondrites (each field of view is 3 x 2 mm): a,
PCA82505; b, TIL82400. Chondrules are prominent, but show some integration with the granular groundmass.
diameter). The interior is light gray with some oxidation.
In thin section the L5 chondrites show a generally
well-developed chondritic structure, with a variety of chon-
drule types, including porphyritic olivine, granular olivine,
granular olivine-pyroxene, and radiating pyroxene. Chondrule
margins are commonly diffuse, tending to merge with the
granular groundmass. The latter consists largely of olivine and
pyroxene with minor subequal amounts of nickel-iron and
troilite. The compositions of the olivine (Fa23,25) and
largely-orthorhombic pyroxene (Fs1921) are essentially uni-
form within individual specimens.
CLASS E6
FIGURE 6-20
ALHA81260 (124.1 g).?A weathered fusion crust covers
about 80% of this stone (4.5 x 5 x 3 cm). The one fracture
surface has weathered to a deep reddish brown. A minute
amount of evaporite deposit is present and is most abundant
immediately underneath the fusion crust. The stone is
extremely hard to break. The interior matrix is bluish black,
with black and white crystal faces being obvious under a
binocular microscope. Only vague traces of chondritic structure
are visible in the thin section, which shows the meteorite to
consist largely of granular enstatite, a considerable amount of
nickel-iron (-20%) and minor amounts of sulfides and
plagioclase. Remnants of fusion crust are present in the section.
Weathering is minor, with a little limonitic staining around
some metal grains. Microprobe analyses show the enstatite is
almost pure MgSiO3 (CaO 0.8%; FeO 0.2%; A12O3, TiO2, and
MnO each <0.1%); plagioclase is somewhat variable in
composition, An13 19. The meteorite is an E6 chondrite; the
only other E6 chondrite from the Allan Hills, ALHA 81021,
FIGURE 6-20.?Micrograph of thin section of the E6 chondrite ALHA81260
(Field of view is 3 x 2 mm). Chondritic structure is barely perceptible, the
section showing a granular aggregate consisting largely of enstatite (white to
gray) and nickel-iron and troilite (black).
is similar but appears to be more weathered. The possibility
of pairing should be considered.
CLASS H6
FIGURES 6-21,6-22
EET83201 (1059 g).?No fusion crust remains on this
polished and rounded stone (10 x 8 x 7 cm). It was chipped
along a crack, exposing a reddish brown interior with metal
flecks. Thin section examination shows well-preserved chon-
drules up to 2 mm in diameter, enclosed in a matrix that is
intensely recrystallized to a coarse polygonal-granular texture.
46 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
1 cm
FIGURE 6-21.?H6 chondrites. Note the oxidation haloes on the surface of
TIL82405.
Plagioclase (An1314Ab80.glOr6) is well-developed and abun-
dant. Orthorhombic pyroxene (Fs 18) and olivine (Fa18.20) are
uniform in composition. Metal and troilite are subequal in
abundance. Chromite is an accessory phase.
EET83215 (510 g).?This meteorite (9 x 7 x 6 cm) consists
of three pieces (one large and two small) that fit together
perfectly. The exterior is shiny, smooth, and reddish brown
with some remnants of fusion crust. Fracturing is extensive.
The interior surfaces are heavily weathered; some metal was
noted. In thin section, chondrules up to 2 mm in diameter are
fairly well-preserved; some retain microcrystalline structure.
Plagioclase is abundant and coarse but is highly maskely-
netized. Olivine and mostly-orthorhombic pyroxene are very
uniform in composition, Fa18 and Fs19 respectively. Metal is
more abundant than troilite; at least two metal phases are
present, including some tetrataenite (approximately 52% Ni).
This meteorite was originally classified as H5-6 in the
Antarctic Meteorite Newsletter, 8(1).
TIL82405 (1001 g).?Three perfectly fitting pieces make
up this specimen (15 x 10 x 14 cm). The fusion crust is
polygonally fractured and shows oxidation haloes. The interior
is gray with small specks of oxidation. A 1-4 mm thick
weathering rind is present. In thin section chondrules are sparse
and poorly defined, tending to merge with the granular
groundmass. The latter consists largely of olivine and
pyroxene, with minor amounts of nickel-iron, plagioclase, and
troilite. Brown limonitic staining surrounds the metal grains.
Microprobe analyses give the following compositions: olivine,
Fa19; pyroxene, Fs17; plagioclase, An13.
FIGURE 6-22 (Below).?Photomicrographs of thin sections of H6 chondrites
(each field of view is 3 x 2 mm), a, TIL82405; b, EET83201. Chondrules are
present, but tend to merge with the granular groundmass.
NUMBER 28 47
CLASS L6
FIGURES 6-23,6-24
ALH81247 (104 g).?This stone (5.5 x 4 x 3 cm) is covered
with a dull, blistery fusion crust. Numerous fractures
criss-cross the surface but do not extend far into the interior.
A minute amount of evaporite deposit is present. The interior
is light gray with numerous inclusions, some more than 1 mm
in largest dimension. A weathering rind 1-9 mm thick is
present.
ALH82105 (363 g).?This stone (8 x 7.5 x 3 cm) is flat
with well-rounded edges and is totally covered with a brown
to black, polygonally fractured fusion crust showing many
oxidation haloes. A continuous weathering rind, 1-5 mm thick,
was exposed on chipping. The interior is whitish gray with a
few areas of oxidation. Abundant metal is obvious.
ALH82118 (110 g).?Remnants of black fusion crust are
present on this meteorite (5 x 4.5 x 3 cm). Elsewhere the
surface is rough and friable, with a light gray matrix dotted
with oxidation haloes around metal grains. One deep fracture
penetrates the stone.
ALH82123 (110 g).?Fusion crust covers most of this stone
(6 x 4 x 3 cm). Chondrules up to 5 mm in diameter are visible
on a fracture surface. A 5 mm thick weathering rind was
exposed when the meteorite was chipped.
ALH82125 (178 g).?A dull to lustrous fusion crust covers
this dumbbell-shaped meteorite (8 x 3.5 x 2.5 cm). The interior
is highly weathered.
ALH83101 (639 g).?This smooth rounded stone (9 x 8 x
5.5 cm) is covered with a black, polygonally fractured fusion
crust. One surface is flat and iridescent. Areas where fusion
crust has weathered away reveal a rough reddish surface with
areas of gray matrix. The interior is light gray and sparsely
dotted with oxidation. Metal flecks are numerous.
1 cm
FIGURE 6-23.?L6 chondrites.
48 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 6-24.?Micrographs of thin sections of L6 chondrites (each field of view is 3 x 2 mm): a, EET83214;
b, EET83206. Chondritic structure is barely discernible in these samples, the chondrules merging with granular
groundmass. Note the dark glassy shock veining in EET83206.
EET82605 (624 g).?This angular stone (9 x 7.5 x 5.5 cm)
is mostly covered with a black fusion crust. Chipping has
revealed a discontinuous weathering rind 1.7-2 mm thick. The
fresher interior is light in color with oxidation scattered
throughout. Several inclusions were noted.
EET82606 (981 g).?This angular meteorite (11.5 x 9 x 7
cm) is smooth and dark reddish brown with remnants of fusion
crust. Several fractures penetrate the stone. Light grayish
yellow matrix with numerous inclusions and oxidation haloes
make up the interior.
EET82607 (165 g).?This stone (5.5 x 4 x 4 cm) appears
to be one-half of what was formerly a thin oblong-shaped
specimen. Fusion crust is present on all but one face; this face
has a rough texture and a reddish brown color, with
lighter-colored inclusions or chondrules and some tiny metal
grains being visible.
EET83202 (1213 g).?This meteorite (12 x 7 x 7.5 cm) is
roughly rectangular, with about 50% of its surface covered
with fusion crust. Where the fusion crust has weathered away,
the surface is smooth and reddish brown. Fractures are
numerous. The interior is light and dark gray with abundant
millimeter-sized light inclusions. This meteorite was originally
classified as L5-6 in the Antarctic Meteorite Newsletter, 8(1).
EET83205 (470 g).?This chondrite (8x7x4 cm) has
patches of shiny fusion crust scattered over its otherwise
reddish brown surface. Several fractures penetrate the interior,
which is white to yellow-gray. A gray to reddish brown
weathering rind is present.
EET83206 (461 g).?This rectangular stone (10 x 5 x 4.5
cm) is covered with a black to reddish brown fusion crust. The
interior is grayish with a discontinuous weathering rind and
some large oxidation haloes. Glassy veins crisscross the
interior.
EET83209 (520 g).?This stone (8 x 7 x 6 cm) is rounded
and smooth with scattered remnants of fusion crust; surfaces
that lack fusion crust are reddish brown and slightly polished.
The interior is reddish to yellowish, heavily weathered but with
some visible metal flecks. Plagioclase is locally maskelyni-
tized.
EET83210 (425 g).?Patches of fusion crust remain on
approximately 30% of this meteorite fragment (9.5 x 6 x 6
cm); the other surfaces are smooth and reddish brown. The
interior is gray with some oxidation staining; metal flecks are
present. A discontinuous weathering rind is present.
EET83214 (1397 g).?This stone is 75% covered with
fractured and weathered black fusion crust; the rest of the
surface is reddish brown, has a rough texture, and shows some
yellowish matrix. A 5 mm thick reddish brown weathering rind
was exposed by chipping. The interior is gray with some
oxidation; metal is abundant.
EET83237 (882 g).?A few small patches of fusion crust
remain on this rounded reddish brown stone (10 x 7 x 5.5
cm). A small area was chipped off, exposing a fracture
(possibly annealed) that is preferentially weathered and a
yellowish matrix. Metal flecks and a few inclusions are visible.
PCA82503 (8308 g ).?This large stone (27 x 17 x 12 cm)
consists of two pieces that fit together perfectly, each covered
with a thin black fusion crust except for the fracture surface.
The bottom (as oriented on the ice) is smooth and has some
deep regmaglypts. The fracture surface has weathered to a
yellowish brown color and has a rough texture. The interior is
light gray with some oxidation haloes. A discontinuous
weathering rind, 1-2 mm thick, is present.
PCA82508 (389 g).?This is a well-rounded oblong
meteorite (9 x 5 x 4 cm) with a black fusion crust coating all
but one corner. This exposed area is somewhat weathered to a
NUMBER 28 49
reddish brown color. The interior is light gray with light and
dark inclusions (chondrules?), and shows some oxidation
haloes.
PCA82509 (285 g).?A brownish black fusion crust
completely covers this cuboidal meteorite (5x5x4 cm).
Chipping has exposed an area that is mostly oxidized but
probably not representative of the entire specimen. Fresh
material is light gray with abundant fresh metal visible.
TIL82401 (281 g).?A thin, dull black fusion crust coats
parts of three surfaces of this fragment (6.5 x 6 x 5.5 cm). The
other surfaces are smooth and reddish brown. Chondrules (1-6
mm diameter) are visible. A wide discontinuous weathering
rind was exposed on chipping, as was fresh gray matrix with
a minor amount of oxidation.
The L6 chondrites are all very similiar in their petrographic
characteristics. The thin sections show sparse, poorly defined
chondrules that tend to merge with the granular groundmass.
Principal minerals are olivine and pyroxene in subequal
amounts, together with minor quantities of plagioclase (or
maskelynite), nickel-iron, troilite, diopside, and accessory
chromite and merrillite. Microprobe analyses (see Appendix,
Table A) show essentially uniform compositions for the
principal minerals: olivine, Fa^.^; orthopyroxene, Fs19.21;
plagioclase, An1(M2. The following meteorites contain maske-
lynite: EET82605, EET82606, PCA82503, PCA82509,
EET83209.
CLASS LL6
FIGURES 6-25,6-26
EET83204 (376 g).?A polygonally fractured fusion crust
has spalled off large areas of this stone (8x6x5 cm). Areas
devoid of fusion crust have a rough texture. The interior is
gray without visible weathering, except for a discontinuous
darker gray rind and several reddish haloes. Metal flecks are
present. A thin section shows poorly defined chondrules up to
2 mm in diameter. The matrix is intensely recrystallized to a
well-developed polygonal granular texture. Metal (two-phase,
mostly as coarse patchy intergrowths) and troilite are both very
low in abundance. Minor local limonitic staining suggests mild
weathering. Olivine and orthopyroxene are essentially uniform
in composition, Fa29_31 and Fs27, respectively. Plagioclase
(Anu0r5.13) is coarse and abundant; the reason for the variation
in the orthoclase content is not known.
PCA82507 (479 g).?A black fusion crust covers most of
this stone (6 x 6 x 6.5 cm). Areas not covered by fusion crust
have a brownish color. Many chondrules are visible, the largest
being 5 mm in diameter. The interior consists of a bluish gray
matrix with white and dark gray inclusions up to 1 mm in size.
There is little obvious metal. Chondritic structure is not
prominent in the thin section examined for this description:
only a few fragments of individual chondrules are present.
This section thus may not be representative of the meteorite
FIGURE 6-25.?LL6 chondrites.
as a whole. The section shows mostly a granular aggregate of
olivine and pyroxene, with minor amounts of plagioclase,
troilite, and a little (-1%) nickel-iron. The thin section reveals
no evidence of weathering. Fusion crust (0.4 mm thick) rims
part of the section. Microprobe analyses give the following
compositions: olivine, Fa30; pyroxene, Fs^; plagioclase, Ann.
TIL82402 (476 g).?Black fusion crust covers all but the
edges of this cuboidal meteorite (7x6x6 cm). The interior
consists of light gray matrix with dark and light inclusions. In
thin section the chondrules are sparse and poorly developed,
tending to merge with the granular groundmass, which consists
largely of olivine and pyroxene, with minor amounts of
plagioclase, troilite, and a little (-2%) nickel-iron. The section
shows a brecciated structure, with medium- to fine-grained
clasts. Weathering is minor, being limited to a little brown
limonitic staining around metal grains. Microprobe analyses
give the following compositions: olivine, Fa^; pyroxene,
plagioclase, An10.
50 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 6-26.?Photomicrographs of thin sections of LL6 chondrites (each field of view is 3 x 2 mm): a,
PCA82607; b, TIL82402. The chondritic structure is almost completely erased by extensive brecciation and
integration with the granular matrix.
CLASS "H?" ACAPULCO-LIKE
FIGURE 6-27
ALHA81261 (11.8 g).?A brown and black fusion crust
encloses about 50% of this small stone (2 x 1.5 x 1.5 cm). The
interior is light to medium gray, with abundant metal grains
being visible. A weathering rind is present. The thin section
shows that this meteorite is an equigranular (grains 0.1-0.4
mm across) aggregate of approximately equal amounts of
FIGURE 6-27.?Photomicrograph of thin section of the "H?" Acapulco-like
chondrite ALHA81261 (field of view is 3 x 2 mm). This meteorite is an
equigranular aggregate consisting mainly of olivine, orthopyroxene, and
plagioclase (white to gray), with minor amounts of nickel-iron, troilite, and
chromite.
olivine and orthopyroxene, with minor amounts of nickel-iron,
plagioclase, troilite, diopside, and accessory chromite. A little
limonitic staining is present around metal grains. Microprobe
analyses show that the mineral are uniform in composition:
olivine, Fan; orthopyroxene, Wo2En87Fsn; plagioclase,
An14Or4. This specimen is identical in all respects with ALHA
77081, classed as an H? meteorite, and the two are almost
certainly paired. The mineral analyses are indistinguishable
from those of Acapulco (Palme et al., 1981).
ALHA81315 (2.5 g) is identical with ALHA 81261 in all
respects.
In the future we will refer to these meteorites, and
ALHA77081, as Class "H?" Acapulco-like.
Achondrites
EUCRTTES
FIGURES 6-28, 6-29
ALHA81313 (0.5 g).?The classification of this very small
(0.8 x 0.7 x 0.4 cm) and completely crusted stone as a eucrite
is tentative as of this writing. It is either an unusual eucrite or,
alternatively, it could be related to the shergottites. Unfortu-
nately, most of the specimen was consumed in producing a
thin section. The section shows a granular aggregate (grains
1-3 mm in maximum dimension) of colorless plagioclase
(maskelynite) and pale gray, weakly pleochroic pyroxene with
trace amounts of nickel-iron, troilite, and chromite. A vague
impression of pyroxene-rich and plagioclase-rich layers is
present, possibly suggesting a cumulate. The pyroxene appears
to be an inverted pigeonite: orthopyroxene with small blebs
of exsolved augite. Point counting gives the following volume
NUMBER 28 51
1 cm
FIGURE 6-28.?Eucrites.
percentages: pyroxene, 54; plagioclase, 46. Microprobe analy-
ses show the maskelynite to be essentially stoichiometric and
fairly uniform in composition, averaging An93 (Na^ 0.6%-
1.4%, K20 <0.4%). The orthopyroxene composition is also
fairly uniform, averaging Wo3En59Fs38; A12O3 0.4%, MnO
0.9%, TiO2 0.2%, Cr2O3 0.3%. The composition of a single
augite bleb is Wo38En42Fs20. In texture and mineral chemistry
this meteorite closely resembles the Moama monomict eucrite
(Lovering, 1975). For this reason, and because its mineral
chemistry is different from that of the shergotites, Delaney and
Prinz (Chapter 8) conclude that 81313 is a eucrite and not a
shergotite as originally suggested.
TIL82403 (49.8 g).?A shiny black fusion crust encloses
70% of this achondrite (4.7 x 4 x 2 cm). The exposed
underlying surface is gray with some white and black-and-
white clasts being visible. The top surface (as oriented on the
ice) contains numerous vugs, some as large as 5 mm in
diameter. The interior matrix is light gray with small white and
darker gray clasts. One large, coarse-grained, black-and-white
clast was exposed when the meteorite was chipped. The thin
section shows a microbreccia of angular fragments (grains up
to 1.2 mm across) of pyroxene (orthopyroxene and pigeonite)
and plagioclase, in a matrix of comminuted pyroxene and
plagioclase. Plagioclase and pigeonite locally form coarse to
fine-grained ophitic intergrowths. Trace amounts of troilite and
nickel-iron are present as minute grains. Microprobe analyses
show a considerable range of pyroxene compositions, over-
lapping both the orthopyroxene and pigeonite fields:
W03.22En3Q40FS43.5g. Plagioclase shows a considerable range
of composition, An7793.
PCA82501 (54.4 g).? This achondrite (4.5 x 3 x 3 cm) has
areas of shiny fusion crust remaining on all surfaces. Some
sides are smooth, while others are rough and contain numerous
vugs. Areas lacking fusion crust reveal the specimen to be
coarse grained, white to dark gray in color, and with some
yellowish oxidation. No individual clasts are visible. A very
52 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 6-29.?Micrographs of thin sections of eucrites (each field of view is 3 x 2 mm): a, PCA81313 (white
is maskelynite, the gray is pyroxene); b, PCA82502. Note the fine-grained unbrecciated texture; c, TIL82403.
This is a microbreccia of angular fragments of pyroxene and plagioclase, in a matrix of comminuted matrix of
the same phases; note the ophitic clast; d, EET 83234. This is a microbreccia of angular fragments of pyroxene
(pale gray) and plagioclase (white); note the dark glassy clasts.
small amount of oxidation is present in the interior. The thin
section shows an ophitic intergrowth of plagioclase and
pigeonite; the plagioclase laths average about 1 mm long. Trace
amounts of troilite and nickel-iron are present as minute grains,
the metal grains commonly being surrounded by rusty limonitic
haloes. Microprobe analyses show pyroxene compositions
ranging fairly continuously from Wo4Fs57 (orthopyroxene) to
Wo21Fs41 (pigeonite), the range in En content being quite
limited. Plagioclase compositions are in the range An80_92. The
meteorite is unbrecciated in the thin section.
PCA82502 (890 g).?This meteorite consists of 3 pieces (6
x 4.5 x 2.8 cm; 4.5 x 4.3 x 3 cm; 11 x 8.5 x 8 cm) that have
areas of extremely shiny fusion crust. These 3 pieces do not fit
together, but their field relationships and their megascopic
appearances suggest they may be paired. The interiors of the
fragments have a light gray matrix with darker gray inclusions
up to several mm across. No weathering is evident, except that
the exterior surfaces are darker gray than the interior surfaces.
The thin section shows a fine-grained ophitic intergrowth of
pigeonite and plagioclase (average length of plagioclase laths
is about 0.1 mm). Small areas of somewhat coarser material
may be partly resorbed clasts of similar composition. Trace
amounts of nickel-iron and troilite are present, as minute
grains. Microprobe analyses show pyroxene compositions
ranging fairly continuously from Wo5Fs61 to Wo34Fs36, the
range in En content being quite limited. The plagioclase
composition is An7792. The meteorite is a eucrite and is
unbrecciated in thin section; it is possibly a fine-grained variant
NUMBER 28 53
ofPCA80501.
EET83229 (312 g).?This meteorite (8 x 6 x 4 cm) is
macroscopically similar to other 1983 Elephant Moraine
eucrites, with the exception of one large (4 x 3 x 0.2 cm) brown
crystalline clast. The thin section shows a typical polymict
eucrite breccia with many pyroxene, plagioclase, and opaque
mineral clasts, and a few small lithic clasts. One lithic clast
has a feldspar phenocryst, an unusual feature for a eucritic
clast. Pyroxene clasts show various degrees of exsolution,
clouding, and compositional dispersion. Feldspar clasts show
variable amounts of shock modification. Many cracks filled
with dark weathering material crosscut the section. Micro-
probe analyses give the following compositions: pyroxene
WO4.39En2g.goFS3j.55; plagioclase An74.93.
EET83231 (66.4 g).?This stone (5.5 x 4 x 4.5 cm) is very
angular and contains numerous vesicles; no fusion crust is
present. The thin section shows a polymict achondritic breccia
containing several fine- and very fine-grained mafic clasts.
Numerous orthopyroxene crystal fragments similar to diogeni-
tic pyroxene are present; however, microprobe analyses
showed no pyroxenes of diogenitic composition. Mafic clasts
vary from coarse-grained subophitic basalts, with and without
optically-zoned pyroxene and feldspar, to uncommon glassy
clasts with fine crystallites. Microprobe analyses give the
following compositions: pyroxene Wo1_20En40.49Fs37.51; pla-
gioclase An80_92.
EET83232 (211 g).?This meteorite (7 x 8 x 4.5 cm) is
macroscopically similar to the other 1983 Elephant Moraine
eucrites. In thin section it is a typical polymict eucrite breccia
with a variety of lithic clasts. Pyroxene clasts include
pigeonites with jim scale exsolution lamellae, and both clouded
and unclouded grains are present. Some pyroxene clasts have
clear zoning that mimics the irregular clast outlines, suggesting
that they were metamorphosed after brecciation. Feldspar clasts
have shock features, and some may be recrystallized. A few
feldspar clasts have abundant inclusions of clinopyroxene up
to 20 fim in size. Mafic clasts vary from coarse to very
fine-grained, and contain cloudy exsolved pyroxene. Silica
minerals in these clasts appear both as interstitial space fillings
and as coarse lath-shaped crystals that appear to crosscut the
earlier texture. No orthopyroxene was recognized. Micro-
probe analyses give the following compositions: pyroxene
WOj.25En424gFS43.52; plagioclase An86.93. This meteorite is a
polymict eucrite similar to EETA79004 and 79011.
EET83234 (180 g).?This specimen (7.5 x 7.5 x 3 cm) is a
fragment similar to other 1983 Elephant Moraine eucrites. It
contains a corner of a brown crystalline clast similar to that in
EET 83229, and may be a piece of that stone. The thin section
shows a typical polymict eucrite with a variety of small mafic
clasts, including extremely fine-grained and glassy ones. Most
pyroxene clasts are pigeonitic. Microprobe analyses give the
following compositions: pyroxene Wo1.33En3g.^Fs^.^; pla-
gioclase An78_96. An unusual feature of this stone is the
presence of pyroxene clasts with blebby rather than lamellar
exsolution. These clasts (Wo6En58_62) may be similar to
pyroxene in Binda and are rare in Elephant Moraine eucrites.
EET83236 (6.4 g).?A shiny black fusion crust with flow
marks covers 60% of this stone (2x2x1 cm). The interior is
bluish gray with numerous white and dark clasts. Several
oxidation haloes were noted. The thin section shows a lightly
brecciated medium-grained eucrite containing pyroxene in an
ophitic to subradiate texture with generally lath-like feldspar.
The pyroxene is generally inverted pigeonite, with herringbone
textures preserved locally. Both pyroxene and plagioclase
crystals are generally clouded, although a few pyroxene grains
are quite clear. The feldspar is commonly clouded in patches
and has a mottled extinction. In places it is nearly isotropic; it
therefore has been substantially shocked. Interstitial silica
minerals, troilite, chromite, and ilmenite are accessory phases.
Microprobe analyses give the following compositions: py-
roxene, Woj.42En3j.39Fs25.59; plagioclase, An89.93.
EET83283 (57.3 g).?This stone (6 x 2.5 x 3 cm) is typical
of the other 1983 Elephant Moraine eucrites. The thin section
shows a typical polymict achondrite with lithic and mineral
clasts similar to the other Elephant Moraine polymict eucrites.
Lithic clasts are generally fine-grained basalts and breccia
fragments. The matrix is very dark and full of holes and cracks,
suggesting that it has been severely weathered. Micro-
probe analyses give the following compositions: pyroxene
Wo2_16En41.6jFs33.4g; plagioclase An8295. Some pyroxene
clasts are shocked orthopyroxene (En5565), but most are
pigeonitic with fine exsolution lamellae; none are as magnesian
as diogenetic pyroxene. This meteorite is generally similar to
EETA79004 and 79011.
HOWARDITES
FIGURES 6-30,6-31
EET82600 (247 g).?Some black pitted fusion crust is
present on one surface of this stone (7x5x5 cm). The other
surfaces are smooth and gray with small white and dark gray
inclusions. Chipping has revealed a gray interior with an
indistinct whitish weathering rind. Inclusions are small and
not very obvious. The thin section shows a microbreccia of
angular fragments (grains up to 2 mm across) of pyroxene
(orthopyroxene and pigeonite) and plagioclase, and rare
plagioclase-pigeonite clasts up to 1.5 mm across, in a
matrix of comminuted pyroxene and plagioclase. Trace
amounts of troilite and nickel-iron are present. Microprobe
analyses show a wide range in pyroxene compositions:
WOi_24En33.77Fs22.53; the grains with En >70 indicate the
presence of a diogenitic component. Plagioclase shows a
considerable range of compositions, An7993. The meteorite is
possibly paired with EETA79006.
EET83212 (402 g).?The exterior color of this achondrite
(7 x 6 x 7 cm) ranges from medium gray to brown-gray, except
for a thin, dull-black fusion crust on two surfaces. The interior
54 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 6-30.?Howardites.
is gray and rich in clasts; the latter include black fine-grained
varieties and possibly some eucritic ones. A 1 cm thick
weathering rind was exposed when the stone was chipped. The
thin section is dominated by a single, very fine-grained mafic
clast of the type common in both Allan Hills and Elephant
Moraine polymict eucrites. Numerous smaller mineral clasts
are enclosed within this large clast. Several outer parts of this
fine-grained clast that border the coarser-grained matrix are
darker than the clast interior, either because the border region
is finer-grained or because of the presence of iron oxide
weathering products. Some mineral clasts have dark fine-
grained "chill zones" around them. Pyroxene grains within this
dark clast have a variety of fine- and coarse-scale exsolution
lamellae. Feldspar grains are partly maskelynitized. One
feldspar clast has a glassy core with a feldspar rim that mimics
the shape of the clast. Heating by the mafic melt that quenched
to form the dark clast apparently caused devitrification of the
previously-shocked feldspar grains. The "normal" breccia of
83212 contains breccia clasts, basaltic clasts with clouded
pyroxenes and intergranular textures, granular mafic clasts
with recrystallized pyroxene, and some glassy material. One
clast of diogenetic orthopyroxene was observed. Micro-
probe analyses give the following compositions: pyroxene
Wo1.35En33.80Fs18.53; plagioclase An84_96.
EET83227 (1973 g).?This meteorite (13 x 10 x 9 cm) has
a rounded shape, and the outer surfaces contain numerous deep
vugs. A few millimeter-sized patches of fusion crust remain
on the gray exterior. Several different kinds of clasts are visible,
the largest being 2 cm in length; they include eucritic clasts,
black fine-grained clasts, pinkish brown fine-grained clasts,
and black and white clasts. Both interior and exterior surfaces
show numerous oxidation haloes up to 1 cm in diameter.
Interior surfaces are lighter gray than the exterior ones. The
thin section reveals a typical polymict achondrite, with one
large medium-grained mafic clast containing ophitic to radial
pyroxene/plagioclase intergrowths. The pyroxene and plagio-
clase in this clast are zoned and show little clouding. Other
clasts include breccia, shocked pyroxene, and twinned feldspar.
No maskelynite was observed. Coarse-grained lithic fragments,
fine-grained granular mafic clasts and rare glassy fragments
are also present. Microprobe analyses give the following
compositions: pyroxene, Woj.39En3Q.73FS23.54*, plagioclase,
An7898. The occurrence of pyroxene grains with En >70
indicates the presence of a diogenitic component in this
meteorite.
EET83228 (1206 g).?One small patch of black fusion crust
remains on this moderately fractured meteorite (12.5 x 11.5 x
8.5 cm). Exterior surfaces are darker gray than interior ones;
many areas are heavily oxidized. Numerous deep vugs are
present on all of the exterior surfaces. Abundant clasts of
various types are readily apparent. The thin section shows a
polymict eucrite with a variety of generally small lithic clasts.
These latter include types seen in both howardites and polymict
eucrites, ranging from medium- and coarse-granular clasts to
interstitial basalts. Microprobe analyses give the following
compositions: pyroxene, Wo1_25En32_80Fs18_54; plagioclase,
An8294. A few large orthopyroxene clasts have concentric
zoning (cores are En70_75), suggesting exchange reactions with
the surrounding breccia. These modified clasts are similar to
clasts in EETA 79004, with which this meteorite may be paired.
EET83235 (254 g).?This meteorite (7 x 6 x 4 cm) looks
similar to the other 1983 Elephant Moraine eucrites except
that it appears to be more heavily weathered, as indicated by
the presence of a thick dark gray weathering rind. The thin
section shows a very dark gray matrix that appears to have
been modified by this weathering, as sulfate is present. One
pyroxenite clast contains two large (-1 mm) pyroxene crystals
showing no exsolution; this may be a fragment of an
orthopyroxenite, but shock modification has produced inclined
extinction in the pyroxene. Feldspar clasts also show abundant
evidence of shock. Pigeonite clasts are abundant, in which the
NUMBER 28 55
FIGURE 6-31.?Photomicrographs of thin sections of howardites (each field of view is 3 x 2 mm): a, EET82600.
This is a microbreccia of orthopyroxene, pigeonite, and plagioclase in a comminuted matrix of pyroxene and
plagioclase. Note the small gabbroic clast. b, EET83228. This is similar to 82600; note the dark glassy clasts.
pyroxene shows [im-scale exsolution. One mafic clast has a
gabbroic texture and contains lath-shaped tridymite (?) crystals
over 1 mm in length. Other clasts are extremely fine-grained
or glassy. Microprobe analyses give the following composi-
tions: pyroxene, Wo1_3gEn22_72Fs26_54; plagioclase, An8696. One
large diogenitic clast was analyzed in which the pyroxene is
Wo2, En72, Fs26.
EET83251 (261 g).?This stone (7 x 5.5 x 4 cm) is another
typical example of the 1983 Elephant Moraine polymict
achondrites. The thin section shows a wide variety of clast
types, including medium- to coarse-grained gabbroic clasts
with zoned pyroxene and plagioclase crystals, fine-grained
basaltic clasts, glassy (or devitrified) clasts, breccia and
recrystallized breccia clasts, pyroxene-rich mafic and breccia
clasts, and orthopyroxene clasts (some containing orthopy-
roxene as magnesium-rich as Eng5). One coarse-grained mafic
clast contains anhedral feldspar crystals (>200 Jim in size)
with 1-10 jim-sized inclusions of clinopyroxene, a feature
generally seen only in monomineralic feldspar clasts in
Victoria Land achondrites. Microprobe analyses give the
following compositions: pyroxene, Wo1.28En37.85Fs14,58; pla-
gioclase, An80.95.
UREILITES
FIGURES 6-32,6-33
ALH82106 (35.1 g), 82130 (44.6 g).?Patches of black
fusion crust cover much of the surfaces of these two specimens.
Exposed interior surfaces are black with moderate to heavy
oxidation. Well-developed crystal faces are obvious. The thin
sections show an aggregate of anhedral to subhedral grains
(0.3-1.8 mm across) of olivine (about 60%) and pyroxene
(about 30%), with about 10% of opaque material that is in part
disseminated throughout and in part concentrated along grain
boundaries. Both olivine and pyroxene show undulose
extinction, suggesting that the specimens have been shocked.
Olivine grains are gray from submicroscopic opaque inclu-
sions, whereas pyroxene grains are clear but are extremely
fractured. The opaque material along grain boundaries consists
of graphite and secondary iron oxides. Microprobe analyses
give the following compositions: olivine is somewhat variable,
with a range of Fa^g and a mean of Fa3; pyroxene is essentially
uniform, Wo5En91Fs4, although one grain of sub-calcic augite
was analyzed that has the composition Wo36En62Fs2. The
mineralogy and textures of these two stones are typical of
ureilites, but the minerals have higher Mg/Fe ratios than those
in any ureilite so far described.
ALH82130 is essentially identical to ALH82106 in all
respects and can confidently be paired with it.
Goodrich and Berkley (1985) have reported precise determi-
nations for Ti, Al, Cr, Mn, Ca, P, and Ni in the cores of olivine
crystals from this meteorite.
ALH83014 (1.3 g).?Weathered fusion crust covers part of
this small ureilite (1 x 0.5 x 0.5 cm). Well-developed crystal
faces are apparent on other surfaces. The overall color is
reddish brown. The thin section shows an aggregate of rounded
to subhedral grains (0.6-3 mm across) of olivine with minor
pyroxene. Small platy crystals of graphite are present in
carbonaceous rims around the silicate grains. Trace amounts
of troilite and nickel-iron are present, the latter being largely
altered to translucent brown limonite. Microprobe analyses
show olivine of uniform composition (Fa18) with notably high
CaO (0.4%) and Cr2O3 (0.7%) contents; the pyroxene is a
pigeonite of composition WOgEn^Fs^. This meteorite appears
56 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
EET 83225 ,0
FIGURE 6-32.?Ureilites.
to be relatively unshocked compared to most ureilites.
PCA82506 (5316 g).?Patches of fusion crust cover 75%
of the surface of this large achondrite (22 x 16 x 9 cm); in
places this fusion crust has a blistery texture. Areas with little
fusion crust are greenish to brown; the interior is grayish green
to brown. The matrix has a blocky texture and many crystal
faces are evident. The thin section shows an aggregate of
anhedral to subhedral grains (0.6-3 mm across) of olivine and
pyroxene. Individual grains are rimmed by carbonaceous
material, included within which are thin stringers of troilite.
Trace amounts of nickel-iron have been largely weathered to
limonite. Microprobe analyses show olivine of uniform
composition (Fa21) with notably high CaO content (0.3%); the
pyroxene is pigeonite with composition Wo6En76Fs18. Some
grains show undulose extinction but this meteorite is otherwise
relatively unshocked compared to most ureilities.
Goodrich and Berkley (1985) have reported precise determi-
nations of Ti, Al, Cr, Mn, Ca, P, and Ni in the cores of olivine
crystals from this meteorite. Berkley and Goodrich (1985)
described cohenite-bearing metallic spherules. Miyamoto et al.
(1985) have estimated a cooling rate of 10?/hour from an initial
temperature of 1200? ? 50? C down to a final temperature of
800? C.
EET83225 (44.0 g).?The surface of this meteorite (5 x 2.5
x 2.5 cm) is covered with a very thin and smooth fusion crust,
which is brownish black with a dull sheen. Well-developed
crystals make up the interior, which is heavily oxidized to a
reddish brown color. The thin section reveals a medium- to
coarse-grained ureilite composed of generally clear crystals of
olivine (Fan) and pyroxene (Wo10En77Fs13), with the pyroxene
predominant in abundance. Grain boundaries are coated with
dark material containing vein-like metal, graphite, and a
yellow/red cathodoluminescent phase that is probably dia-
mond. Tiny metallic inclusions occur in some olivine and
pyroxene grains. The section shows a distinct, dimensionally-
dependent, preferred orientation of both pyroxene and olivine,
suggesting cumulus structure.
AUBRITES
FIGURE 6-34
ALH83009 (1.7 g), 83015 (3.1 g).?These two small white
specimens appear visually to be identical, and this is confirmed
by petrographic examination. Both consist almost entirely of
orthopyroxene clasts up to 5 mm in size set in a comminuted
groundmass of the same mineral. One grain was found that has
inclined extinction and appears to be clinoenstatite. Accessory
minerals include olivine, plagioclase, nickel-iron, troilite,
daubreelite, and alabandite. Rusty haloes surround the metal
grains. Microprobe analyses show that the olivine and
pyroxene are essentially pure magnesium silicates: olivine FeO
~0%-0.06%; pyroxene FeO ~0%-0.17%; CaO ~0.05%-0.46%
with a mean of 0.26%. Plagioclase is An90Or3. Silicon was not
detected in the metal. ALH83009 differs from ALHA78113
in not having the dark clasts observed in the latter meteorite.
DlOGENITES
FIGURES 6-35,6-36
ALHA81208 (1.6 g).?An evaporite deposit coats the
oxidized fusion crust that totally covered this small stone (2.1
x 1 x 0.5 cm). The stone crumbled when it was chipped,
revealing the interior to be completely weathered. The thin
section consists almost entirely of orthopyroxene clasts,
ranging up to 3 mm in maximum dimension, with accessory
chromite. The individual clasts are rimmed by dark brown to
black material, which consists in part of limonite. Remnants
of fusion crust are present in the thin section, and have an outer
crust of brown limonite. Microprobe analyses show that the
NUMBER 28 57
FIGURE 6-33.?Photomicrographs of thin sections of ureilites (each field of view is 3 x 2 mm): a, ALH82106;
b, PCA82506; c, ALH83014; d, EET83225. Note the distinctly different textures in these four ureilites.
pyroxene is essentially uniform in composition, except for
some variation in calcium content (CaO 1.2%-2.5%); the mean
composition is Wo3En72Fs25, with 0.7% A12O3, 0.14% TiO2,
and 0.6% MnO. The meteorite is classified as a diogenite,
although the amount of limonite suggests that it may be a
silicate fragment from a mesosiderite. It is therefore listed in
the Appendices to this volume as a diogenite/mesosiderite.
TIL82410 (18.8 g).?A dull, blistery fusion crust covers one
surface and is present in patches on other surfaces of this stone
(3x2.5xl.5cm). Areas without fusion crust have a pinkish
tinge. Mineral clasts up to 5 mm in longest dimension are
abundant, as are gray veins (1-5 mm wide), which stand out
FIGURE 6-34 {Left).?Photomicrograph of thin section of the aubrite
ALH83015 (field of view is 3 x 2 mm). This is a microbreccia consisting
almost entirely of enstatite crystals.
58 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
in relief relative to the surrounding material. A single green
crystal and several reddish brown grains are present. The thin
section shows angular clasts of pyroxene, up to 3 mm in
greatest dimension, in a groundmass of comminuted pyroxene.
The only other minerals noted were rare grains of plagioclase
and trace amounts (less than 1%) of nickel-iron. Remnants of
fusion crust are present along one edge. The section is stained
brown with limonite. Microprobe analyses show the pyroxene
to be uniform in composition: Wo2En74Fs24, with 0.47%
A12O3, 0.64% MnO, and 0.07% TiO2.
EET83246 (48.3 g).?Shiny patches of fusion crust cover
one surface and dull pitted fusion crust covers the opposite
surface of this meteorite (4 x 3.5 x 2 cm). A highly polished
FIGURE 6-35 (Right).?Diogenite. Areas of black fusion crust have flaked off,
revealing coarsely crystalline orthopyroxene.
EET 83246
FIGURE 6-36.?Photomicrographs of thin sections of diogenites (each field of view is 3 x 2 mm): a, ALHA81208;
b, TIL82410; c, EET83246; d, EET83247. Note the distinctly different textures in these four diogenites.
NUMBER 28 59
fracture surface exposes the greenish gray crystalline interior.
Many clasts are visible, the largest of which is 1 cm long. The
thin section shows clasts of orthopyroxene up to 9 mm long,
in a groundmass of comminuted pyroxene and accessory
chromite, troilite, and nickel-iron. The pyroxene is very
uniform in composition, Wo2 6En73 ^s^, with 0.7% A12O3 and
0.5% MnO.
EET83247 (22.5 g).?Shiny black fusion crust covers about
one quarter of the surface of this specimen (4 x 2.5 x 1.5 cm).
About half of the exterior surface has weathered to a reddish
brown, and the remainder is medium gray with large
cream-colored clasts. One fine-grained black clast was also
noted. Most of the exposed interior has been heavily oxidized.
The thin section shows a cataclastic texture, and there is a
continuous range in clast size from less than 0.1 mm to 2 mm.
The meteorite consists almost entirely of orthopyroxene, with
accessory amounts of chromite, troilite, and nickel-iron. Brown
limonitic staining pervades the section. The pyroxene is
uniform in composition, Wo2En75Fs23, with 0.6% A12O3 and
0.5% MnO.
These two EET diogenites are not paired, and appear to be
different from the other Elephant Moraine diogenite, EETA79002.
ACHONDRTTE, UNCLASSIFIED
FIGURE 6-37
ALHA81187 (40.0 g).?Several cracks penetrate the mostly
weathered interior of this stone (4.5 x 2.5 x 2 cm). Fusion crust
covers two surfaces, one of which shows remnants of flow
features. The thin section shows an aggregate of anhedral to
subhedral grains, 0.05-0.6 mm across, of pyroxene to olivine,
with about 20% of disseminated nickel-iron and minor amounts
of plagioclase, troilite, and schreibersite. The proportion of
pyroxene to olivine is estimated at 4:1. Weathering is
extensive, with veinlets and small areas of brown limonite
throughout the section. Microprobe analyses give the following
compositions: olivine, Fa4; pyroxene, Wo3En90 5Fs6 5; plagio-
clase, Anlg. The meteorite is tentatively considered to be an
achondrite (unclassified), but it may belong to the small group
of forsterite chondrites (Graham et al., 1977).
Literature Cited
Antarctic Meteorite Newsletter, 6(2).
Antarctic Meteorite Newsletter, 8(1).
Antarctic Meteorite Newsletter, 8(2).
Berkley, J.L., and C.A. Goodrich
1985. Cohenite-bearing Metallic Spherules in Ureilites: Petrology and
Implications. In Lunar and Planetary Science XVI, pages 49-50.
Houston: The Lunar and Planetary Institute.
FIGURE 6-37.?Photomicrograph of thin section of the unclassified achondrite
ALHA81187 (field of view is 3 x 2 mm). It consists mainly of olivine and
orthopyroxene, with minor plagioclase (white to gray), some nickel-iron and
troilite.
Dodd, R.T, Jr., W.R. Van Schumus, and D.M. Koffman
1985. A Survey of the Unequilibrated Ordinary Chondrites. Geochimica
et Cosmochimica Acta, 31:921-951.
Goodrich, C.A., and J.L. Berkley
1985. Minor Elements in Ureilites: Evidence for Reverse Fractionation
and Interstatial Silicate Liquids. In Lunar and Planetary Science
XVI, pages 280-281. Houston: The Lunar Planetary Institute.
Graham, A.L., A.J. Easton, and R. Hutchison
1977. Forsterite Chondrites; the Meteorites Kakangari, Mount Morris
(Wisconsin), Pontlyfini, and Winona. Mineralogical Magazine,
41:201-210.
Lovering, J.F.
1975. The Moama Eucrite?A Pyroxene-Plagioclase Adcumulate. Meteo-
ritics, 10:101-114.
Miyamoto, M., H. Toyoda, and H. Takeda
1985. Thermal History of Ureilite as Inferred from Mineralogy of Pecora
Escarpment 82506. In Lunar and Planetary Science XVI, pages
567-568. Houston: The Lunar and Planetary Institute.
Palme, H., L. Schultz, B. Spettel, H.W. Weber, H. Wanke, M. Christophe
Michael-Levy, and J.C. Lorin
1981. The Acapulco Meteorite: Chemistry, Mineralogy and Irradiation
Effects. Geochimica et Cosmoshimica Acta, 45:727-752.
Scott, E.R.D.
1985. Further Petrologic Studies of Metamorphosed Carbonaceous Chon-
drites. In Lunar and Planetary Science XVI, page 748. Houston: The
Lunar and Planetary Institute.
Van Schumus, W.R., and J.A. Wood
1967. A Chemical-Petrographic Classification System for the Chondritic
Meteorites. Geochimica et Cosmochimica Acta, 31:747?765.
Wieler, R., H. Baur, Th. Graf, and P. Signer
1985. He, Ne, and Ar in Antarctic Meteorites: Solar Noble Gasses in an
Enstatite Chondrite. In Lunar and Planetary Science XVI, pages
902-903. Houston: The Lunar Planetary Institute.
7. Descriptions of Some Antarctic Iron Meteorites
Roy S. Clarke, Jr.
This chapter provides brief descriptions of three octahedrites
and two ataxites that were collected during the 1983 field
season. The descriptions are preliminary and are based on
material prepared for publication in the Antarctic Meteorite
Newsletter. Previously unpublished chemical values by Eugene
Jarosewich are included for three of the specimens.
Octahedrites
EET83245 (59 g).?This specimen (5.5 x 2.5 x 1.3 cm) from
Elephant Moraine has a smoothly curved top surface that meets
a flat bottom surface at one side, and an irregular narrow
surface that is perpendicular to the bottom surface on the
opposite side. The shield-shaped specimen is completely
covered with a reddish brown coating of terrestrial iron oxides.
No remnant fusion crust was visible. The curved surface
appears to have been an exposed surface during weathering:
wind ablated, polished, and slightly pitted. The other two
surfaces are more deeply corroded.
A slice from near one end of the specimen yielded a 1.4 cm2
metallographic section of mainly kamacite. The wind-ablated
surface was also an ablation surface during atmospheric
passage, as it has a heat-altered zone extending at least 1 mm
into the interior. Fusion crust, however, has been removed by
weathering. The bottom surface appears to consist of either
weathered fusion crust or, more likely, weathered melt material
that filled a crack during atmospheric heating. Some interior
material along this bottom surface is also heat altered.
Microrhabdites occur in abundance throughout, with occa-
sional rhabdites and very thin lamellar schreibersites along
subgrain boundaries. One grain boundary contains schreiber-
site and heat-altered taenite. The presence of taenite in what
appears to be a relatively large mass of kamacite suggests that
this specimen is a fragment of a coarsest octahedrite. A bulk
value of 6.1 weight percent Ni is consistent with a I IB chemical
classification.
EET83333 (188 g).?This specimen (5 x 4 x 2.5 cm) from
Elephant Moraine is irregularly shaped, weathered and pitted,
Roy S. Clarke, Jr., Department of Mineral Sciences, National Museum
of Natural History, Smithsonian Institution, Washington, DC. 20560.
and mostly covered with a reddish brown coating of secondary
oxides. Tiny areas of remnant fusion crust have been preserved
in several depressions. Silicates are exposed at the bottoms of
other depressions, the largest silicate area measuring 10 x 5
mm. Ablative melting of inclusions appears to have caused
other surface depressions.
A median section through the specimen provided an area of
approximately 8 cm2 for examination (Figure 7-1). The surface
is silicate-rich, containing a number of millimeter-sized silicate
regions as well as numerous smaller individual crystals
unevenly distributed in the metal. Silicate associations
comprise 5%-10% of the surface area, two clusters having
maximum dimensions of 5 mm. The metal is polycrystalline
kamacite with individual crystals in the millimeter-size range.
Longest dimensions are normally less than 5 mm, and the
shortest normally more than 1 mm. Taenite and pearlitic
plessite areas are distributed along grain boundaries and at
junctions of three or more kamacite grains. A striking feature
of this meteorite, readily visible on the etched surface shown
in Figure 7-1, is a continuous and unusually thick circumferen-
tial heat-altered zone. The thickness of the a2 structure
averages about 5 mm and ranges from 2 to 7 mm. About half
of the area of the slice is heat altered. Although small areas of
fusion crust were tentatively identified in surface depressions,
none was recognized in polished section. Weathering is most
obvious near the surface and has penetrated into the interior
along grain boundaries.
Interior kamacite areas contain numerous straight Neumann
bands and numerous curved subboundaries. Subboundaries are
populated with occasional schreibersites, some of which have
distinct rhabdite morphologies. Kamacite areas tend to be
mottled, suggesting the presence of unresolvable microrhab-
dites. Large schreibersites occur along crystal boundaries, and
several areas of massive schreibersite occur in association with
silicate-graphite-troilite areas. Schreibersite also occurs at
taenite borders. The plessite has a well-developed pearlitic
structure and is present in abundance, consistent with a medium
or coarse octahedrite. A distinct Widmanstatten pattern is not
sufficiently well developed to obtain reliable band widths.
Silicate areas contain coarse (0.1 to 0.5 mm), colorless, and
transparent crystals associated with abundant troilite and traces
61
62 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 7-1.?Polished and etched surface of EET83333. The mottled gray rim
zone is atmospherically heat-altered to a depth of 7 mm at one point. The dark
gray inclusions are silicate-graphite-troilite areas. Kamacite grain boundaries
and areas of Widmantatten pattern may also be seen. The maximum width of
the slice is 4 cm.
of included kamacite and taenite. Graphite occurs in some of
the silicate areas, generally at silicate/metal interfaces, and it
is coarse-grained where present. All the troilite in this section
occurs with silicates. Survey electron microprobe examination
of the silicates identified plagioclase (An9), olivine (Fa5), and
pyroxene (Fs7).
This individual is a silicate-rich octahedrite, probably a
Group I iron. The unusually thick heat-altered zone suggests
an atypical passage through the atmosphere.
EET83390 (15.1 g).?This specimen (2 x 1.8 x 1 cm) from
Elephant Moraine is irregular in shape and deeply weathered.
The surface is covered with reddish brown secondary oxides,
and contains several small depressions that may have resulted
from atmospheric melting.
A median section provided an area of 1 cm2 for examination.
The structure revealed is that of a heat-affected octahedrite,
either a medium or coarse octahedrite. The few structures
available for band width measurements indicate a 1 to 1.5
mm range. Throughout the section kamacite has been
transformed to a 2 by atmospheric heating. Most of the rim of
the section is coated with layered secondary oxides from 0.1
to 1 mm thick.
Taenite and comb plessite areas also appear to have been
somewhat heat-affected. Microrhabdites are present, and
several remant Neumann bands are suggested by linear arrays
of microrhabdites. Major grain boundaries are populated over
much of their lengths by either grain boundary schreibersite
or secondary iron oxides that have invaded the interior. Some
schreibersite is associated with taenite-plessite areas.
This specimen appears to be a small individual that was
severely heated upon passage through the atmosphere. It is an
octahedrite and may prove on further study to be a Group III
iron.
Ataxites
EET83230 (530 g).?This specimen (5.5 x 5 x 5 cm) from
Elephant Moraine is a rounded, and roughly equidimensional
individual, reminiscent of a small cobble. It is completely
covered with a secondary reddish brown coating of iron oxides,
and no traces of fusion crust remain. The surface that has been
recently exposed to wind ablation in our atmosphere is slightly
smoother than the other surfaces, having rounded edges and a
slightly distorted rectangular outline.
A slice through one side of the specimen produced a 15 cm2
surface for examination. The matrix is martensitic, containing
a few widely dispersed kamacite spindles. An occasional
spindle will contain a very small schreibersite. The section's
most interesting feature is a concentration, in one half of the
slice, of about a dozen mm-sized iron phosphate crystals
(Figure 7-2), some with euhedral outline and/or enclosed
troilite. These inclusions are partially bordered by thin
kamacites.
This individual is an unusual phosphate-rich ataxite with a
bulk value of 16.1 weight percent Ni.
ILD835OO (2523 g).?This specimen (13.5 x 12 x 4 cm)
was found near Inland Forts by Bob Ackert of the University
of Maine at Orono. It was found "imbedded in loose sandy till
with abundant pebbles and cobbles of the Beacon Sandstone
and dolorite. The glacial deposit overlies the Beacon Sand-
stone. The top of the white evaporite deposit marks the depth
at which the iron was buried" (Figure 7-3). The specimen is
flat with an outline similar to that of a policeman's badge. It
has three distinct surface types. The exposed surface as found
is slightly irregular and covered with a scaley reddish brown
to dark reddish brown iron oxide coating. This surface is
bordered on the sides by a <1 cm thick band of cream-colored
soil and clay. The sides and bottom of the specimen below this
band have a much different appearance. These surfaces are
rough, range in color from black to reddish brown, and have
numerous adhering soil particles and sand grains.
A metallographic surface of 9 cm2 was prepared for
examination. The most prominant features in the martensitic
matrix are centimeter-long lamellar inclusions that appear to
be oriented according to parent taenite crystallography. They
have thin kamacite borders that occasionally enclose schreiber-
site. Most appear to have contained very thin cores that have
been replaced by oxides due to weathering. The best preserved
of these lamellae contain cores of chromite a few microns thick.
The matrix contains a high concentration of -50 jim-sized
schreibersite grains surrounded by kamacite. The orientation
of the kamacite seems to have been controlled by schreibersite
precipitation. Several troilites are present in association with
lamellar and/or equidimensional chromite. A very small crystal
tentatively identified as tridymite was found within troilite, at
its border with kamacite.
This specimen is an unusual ataxite with a bulk value of
18.9 weight percent Ni.
NUMBER 28 63
FIGURE 7-2.?A large crystal of FejtPO^ in EET83230 photographed in
reflected light. A martensitic matrix surrounds the phosphate, as does a thin rim
of kamacite. Troilite intrudes into the center of the crystal. The maximum
length between crystal edges is 0.7 mm.
FIGURE 7-3.?ILD835OO was found partially within soil near Inland Forts. The
dark surface area is typical of weathered meteoritic iron that has been exposed
to the atmosphere, developing a thin coating of pitted, reddish brown iron
oxides. The light-colored areas along the left side and bottom of the photograph
were in soil. Weathering was more severe and soil particles still adhere.
Maximum length is 15 cm.
8. Overview of Some Achondrite Groups
Jeremy S. Delaney and Martin Prinz
Introduction
Many meteorites have been collected in Antarctica during
every field season between 1976 and 1984 (Table 8-1). Prior
to 1969, only four meteorites from Antarctica were known
(Hey, 1966; Hutchison et al., 1977), but since then nearly 6700
samples have been collected from several sites all over the
Antarctic continent. Most of the samples collected are ordinary
chondrites, but numerous achondritic samples have also been
collected (Table 8-2).
Achondritic meteorites have been collected at localities near
the Transantarctic Mountains from latitudes 76?S in Victoria
Land to 80?30/S in the Thiel Mountains-Pecora Escarpment
region. For brevity, all the meteorites collected by American
expeditions to Antarctica are described as "Victoria Land"
achondrites since most of the meteorite deposits (away from
the Yamato Mountains area) are in Victoria Land. Studies of
meteorite suites are reviewed and some emphasis is given to
new samples from the 1983 season that have not yet been
widely studied. The Victoria Land achondrites sample all the
known achondritic meteorite suites and include several unique
meteorite types. (Note that the terms "sample" and "meteorite"
are not used interchangeably in this study. A sample is taken
to mean one individual fragment that has been or can be
assigned a sample number such as those in Table 8-3. A
meteorite, however, is taken to consist of one sample or several
samples that are parts of the same original fall. The number
of samples available is, therefore, larger than the number of
meteorites that are represented by these samples.)
The most common achondrite samples are the basaltic
achondrites (44 samples). Of these, the polymict achondrites
are the most abundant (31 samples). There are only seven
eucrites and five diogenites. Ureilites are the next most
abundant type (11 samples) and other achondrite groups are
represented by smaller numbers of samples. Specimens of the
shergottite-nakhlite-chassingite group have been collected in
Victoria Land but are omitted from this review. Table 8-3
includes the mesosiderite sample numbers, since these stony
Jeremy S. Delaney and Martin Prinz, Department of Mineral Sciences,
American Museum of Natural History, New York, New York 10024.
irons have a basaltic achondrite silicate fraction. The 70
achondrite samples in Table 8-3 do not represent 70 meteorites.
Many samples may be grouped as a single meteorite. In
particular, the polymict basaltic achondrites appear to be
samples of four to six meteorite showers, each represented by
one to many samples (Delaney, O'Neil, et al., 1984).
The problem of determining the number of meteorite falls
has been addressed using several different techniques: field
relations (Marvin, 1984), petrography (Delaney, Takeda, Prinz,
et al., 1983; Delaney, O'Neil, et al., 1984a; Delaney, Prinz, et
al., 1984), chemical composition (Reid and Le Roex, 1984;
Fukuoka, 1984), terrestrial ages (Webster et al., 1982; Schultz
and Freundel, 1984). The total number of samples associated
with each fall is presently unknown, but the achondrite
specimens from the Victoria Land sites (Table 8-3) are
probably samples of fewer than 30 meteorites, distributed
among eight achondrite types. More than half of the specimens
are polymict eucrites.
Basaltic Achondrites
The number of basaltic achondrite samples (eucrites,
polymict eucrites, howardites, diogenites) from Victoria Land
continues to grow rapidly. The number of well-distinguished
meteorites is, however, fairly small as most samples may
almost certainly be grouped as members of showers or as
fragments of broken meteorites.
The Victoria Land basaltic achondrites are generally similar
to the non-Antarctic meteorites. The most abundant non-
Antarctic suites are eucrites and polymict achondrites and these
are also the most important Victoria Land suites. Diogenites,
members of a closely related achondrite group, are also
represented in both suites. Statistical analyses comparing the
number of non-Antarctic falls with Victoria Land finds for
each achondrite group suggest that the Antarctic samples are
derived from a similar population to the present day meteorite
influx. In general, similarities between the Antarctic meteorite
collections and the non-Antarctic collection seem to be
increasing as the number of Antarctic meteorites increases.
65
66 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 8-1.?Number of meteorite specimens collected at Antarctic localities.
Year
1969
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
Total
Van-Year
1969
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
Total
Allan
Hills
-
-
-
9
307
262
54
32
315
145
102
17 +
1243
Outpost
Nun.
_
-
-
-
-
-
-
-
1
-
-
-
-
1
Bates
Nun.
-
-
-
-
-
4
-
-
-
-
-
-
4
Pecora
Esc.
_
-
-
-
-
-
-
-
-
-
29
-
-
29
Belgica
Mtn
-
-
-
-
-
-
5
-
-
-
-
-
5
Purgatory
Peak
_
_
-
-
-
1
-
-
-
-
-
-
-
1
Derrick
Peak
-
-
-
-
-
9
-
-
-
-
_
-
9
Reckling
Peak
-
-
-
-
-
4
15
68
-
-
-
-
87
Inland
Forts
-
-
-
-
-
-
-
-
-
-
1
-
1
Taylor
Glac.
-
-
-
-
-
-
-
-
-
1
-
-
1
Elephant
Moraine
-
-
-
-
-
-
10
-
-
17
84
-
Ill
Thiel
Mtn
-
-
-
-
-
-
-
-
-
16
-
-
16
Meteorite
Hills
_
-
-
-
-
-
28
-
-
-
-
_
-
28
Yamato
Mtn
9
12
663
307
_
-
-
3676
13
133
211
42
58
5124
Mount
Baldr
-
-
-
2
-
-
-
-
-
-
_
-
2
NOTES.?Achondrite classes not represented in Antarctica: 1, nakhlites; 2, angrites; 3,
chassignites. Nun. = Nunatak; Glac. = Glacier, Esc. = Escarpment; Mtn = Mountains.
Meteorites found before 1969: Adelie Land; Lazarev; Thiel Mtn; Neptune Mtn.
TABLE 8-2.?Number of achondritic meteorites from Victoria Land.
Type
Lunar
Shergottites
Aubrites
Ureilites
Winonaites
Eucrites
Diogenites
Polymict
eucrites
Allan
Hills
1
1
3
-
1
1
1
2-3
Elephant
Moraine
_
1
-
1
-
1
3
2-3
Reckling
Peak
_
-
-
1
-
2
-
-
Pecora
Escarp.
_
-
-
1
-
2
-
-
Thiel
Mtn
_
-
-
-
-
1
1
-
NUMBER 28 67
Type
TABLE 8-3.?Victoria Land achondrites sample numbers.
Numbers
Lunar A81005
Winonaites A81187
Aubrites A78113, A83OO9, A83015
Shergottites A77005, E79001
Diogenites A77256, E79002, T82410, E83246, E83247
Eucrites R80204, R80224, A81011(?), A81313(?), T82403, P82501,
P82506, E83236
Ureilites A77257, A78019, A78262, R80239, A81101, P82506,
A82106, A82130, A83014, E83225
Mesoside- A77219, R79015, R80229, R80246, R80258, R80263,
rites R81059,R81098(?), A81028
Polymict A76005, A77302, A78006(?), A78040, A78132, A78158,
eucrites A78165, A79017, A80102, A81001(?), A81006, A81007,
A81008, A81OO9(?), A81010, A81012, E79004, E79005,
E79006, E79011, E82600(?), E83212, E83227, E83228,
E83229, E83231, E83232, E83234, E83235, E83251,
E83283
NOTES.?Numbers followed by (?) have been given different classifications
in Antarctic Meteorite Newsletters. A, E, P, R, T, are Allan Hills, Elephant
Moraine, Pecora Escarpment, Reckling Peak, Thiel Mountains, respectively.
COMPARISON OF ANTARCTIC AND NON-ANTARCTIC BASALTIC
ACHONDRITES
Although there are overall similarities, there are some
differences in detail, between the Antarctic and non-Antarctic
samples. The most important of these are between the suites
of polymict achondrites. These meteorites sample a continuum
of breccias that represent the crust and regolith of at least one
basaltic achondrite parent body, and are dominated by two
lithological components that are present in varying proportions:
orthopyroxenites and mafic rocks. Minor amounts of other
rock types are also present. The presence and amount of these
two main components is used as a basis for classifying the
polymict basaltic achondrites and, therefore, a brief description
of each is given.
ORTHOPYROXENITES.?This component is represented by
mineral clasts of orthopyroxene with compositions similar to
diogenetic pyroxene (En70_75) and very rare lithic clasts of
orthopyroxenite containing variable but minor amounts of
olivine, chromite, troilite, and metal. The range of pyroxene
compositions (En70.86) sampled by the polymict achondrites is,
however, greater than that of the diogenites. The orthopyroxe-
nite component of these meteorites, therefore, cannot be simply
equated with the diogenites as they are represented by the
present meteorite collections. Study of pyroxene-rich achon-
drites from the Yamato collections of Antarctic achondrites
has extended the range of compositions in pyroxenitic
meteorites toward more iron rich pigeonitic compositions
(En6070) (Takeda and Mori, 1984). Some of these Yamato
samples are comparable with the Binda pyroxene-rich cumulate
and appear to represent a transitional facies between the
orthopyroxenite and mafic components of polymict achon-
drites (Takeda and Mori, 1984). There are no unbrecciated or
monomict achondrites as magnesian as the most magnesian
orthopyroxenes (En80+) found in polymict achondrites.
MAFIC CLASTS.?The most common type of mafic clast in
polymict achondrites is eucritic and has approximately equal
volumes of pigeonite and plagioclase with compositions
similar to the eucrites (En30.40Wo4.15 and An80_92, respectively).
There is, however, a great variety of mafic clast types present
in these meteorites. This variability is not as well documented
as the typical eucritic meteorites. Numerous studies have
recognized, however, that these clasts represent an additional
important suite of mafic rocks from the basaltic achondrite
parent body (Bunch, 1976; Delaney et al., 1981; Dymek et al.,
1976; Simon and Papike, 1983; Treiman and Drake, 1984).
These clasts extend the compositional ranges for the major
minerals beyond the limited range of clasts in the eucrites, and
provide greater insight into the nature of the solid-liquid
fractionation on the basaltic achondrite parent body than is
available by studying the eucrites alone.
Prior to the discovery of polymict achondrite breccias in
Antarctica, the non-Antarctic polymict breccias were generally
referred to as howardites, and all the non-Antarctic examples
contain clasts of both orthopyroxenitic and mafic material.
Some of the first polymict achondrites found at both Yamato
Mountains and Allan Hills in Antarctica differ from those
previously known, however, as they contain a variety of mafic,
or eucritic, clast types but no orthopyroxenite component
(Miyamoto et al., 1978; Takeda et al., 1978; Olsen et al.,
1978). For this reason, they were called polymict eucritic
breccias or, more commonly, polymict eucrites. Further study
revealed rare orthopyroxene grains in some of the Yamato
samples, and when the first Elephant Moraine samples were
studied a small orthopyroxenite component was recognized in
EET79005 and 79006 (Simon and Papike, 1983; Delaney et
al., 1982). As more Antarctic samples become available, it is
clear that these polymict basaltic achondrites have continu-
ously variable amounts of the two main components. The
most orthopyroxene-rich meteorite appears to be Yamato 7308
(with 76% vol. opx.) and the most mafic clast-rich meteorite
is the Allan Hills I meteorite represented by ALHA 76005,
77302, 78040, and numerous other specimens. This Allan Hills
meteorite contains no orthopyroxenite component. Delaney,
Takeda, and Prinz (1983a) suggest that those meteorites
containing more than 90% (vol.) of eucritic, or mafic, material
be called polymict eucrites and those with less than 90% be
called howardites. Mason (1983b) suggests, alternatively, that
meteorites containing any orthopyroxenite component should
be called howardites.
As a group, the non-Antarctic polymict achondrites all
contain an orthopyroxenite component and most have more
than 10% (vol). The Victoria Land polymict achondrites, in
contrast, contain either no orthopyroxene or less than 10%
(vol.). Polymict achondrites with abundant orthopyroxene are,
however, found in Antarctica at Yamato Mountains, especially
68 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
in the 1979 collections (Takeda et al., 1984; Delaney, Prinz,
et al., 1984). Indeed, the Victoria Land and Yamato collections
together sample a greater variety of polymict basaltic
achondrites than do the non-Antarctic collection.
A number of clast types in the Antarctic samples has been
described by Delaney, O'Neil, et al. (1984). All of these clast
types have been recognized in both non-Antarctic howardites
and polymict eucrites. At present, no clast type is known that
occurs only in meteorites from one part of the world. The
Victoria Land, Yamato, and non-Antarctic polymict basaltic
achondrites are, therefore, believed to be a part of a continuum
of breccias that sample a significant part of the regolith of their
parent body or bodies.
NEW SAMPLES.?Samples of all the basaltic achondrite types
are represented in the Victoria Land collections but the
polymict eucrites are by far the most abundant. In the 1983
season, 13 basaltic achondrites were collected at the Elephant
Moraine meteorite deposit. Two diogenites (EET83246;
83247), one eucrite (83236), and 10 polymict basaltic
achondrites were collected (Table 8-1). Preliminary descrip-
tions of these samples are given in Antarctic Meteorite
Newsletter, 8(1), 1985.
Diogenites
The two new Elephant Moraine diogenites increased the
number of Victoria Land samples to five (Table 8-3). This is
a small number of samples compared with the 35, or more,
diogenite samples recovered at Yamato Mountains (Takeda et
al., 1981). Because the total number of meteorites represented
both at Yamato Mountains and Victoria Land is either four or
five, there is a similar number of meteorites available from
each site. Unlike the Yamato diogenites, however, the Victoria
Land samples are similar to most non-Antarctic diogenites as
they are brecciated orthopyroxenites dominated by En70.75
pyroxene.
Eucrites
The eucrite EET 83236 is the eighth recovered from Victoria
Land and Thiel Mountains localities. It is a typical eucrite
containing lithic fragments with ophitic to radiate textures. It
is mineralogically similar to the other Antarctic and the
non-Antarctic eucrites (Tables 8-3 and 8-4, Figure 8-1, cf.
Delaney, Takeda, and Prinz, 1984).
The Victoria Land eucrites appear to represent eight different
meteorite falls as all have distinctive textures or mineral
compositions, or are separated by long distances from similar
meteorites. The eucrites, therefore, differ significantly from the
polymict achondrites as they are not found as groups of
samples at a single locality. Each of the Antarctic eucrites has
uniform Fe/(Fe+Mg) in its pyroxene and thus has been
thermally processed in the same way as most non-Antarctic
eucrites. Allan Hills 81011 is unique as it appears to be a
genomict breccia (Mason, 1983a). Treiman (1984) describes
81011 as a polymict eucrite having equilibrated basaltic clasts
in a vesicular glass matrix, and as representing a major impact
on the parent body. Allan Hills 81313, which contains
maskelynite and was described as a shergottite, is also
significantly different. Other eucrites (e.g. Padvarninkai;
Reckling Peak 80204) contain variable amounts of maskelynite
and, because mineral compositions in ALH81313 are identical
to those in typical eucrites and quite different from any
shergottite, it is suggested that this sample be classified as an
eucrite.
Allan Hills 81001 was classified as an anomalous eucrite
as it differs from most eucrites in several ways (Mason, 1983a).
This sample closely resembles the fine-grained eucritic clasts
typically found in Allan Hills polymict eucrites. It may be a
large clast that separated from the Allan Hills I polymict eucrite
shower during atmospheric descent and landed on the Antarctic
ice as a separate object (Delaney, 1984). Whether this sample
should be treated as a separate meteorite fall or grouped with
the Allan Hills I polymict eucrite is not clear. Both approaches
to classifying this sample have disadvantages. Perhaps further
study can demonstrate that Allan Hills 81001 should be treated
as a unique meteorite, but we assume here that it is a member
of the Allan Hills polymict eucrites.
There are eight Victoria Land eucrites, represented by eight
samples. In contrast, there are four to six Victoria Land
polymict eucrites represented by at least 32 samples. Similar
sample/meteorite ratios are calculated for the Yamato achon-
drites. Delaney (1984) has suggested that the eucrites were
strong meteorites that are represented by individual falls
whereas the polymict eucrites were friable and fell as showers.
Statistics for known eucrite falls support this suggestion as
showers are uncommon among the known eucritic falls.
Polymict Achondrites
Polymict basaltic achondrites are the most abundant Victoria
Land achondrites. Of the 40 or more samples known, 16 are
from Allan Hills and 16 from Elephant Moraine (Table 8-3).
The Allan Hills and Elephant Moraine suites together appear
to represent four or five meteorites that have been called Allan
Hills I, Allan Hills II, Elephant Moraine I, and Elephant
Moraine II by Delaney, O'Neil, et al. (1984). The samples
collected at Elephant Moraine during the 1983 field season
represent both Elephant Moraine I and II meteorites on the
basis of their textures and mineral composition. Feldspar Na/)
contents and pyroxene compositions, generated by electron
microprobe modal analysis, for the Elephant Moraine 1983
series are given in Figures 8-2 and 8-3. These data were
generated under the same conditions as the data presented by
Delaney, O'Neil, et al. (1984) for all the polymict eucrite suites
previously identified and may be compared directly with those
results (Figures 8-4 and 8-5).
Most polymict eucrites have pyroxene and feldspar of
NUMBER 28 69
TABLE 8-4.?Modes of Victoria Land 83-series achondrites (A = aubrite, alab = alabandite, D = diogenite, db =
daubreelite, E = eucrite, gyps = gypsum or anhydrite, nd = not detected, PA = polymict basaltic achondrite, tr = trace,
unrep = unrepresentative sample).
Number
83009 A
83015 A
83212 PA
83227 PA
83228 PA
83229 PA
83231 PA
83232 PA
83235 PA
83236 E
83237 PA
83246 D
83247 D
83251 PA
83283 PA
Number
83009 A
83015 A
83212 PA
83227 PA
83228 PA
83229 PA
83231 PA
83232 PA
83235 PA
83236 E
83237 PA
83246 D
83247 D
83251 PA
83283 PA
Oliv
0.4
2.96
0.3
nd
0.10
nd
nd
0.25
nd
nd
nd
0.43
nd
Kam
0.2
0.3
nd
nd
nd
nd
nd
nd
nd
Opx
99.0
95.1
15.2
19.2
19.7
13.1
26.8
24.6
24.6
98.2
98.7
22.6
22.7
Taen
nd
nd
nd
nd
nd
nd
Pig
0.2
0.4
43.8
28.5
33.3
33.7
16.1
14.2
12.0
0.63
nd
29.6
30.4
Others
db, alab
db, alab
unrep
gyps
Aug
nd
nd
4.7
6.2
7.3
8.3
11.8
12.8
14.0
0.21
nd
8.2
7.9
Feld
0.2
1.04
33.5
41.7
36.0
38.1
40.0
39.3
40.9
nd
0.1
34.3
35.5
Area (mm2)
92
103
48
107
91
117
118
136
150
86.7
SiO2
nd
nd
2.0
3.7
3.0
4.9
4.0
6.6
7.4
0.8
1.0
3.2
2.9
Em
nd
nd
0.17
0.31
0.57
1.3
1.1
1.05
0.69
nd
nd
0.37
0.24
Chr
nd
nd
0.26
0.50
0.05
0.30
0.05
tr
0.05
0.21
0.2
0.11
0.06
Phos
nd
nd
nd
0.05
0.05
nd
0.11
nd
0.05
nd
nd
0.05
nd
Trail
tr
tr
tr
0.3
tr
0.4
0.27
nd
nd
nd
EET 83236
= 276
FIGURE 8-1.?Modal distribution of pyroxene composition in the eucrite
EET83236, shown in a standard pyroxene quadrilateral. Dotted contour
includes 95% of modal analyses; solid line includes 50% of analyses.
70 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
83236
n = 312
83231
n = 220 83251
n= 165
83232
n = 189 J]
83283
n = 185
0.4 1.0 1.6 2.2 2.8
%Na2O
0.4 1.0 1.6 2.2 2.8 3.4
%Na2O
FIGURE 8-2.?Modal distribution of Na2O in basaltic achondrite feldspar. Data
are generated by a rapid electron microprobe modal technique and are of low
precision. Area of each histogram totals 100%.
variable composition (Delaney, O'Neil, et al., 1984). The
feldspar usually varies between An80 and An95 with most
having compositions near An90 (Nap -1.0-1.2% wt.). The
pattern of feldspar composition distribution can be used to
distinguish between the more sodic Yamato and the more calcic
Victoria Land polymict eucrites (Delaney, O'Neil, et al., 1984),
but among the Victoria Land suites only Allan Hills I and Allan
Hills II may be distinguished on the basis of feldspar
composition alone (Figure 8-5). The two Elephant Moraine
groups recognized by Delaney, O'Neil, et al. (1984) have
indistinguishable feldspar distributions (Figures 8-2 and 8-5).
The pyroxene distributions in these meteorites are distinct,
however, and are used to assign the samples to the appropriate
suites.
Delaney, O'Neil, et al. (1984) described pyroxene from the
Allan Hills I suite as dominated by homogeneous, eucritic
pyroxene (i.e., lying on tie lines, between orthopyroxene and
pigeonites (Ery^Wo^) and augites (~Wo4(M5) (Figure 8-4),
with compositions appropriate for equilibration at 800?-900?
C (Lindsley and Andersen, 1983). In addition, Allan Hills I
contains minor zoned pigeonite of the "Pasamonte-type"
(Takeda, 1979). Allan Hills II (78006) differs in having almost
no zoned pigeonite. Instead, it contains about 2%-4% of
homogeneous magnesian orthopyroxene (plus olivine), similar
to diogenitic pyroxene, and small amounts of pyroxene with
compositions between the eucritic and diogenitic ranges
(Figure 8-4).
The two Elephant Moraine suites have different pyroxene
distribution patterns (Figure 8-4). Elephant Moraine I is
dominated by compositionally homogeneous pyroxene
(En40_45) with minor amounts of the other pyroxene compo-
nents described by Takeda (1979) and Delaney, O'Neil, et al.
(1984). This suite has a variety of pyroxene textural types in
its mineral and Iithic clasts. All but a few clasts appear to
contain homogenized (with respect to Fe and Mg) pyroxene
that reflects the influence of a late metamorphic overprint
(Delaney et al., 1982). The Elephant Moraine II suite has much
more variable pyroxene compositions. This suite has the
textural and compositional variability of the most abundant
non-Antarctic polymict achondrites, the howardites. All the
textural types described by Takeda (1979) and Delaney,
O'Neil, et al. (1984) occur in Elephant Moraine II, and the
entire pyroxene compositional range from En^WOj to
En20Wo40 is present. This suite differs from the howardites,
however, as it contains in excess of 90% of eucritic components
and only 2%-7% of diogenitic pyroxene. It, therefore, falls
within the modal composition range of polymict eucrites as
defined by Delaney, Takeda, and Prinz, 1983b, and Delaney,
Takeda, Prinz, et al., 1983.
The 10 new polymict achondrites from the 1983 Elephant
Moraine collections appear to fit into the two previously
described suites from this locality. Three samples have
distribution patterns for their pyroxene compositions that are
similar to Elephant Moraine I. The modal pyroxene data for
these samples are given in Figure 8-3. (EET83212 is omitted,
as the original thin section studied is dominated by a single
mafic clast and is, therefore, unrepresentative). The Elephant
Moraine I suite is dominated by pyroxene compositions
scattered about tie lines based at En4(M5 Wo^ with a sparsely
populated tail toward more magnesian compositions (Figure
8-4) (Delaney, Takeda, and Prinz, 1984). This distribution is
seen in EET83235, 83237, and 83283 (Figure 8-3).
The modal compositions of many polymict eucrite samples
are given by Delaney, Takeda, and Prinz (1984) and modes of
the Elephant Moraine-83 series are given for comparison
NUMBER 28 71
EET 83228
N=32I
\ \\ \
\ \\EET 83237 \ \
N = 300
EET 83231
N=3I3
) \
EET 83283 .'
N=379
FIGURE 8-3.?Modal distribution of pyroxene compositions in the 1983 Elephant Moraine polymict eucrites.
(Low precision data from automated modal program.) Contours as in Figure 8-1.
(Table 8-4). No major differences exist between the 83-series
samples and the previously described samples (Delaney,
Takeda, and Prinz, 1984). It is difficult to distinguish Elephant
Moraine I and II on the basis of the modal abundance of the
minerals alone (Table 8-4) although the distribution of
pyroxene compositions is distinct in the two suites (Figures
8-3 and 8-4). The new samples extend the modal ranges of the
two Elephant Moraine suites and confirm the indications that
modal heterogeneity exists within each suite as seen previously
within the Allan Hills I suite of polymict eucrites (Delaney,
Takeda, and Prinz, 1984).
On the scale of a thin section there are detectable modal
differences between different samples in all the Victoria Land
suites, but when the distribution of mineral compositions
within individual thin sections are compared, each suite has a
coherent signature from sample to sample. The data presented
for the Elephant Moraine 1983 samples, however, seem to
lessen the differences between Elephant Moraine I and II. All
of these samples may, therefore, be fragments of a single
heterogeneous meteorite, with variable degrees of metamor-
phism detectable in different samples rather than two distinct
meteorites, as previously suggested (Delaney et al., 1984c).
72 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 8-4.?Modal distribution of pyroxene compositions in suites of Antarctic polymict eucrites. Figure
includes three non-Antarctic polymict achondrites for comparison. Contours as in Figure 8-1.
In general, all the Victoria Land samples are heterogenous
when compared on the scale of a thin section (2.5 cm diameter),
but comparison of chemical analyses of larger samples (e.g.,
Reid and Le Roex, 1984) may indicate that they are chemically
uniform at the "hand sample" scale.
Because the polymict basaltic achondrites sample a contin-
uum of breccias made up of several lithic components, the
assignment of a rigidly constrained rock name is difficult. Two
names are presently in common use: polymict eucrite and
howardite. No consensus presently exists with regard to the
usage of these terms, but polymict eucrites are dominated by
clasts of various eucritic components while howardites contain
additional pyroxenitic (or diogenitic) components. Using the
nomenclature scheme of Delaney, Takeda, Prinz, et al. (1983)
all the Elephant Moraine 83-series samples are "polymict
eucrites." Using the Mason (1983b) scheme, the samples of
Elephant Moraine II are "howarditic." Similar ambiguities
(caused by the different nomenclature schemes) occur when
the various nomenclatures are applied to other Victoria Land,
Yamato, and non-Antarctic polymict basaltic achondrites.
Comparison of the Victoria Land polymict achondrites with
the Yamato Mountains collection and the non-Antarctic
specimens reveals several differences from suite to suite. All
three collections of meteorites contain polymict achondrites
containing a variety of clast rock types. In both of the major
Antarctic collections (Yamato Mountains and Victoria Land)
the vast majority of lithic clasts may be descibed as eucritic.
Pyroxenitic material is rare or uncommon. The non-Antarctic
collection, on the other hand, contains many meteorites with a
large proportion of pyroxenitic clasts (10%-50% of the
NUMBER 28 73
original meteorite) while those dominated by eucritic material
are less common. Only about 25% of all non-Antarctic
polymict basaltic achondrites are dominated by eucritic clasts
(i.e., contain more than 90% of eucritic material). The most
characteristic lithic clast type in the Antarctic meteorites is
unequilibrated eucritic, described by Takeda et al. (1978) as
"Pasamonte-type." These clasts, which are usually less than 1
cm in diameter, are found in all the Antarctic suites but are not
as common in the non-Antarctic collections. The non-Antarctic
polymict breccias generally have not been characterized as
well as the Antarctic samples. Small lithic clasts of unequili-
brated eucritic material have been recognized in many
non-Antarctic polymict achondrites but they do not appear to
be as abundant or as large as in the Antarctic collections.
Ureilites
Two new ureilites (ALH83014 and EET83225) were
collected in the 1983 field season. There are now 10 ureilites
from Victoria Land (with a total mass of 7.6 kg). Modes of
nine Victoria Land samples are given in Table 8-5 along with
the mean mode and standard deviation of the non-Antarctic
ureilites described by Berkley et al. (1980). The range of modal
composition in the Victoria Land ureilites is essentially
identical to that of non-Antarctic ureilites. EET83225 is one
of the most pyroxene-rich, having similar olivine/pyroxene
ratios to Dingo Pup Donga and the paired ureilite samples
ALHA82106 and 82130. ALH83014 is a ureilite having a
generally unshocked texture with euhedral to subhedral
graphite crystals present in veins between the silicates (Figure
8-6). Texturally and modally (Table 8-5) ALH83014 is similar
to ALHA78019. It has less metal + sulfide + graphite, however,
and the cores of silicate mineral grains are more magnesian
than in 78019. ALH83014 may be the second relatively
unshocked ureilite found with euhedral graphite blades but
pairing with ALH78019 may be demonstrated by further work.
Detailed chemical and petrographic study of these two samples
should provide useful constraints on the origin of the intensely
shocked ureilites. Olivine cores in 83014 are generally Fo81_83
with forsterite rims (Fo90_98) while pigeonite cores are
En76-78W?8-9-
EET83225 has a well-developed preferred orientation of its
olivine and pigeonite grains with carbonaceous material,
including diamond, limited to the grain boundaries. Unlike
other pyroxene-rich ureilites (e.g., ALHA82106 and 82130)
EET83225 does not contain any augitic pyroxene. None of the
Victoria Land ureilites resembles the augitic ureilite Yamato
74130 described by Takeda et al. (1979). Some of the Victoria
Land ureilites contain only pigeonitic pyroxene whereas others
have more variable pyroxene compositions indicating that
some exsolution'and possibly some inversion to orthopyroxene
occurred. (Note that the assignment of pyroxene "polymorphs"
in Table 8-4 is based only on composition and does not imply
that three polymorphs have been identified crystallographi-
cally. Indeed some of the "pigeonite" identified by this
program may represent analyses of overlapping orthopyroxene
and augite. See Delaney, O'Neil, et al. (1984) for more detail
of methods applied.)
Compositional variation of the olivine in the Victoria Land
ureilites is summarized in Figure 8-7. These data are of low
precision as they are generated by electron microprobe modal
analysis but they are consistent with published analyses and
provide an unbiased estimate of the modal olivine composi-
tional range. Only two of the analyzed ureilites have the same
olivine distribution pattern (ALHA82106, 82130) suggesting
that these are the only paired samples in this group (Mason,
1984). Study of the distribution of pyroxene compositions is
in progress. Ureilites generally have olivine in the Fo80 to Fo90
range with a few more magnesian compositions present. These
patterns reflect the variable reduction of iron-bearing olivine
to forsterite plus metal that is typical of these meteorites.
Reckling Peak 80239 has a distinctive bimodal distribution
with about 25% of its olivine analyses more magnesian than
Fo95. This distribution suggests that evidence of reduction
reactions is particularly well preserved in this sample. The
paired samples, Allan Hills 82106 and 82130, have more
magnesian olivine but it is not clear if these compositions were
formed by the late redox processes that are typical of ureilites
rather than early magmatic reduction processes. The high
augite content of these samples (Table 8-4) is, however,
consistent with their position on the reverse fractionation trend
described by Goodrich and Berkley (1985). They defined
Fe-depletion in later formed silicates as a result of reduction
by magmatic graphite.
Subhedral-euhedral graphite grains have been described in
only two ureilites (ALHA78019 and ALH83014) although all
ureilites have interstitial graphite, often containing diamond
or lonsdaleite (Berkley and Jones, 1982). The presence of
euhedral graphite grains in ALHA78019 has been interpreted
as representing crystallization of magmatic carbon. Similarly
the presence of round inclusions in olivine, containing
kamacite, troilite, and cohenite (Fe3C), in at least four Victoria
Land ureilites (ALHA78019, 77257, 78262, and RKPA 82506)
is also believed to support crystallization from a carbon
saturated silicate melt (Berkley and Goodrich, 1985). Study
of these and other minor phases in ureilites (e.g. Berkley and
Goodrich, 1985; Goodrich and Berkley, 1985) should provide
useful insight into these meteorites.
Aubrites
The one aubrite found between 1976 and 1982, Allan Hills
78113, is a polymict breccia showing similarities to Cumber-
land Falls and containing chondritic inclusions that have been
described as F-chondritic (Verkouteren and Lipschutz, 1983),
as unequilibrated enstatite chondrites (Prinz et al., 1984), and
as reduced LL chondrites (Kallemeyn and Wasson, 1985). The
74 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
a)
b)
c)
d)
0.4 1.2
Allan Hills I
76005
N = I38
78040,61
N=259
81006,19
N = 2I5
81007,6
N = IO3
81009,17
N=I73
f) ?' Allan Hills81010,8
N = 2I8
I
g)
h)
i)
2.0
Na20%
2.8 3.6
81012,5
N = 263
Allan Hillsl
78006,10
N=253
Bialystok
AMNH 4007
NMNH 382
N=426
Macibini
4560-1
= 357
FIGURE 8-5.?Modal distribution of feldspar composition in suites of Antarctic polymict eucrites. Area of
histogram is 100%. (Scale bars are the same for all figures, with the left margin at 0.4 in all cases.)
aubritic host was described by Score et al. (1982) and Watters
and Prinz (1979). Volatile trace elements were analyzed by
Biswas et al. (1981) and Verkouteren and Lipschutz (1983).
The mineralogy of the ALHA 78113 host is typical of aubrites.
Two new aubritic samples from Allan Hills were identified
in the 1983 collection. These samples (ALHA83009 and
83015) are quite similar to each other but appear to be distinct
fromALHA78113.
NUMBER 28 75
k) Elephant Moraine79004,32
N=II9
Yamato
74I59.7IA
N=IO6
79005,37
N=I46
r)
m) 82600,10
790020,81 FC
= 85
N=I65
n) JodzieFMNH 1371
t)
N = 23I
791186,81-3
N=2I4
0) Petersburg
2251-1
U)
N=I23
791960,91-
N=295
FIGURE 8-5.?Continued. 0.4 1.2 Na2O2.0Vo 2.8
Summary
The Victoria Land achondrites have provided impetus to
research on achondritic meteorites in general, by providing
sufficient samples of uncommon meteorite types that detailed
study is now easier. Initially, many Antarctic achondrites
appeared to be different from the non-Antarctic collections
but, as more research is published and more Antarctic
meteorites are found, it is clear that the Antarctic and
non-Antarctic collections are sampling similar populations of
meteorites.
The basaltic achondrite samples increase the known
diversity of these meteorites. These meteorites contain clasts
of many rock types ranging from magnesian orthopyroxenites
(En^gsWO}) with minor olivine (as magnesian as Fo90) to very
iron rich mafic clasts dominated by En30Wo15_30 pigeonites and
76 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 8-5.?Modes of Victoria Land ureilites (nd = not detected, tr = trace. Non-Antarctic data from Berkley
et al., 1980.)
Number
83225
83014
82506
82130
82106
81101
80239
78019
77257
Oliv
52.1
85.2
67.1
46.1
47.9
58.9
59.0
76.0
81.5
Non-Antarctic ureilites:
Mean
S.D.
65.9
10.4
Opx
2.9
1.5
3.6
29.2
31.8
17.1
7.1
4.6
7.6
Pig
40.8
11.3
24.3
11.9
8.9
13.8
29.0
8.8
5.8
31.9
10.6
Aug
nd
nd
nd
7.6
6.4
0.24
nd
0.3
0.1
Feld
nd
nd
nd
nd
0.1?
nd
tr?
nd
0.1?
-
-
SiO2
0.1
0.1
0.5
nd
nd
0.5
nd
nd
nd
0.1
-
Sulf Metal Other
Combined
4.1
1.9
4.5
5.1
5.0
8.9
4.9
10.6
4.9
0.9 1.2
0.6 1.1
Area
mm2
60
64
180
154
109
162
74
54
36
-
-
Number
points
725
879
641
860
990
847
888
828
717
-
-
P.t.s
LIB
,25
,10
,6
,11
,6
,15
,42
-
-
'Catalogue number of polished thin section examined in this study; LIB = Library section.
FIGURE 8-6.?Euhedral to subhedral graphite crystals in ALH83014: a,
transmitted light; b, reflected light. Long dimension of photographs is ~2 mm.
augites. The chsts described in numerous studies document
continuous trends of Fe/Mg increase with increasing modal
abundance of pigeonite, augite, feldspar, and silica. These
trends appear to reflect general trends of solid-liquid fractiona-
tion on the basaltic achondrite parent body that are independent
of the present state of brecciation and mixing of the known
samples. Metamorphism is known to have modified the
compositions of lithic clasts in many polymict samples from
Victoria Land and in most eucrites, but no systematic studies
have yet tried to distinguish between unmodified igneous clasts
and metamorphosed clasts. Detailed study of the original trends
of igneous fractionation from clast to clast requires that
metamorphosed clasts be eliminated from this type of study.
Similarly, impact-melt clasts in these meteorites have received
little attention and definitive tests to distinguish between
impact-generated clasts and original igneous clasts are not
available. The small samples of the polymict basaltic
achondrites in the non-Antarctic collections were generally
insufficient for these types of studies to be completed, but the
large number of Victoria Land samples presently available
makes more complete and detailed study possible. In particular,
the identification of large unbrecciated lithic clasts in these
breccias is of great importance for the study of rock types that
differ from the typical eucrites and diogenites.
The Antarctic ureilite collections have more than doubled
the number of samples available and have provided examples
of previously unknown types that constrain models of ureilite
origin more closely. In general, the popular model of a cumulus
origin (Berkley et al., 1980) is supported by evidence from the
Victoria Land samples, but controversy about the relationships
between the silicate and carbonaceous fractions continues.
The Antarctic aubrites do not differ greatly from the
non-Antarctic collection but study of the dark inclusions in
these meteorites is revealing chondritic material unlike the
previously known chondrite groups. Further study should
distinguish between the competing hypotheses that these
NUMBER 28 77
30
20
10
0
70 r
50
30
10
0L
20
10
0
50r
40
30
20
10
0L
EET
83225
NS434
N=338
ALHA
81101
N=426
70
ALHA
78019,15
70 80 90 100
ALHA
82130
80 90 100
80 90 100
70 80 90 100
PCA
82506,25
80 90 100
ALHA
82106,6
N=436
80 90 100
RKPA
80239,6 VJl
20
10
ALHA
77257,42
N=262
70 80 90 100
FIGURE 8-7.?Modal distribution of olivine compositions (mole % forsterite) in Victoria Land ureilites. Data
are of low precision but provide a consistent criterion of comparison for these meteorites. Area of histogram is
100%.
78 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
inclusions represent a new type of chondrite, or that they are
actually inclusions of ordinary chondritic material that was
subjected to metamorphism and metasomatism after incorpora-
tion in an aubritic host.
The discovery of unusual material in the Antarctic
achondrites is prompting increasing study of non-Antarctic
collections with the result that previously unrecognized
material is being identified. With the assured supply of
carefully sampled achondrites from Antarctica, the next
decades of research on achondritic meteorites should prove
very rewarding and fruitful.
Literature Cited
Berkley, J.L., and C.A. Goodrich
1985. Cohenite-bearing Metallic Spherules in Ureilites: Petrology and
Implications. In Lunar and Planetary Sciences XVI, pages 49?50.
Houston: Lunar and Planetary Institute.
Berkley, J.L., and J.H. Jones
1982. Primary Igneous Carbon in Ureilites: Petrological Implications.
Journal of Geophysical Research, 87(supplement):A353-A364.
Berkley, J.L., GJ. Taylor, K. Keil, G.E. Harlow, and M. Prinz
1980. The Nature and Origin of Ureilites. Geochimica et Cosmochimica
Ada, 44:1579-1597.
Biswas, S., T.M. Walsh, H.T. Ngo, and M.E. Lipschutz
1981. Trace Elements of Selected Antartic Meteorites?II: Comparison
with Non-Antarctic Specimens. Memoirs of the National Institute
of Polar Research (Japan), special issue, 20:221-228.
Bunch, T.E.
1976. Petrography and Petrology of Basaltic Achondrite Polymict Breccias
(Howardites). In Proceedings of the Sixth Lunar and Planetary
Science Conference, pages 469-492.
Delaney, J.S.
1984. Why Did So Many Polymict Eucrites Land and Survive Only in
Antarctica? In Lunar and Planetary Science XV, pages 206-207.
Houston: Lunar and Planetary Institute.
Delaney, J.S., C. O'Neil, C.E. Nehru, M. Prinz, C. Stokes, H. Kojima, and K.
Yanai
1984. The Classification and Reconnaissance Petrography of Basaltic
Achondrites from the Yamato 1979 Collection Including Pigeonite
Cumulate Eucrites, a New Group. Memoirs of the National Institute
of Polar Research (Japan), special issue, 35:53-80.
Delaney, J.S., M. Prinz, C.E. Nehru, and G.E. Harlow
1981. A New Basalt Group from Howardites: Mineral Chemistry and
Relationships with Basaltic Achondrites. In Lunar and Planetary
Science XII, pages 211-213. Houston: Lunar and Planetary Institute.
Delaney, J.S., M. Prinz, C.E. Nehru, and C. O'Neil
1982. The Polymict Eucrites Elephant Moraine A79004 and A79011 and
the Regolith History of a Basaltic Achondrite Parent Body. In
Journal of Geophysical Research, supplement, 87:A339?A352.
Delaney, J.S., M. Prinz, C.E. Nehru, and C.P. Stokes
1984. Allan Hills A81001, Cumulate Eucrites and Black Clasts from
Polymict Eucrites. In Lunar and Planetary Science XV, pages
212-213. Houston: Lunar and Planetary Institute.
Delaney, J.S., H. Takeda, and M. Prinz
1983a. Modal Comparison of Yamato and Allan Hills Polymict Eucrites.
Memoirs of the National Institute of Polar Research (Japan), special
issue, 30:226-233.
1983b. Reply to B. Mason: "Definition of a Howardite." Meteoritics,
18:247-248.
1984. The Polymict Eucrites. Journal of Geophysical Research, supple-
ment, 89:C251-C288.
Delaney, J.S., H. Takeda, M. Prinz, C.E. Nehru, and G.E. Harlow
1983. The Nomenclature of Polymict Basaltic Achondrites. Meteoritics,
18:103-111.
Dymek, R.F., A.L. Albee, A.A. Chodos, and GJ. Wasserburg
1976. Petrography of Isotopically-dated Clasts in the Kapoeta Howardite
and Petrologic Constraints on the Evolution of Its Parent Body.
Geochimica et Cosmochimica Acta, 40:1115-1130.
Fukuoka, T.
1984. Comparison of Chemical Compositions of Yamato Polymict
Eucrites. Meteoritics, 19:227.
Goodrich, C.A., and J.L. Berkley
1985. Minor Elements in Ureilites: Evidence for Reverse Fractionation
and Interstitial Silicate Liquid. In Lunar and Planetary Science
XVI, pages 280-281. Houston: Lunar and Planetary Institute.
Hey, M.H.
1966. Catalogue of Meteorites, lxviii + 637 pages. London: British
Museum (Natural History).
Hutchison, R., A.W.R. Bevan, and J.M. Hall
1977. Appendix to the Catalogue of Meteorites, xxvii + 297 pages.
London: British Museum (Natural History).
Kallemeyn, G.W., and J.T. Wasson
1985. The Compositional Classification of Chondrites: IV Ungrouped
Chondritic Meteorites and Clasts. Geochimica et Cosmochimica
Acta, 49:261-270.
Lindsley, D.H., and D.J. Andersen
1983. A Two-Pyroxene Thermometer. Journal of Geophysical Research,
supplement, 88:A887-A907.
Marvin, U.B.
1984. Meteorite Distributions on the Main Icefield of the Allan Hills
Region, Antarctica. Meteoritics, 19:265-266.
Mason, B.
1983a. [Description.] Antarctica Meteorite Newsletter, 6:7.
1983b. Definition of a Howardite. Meteoritics, 18:245.
1984. [Description.] Antarctic Meteoritic Newsletter, 7:10.
Miyamoto, M., H. Takeda, and K. Yanai
1978. Yamato Achondrite Polymict Breccias. Memoirs of the National
Institute of Research (Japan), special issue, 8:185-197.
Olsen, E.J., A. Noonan, K. Fredriksson, E. Jarosewich, and G. Moreland
1978. Eleven New Meteorites from Antarctica, 1976-1977. Meteoritics,
13:209-225.
Prinz, M., C.E. Nehru, M.K. Weisberg, and J.S. Delaney
1984. Type 3 Enstatite Chondrites: A Newly Recognized Group of
Unequilibrated Enstatite Chondrites (UEC's). In Lunar and
Planetary Science XV, pages 653-654. Houston: Lunar and
Planetary Institute.
Reid, A.M., and A.P. Le Roex
1984. Compositions of 7 Allan Hills Polymict Eucrites and One Diogenite.
Meteoritics, 19:299.
Schultz, L., and M. Freundel
1984. Terrestrial Ages of Antarctic Meteorites. Meteoritics, 19:310.
Score, R., T.V.V. King, CM. Schwarz, A.M. Reid, and B. Mason
1982. Descriptions of Stony Meteorites. In U.B. Marvin and B. Mason,
editors, Catalogue of Meteorites from Victoria Land, Antarctica,
1978-1980. Smithsonian Contributions to the Earth Sciences,
24:19-48.
Scott, E.R.D.
1984. Pairing of Meteorites Found in Victoria Land, Antarctica. Memoirs
of the National Institute of Polar Research (Japan), special issue,
35:102-125.
Simon, S.B., and JJ. Papike
1983. Petrology of Igneous Lithic Clasts from Polymict Eucrites ALHA
76005 and ALHA 77302. Meteoritics, 18:35-50.
Takeda, H.
1979. A Layered Crust Model of a Howardite Parent Body. Icarus,
NUMBER 28 79
40:445-470.
Takeda, H., M.B. Duke, T. Ishii, H. Haramura, and K. Yanai
1979. Some Unique Meteorites Found in Antarctica and Their Relation
to Asteroids. Memoirs of the National Institute of Polar Research
(Japan), special issue, 15:54?76.
Takeda, H., M. Miyamoto, K. Yanai, and H. Haramura
1978. A Preliminary Examination of the Yamato-74 Achondrites. Memoirs
of the National Institute of Polar Research (Japan), special issue,
8:170-184.
Takeda, H. and H. Mori
1984. The Diogenite-Eucrite Links and the Crystallization History of a
Crust of Their Parent Body. Journal of Geophysical Research,
supplement, 90:C636-C648.
Takeda, H., H. Mori, and K. Yanai
1981. Mineralogy of the Yamato Diogenites As Possible Pieces of a Single
Fall. Memoirs of the National Institute of Polar Research (Japan),
special issue, 20:81-99.
Treiman, A.H.
1984. Polymict Eucrite ALHA 81011: Equilibrated Clasts in a Glassy
Matrix. Meteoritics, 19:323-324.
Treiman, A.H., and M.J. Drake
1984. Basaltic Volcanism on the Eucrite Parent Body: Petrology and Phase
Equilibria of ALHA 80102 and the Discovery of Ferroan Troctolite.
In Lunar and Planetary Science XV, pages 862-863. Houston: Lunar
and Planetary Institute.
Verkouteren, R.M., and M.E. Lipschutz
1983. Cumberland Falls Achondritic Inclusions?II: Trace Elements of
Forsterite Chondrites and Meteorites of Similar Redox State.
Geochimica et Cosmochimica Acta, 47:1625-1633.
Watters, T.R., and M. Prinz
1979. Aubrites: Their Origins and Relationship to Enstatite Chondrites.
In Proceedings of the Tenth Lunar and Planetary Science
Conference, pages 1073-1093.
Weber, H.W. O. Braun, L. Schultz, and F. Begemann
1982. The Noble Gases in Antarctic and Other Meteorites. Zeitschritt fur
Naturforsch, 38A:267-272.
9. Antarctic Carbonaceous Chondrites: New Opportunities
for Research
Harry Y. McSween, Jr.
Introduction
Milestones in the understanding of carbonaceous chondrites
reached previously can be traced in a series of reviews on the
subject (Mason, 1963; Hayes, 1967; Mason, 1971; Nagy, 1975;
McSween, 1979a). One might logically expect that this paper
on Antarctic carbonaceous chondrites, most of which have
been found since the last review article was published, should
provide an updated account of new discoveries and insights.
This, unfortunately, is not true, because this subset of
carbonaceous chondrites has not yet been thoroughly studied.
The Antarctic meteorite bonanza is just too vast to be
assimilated quickly, and other classes of meteorites (especially
the achondrites) - have received more attention. Those major
contributions that have been made during the last few years are
derived mainly from studies of non-Antarctic carbonaceous
chondrites.
The intent of this paper is to describe what kinds of
carbonaceous meteorites are available in the Antarctic collec-
tions of the United States and Japan, and to summarize briefly
what research has been done. Some new data that bear on the
question of pairings among Antarctic carbonaceous chondrites
will also be presented. The importance of this paper really lies
in what it does not say?the still available research opportuni-
ties that these meteorites offer.
Classification of Carbonaceous Chondrites
The classification used for carbonaceous chondrites is
somewhat unwieldy and has evolved in a number of steps. Van
Schmus and Wood (1967) distinguished Cl, C2, and C3
chondrites based on petrographic and chemical characteristics.
This sequence supposedly reflected a sort of decreasing
"primitiveness," distinct from the grade of thermal metamor-
phism described by petrologic types 4 to 6. Van Schmus and
Hayes (1974) recognized two groups of C3 chondrites, which
they called the Ornans (now abbreviated CO3) and Vigarano
Harry Y. McSween, Jr., Department of Geological Sciences,
University of Tennessee, Knoxville, Tennessee 37996.
(CV3) subtypes. Wasson (1974) stressed that Cl, C2, and C3
chondrites were not an isochemical group and devised the
names Cl (Ivuna type, formerly Cl) and CM (Mighei type,
formerly C2) to parallel the classification of C3 chondrites into
CV and CO groups. McSween (1979a) accepted Wasson's
chemical distinctions and added another: CR (Renazzo group).
He also suggested a reinterpretation of petrologic types 3 to 1
to reflect increasing degrees of aqueous alteration. A few
carbonaceous chondrites have been thermally recrystallized
and are assigned to petrologic type 4.
In Table 9-1 are listed carbonaceous chondrites recognized
in the Antarctic collections of the Unites States (Victoria Land)
and Japan (Queen Maud Land) through 1984. Included are
classification, original weights, and the best descriptive
references for each. In many cases no descriptive references
are available, except in the original newsletter announcements,
which are not referenced here. Classifications are the generally
accepted assignments published in the newsletters of the
Antarctic Meteorite Working Group and the National Institute
of Polar Research. Recrystallized chondrites classified as C4
are difficult to assign to a specific group, even if adequate
chemical data are available.
Petrologic, Chemical, and Isotopic Studies of Antarctic
Carbonaceous Chondrites
CM2 CHONDRITES
Most of the work on CM chondrites has been done on
Yamato samples; the Allan Hills samples are almost un-
touched. Brief petrographic descriptions are available for
Y-74641, Y-74642, Y-74662 (Mason and Yanai, 1983),
Y-75293, Y-790123 (Dceda, 1983a), and Y-793321, Y-790003,
Y-791198, Y-791824, B-7904 (Kojimaetal., 1984). McSween
(1979b) also provided some petrographic data on ALHA77306,
and Steele et al. (1985) studied cathodoluminescence zoning
of olivines in B-7904. Although some petrographic differences
are apparent, these meteorites do not expand the limits of
primary petrographic variation already known from non-
81
82 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 9-1.?Antarctic carbonaceous chondrites. TABLE 9-1.?Continued.
Sample Classification
Meteorites from Victoria Land
ALHA77306
ALHA78261
ALHA81002
ALHA81004
ALHA81312
ALH82100
ALH82131
ALH83016
ALH831OO
ALH83102
EET83224
EET83226
EET83250
ALH84029
ALH84030
ALH84031
ALH84032
ALH84033
ALH84034
ALH84042
ALH84044
ALHA77003
ALHA77029
ALHA77307
ALH82101
RKPA 80241
ALHA81OO3
ALHA81258
ALHA84028
ALH82135
PCA82500
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
C03
C03
C03
C03
CV3
CV3
CV3
CV3
C4
C4
Weight (g)
19.9
5.1
14.0
4.7
0.7
24.3
1.0
4.1
434.6
1240.8
8.6
33.1
11.5
119.8
6.2
12.5
7.9
60.4
44.1
51.2
147.4
779.6
1.4
181.3
29.1
0.1
10.1
1.1
735.9
12.1
90.9
Best descriptive references
McSween (1979b)
Ikeda(1982)
McKinley and Keil (1984)
Nagahara and Kushiro
(1982)
Scott (1984)
Scott (1985)
Scott and Taylor (1985)
Sample Classifi cation
Meteorites from Queen Maud Lana
Y-74641
Y-74642
Y-74662
Y-75260
Y-75293
B-7904
Y-790003
Y-790032
Y-790112
Y-790123
Y-791198
Y-791824
Y-793331
Y-793332
Y-74135
Y-790992
Y-791717
Y-75260
Y-6903
Y-790112
Y-793495
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
CM2
C03
C03*
C03
CV3
CV4
CR2
CR2
* Y-790992 is listed only as a C3;
Weight (g)
I
4.5
10.6
151
4.0
8.1
1234
4.3
6.1
24.0
6.8
179.8
23.3
379.3
7.7
25,3332
4.0
150
24.0
45.0
Best descriptive references
Mason and Yanai (1983)
Mason and Yanai (1983)
Ikeda(1983a)
Ikeda (1983a)
Kojima et al. (1984)
Ikeda (1983)
Kojima et al. (1984)
Kojima et al. (1984)
Kojima et al. (1984)
Kojima et al. (1984)
Okada and Shima (1979);
Scott (1985)
, but I have assigned it to C03 based on
inspection of a thin section in the collection of the National Institute of Polar
Research. Ikeda
ALHA77003.
(1983a) also noted that this meteorite was similar to
Antarctic CM chondrites.
High-resolution electron microscope studies of the matrices
of ALHA77306 (McKee and Moore, 1980) Y-74662 (Akai,
1982), Y-793321, B-7904 (Akai, 1984) and Y-791198 (Akai
and Kanno, 1985) have been reported. These studies have
identified a bewildering variety of phyllosilicates with platy,
tubular, and poorly crystalline structures, much like those
found in non-Antarctic CM chondrites. Ikeda (1983a) reported
the chemical compositions of matrix phyllosilicates in
Y-790123, Y-75293, and Y-74662 to be similar to other
published analyses. Fujimura et al. (1982) documented
preferred orientations of phyllosilicates in Y-74642 and
Y-74662 by x-ray pole figure goniometry, indicating anisotro-
pic deformation of these meteorites.
Bulk chemical data are available for Y-74642, Y-74662,
Y-790032, and Y-791198 (Haramura et al., 1983). Trace
element data for Y-74662 were determined by Knab and
Hintenberger (1978). Carbon and sulfur determinations have
been reported for Y-76442 and ALHA77306 (Gibson and
Yanai, 1979) and B-7904, Y-791824, Y-793321 (Gibson et
al., 1984). Carbon and nitrogen abundances in Y-791198 were
published by Shimoyana et al. (1985). Major element
concentrations, including sulfur, are near normal CM levels,
but depletions of carbon in some meteorites may reflect
exposure to liquid water in the Antarctic environment.
The apparent leaching of carbon in some CM chondrites is
a disturbing finding, especially for what it portends for studies
of organic compounds. ALHA77306 has significantly lower
amino acid concentrations than non-Antarctic CM chondrites
(Cronin et al., 1979), and Y-7891824, Y-793321, and B-7904
contain practically none of these compounds (Gibson et al.,
1984; Shimoyama and Harada, 1984). However, amino acids
in Y-74662 and Y-79118 are at higher concentrations
(Shimoyama et al., 1979, 1985). Aspartic acid, serine, glycine,
alanine, theonine, glutamic acid, valine, norvaline, and leucine
have been identified, as well as aromatic compounds from
pyrolysis experiments (Holzer and Oro, 1979; Murae et al.,
1983, 1984).
NUMBER 28 83
Stable light isotope (N, C, H) compositions reported for
Y-790003 and Y-790032 (Grady et al., 1983) indicate that
Y-790003 is highly unusual. It is characterized by enrichment
of heavy carbon and nitrogen, but not deuterium, and falls
outside the known ranges for CM chondrites. Isotopic
abundances of noble gases (He, Ne, Ar, Kr, Xe) in B-7904,
Y-74662, and Y-791198 are similar to other non-Antarctic
CM chondrites (Nagao et al., 1984; 1985); however, a new
component of Kr and Xe has been reported in B-7904. No data
are available on cosmogenic nuclides.
Magnetic studies of Y-74662 (Nagata, 1980; Brecher, 1980)
confirmed its CM2 classification. The magnetic properties of
ALHA77306 have been used to estimate its magnetite content
at less than 0.8 weight percent (Hyman and Rowe, 1979).
CR2 CHONDRITES
From inspection of thin sections in the collection at the
National Institute of Polar Research in 1982, the author
tentatively classified Y-790112 and Y-793495 as CR chon-
drites, as subsequently reported in the National Institute of
Polar Research special issue of 1982. Oxygen isotopic analysis
of Y-790112 (Clayton et al., 1984) has confirmed this
classification. A bulk chemical analysis of this meteorite was
given by Haramura et al. (1983). Light element stable isotope
analysis is also consistent with the CR assignment (Grady et
al., 1983), though data from Y-790112 indicate the CR group
is highly variable in its isotopic character. Nothing is known
about Y-793495. This is a particularly important pair of
meteorites, because so little is known about the CR group with
only two non-Antarctic members.
CO3 CHONDRITES
The two large CO chondrites in the Allan Hills collections
(ALHA77003 and 77307) have understandably received most
of the attention accorded to this group, although massive
Y-791717 offers an exciting opportunity. Petrographic descrip-
tions of ALHA77003 (Ikeda, 1982), ALHA77307 (Nagahara
and Kushiro, 1982), and ALHA77029 (McKinley and Keil,
1984) have been published. The latter was found in a collection
of pebble-sized meteorites. Scott et al. (1981) and Scott (1984)
provided some additional petrographic data on all three
meteorites. ALHA77307 appears to be the least metamor-
phosed of the three chondrites. Brief petrographic descriptions
and studies of the alteration of Y-791717 and Y-74135 were
presented by Kojima et al. (1984).
Bulk chemical analyses have been performed for ALHA77003
(Rhodes and Fulton, 1980; Jarosewich, 1980; Kallemeyn and
Wasson, 1982a), ALHA77029 (Kallemeyn and Wasson,
1982a), ALHA77307 (Biswas et al., 1981; Kallemeyn and
Wasson, 1982a), and Y-791717 (Haramura et al., 1983). The
chemical composition of ALHA77307 has resulted in some
uncertainty about its classification. Biswas et al. (1981)
assigned this meteorite to the CV group, based on its high Cd
concentration, but Kallemeyn and Wasson (1982b) concluded
that its composition was similar in most respects to CO and
CM chondrites. They also suggested that weathering may have
been a factor in altering its composition. Its thermolumines-
cence properties are consistent with the CO classification,
although it is not a normal member of that group (Sears and
Ross, 1983). Petrographic data (Scott et al., 1981) also suggest
ALHA77307 is an unusual member of this class, although
Kainsaz, which it most resembles, is also unusual.
Organic constituents have been analyzed only in ALHA77307
(Moore et al., 1981; Murae et al., 1983). It contains only traces
of amino acids, and pyrolysis experiments indicate highly
volatile products.
Wieler et al. (1985) reported isotopic measurements of noble
gases in ALHA77307 and ALHA82101. The only cosmogenic
nuclide data available for these meteorites is for ALHA77003.
Nishiizumi (1984) summarized 53Mn, 26A1, 36C1, and 14C
activities and calculated a cosmic ray exposure age of 20
million years.
CV3 CHONDRITES
Virtually nothing is known about any of these chondrites,
but most are very small, and representative samples may be
difficult to obtain. Scott (1984) briefly mentions RKPA80241.
C4 CHONDRITES
Petrographic descriptions of Y-6903 (Okada and Shima,
1979; Scott, 1985), PCA82500 (Scott et al., 1984), and
ALH82135 (Scott, 1985) indicate that these meteorites are
recrystallized and resemble Karoonda, though each is distinc-
tive in some ways. The oxygen isotopic composition of Y-6903
is identical to that of Karoonda, and 18O fractionation between
plagioclase and magnetite corresponds to an equilibration
temperature of 600? C (Clayton et al., 1979).
Bulk chemical analyses of Y-6903 and PCA82500 were
reported by Kallemeyn (1985). Y-6903 may be a metamor-
phosed CVF chondrite, but compositional data for PCA82500
suggest affinities with both the CO and CV groups, as already
noted for Karoonda (Kallemeyn and Wasson, 1982b). An
analysis for carbon and sulfur in Y-6903 was reported by
Gibson and Yanai (1979). Noble gas isotopic abundances for
ALH82135 and PCA82500 were determined by Wieler et al.
(1985).
Pairing of Antarctic Carbonaceous Chondrites
Very little information exists on which to make pairing
assignments for these meteorites. Of both Antarctic collections,
the only carbonaceous chondrite for which a terrestrial age has
been determined is ALHA77003. Its reported 14C age is
35,600?500 years (Fireman, 1983), and its 36C1 age is
84 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
110,000170,000 years (Nishiizumi, 1984). Four CM2 chon-
drites from the Allan Hills (77306, 78261, 81002, and 81004),
and two Allan Hills CO3 chondrites (77003, and 82101) have
been previously paired, based on petrographic similarities
(Antarctic Meteorite Working Group, 1984). However, marked
differences in olivine compositions (Scott et al., 1981) and
noble gas abundances (Wieler et al., 1985) between ALHA77003
and ALH82101 suggest that these specimens are not paired.
To assist in this thorny problem of pairing assignments,
provided below are partial modal analyses of the Victoria Land
CM and CO chondrites (except ALH84033), obtained using
optical point-counting methods outlined by McSween (1979b).
It must be noted that no accurate determination of modal
variability within any one meteorite has ever been made;
however, point counts by the author on two thin sections for
each of two different CO chondrites agreed within about 10
percent. An additional problem hampering accurate modal
analyses is brecciation. Both of these meteorite classes are now
known to contain clasts with different petrographic properties
(McSween, 1979b; Rubin et al., 1984), and these could
introduce substantial variations on a thin-section scale within
one meteorite. In order to minimize these effects, I have relied
only on matrix/chondrule ratios (rather than differences in the
relative proportions of inclusions, chondrules, monomineralic
fragments, etc.), where chondrules refer to everything that is
not fine-grained, opaque matrix. This gross parameter, when
combined with subjective assessment of degrees of hydrous
alteration in CMs, and oxidation or textural blurring due to
thermal metamorphism in COs, provides the basis for the
pairings suggested in Table 9-2.
Three possible groupings of CM chondrites are proposed.
The relatively unaltered chondrites are subdivided into two
groups from the Allan Hills and two unpaired samples from
Elephant Moraine based on matrix/chondrule ratios. However,
petrographic variability within a large CM chondrite might
permit these groupings to overlap. Microprobe defocused beam
analyses of matrix would certainly help define these two
groups. None of the altered CM chondrites from the Allan Hills
are paired because of large differences in matrix/chondrule
ratios. None of the Elephant Moraine specimens are paired for
the same reason. No modal data are presented for the large
group of highly altered CM chondrites from the Allan Hills,
but they are paired because of their exceptional petrography.
Chondrules and inclusions are so heavily altered that it is
difficult to distinguish these from matrix in many cases. This
alteration is so distinctive that these meteorites can probably
be paired with confidence.
No obvious pairings exist among CO3 chondrites. Based
on matrix/chondrule ratios, ALHA77129 and ALHA77307
could be paired, but differences in textural blurring, equilibra-
tion seen in olivine histograms (Scott et al., 1981), and bulk
compositions (Kallemeyn and Wasson, 1982a) preclude
pairing of any of these CO3 chondrites.
TABLE 9-2.?Pairing information.
Meteorite
CM2
j?ALHA81002
I ALHA810O4
1? ALH82100
1?ALHA78261
II ALH82131
1?ALH83016
ALHA77306
ALHA81312
EET83224
EET83226
EET83250
??ALH831OO
III
ALH83102
ALH84029
ALH84030
ALH84031
ALH84032
ALH84034
ALH84042
? ALH84044
C03
ALHA77003
ALHA77029
ALHA77307
Matrix/Chondrule
volume ratio
3.70
2.78
3.33
2.27
low*
1.96
4.17
1.52
1.75
0.65
2.50
t
t
t
t
t
t
t
t
t
0.43
0.79
0.76
Subjective
observations
relatively unaltered
relatively unaltered
relatively unaltered
relatively unaltered
relatively unaltered
relatively unaltered
altered
altered
relatively unaltered
relatively unaltered
altered with clasts
highly altered
highly altered
highly altered
highly altered
highly altered
highly altered
highly altered
highly altered
highly altered
metamorphosed, reduced
metamorphosed, reduced
unmetamorphosed, oxidized
I, II, III Tentatively paired groups
?Sample too small for modal analysis
f Sample too highly altered for modal analysis
Conclusions
The Antarctic meteorite collections from Victoria Land and
Queen Maud Land contain all of the known classes of
carbonaceous chondrites except CI (Cl). These specimens
greatly enlarge the limited quantities of carbonaceous chon-
drites in museum collections. Moreover, available pairing
information, though limited, suggests that they represent many
different falls. Unfortunately, many of these meteorites are
small, and work has understandably focused on the larger
specimens. Studies of even large Antarctic carbonaceous
chondrites are very limited, however, and should be pursued
more vigorously.
ACKNOWLEDGMENTS.?This work was partly supported by
NASA grant NAG 9-58.
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1974. Meteorites. 316 pages. New York: Springer.
Wieler, R., H. Baur, Th. Graf, and P. Signer
1985. He, Ne and Ar in Antarctic Meteorites: Solar Noble Gases in an
Enstatite Chondrite. In Lunar and Planetary Science XVI, pages
902-903. Houston, Texas: Lunar and Planetary Institute.
10. The Emerging Meteorite: Crystalline Structure
of the Enclosing Ice
Anthony J. Gow and William A. C as sidy
Introduction
While searching for meteorites in the Far Western Icefield
of the Allan Hills region during the austral summer of
1982-1983, Carl Thompson discovered a small, walnut-sized
meteorite with just its tip protruding above the ice surface
(Cassidy et al., 1983). Closer inspection showed that this
meteorite was not surrounded by a zone of clear ice as would
have been expected if melting and refreezing had occurred
around the stone. The meteorite appeared to be still embedded
in the original ice and becoming exposed for the first time at
the ablation surface. If this interpretation were proved correct,
this would be the first example observed in Antarctica of an
emerging stone, a discovery of special importance because the
terrestrial age of the meteorite would be the same as that of the
enclosing ice. Since the terrestrial age of the stone can be
determined by measurement of several different nuclides (e.g.,
26A1, 10Be, ^Cl, 81Kr, 58Mn, and 14C), such dating would
furnish, for the first time, a good measure of the time that has
elapsed since the meteorite embedded itself in the Antarctic ice
sheet. This, in turn, would provide an independent check on
age determination methods currently being developed for
dating ancient ice. Because of the potentially unique nature of
this meteorite it was left untouched and collected within a block
of ice measuring approximately 36 cm long by 30 cm wide and
10 to 20 cm deep. This sample was shipped frozen to the U.S.
Army Cold Regions Research and Engineering Laboratory in
Hanover, New Hampshire, where the meteorite was removed
by sterile procedures and the crystalline structure of the ice in
contact with the meteorite was examined in a series of
orthogonal thin sections. This study was undertaken to
determine if the crystalline properties of the ice were consistent
with the notion that the ice enclosing the meteorite is coeval
with the terrestrial age of the meteorite.
Anthony J. Gow, US. Army Cold Regions Research and Engineering
Laboratory, 72 Lyme Road, Hanover, New Hampshire 03755-1290.
William A. Cassidy, Department of Geology and Planetary Science,
University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
Sample Processing
Prior to processing, the ice block was remeasured and
photographed from several different directions. Figure 10-1
shows the disposition of the meteorite in the ice prior to cutting
the block with a band saw. A narrow sublimation cavity around
the meteorite (Figure 10-2) was rimmed by sublimation
crystals and contained sparse grains of a fine, reddish dust
which could have been derived from the meteorite, but might
be windblown terrestrial contamination. The ice block
displayed three mutually perpendicular sets of parallel cracks,
which were features observed at the find site.
Saw cuts were made on either side of the meteorite and the
block was then split apart by wedging, as illustrated in Figure
10-3. A close-up view of the meteorite still embedded in one
wall of the cleaved ice is shown in the Frontispiece. Inspection
of the ice in contact with the meteorite showed no trace of
melting anywhere along the contact margin. The meteorite was
removed with a pair of pre-cleaned tongs (Figure 10-4) and
transferred to a polyethylene bag. This bag was then enclosed
in a second bag (as is done in the field) and placed in a
thick-walled styrofoam container, which was then filled with
dry ice and air-shipped to the curatorial facility of the NASA
Johnson Space Center, Houston, Texas. The 9.9 kilogram piece
of ice (Figure 10-5), from which the meteorite was extracted,
was shipped to Dr. K. Nishiizumi at the University of
California at San Diego for further processing and dating. As
a member of the meteorite-collecting expedition of 1983-1984,
Dr. Nishiizumi returned to the site, marked by a flag, where
the block had been removed and collected additional ice for
his analyses. Crystal structure studies were performed on thin
sections cut from slabs VI, V2, and HI in the region of the
mold of the meteorite in the other half of the sawn block
(Figure 10-5). Ice from piece V2 was also used to prepare
samples for conventional chemical analysis by J. Cragin at
CRREL and for stable isotope measurements by S. Epstein at
the California Institute of Technology. Results of these
investigations together with those of terrestrial age dating of
the meteorite are not yet available. The meteorite, ALH82102,
87
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 10-1.?Block of ice with enclosed meteorite, collected from the Allan Hills Far Western Icefield and
shipped frozen (T = -12? C) to the Cold Regions Research and Engineering Laboratory in New Hampshire.
Traces of a dominant fracture plane cross the ice from left to right. (Scale in cm).
a 48 g H5 chondrite with an almost complete fusion crust, is
described in the chapter on stony meteorites by Mason et al.,
Chapter 6.
Ice Structure Analysis
Three thin sections were cut in mutually perpendicular
directions. This was done in order to evaluate the three-
dimensional picture of the crystal/bubble structure of the ice.
Figure 10-6a shows a picture of Section VI, a thick (3 mm)
slice that was photographed in reflected light to show the
extremely bubbly nature of the ice. On average, bubble
abundances occur in excess of 100 per cubic centimeter of ice.
Bubble sizes seldom exceed 1 mm in diameter though
elongated bubbles in some sections of the ice may measure 2
mm or more in length. The generally irregular (non-spherical)
shapes of bubbles would suggest that they have been formed
by "exsolution," that is, were re-formed from air previously
dissolved under pressure in buried ice. Such a process was first
documented in deep ice cores from Byrd Station, Antarctica,
where bubbles in concentrations exceeding 200 per cm3 of ice
in the top 800 m had completely disappeared by 1100 m depth
(Gow et al., 1968; Gow and Williamson, 1975). Such a process
is believed to be pressure-induced since "exsolution" or
reappearance of non-spherical and generally irregularly shaped
bubbles began to occur some days after cores were pulled to
the surface. In contrast to exsolved bubbles, original bubbles
derived from air trapped between grains of snow in the upper
layers of the Antarctic Ice Sheet tend to retain rounded,
substantially spherical outlines up to the time they become
absorbed in deeper ice.
Considering probable ice temperatures upstream of the find
site (the depth at which bubbles are absorbed by the ice depends
on temperature as well as pressure), we surmise that the ice
NUMBER 28 89
FIGURE 10-2.?Closeup of the meteorite in situ, rimmed by a narrow sublimation cavity in which feathery ice
crystals protrude from the ice walls. The cavity and its crystals, observed in the field survived transport to
CRREL.
containing the meteorite must have been buried to a depth of
at least 700 m in order for complete dissolution of original air
bubbles to have occurred (Miller, 1969, and Gow and
Williamson, 1975). Based on our estimate of its burial depth
and the time needed for it to have reached the surface by
upward flow and ablation, assuming an ablation rate of 5 cm
of ice per year (see Nishio et al., 1982), the meteorite is
believed to have impacted the surface at least 30,000 years
ago. This is somewhat older than the 20,000 years that Nishio
et al. (1982) estimate for the age of ice samples located close
to Allan Hills. However, our estimate is not in disagreement
with minimum ages given by Whillans and Cassidy (1983) for
ice reaching the surface in the region of the Far Western
Icefield where the meteorite was discovered.
A photograph of the vertical section, taken in cross-polarized
light to reveal the outlines of individual crystals, is shown in
the Frontispiece of this volume. It shows a general flattening
of grains in the horizontal plane with respect to the top surface
of the ice block. The only exception is in the immediate vicinity
of the meteorite mold where crystals curve upwards. We would
attribute this curving upwards of the crystals to reaction
between the meteorite and the enclosing ice, most likely as a
result of differential deformation of ice due to the presence of
the non-deformable meteorite. In the horizontal section (Figure
10-66, Section HI) taken from near the bottom of the ice block
the crystals have become more equidimensional. Also, the
c-axes of crystals tend to be clustered together in a very broad
maximum about the vertical axis, which would be compatible
with effects due to horizontal shearing of the ice. Coarser-
grained ice in immediate contact with the meteorite exhibited
no structural characteristics consistent with melting and
refreezing or annealing.
On the basis of the above observations, we conclude that the
meteorite was just beginning to emerge at the ablation surface
when discovered on 2 January 1983, and that the ice enclosing
the meteorite is coeval with the impact age of the meteorite.
The terrestrial age measurement of the meteorite therefore will
determine the age of the enclosing ice.
36 cm
SAW CUTS
10 em
FIGURE 10-3.?Splitting the ice block without touching the meteorite: a, Bill Cassidy making the first saw cut
from one edge toward the stone. A second cut was made from the opposite edge, a wedge inserted in the cut,
and the block split open. Spectators are Ursula Marvin and Tony Gow. b, diagram of the sawing and splitting
process.
NUMBER 28 91
Literature Cited
Cassidy, W.A., T. Meunier, V. Buchwald, and C. Thompson
1983. Search for Meteorites in the Allan Hills/Elephant Moraine Area,
1982-1983. Antarctic Journal of the United Sttates, 18(5):81-82.
Gow, A.J., H.T. Ueda, and D.E. Garfield
1968. The Antarctic Ice Sheet: Preliminary Results of Drilling to Bedrock.
Science, 161:1011-1013.
Gow, A.J., and T. Williamson
1975. Gas Inclusions in the Antarctic Ice Sheet and Their Glaciological
Significance. Journal of Geophysical Research, 80(36):5101-5108.
Miller, S.L.
1969. Clathrate Hydrates of Air in Antarctic Ice. Science, 165:489-490.
Nishio, F., N. Azuma, A. Higashi, and J.O. Annexstad
1982. Structural Studies of Bare Ice near the Allan Hills, Victoria Land,
Antarctica: A Mechanism of Meteorite Concentration. Annals of
Glaciology, 3:222-226.
Whillans, LA., and W.A. Cassidy
1983. Catch a Falling Star: Meteorites and Old Ice. Science, 222:55-57.
NISHIIZUMI
EPSTEIN
> (1b) 2.260 kg \\ (1a) 1.660 kg
FIGURE 10-4.?Extraction of the meteorite at CRREL, using precleaned
stainless steel tongs and a polyethylene bag.
FIGURE 10-5.?Subsamples of the ice block. Portions of samples la, lb, VI,
and part of V2 remain at CRREL and are available for further study.
FIGURE 10-6.?Orthogonal sections through the ice: a, a vertical thick section (VI), taken in reflected light
(scale in cm), showing the very bubbly nature of the ice. The cavity that held the stone is at upper left. A
photograph of this same section after thinning, taken in cross-polarized light, is shown in the Frontispiece, b,
horizontal thin section (HI) in cross-polarized light. The grains are more equidimensional in this section. The
small gray inclusions are air bubbles (scale in cm).
11. Significance of Terrestrial Weathering Effects
in Antarctic Meteorites
James L. Gooding
Introduction
Terrestrial weathering of Antarctic meteorites represents a
mixed blessing for planetary geoscience but may be a potential
bonanza for Earth science. With respect to cosmochemistry,
weathering can produce undesirable physical, chemical, and
isotopic changes that might confuse or obscure the records of
pre-terrestrial origin and evolution that are sought in meteor-
ites. At the same time, as an analog in comparative planetology,
the ultra-low-temperature weathering of meteorites in an icy
"regolith" represents a window into the processes of mineral
and rock alteration that have probably operated on icy planetary
bodies such as Mars, comets, asteroids, and satellites of Jupiter
and Saturn. For Earth science, terrestrial weathering effects in
Antarctic meteorites represent distinctive "marker horizons"
which, if they can be quantitatively calibrated and correlated
with other measurable properties, might yield important
information about histories of Antarctic ice sheets.
Major issues surrounding the terrestrial weathering of
Antarctic meteorites include the following questions:
1. How can weathering effects be recognized and quantified?
2. Are degrees of weathering correlated with terrestrial ages?
3. How are cosmochemical studies affected by weathering?
To date, answers to these questions have been incomplete
and unsatisfying and it is time to apply greater research
emphasis to the problem.
Recognition and Quantification of Weathering Effects
In the broadest sense, "weathering" is the collection of
processes which, through surface/atmosphere interactions,
leads to the decomposition or alteration of rocks, minerals, or
mineraloids, and the possible formation of new phases. Even
casual observations of Antarctic meteorites reveal that most
specimens are rusty and cracked and that outer surfaces are
partially eroded and discolored relative to interior surfaces that
are exposed upon chipping. Therefore, it is clear that both
James L. Gooding, Code SN2, Planetary Materials Branch, NASA/
Johnson Space Center, Houston, Texas 77058.
physical and chemical weathering have affected Antarctic
meteorites. Products of chemical weathering include carbon-
ates, sulfates, and hydrous iron oxides (Marvin, 1980;
Gooding, 1981) as well as clay mineraloids (Gooding, 1984a,b;
1986b). Aluminosilicate weathering products, in particular, are
easily overlooked because of their small grain sizes and their
resemblance to primary felsic minerals (Figures 11-1, 11-2).
Because rust is so common and conspicuous, however, degree
of rustiness has been adopted as the conventional means for
expressing the "degree of weathering" of a given specimen.
Under the current curatorial practices that apply to the
American collection, preliminary examination and classifica-
tion of each Antarctic meteorite specimen includes assignment
to an A, B, or C weathering type according to the following,
generalized definitions:
A: Minor rustiness; rust haloes on metal particles and
rust stains along fractures are minor.
B: Moderate rustiness; large rust haloes occur on metal
particles and rust stains on internal fractures are
extensive.
C: Severe rustiness; metal particles have been mostly, if
not totally, converted to rust and the specimen is
stained by rust throughout.
Unfortunately, the A-B-C system is only qualitative and its
application is largely subjective. In addition, its dependence
on meteoritic metal as an index phase makes it difficult, if not
impossible, to apply uniformly to all types of meteorites. Not
only is it difficult to compare achondrites with chondrites by
the A-B-C system, but comparisons within either group can
be just as problematical, as exemplified by the case of aubrites
vs. eucrites or the case of H-chondrites vs. C-chondrites,
respectively. In practice,the A-B-C assignment for a meteorite
that contains little or no metal is based mostly on overall
rustiness that has developed by weathering of iron sulfides or
mafic silicates.
Reflectance spectrophotometry might offer a means of more
objectively and quantitatively ranking meteorite specimens
according to their degrees of rustiness. As shown in Figure
11-3, there appears to be an inverse correlation between
93
94 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 11-1.?Scanning electron image of Antarctic weathering products that fill cavities in the fusion crust
of the "emerging stone," ALH82102 (H5 chondrite). The etched appearance of portions of the fusion crust
suggests aqueous leaching whereas the vug fillings clearly suggest aqueous precipitation. Points A and B
correspond to elemental analyses that are depicted in Figure 11-2. Scale bar is 10 |lm.
measurable "redness" and measurable degree of iron oxidation
for ordinary chondrites. The trend is most clear for samples of
the Holbrook, Arizona chondrite that were recovered at
different times after its fall to Earth in 1912. As previously
noted (Gibson and Bogard, 1978), the 1931 Holbrook specimen
appears to be more weathered than the 1968 specimen even
though the same climate prevailed during weathering of both
specimens. Therefore, variations among microenvironments
(depth of burial in soil, quality of drainage, etc.) that apparently
affected weathering of Holbrook specimens must be considered
in deducing the weathering histories of Antarctic meteorites.
Not only are differences in Antarctic weathering to be expected
between meteorites found in moraines and those found on open
ice sheets, but differences in degrees of weathering among
finds on ice sheets might exist as a function of the time that
each specimen spent encased in ice relative to the time that it
spent exposed at the ice/atmosphere surface (Gooding, 1986a).
Results for the Antarctic L6 chondrites in Figure 11-3
underscore one of the deficiencies of the A-B-C system. Even
though all three L6-chondrite specimens were categorized as
transitional A/B in terms of degree of weathering, they yield
substantially different values for the spectrophotometric index
and possibly also for the rust index (note that a relatively small
change in the ratio total-Fe/(FeO + FeS) corresponds to a
significant change in oxidation state). Therefore, at least in its
present form, the A-B-C system of categorizing degree of
weathering should not be considered quantitative and should
not be overinterpreted. Indeed, a reliable and quantitative index
flLH82182,S flLUMINOSILICflTE/S flLH82182,Sfl-88HD/lSKV
1888
COUNTS
ENERGY (KEY) 18.8
HLH82182.5 GLflSSY FUSION CRUST flLH82182,Sfl-88HB/15KV
1888
COUNTS
ENERGY IKEVJ 18.8
FIGURE 11-2.?Energy-dispersive x-ray emission spectra for areas on the fusion crust of ALH82102 as depicted
in Figure 11-1. (A) complex weathering-product assemblage, possibly consisting of silica and/or an
aluminosilicate mixed with a sulfate, that fills a cavity. (B) fusion crust, representing approximately the
pre-terrestrial bulk major-element composition of the meteorite. Note the elemental fractionations that have
occurred during weathering of the fusion crust (i.e., A vs. B).
96 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
0.9 -
0.8 -
0.7 -
0.6 -
0.5 -
0.4
1 1 1
WEATHERED CHONDRITES:
SPECTROPHOTOMETRY VS. RUST INDEX
O ALHA77296
1912 ? (A/B)
ALHA77270 ?
(A/B) H6
ALHA77155
(A/B) A
O1968
?
ALHA76008
(B/C)
I I
o
?
L6
HOLBROOK,
ARIZONA
(L6)
ALLAN HILLS,
ANTARCTICA
-
O1931
I
2 3
WEIGHT RATIO TOTAL Fe/(Fe? + FeS)
FIGURE 11-3.?Ratio of diffuse spectral reflectance at 0.5 Jim wavelength to
that at 0.6 \im, as a function of an independently determined "rust index" that
is based on the oxidation of meteoritic metal and troilite. Decrease in the value
of the spectrophotometric ratio corresponds to an increase in the visually
perceptible degree of reddish coloration. Increase in the rust index corresponds
to increase in degree of terrestrial oxidation. Each reflectance target was
prepared by pulverizing and homogenizing a visually representative sample
from the outer 1 cm of the specimen. Spectrophotometric data are from
Gooding (1981) whereas chemical data are from Gibson and Bogard (1978)
and Jarosewich (1984).
for degree of weathering remains a major need in research on
Antarctic meteorites. Attention must be paid to the fact that
oxidation of iron is only one of several processes that occur
during Antarctic weathering and that, because of the wide
variation of metal and total iron contents among meteorites, a
simple rust index might not be the best measure of degree of
weathering.
Correlations between Weathering and Terrestrial Age
The situation can be stated succinctly: no correlation
between degree of weathering and terrestrial residence age has
yet been demonstrated for Antarctic meteorites. It is intuitively
reasonable to suspect that, at least for a given meteorite type
(e.g., L6 chondrite), degrees of weathering among Antarctic
specimens might be correlatable with the lengths of time that
the specimens have spent on Earth. Either the presence or
absence of such a correlation would be of great significance
in efforts to identify the mechanisms that are responsible for
transportation and concentration of meteorite specimens by
Antarctic ice.
Previous conclusions regarding the absence of a correlation
between degree of weathering and terrestrial residence age
have relied on the fact that no systematic increase in terrestrial
age occurs with alphabetic letter among specimens that have
been categorized by A-B-C designations (e.g., Nishiizumi,
1986). As discussed above, though, weathering types defined
by the A-B-C system cannot be treated as quantitative
classifications. Consequently, the apparent lack of correlation
between terrestrial age and degree of weathering might only
reflect the irreconcilable mixture of quantitative measurements
with qualitative estimates. Further progress on this problem
cannot be expected until a quantitative index for degree of
weathering is developed.
As shown in Figure 11-4, there may exist sensible inverse
correlations between the spectrophotometric rust index and
terrestrial age. Chondrites from Allan Hills, Antarctica, appear
to have rusted much more slowly than did the Holbrook
samples, based on the observation that the slopes of their
respective trendlines differ by a factor of 10. Not surprisingly,
the metal-rich H-chondrites seem to be systematically more
rusty than the L6 chondrites among the Antarctic specimens.
For the few data that are available, the trends in Figure 11-4
are not impressive but suggest that further work along these
lines might produce a much better test of weathering/age
correlations than has been made to date.
Possible Consequences for Cosmochemistry
Ultrasensitive analytical techniques and interpretive models
that comprise current wisdom in cosmochemistry were
developed mostly from experience with lunar samples and
freshly fallen meteorites (Allende, Murchison, etc.). However,
none of the meteorites recovered from Antarctica can be
considered "pristine." Elemental fractionations occur during
weathering (Jarosewich, 1984) although the degree to which a
particular chemical study is likely to be affected might be
determined largely by the samples and methods that are
employed. Although untreated aliquots that are isochemically
weathered at the scale of sampling may appear undisturbed in
bulk analyses, disturbances may become apparent in analyses
that sample a meteorite at less than the scale of weathering
(e.g., aliquots of a few milligrams) or that depend upon
mineralogical or ion-exchange separations or gas extractions.
Phase locations and solubilities of analyte species are subject
to change by chemical weathering.
Textural relationships between weathering products and
their hosts clearly show that aqueous transportation has played
a key role during weathering of Antarctic meteorites (Gooding,
1981, 1986b; Figure 11-1). In at least some cases, aqueous
leaching and precipitation have produced significant elemental
fractionations between the progenitors and products of
chemical weathering (Figure 11-2). The same aqueous
geochemical processes might be responsible for the uptake or
loss, as well as the internal redistribution, of other elements.
Pre-terrestrial gases can be lost by solution weathering of their
host phases, whereas terrestrial gases can be incorporated
during growth of secondary minerals and mineraloids.
NUMBER 28 97
WEATHERED CHONDRITES:
SPECTROPHOTOMETRY VS. TERRESTRIAL AGE
0.9
0.8
0.7
0.6
0.5
0.4
o L6 H6
E
(O
d
-^
?
a.
d
cr
1912 ALHA77296 (A/B)
\ 1968\
o
Y
ALLAN HILLS,
ANTARCTICA
(SLOPE =-0.016)
'HOLBROOK,
ARIZONA
(SLOPE = -0.16)
1931
ALHA77270
???__?_ (A/B)
m ALHA77272
W (B/C)
9 ALHA77155
" (A/B)
ALHA76008
(B/C)
o ALHA76006
(C)
3 4 5
LOG t (TERR) (Y)
FIGURE 11-4.?Spectrophotometric index (defined in Figure 11-3) as a function of terrestrial residence age.
Terrestrial ages of Antarctic specimens are from the compilation by Nishiizumi (1984). Trendlines represent
linear least-squares fits through the respective data points. The "Allan Hills" trendline is defined by ALHA77270,
ALHA77272, and ALHA77296, assuming Holbrook-1912 as the control point for an unweathered L6 chondrite.
No terrestrial age has been published for ALHA77155.
Lipschutz (1982) briefly reviewed published trace-element
data for Antarctic meteorites in the context of the weathering
problem and concluded that loss of elements by natural
leaching is the most serious problem but that, by restriction of
work to samples from >1 cm depth in type A specimens, bulk
trace-element analyses can be obtained for Antarctic meteorites
without interference from weathering effects. Unfortunately,
many of the most interesting Antarctic specimens are small
(e.g., lunar meteorite ALHA81005: 3 cm maximum dimension)
and the 1 cm depth criterion has not been applied during
sampling. Furthermore, at least some type A specimens contain
non-rusty weathering products (salt minerals, clay mineraloids)
that might constitute important sources of interference in other
types of analyses, especially isotopic and gas analyses. For
example, the shergottites EETA79001 and ALHA77005 were
both categorized as type A even though they contain
aluminosilicate weathering products of the types that can be
expected to be strong and fractionating sorbents of gases
(Gooding, 1984b).
Clayton et al. (1984) reported effects of Antarctic weathering
in some of their oxygen isotopic analyses and Kaneoka (1984)
and Spangler and Warasila (1985) presented clear evidence for
disturbance by weathering of K-Ar systematics in both
chondrites and achondrites from Antarctica. Disturbance of
noble gas abundances occurred during weathering of the
Holbrook chondrite (Gibson and Bogard, 1978) but, unfortu-
nately, comparison of results for Holbrook with results for
Antarctic specimens might be less straightforward than
expected. Although rust in Antarctic L-chondrites is very
similar to that in Holbrook (Gooding, 1981), Antarctic
specimens also contain non-rusty aluminosilicates and salt
minerals (Figures 11-1, 11-2) that are rare to absent in
Holbrook. Therefore, effects of Antarctic weathering on
cosmochemical properties of meteorites might be significantly
different from effects of temperate-latitude weathering.
Ideally, every Antarctic meteorite sample that is destined for
a critical cosmochemical analysis should first be mineralogi-
cally examined for overall evidence of weathering (not just
rustiness) so that problems (and possible data corrections) can
be assessed in advance of sample consumption. Such
precautions are especially important for studies that attempt
to define new meteorite groups or sub-divide previously
recognized meteorite groups using elemental or isotopic
parameters that might be sensitive to disturbance by weather-
ing.
Summary
The current inadequate understanding of weathering histo-
ries of Antarctic meteorites, and their possible effects on
98 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
measurable properties of the specimens, stems from a general
lack of attention to the problem. A first major element of
progress would be to augment or replace the currently used
A-B-C system of categorizing degree of weathering with a
system that is more objective and quantitative. Reflectance
spectrophotometry might be a useful method for quantifying
degree of rustiness although other methods may be required
to quantify abundances of non-rusty weathering products.
Literature Cited
Clayton, R.N., T.K. Mayeda, and K. Yanai
1984. Oxygen Isotopic Compositions of Some Yamato Meteorites. In
Proceedings of the Ninth Symposium on Antarctic Meteorites.
Memoirs of National Institute of Polar Research (Japan), special
issue, 35:267-271.
Gibson, E.K., Jr., and D.D. Bogard
1978. Chemical Alterations of the Holbrook Chondrite Resulting from
Terrestrial Weathering. Meteoritics, 13:277-289.
Gooding, J.L.
1981. Mineralogical Aspects of Terrestrial Weathering Effects in Chon-
drites from Allan Hills, Antarctica. In Proceedings of the Twelth
Lunar and Planetary Science Conference, pages 1105-1122. New
York: Pergamon Press.
1984a. Low-Temperature Aqueous Alteration in the Early Solar System:
Possible Clues from Meteorites Weathered in Antarctica. In Lunar
and Planetary Science XV, pages 308-309. Houston: Lunar and
Planetary Institute.
1984b. Search for "Martian(?) Weathering" Effects in Achondrites
EETA79001 and ALHA77005: Complications from Antarctic
Weathering. In Lunar and Planetary Science XV, pages 310-311.
Houston: Lunar and Planetary Institute.
1986a. Weathering of Stony Meteorites in Antarctica. In J.O. Annexstad,
L. Schultz, and H. Wanke, editors. Workshop on Antarctic
Meteorites. LPI Technical Report, 86-01:48-54. Houston: Lunar and
Planetary Institute.
1986b. Clay-mineraloid Weathering Products in Antarctic Meteorites.
Geochimica et Cosmochimica Acta, 50:2215?2223.
Jarosewich, E.
1984. Bulk Chemical Analyses of Antarctic Meteorites, with Notes on
Weathering Effects on FeO, Fe-metal, FeS, H2O, and C. In U.B.
Marvin and B. Mason, editors, Field and Laboratory Investigations
of Meteorites from Victoria Land, Antarctica. Smithsonian Contri-
butions to the Earth Sciences, 26:111-114.
Kaneoka, I.
1984. Characterization of Ar-Degassing from Antarctic Meteorites. In
Proceedings of the Ninth Symposium on Antarctic Meteorites.
Memoirs of National Institute of Polar Research (Japan), special
issue, 35:272-284.
Lipschutz, M.E.
1982. Weathering Effects in Antarctic Meteorites. In U.B. Marvin and B.
Mason, editors, Catalog of Meteorites from Victoria Land,
Antarctica, 1978-1980. Smithsonian Contributions to the Earth
Sciences, 24:67-69.
Marvin, U.B.
1980. Magnesium Carbonate and Magnesium Sulfate Deposits on
Antarctic Meteorites. Antarctic Journal of the United States,
XV(5):54-55.
Nishiizumi, K.
1984. Cosmic-Ray-Produced Nuclides in Victoria Land Meteorites. In
U.B. Marvin and B. Mason, editors, Field and Laboratory
Investigations of Meteorites from Victoria Land, Antarctica.
Smithsonian Contributions to the Earth Sciences, 26:105-109.
1986. Terrestrial and Exposure Histories of Antarctic Meteorites. In J.O.
Annexstad, L. Schultz, and H. Wanke, editors. Workshop on
Antarctic Meteorites. LPI Technical Report, 86-01:48-54. Houston:
Lunar and Planetary Institute.
Spangler, R.R. and R.L. Warasila
1985. 39Ar-40Ar Ages of ALHA77302, 77256, and 77219. In Lunar and
Planetary Science XVI, pages 805-806. Houston: Lunar and
Planetary Institute.
12. Trace Element Variations between Antarctic (Victoria Land)
and Non-Antarctic Meteorites
Michael E. Lipschutz
Studies, mainly of contemporary meteorite falls, reveal that
the Earth is today sampling 70-80 parent bodies (Dodd, 1981)
and/or source regions. These are far fewer than the 3330
numbered asteroids (Marsden, 1985), let alone the 15,000
discovered by the Infrared Astronomy Satellite (Tedesco,
1984). Even if non-Antarctic finds are considered to be heavily
biased toward irons because of their recognition factor and
greater resistance to weathering, the number of extraterrestrial
sources is not increased markedly. Has the Earth always
sampled the same few sources, or has the meteoroid complex
varied in time or space?
Until the Antarctic meteorite discoveries, this question could
not be addressed, since most witnessed falls have occurred
during the most recent 200 years before present (B.P.).
Non-Antarctic finds extend this to 1000-10,000 years B.P. but
their utility is limited because many meteorites are degraded
and contaminated during weathering in warmer latitudes. This
is too short an interval in which to expect a detectable temporal
source variation. Antarctic meteorites allow a farther look
backward since their terrestrial ages generally are 0.1-0.7 Myr
B.P. (Bull and Lipschutz, 1982) and, with some caveats,
weathering has not reduced their scientific value (Lipschutz,
1982; Dennison and Lipschutz, in prep. a). While terrestrial
age distributions for meteorites from Victoria Land and Queen
Maud Land overlap, these two major Antarctic sample
populations have different mean ages?0.3 and 0.1 Myr B.P.,
respectively?and mass distributions that differ from each
other and from those of non-Antarctic falls (Bull and Lipschutz,
1982). In view of these differences, these three sample
populations are treated here as different ones?referring to
each by name: the adjective "Antarctic" will be applied when
specific sample population designation is unnecessary.
Because relatively few Antarctic meteorite fragments
recovered to date (over 1900 by the United States-led Antarctic
Search for Meteorites and over 5100 by the Japanese Antarctic
Research Expedition teams) can be paired with confidence, the
Michael E. Lipschutz, Department of Chemistry, Purdue University,
W. Lafayette, Indiana 47907.
number of distinct meteorite events represented by the
Antarctic finds is somewhat uncertain. Many Antarctic
specimens are unpaired but a very few have numerous
well-established siblings, numbering up to 148 (Mason and
Yanai, 1983). Taking an overall average of 5 fragments per
fall (estimated as 2-6 per fall by Scott, 1984), the Antarctic
population represents about 1400 distinct events. This number
is comparable (within a factor of 2) to the 2611 known, distinct
non-Antarctic meteorites currently cataloged (Graham et al.,
1985).
From the first, it was recognized that the Antarctic
population includes a substantial number of meteorites of rare
or unique type compared with the non-Antarctic ones
(Kusunoki, 1975). Subsequently, recovery and study of such
exciting specimens has proven to be very nearly an annual
event as, for example, in the cases of lunar and putative Martian
meteorites (Marvin, 1983; Yanai and Kojima, 1984). Represen-
tatives of some rare types resemble their non-Antarctic
congeners but, curiously, often show subtle differerences from
them in composition. This seems to reflect preterrestrial
processes rather than terrestrial weathering (Biswas et al., 1980,
1981; Lipschutz, 1982). Antarctic and non-Antarctic meteorites
differ in other ways. For example, general differences occur
in the distribution of iron meteorite chemical groups (Clarke,
1986) and in the textures and mineral compositions of Antarctic
and non-Antarctic diogenites and eucrites (Mason and Yanai,
1983). Of course, these comparisons are based on poor
statistics since we are dealing with representatives of rare
meteorite types.
Subject to inevitable uncertainty because of pairing prob-
lems, Antarctic and non-Antarctic populations differ in their
constituent meteorite proportions. Considering just the most
general classification (Table 12-1), the Victoria Land popula-
tion (corrected for known pairing) contains fewer irons, LL
chondrites, and perhaps stony-irons than do non-Antarctic falls.
Furthermore, the high iron to low iron (H/L) chondrite ratio is
over 3 in the Victoria Land population and 1 in non-Antarctic
falls (and finds). In the only comprehensive study of a single
year's (1974) collection in Queen Maud Land, Mason and
99
100 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Yanai's (1983) data yield an HA- chondrite ratio (corrected for
paired samples) of 155/54, or nearly 3. These differences
cannot reasonably be ascribed to Antarctic weathering; they
hint at some major difference in the nature of meteorites
landing in Antarctica and those landing elsewhere. Possibly
the parent bodies of Antarctic meteorites followed more highly
inclined orbits, or, more likely, a temporal change has taken
place in the meteorite flux (Dennison et al., 1986).
Indications for differences between meteorite types in
Antarctic and non-Antarctic sample populations do not
necessarily mean that any given meteorite type will differ in
the two sample populations. To identify the significant
differences, one must compare parameters known to vary
widely and be indicative of meteoritic genetic processes.
Volatile and/or mobile trace element contents (Ag, Au, Bi, Cd,
Co, Cs, Ga, In, Rb, Sb, Se, Te, Tl, and Zn) provide such a
parameter for comparison between non-Antarctic ordinary
chondrite falls and Victoria Land chondrites.
Data for a given volatile/mobile trace element in a sample
population distribute either normally or lognormally and may
be treated as Gaussian in either case (Dennison et al., 1986).
Generally, distributions for a given element in two sample
populations overlap and one must use standard statistical tests
to examine the likelihood that the sample populations derive
from the same parent population. If, statistically, this is
unlikely for a number of different elements, it may be
concluded that the sample populations derive from different
parent populations.
As part of a series of systematic studies of equilibrated
ordinary chondrites, Dennison et al. (1986) compared volatile/
mobile trace element data for 23 Antarctic finds and 20
non-Antarctic H5 chondrite falls. Taking >95% confidence
level as significant and 90%-94% as possibly so, Dennison
et al. (1986) found differences for 8 of 13 elements tested
(Table 12-2). This greatly exceeds the proportion expected to
arise by chance (1-2 of 13 elements at the >90% confidence
level). Dennison et al. (1986) and Dennison and Lipschutz (in
prep. a,b) extended the comparison to H4-6 chondrites. They
considered a variety of more or less plausible explanations for
the differences, especially weathering, and concluded that the
difference was a real one reflecting preterrestrial genetic
differences. More recently, Kaczaral and Lipschutz (in prep.)
found that L4-6 chondrites from Victoria Land also differ
compositionally from non-Antarctic falls: we take this as
additional support for the unimportance of a weathering effect
on trace element contents of Antarctic meteorites.
For L6 chondrites, the trace element data suggest, on
average, more severe thermal processing (perhaps by shock)
for the Victoria Land samples than for non-Antarctic falls
(Kaczaral and Lipschutz, in prep.). This suggestion is currently
being tested by petrographic and thermoluminescence studies.
For H5 chondrites, genetic processes responsible for the
compositional differences are less obvious (Dennison and
Lipschutz, in prep. b).
TABLE 12-1.?Comparative numbers of selected meteorite types found in
Victoria Land and falling in non-Antarctic regions (numbers cited for H, L,
and LL chondrites count as part of the total for chondrites).
Meteorite type
Chondrites
H
L
LL
Achondrites
[rons
Stony Irons
Total
Victoria Land*
No.
756
542
167
24
45
14
3
818
%
92.4
66.3
20.4
2.9
5.5
1.7
0.4
100.0
Non-Antarcticf
No.
784
276
319
66
69
42
10
905
%
86.6
30.5
35.2
7.3
7.6
4.6
1.1
100.0
*J. Gooding (personal communication, 1985). Data do not include 281
samples paired with ones already classified.
tGraham et al. (1985).
Major and trace element distributions for ordinary chondrites
from Victoria Land are more coherent than those for
non-Antarctic falls (Fulton and Rhodes, 1984; Dennison et al.,
1986; Dennison and Lipschutz, in prep. a,b; Kaczaral and
Lipschutz, in prep.), hinting again at preterrestrial composi-
tional differences between Antarctic and non-Antarctic meteor-
ites. Dennison et al. (1986) illustrate one in which meteorite
sample populations falling on Earth at specific times in the
past could differ in the proportions of constituent types. Such
distributions preserved, for example, in the Antarctic ice sheet
would constitute "snap-shots in time" of the meteoroid
distribution. As yet, we do not know whether the Antarctic
sample population is a single one or if the Victoria Land and
Queen Maud Land (and others) constitute differing sample
populations separated in time, having average ages of 0.3 Myr
B.P. (Victoria Land) and 0.1 Myr B.R (Queen Maud Land) (Bull
and Lipschutz, 1982). Another possibility is that Antarctic
meteorites preferentially derive from parent bodies in highly
inclined orbits.
It seems too optimistic to expect that the Victoria Land
population is a "pure" sample of a single parent region (or
body) "unsullied" by earlier and later events, and it would be
premature to attempt resolution of the near-Earth meteorite
flux with only 2 distributions, Victoria Land and non-Antarctic
falls. Indeed, it is astonishing that any differences are detectable
in chondrite sample populations separated by only 0.2 Myr,
when typical cosmic ray exposure ages had been taken to imply
an averaging of the chondritic flux over the past 1-10 Myr
(Wetherill, 1974).
Nevertheless, the trace element evidence seems compelling
that meteorites from Victoria Land sample a population
different from that falling today in non-Antarctic regions.
Hence, Antarctic meteorites are a more valuable scientific
resource than hitherto suspected. Antarctic meteorites may
include collision debris from disrupted parent asteroids that
was long since swept up and no longer exists among
NUMBER 28 101
TABLE 12-2.?Comparison of statistically significant differences in H5 and L6 chondrites from
Victoria Land, Antarctica, with contemporary non-Antarctic falls. (Ant. = Chondrites from Victoria
Land; Non = non-Antarctic chondrite falls; Sig. = significance level at which it may be concluded
that the respective sample populations do not derive from the same parent population. Numbers in
parentheses are number of samples analyzed in that population.)
Element
Co (ppm)*
Au (ppb)*
Sb (ppb)
Se (ppm)*
Rb (ppm)
Cs (ppb)
Te (ppb)
Bi (ppb)
Ag (ppb)
In (ppb)
Tl (ppb)
Zn (ppm)*
Cd (ppb)
Ant. (23)
83
9.0
2.0
2.8
0.21
0.81
43
0.72
H5
Non (20)
69
8.2
2.5
1.1
0.49
0.24
53
3.7
Sig.
97
99
97
98
96
96
96
99
Ant. (13)
480
140
2.6
4.02
340
0.58
45
1.6
L6
Non (25)
600
160
2.2
12.4
380
2.7
71
14.2
Sig.
97
90
95
99
90
99
97
99
*Arithmetric means, all others are geometric means: the specific choice is determined by the data
distribution in the populations tested. Further information (e.g., standard deviation, etc.) is in
Dennison et al. (1986) and Kaczaral and Lipschutz (in prep.).
contemporary falls elsewhere on Earth. From the standpoint
of studies of extraterrestrial materials and processes, Antarctic
meteorites offer the potential of an enhanced understanding of
planetary surfaces, the genesis, evolution, and composition of
meteorite planet bodies, and temporal variations in meteorite
and cosmic ray fluxes.
Furthermore, since the fall of Antarctic meteorites can be
dated, they provide a potential source of information on the ice
sheet region with which they are associated. Ancillary
measurements, in concert with meteoritic terrestrial ages, could
provide information on the ancient trapped atmosphere, ice
sheet dynamics, and oxygen isotopic variations, leading to a
predictive model for discovering new meteorite concentrations.
ACKNOWLEDGMENTS.?This research would not have been
possible except for the aid of the staff of the University of
Missouri Research Reactor, irradiation support through DOE
grant DEFG 0280 ERR 10725 and research support by NASA
grant NAG 9-48 and NSF grants DPP-8111513 and 8415061.
Literature Cited
Biswas, S., H.T. Ngo, and M.E. Lipschutz
1980. Trace Element Contents of Selected Antarctic Meteorites, I:
Weathering Effects and ALH A77005, A77257 and A77299.
Zeitschrift fur Naturforschung, 35a: 190-196.
Biswas, S., T.M. Walsh, H.T. Ngo, and M.E. Lipschutz
1981. Trace Element Contents of Selected Antarctic Meteorites, II:
Comparison with Non-Antarctic Specimens. Memoirs of the
National Institute of Polar Research (Japan), special issue
20:221-228.
Bull, C.B.B., and M.E. Lipschutz
1982. Workshop on Antarctic Glaciology and Meteorites. Lunar and
Planetary Institute Technical Report, 82-03:22.
Clarke, R.S., Jr.
1986. Antarctic Iron Meteorites: An Unexpectedly High Proportion of
Falls of Unusual Interest. In J.O. Annexstad, L. Schultz, and H.
Wanke, editors, Workshop on Antarctic Meteorites. Lunar and
Planetary Institute Technical Report, 86-01:28-29.
Dennison, J.E., and M.E. Lipschutz
In prep. a. Chemical Studies of H Chondrites?II: Weathering of
Antarctic Samples.
In prep. b. Chemical Studies of H Chondrites?III: Antarctic H4-6
Samples.
Dennison, J.E., D.W. Lingner, and M.E. Lipschutz
1986. Antarctic and Non-Antarctic Meteorites for Different Populations.
Nature, 319:390-393.
Dodd, R.T.
1981. Meteorites, A P etrologic-Chemical Synthesis. 368 pages. Cambr-
idge, England: Cambridge University Press.
Fulton, C.R., and J.M. Rhodes
1984. The Chemistry and Origin of the Ordinary Chondrites: Implications
from Refractory-Lithophile and Siderophile Elements. In Proceed-
ings of the Fourteenth Lunar and Planetary Science Conference.
Journal of Geophysical Research, 89(supplement): B543-B558.
Graham, A.L., A.W.R. Bevan, and R. Hutchison
1985. The Catalogue of Meteorites. 4th edition, 460 pages. London: British
Museum.
Kaczaral, P.W., and M.E. Lipschutz
In prep. Chemical Studies of L Chondrites, IV: Antarctic L4-6 Chondrites
and Their Origin.
Kusunoki, K.
1975. A Note on the Yamato Meteorites Collected in December 1969.
Memoirs of the National Institute of Polar Research (Japan), special
issue, 5:1-8.
102 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Lipschutz, M.E.
1982. Weathering Effects in Antarctic Meteorites. In U.B. Marvin and B.
Mason, editors, Catalog of Meteorites from Victoria Land,
Antarctica, 1978-1980. Smithsonian Contributions to the Earth
Sciences, 24:67-69.
Marsden, B.G.
1985. Minor Planet Circular, 10063.
Marvin, U.B.
1983. The Discovery and Initial Characterization of Allan Hills 81005:
The First Lunar Meteorite. Geophysical Research Letters, 10:775-
778.
Mason, B., and K. Yanai
1983. A Review of the Yamato-74 Meteorite Collection. Memoirs of the
National Institute of Polar Research (Japan), special issue, 30:7-28.
Scott, E.R.D.
1984. Pairing of Meteorites Found in Victoria Land, Antarctica. Memoirs
of the National Institute of Polar Research (Japan), special issue,
35:102-125.
Tedesco, E.F.
1984. IRAS Asteroid Workshop No. 3. Jet Propulsion Laboratory
(Pasadena) Report, D-1617.
Wetherill, G.W.
1974. Solar System Sources of Meteorites and Large Meteoroids. Annual
Review of Earth and Planetary Science, 2:303-331.
Yanai, K., and H. Kojima
1984. Lunar Meteorites in Japanese Collection of the Yamato Meteorites.
Meteoritics, 19:342-343.
13. Pairing of Meteorites from Victoria Land
and the Thiel Mountains, Antarctica
Edward R.D. Scott
Introduction
The identification of meteorite specimens that belong to the
same fall is useful for a variety of reasons: it minimizes
unnecessary duplication of research, waste of specimens, and
conserves curatorial resources. It can also improve our
understanding of the mechanisms that preserve and transport
meteorites in Antarctica. This article reviews what is known
about possible pairings among Victoria Land and Thiel
Mountains specimens and is based largely on lists of paired
specimens in the Antarctic Meteorite Newsletters and a
previous review (Scott, 1984b). The Newsletter lists were
compiled largely by R.A. Score, B. Mason, and C. M. Schwarz
from their own petrologic studies of thin sections and specimen
exteriors. Estimates of the reliability of these pairings are
included here, as well as an assessment of the number of
unidentified pairings.
Coordinates of the discovery locations of -76 to -78
specimens have been published by Yanai (1982, 1984).
Discovery locations have not been published for other
specimens, except for 18 Reckling Peak samples found during
the 1979-1980 season (Cassidy and Rancitelli, 1982). How-
ever, geographic propinquity is only one guide to pairing as
Antarctic specimens found less than a meter apart may belong
to different falls, whereas specimens recovered 20 km apart
may be paired. In addition, it is likely that strong winds can
transport even 200-gram specimens over distances of many
kilometers (Scott, 1984b).
Table 13-1 lists all proposed pairings among Victoria Land
and Thiel Mountains specimens (excluding typographical
errors in the Antarctic Meteorite Newsletters). Estimates of the
reliability of these pairings were made by evaluating the criteria
used for pairing, and by comparing studies of paired specimens
using different techniques (Scott, 1984b). For type 3 ordinary
chondrites, irons, most achondrites, and carbonaceous chon-
drites, which are all relatively uncommon, there is general
Edward R.D. Scott, Department of Geology and Institute of
Meteoritics, University of New Mexico, Albuquerque, New Mexico
87131.
agreement between different investigators. However, for many
type 4 to type 6 ordinary chondrites, and some polymict
eucrites, mesosiderites, and CM2 chondrites, there are dis-
agreements among petrologists and noble gas and cosmogenic
nuclide analysts. In most cases, proposed pairings have not
been tested by other investigators, so that there are considerable
uncertainties in many of the confidence levels listed in Table
13-1.
With the exception of cosmogenic nuclide studies, there
have been few investigations of chemical and mineralogical
variations in large (multikilogram) meteorites. This enhances
the difficulties in pairing Antarctic specimens, especially for
brecciated meteorites such as the polymict eucrites. We do not
know whether, for example, a 15% difference in the plagioclase
content of then sections of two polymict eucrites or a 40%
difference in the Cr concentrations of 2-gram samples of two
ordinary chondrites provides good evidence against pairing.
Table 13-1 also includes one to four references for each
group of paired specimens; additional references are given in
Scott (1984b). Where possible, references are placed opposite
the specimens to which they refer, but in some cases a paper
may also refer to specimens on different lines of the same
pairing group. A numerical list of the specimens in Table 13-1
is given in Table 13-2 together with the pair number and
confidence level given in Table 13-1. These tables show that
the proportion of specimens with suggested pairings from a
given field season has decreased from 1977 to 1981: 75% of
the 102 ALHA77- samples classified by Score et al. (1982b)
are listed in the pairing tables, but only 22% of the 313
characterized ALHA81- specimens. This is partly because field
investigators since Cassidy (1980) have not published sug-
gested pairings, but also because the preliminary examination
teams have begun to concentrate their efforts on identifying
pairs of the rarer meteorites. This change is reasonable as few
researchers study type 4-6 ordinary chondrites, and pairings
among rarer meteorites are easier to identify. The proportion
of types 4-6 ordinary chondrites among lists of paired
specimens is 75% for pairing lists published in 1982 and 1983
{Antarctic Meteorite Newsletter, 5(1) and 6(2)), close to the
103
104 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 13-1.?Meteorite specimens that have been paired and the confidence levels of these pairings (confidence
level: a = high (>95%); b = medium (80% - 90%; c = low (50% -75%); x = unpaired or highly uncertain pairing).
Pair
number Specimens
Confidence
level References
UNGROUPED METEORITES
1.1 ALHA77081, 81261, 81315
EUCRITES AND HOWARDITES
2.1 ALHA76005, 77302,78040,78132, 78158,
78165,79017,81009
80102, 81006-81008, 81010, 81012
81001
2.2a EETA79004, 79011, 83228, 83229, 83231,
83232, 83234, 83251, 83283
2.2b EETA79005, 79006, 82600, 83227, 83235
Alternative view
2.2a EET83231,83232
79004
2.2b EETA79011,83229, 83234, 83283
2.2c EETA79005, 79006, 82600, 83212, 83227,
83228, 83235, 83251
AUB RITES
3.1
3.2
3.3
UREILITES
3.4
3.5
ALH83009, 83015
ALH84007, 84008, 84011
EET83246, 83247
ALHA78019, 78262
ALH82106, 82130
MESOSIDERTTES
IRONS, GROUP IIB
5.2 DRPA78001-78016
CM2 CHONDRITES
6.1 ALHA81002, 81004, 82100
78261,82131,83016
77306
6.2 ALH83100, 83102, 84029 - 84032, 84034,
84042, 84044
CO3 CHONDRITES
6.3 ALHA77003,82101
CV3 CHONDRITES
9.10 ALHA81OO3,81258
EH3/4 CHONDRITES
7.1 ALHA77156,77295
81189
E6 CHONDRITES
7.2 ALHA81021,81260
4.1
4.2
IRONS,
5.1
ALHA77219, 81059, 81098
RKPA79015, 80229, 80246, 80258, 80263
GROUPIA
ALHA76002, 77250, 77263, 77289, 77290,
77283
b
b
a
X
Mason, 1985
Score, King, et al., 1982; Schultz, 1985
Delaney et al., 1984
Delaney and Prinz, Chapter 8
Delaney et al., 1984; Delaney and Prinz, Chapter 8
Delaney et al., 1984;
Delaney and Prinz, Chapter 8
Mason et al., Chapter 6
Mason et al., Chapter 6
Mason et al., Chapter 6
Mason et al., Chapter 6
Delaney, 1985; Mason et al., Chapter 6
MacPherson, 1985b; Mason et al., Chapter 6
B. Mason, pers. communication
Score et al., 1981; Score, King, et al., 1982; Berkley
and Jones, 1982
Mason, 1984b
Mason, 1983a,b; Hewins, 1984
Clarke and Mason, 1982
Clarke et al., 1980
Malvinetal., 1984
Clarke, 1982
McSween, Chapter 9
Mason, 1983a; McSween, Chapter 9
Score, King, et al., 1982
MacPherson, 1985a,b
Scott, 1984b; Wieler et al., 1985
Mason, 1985
McKinley and Keil, 1984;
Wieler et al., 1985; this work
Mason, 1985
NUMBER 28 105
TABLE 13-1.?Continued.
Pair
number Specimens
Confidence
level References
H4 CHONDRITES
8.1 ALHA77004, 77190-77192, 77208, 77223- b
77226,77232, 77233
77221 c
8.2 ALHA77009, 81022 c
78084 x
8.3
8.4
8.5
8.6
ALHA78193, 78196, 78223
ALHA80106, 80121, 80128, 80131
ALHA81041, 81043-81052
RKPA80237, 80267
80232
H5 CHONDRITES
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
9.10
9.11
ALHA77014, 77264
ALHA77021, 77025, 77061, 77062, 77064,
77071, 77074, 77086, 77088, 77102
ALHA77118, 77119, 77124
ALHA78209, 78221, 78225, 78227, 78233
ALHA79031,79032
ALHA80111, 80124, 80127, 80129, 80132
RKPA80217, 80218
RKPA 80220, 80223
RKPA 80250, 80251
TIL82412, 82413
TIL82414, 82415
H6 CHONDRITES
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
10.9
11.1
11.2
11.3
ALHA77144, 77148
ALHA77271,77288
ALHA78211, 78213, 78215, 78229, 78231
ALHA80122, 80126, 80130
ALHA81035, 81038, 81103, 81112
MBRA76001,76002
RKPA80203, 80206, 80208, 80211, 80213,
80214, 80221, 80254, 80255, 80265,
80266
80231, 80262
EET82610,82615
PCA 82526, 82527
ALHA77011, 77015, 77031, 77033, 77034,
77036, 77043, 77047, 77049, 77050,
77052, 77115, 77140, 77160, 77163-
77167, 77170, 77175, 77178, 77185
77211, 77214, 77241, 77244, 77249,
77260, 77303, 78013, 78015, 78017,
78037, 78038, 78041, 78162, 78170,
78176, 78180, 78186, 78188, 78235,
78236, 78238, 78239, 78243, 79001,
79045, 80133, 81025, 81030-81032,
81053, 81060, 81061, 81065, 81066,
81069, 81085,81087, 81121, 81145,
81156, 81162, 81190, 81191, 81214,
81229, 81243, 81259, 81272, 81280,
81292, 81299
ALHA77215-77217, 77252
RKPA79OO8, 80207
b
c
c
b
X
c
c
X
c
b
b
c
c
c
c
c
c
c
a
b
c
c
a
b
c
c
c
a
a
X
Cassidy, 1980
Scott, 1984b
Score et al., 1984; Mason, 1983a
Scott, 1984b; Sarafin et al., 1985
Anonymous, 1981
Mason and Clarke, 1982
Score, 1983; Mason, 1983b
Mason and Clarke, 1982
Scott, 1984b
Cassidy, 1980
Cassidy, 1980;
Score etal., 1981
Cassidy, 1980
Anonymous, 1981
Score etal., 1981
Mason and Clarke, 1982; Vogt et al., 1985
Score, Schwarz, et al., 1982
Score, Schwarz, et al., 1982
Score, Schwarz, et al., 1982
Mason, 1984b
Mason, 1984b
Cassidy, 1980
Cassidy, 1980; Scott, 1984b
Anonymous, 1981
Mason and Clarke, 1982
Mason, 1983a,b; Anonymous, 1984
Weber and Schultz, 1980
Mason and Clarke, 1982
Scott, 1984b
Mason, 1984b
Mason, 1984b
McKinley et al., 1981; Scott, 1984b, this work;
Nishiizumi et al., 1983; Wieler et al., 1985
L4 CHONDRITES
12.1 RKPA80216, 80242
Score, 1980; Nautiyal et al, 1982
Wieler et al., 1985; this work
Score, Schwarz, et al., 1982
106 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 13-1.?Continued.
Pair
number Specimens
L5 CHONDRITES
13.1
13.2
13.3
ALHA81018, 81023
81017
PCA82504, 82505
RKPA80209, 80228, 80268
L6 CHONDRITES
14.1
14.2
14.3
14.4
14.5
14.6
14.7
14.8
14.9
14.10
14.11
14.12
ALHA76003, 76007
ALHA77001, 77292, 77293, 77296, 77297
77150,77180,77305
ALHA77272, 77273
77280, 77282
77231, 77269, 77270, 77277, 77281, 77284
ALHA78043, 78045
ALHA78103, 78105
78104, 78251
ALHA78112, 78114
ALHA78126, 78130, 78131
ALHA80101, 80103, 80105, 80107, 80108,
80110, 80112-80117, 80119, 80120,
80125,81017,81107,81262
ALHA81027-81029
BTNA78001, 78002
EET82605, 82606
RKPA78001, 78003
79001, 79002, 80202, 80219, 80225,
80252, 80261, 80264
LL3 CHONDRITES
15.1 ALHA76004, 81251
LL6 CHONDRITES
16.1 RKPA 80238, 80248
80222
Confidence
level
c
X
c
c
X
b
X
a
b
X
b
b
X
X
X
a
b
b
a
c
b
c
b
a
b
References
Mason, 1983a
Marvin, Chapter 14
Mason, 1984a
Mason and Clarke, 1982
Weber and Schultz, 1980
Cassidy, 1980
Anonymous, 1984; Scott 1984b
Cassidy, 1980
Goswami and Nishiizumi, 1983
Anonymous, 1984; Scott, 1984b
Score et al., 1981
Anonymous, 1984
Scott, 1984a
Score et al., 1981; Nishiizumi et al., 1983
Score et al., 1981; Scott, 1984b
Score, Schwarz, et al., 1982; Mason and Clarke, 1982
Marvin, Chapter 14
Mason, 1983a,b
Score et al., 1981; R. Score, pers. communication
Mason, 1984a
Score etal., 1981
Mason and Clarke, 1982; Scott, 1984b
Scott, 1984b; Wieler et al., 1985
Mason and Clarke, 1982
Sarafin and Herpers, 1983; Signer et al., 1983
proportion among falls, 68% (Wasson, 1974). However, in two
recent lists (Antarctic Meteorite Newsletter, 7(2) and 8(1)), the
proportion is only 25%.
Another measure of the concentration of effort on the rarer
meteorites is the number of proposed pairings of specimens
collected in different years. For the types 4-6 ordinary
chondrites in Table 13-1, only three of 43 pairing groups
contain specimens found in different years. However, for the
remaining meteorites, the corresponding figure is 13 out of 23
pairing groups. It is likely that most of the paired specimens
among type 3 chondrites (Scott, 1984a), polymict eucrites
(Delaney and Prinz, 1984), and other rarer meteorite types
have been identified. By contrast, it is certain that for types
4-6 ordinary chondrites, most of the paired specimens have
not been recognized.
Justifiably, no attempts have been made to identify paired
specimens among the 120 ALHA77- and 21 ALHA78- small
specimens of types 4-6 ordinary chondrites that were classified
by McKinley and Keil (1984) and by SJ.B. Reed and S.O.
Agrell (Antarctic Meteorite Newsletter 7(1), 1984).
To illustrate the importance of identifying paired specimens,
it is noted that petrologic descriptions of what are very
probably a set of paired L3 chondrites have been published
under various meteorite names: ALH-77015 (Nagahara, 1981;
Fujimake et al., 1981), ALH-77294 (Kimura, 1983), and
ALHA77011 (McKinley et al., 1981). The Nomenclature
Committee of the Meteoriu'cal Society recommends that the
lowest specimen number be adopted as the meteorite name
(Graham, 1980). However, in some cases the number of the
largest or best-distributed specimen may be a more appropriate
meteorite name. To distinguish specimen and meteorite names,
it may be useful to italicize the latter. Since no two Antarctic
specimens can be paired with complete certainty unless they
fit together like pieces of a jigsaw puzzle, it is important that
specimen numbers of analyzed paired samples should be
published, in addition to the meteorite name.
NUMBER 28 107
TABLE 13-2.?Numerical list of meteorite specimens that have been paired and the confidence level of these
pairings (confidence level: a = high; b = medium, c = low; x = unpaired or highly uncertain pairing).
Specimen
number
ALHA
76002
76003
76004
76005
76007
77001
77003
77004
77009
77011
77014
77015
77021
77025
77031
77033
77034
77036
77043
77047
77049
77050
77052
77061
77062
77064
77071
77074
77081
77086
77088
77102
77115
77118
77119
77124
77140
77144
77148
77150
77156
77160
77163-77167
77170
77175
77178
77180
77185
77190-77192
77208
77211
77214
77215-77217
77219
77221
77223-77226
77231
Pair
number
5.1
14.1
15.1
2.1
14.1
14.2
6.3
8.1
8.2
11.1
9.1
11.1
9.2
9.2
11.1
11.1
11.1
11.1
11.1
11.1
11.1
11.1
11.1
9.2
9.2
9.2
9.2
9.2
1.1
9.2
9.2
9.2
11.1
9.3
9.3
9.3
11.1
10.1
10.1
14.2
7.1
11.1
11.1
11.1
11.1
11.1
14.2
11.1
8.1
8.1
11.1
11.1
11.2
4.1
8.1
8.1
14.3
Confidence
level
a
X
b
a
X
b
X
b
c
a
c
a
c
c
a
a
a
a
a
a
a
a
a
c
c
c
c
c
a
c
c
X
a
c
c
c
a
c
c
X
a
a
a
a
a
a
X
a
b
b
a
a
a
b
c
b
X
Specimen
number
ALHA (continued)
77232
77233
77241
77244
77249
77250
77252
77260
77263
77264
77269
77270
1121 \
11212
77273
77277
77280
77281
77282
77283
77284
77288
77289
77290
77292
77293
77295
77296
77297
77302
77303
77305
77306
78013
78015
78017
78019
78037
78038
78040
78041
78043
78045
78084
78103
78104
78105
78112
78114
78126
78130
78131
78132
78158
78162
78165
78170
Pair
number
8.1
8.1
11.1
11.1
11.1
5.1
11.2
11.1
5.1
9.1
14.3
14.3
10.2
14.3
14.3
14.3
14.3
14.3
14.3
5.1
14.3
10.2
5.1
5.1
14.2
14.2
7.1
14.2
14.2
2.1
11.1
14.2
6.1
11.1
11.1
11.1
3.4
11.1
11.1
2.1
11.1
14.4
14.4
8.2
14.5
14.5
14.5
14.6
14.6
14.7
14.7
14.7
2.1
2.1
11.1
2.1
11.1
Confidence
level
b
b
a
a
a
a
a
a
a
c
X
X
a
a
a
X
b
X
b
X
X
a
a
a
b
b
a
b
b
a
a
X
X
a
a
a
c
a
a
a
a
b
b
X
b
X
b
X
X
X
X
X
a
a
a
a
a
108 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 13-2.?Continued.
Specimen
number
ALHA (continued)
78176
78180
78186
78188
78193
78196
78209
78211
78213
78215
78221
78223
78225
78227
78229
78231
78233
78235
78236
78238
78239
78243
78251
78261
78262
79001
79017
79031
79032
79045
80101
80102
80103
80105
80106
80107
80108
80110
80111
80112-80117
80119
80120
80121
80122
80124
80125
80126
80127
80128
80129
80130
80131
80132
80133
81001
81002
81003
Pair
number
11.1
11.1
11.1
11.1
8.3
8.3
9.4
10.3
10.3
10.3
9.4
8.3
9.4
9.4
10.3
10.3
9.4
11.1
11.1
11.1
11.1
11.1
14.5
6.1
3.4
11.1
2.1
9.5
9.5
11.1
14.8
2.1
14.8
14.8
8.4
14.8
14.8
14.8
9.6
14.8
14.8
14.8
8.4
10.4
9.6
14.8
10.4
9.6
8.4
9.6
10.4
8.4
9.6
11.1
2.1
6.1
6.4
Confidence
level
a
a
a
a
b
b
b
b
b
b
b
b
b
b
b
b
b
a
a
a
a
a
X
c
c
a
a
b
b
a
b
b
b
b
c
b
b
b
c
b
b
b
c
c
c
b
c
c
c
c
c
c
c
a
b
b
c
Specimen
number
ALHA (continued)
81004
81006-81008
81009
81010
81012
81017
81018
81021
81022
81023
81025
81027-81029
81030-81032
81035
81038
81041
81043-81052
81053
81059
81060
81061
81065
81066
81069
81085
81087
81098
81103
81107
81112
81121
81145
81156
81162
81189
81190
81191
81214
81229
81243
81251
81258
81259
81260
81261
81262
81272
81280
81292
81299
81315
82100
82101
82106
82130
82131
83009
Pair
number
6.1
2.1
2.1
2.1
2.1
13.1
14.8
13.1
7.2
8.2
13.1
11.1
14.9
11.1
10.5
10.5
8.5
8.5
11.1
4.1
11.1
11.1
11.1
11.1
11.1
11.1
11.1
4.1
10.5
14.8
10.5
11.1
11.1
11.1
11.1
7.1
11.1
11.1
11.1
11.1
11.1
15.1
6.4
11.1
7.2
1.1
14.8
11.1
11.1
11.1
11.1
1.1
6.1
6.3
3.5
3.5
6.1
3.1
Confidence
level
b
b
a
b
b
X
b
c
c
c
c
a
b
a
c
c
c
c
a
b
a
a
a
a
a
a
a
b
c
b
c
a
a
a
a
X
a
a
a
a
a
b
c
a
c
a
b
a
a
a
a
a
b
X
a
a
c
a
NUMBER 28 109
TABLE 13-2.?Continued.
Specimen
number
ALHA (continued)
83015
83016
83100
83102
84007
84008
84011
84029-84032
84034
84042
84044
BTNA
78001
78002
DRPA
A78001-78016
EETA
79004-79006
79011
82600
82605
82606
82610
82615
83227-83229
83231
83232
83234
83235
83246
83247
83251
83283
MBRA
76001
76002
PCA
82504
82505
82526
82527
RKPA
78001
78003
Pair
number
3.1
6.1
6.2
6.2
3.2
3.2
3.2
6.2
6.2
6.2
6.2
14.10
14.10
5.2
2.2
2.2
2.2
14.11
14.11
10.8
10.8
2.2
2.2
2.2
2.2
2.2
3.3
3.3
2.2
2.2
10.6
10.6
13.2
13.2
10.9
10.9
14.12
14.12
Confidence
level
a
c
b
b
b
b
b
b
b
b
b
a
a
a
b
b
b
c
c
c
c
b
b
b
b
b
X
X
b
b
a
a
c
c
c
c
b
b
Specimen
number
RKPA (continued)
79001
79002
79008
79015
80202
80203
80206
80207
80208
80209
80211
80213
80214
80216
80217
80218
80219
80220
80221
80222
80223
80225
80228
80229
80231
80232
80237
80238
80242
80246
80248
80250
80251
80252
80254
80255
80258
80261
80262
80263
80264
80265
80266
80267
80268
TIL
82412
82413
82414
82415
Pair
number
14.12
14.12
11.3
4.2
14.12
10.7
10.7
11.3
10.7
13.3
10.7
10.7
10.7
12.1
9.7
9.7
14.12
9.8
10.7
16.1
9.8
14.12
13.3
4.2
10.7
8.6
8.6
16.1
12.1
4.2
16.1
9.9
9.9
14.12
10.7
10.7
4.2
14.12
10.7
4.2
14.12
10.7
10.7
8.6
13.3
9.10
9.10
9.11
9.11
Confidence
level
c
c
X
b
c
b
b
X
b
c
b
b
b
b
c
c
c
c
b
b
c
c
c
b
c
X
b
a
b
b
a
c
c
c
b
b
b
c
c
b
c
b
b
b
c
c
c
c
c
110 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Pairing Notes
Pair Number 2.2
There is some disagreement on the classification and pairing
of the 16 eucrites, polymict eucrites and howardites that have
been recovered from Elephant Moraine. On the basis of
pyroxene analyses, Mason et al. (this volume) believe that 15
specimens come from three different falls; EET83236 may be
unpaired. Delaney and Prinz (this volume) argue instead, from
their petrographic studies, that 14 of these 15 specimens belong
to two falls; they exclude EET83212 because the section
studied appeared atypical. Both pairing schemes are listed in
Table 13-1. EETA79005, 79006 and 82600, which are paired
by both groups, have similar terrestrial and cosmic-ray
exposure ages of 0.17-0.19 and 26-28 million years,
confirming their pairing (Schultz, 1985). Schultz believes, as
do Delaney and Prinz, and Mason et al. that EETA79004 is
not paired with these three; its terrestrial and exposure ages are
0.25 and 22 million years.
Pair Number 7.1
Concentrations of spallogenic noble gases in two EH3/4
chondrites, ALHA77156 and ALHA77295, are very similar
(Weiler et al., 1985), confirming their pairing on petrographic
grounds by McKinley and Keil (1984). Since they were found
18 km apart, this additional evidence for pairing is valuable.
Petrologic studies by Prinz et al. (1985) show that ALHA81189
is a highly unequilibrated enstatite chondrite like 77156.
However, their modal analyses suggest that 81189 has a much
higher abundance of olivine (8% cf. 2% in 77156) and is not
paired.
Pair Number 11.1
Confirmation that ALHA77047, 78015, 81030-81032, and
81121 are paired with many other L3 specimens that contain
abundant graphite-magnetite aggregates is provided by their
concentrations of spallogenic and trapped noble gases (Weiler
et al., 1985). These authors also confirm that ALHA81024 is
not part of this meteorite shower, even though it also contains
abundant graphite-magnetite aggregates (Scott, 1984b). There
are seven other unpaired L3 specimens from Allan Hills in
United States collections: 77013, 77176, 77197, 78046, 78119,
78133, and 83010. Wieler et al. (1985) have analyzed all but
78046, 78119, and 83010, and their data support this
conclusion.
Pair Number 11.3
RKPA79008 and 80207, which were originally classified
as L3 chondrites (Score et al., 1982b, 1984), contain similar
concentrations of spallogenic 21Ne, and concentrations of solar
wind noble gases that are within a factor of two. Since only
two other Antarctic and six non-Antarctic L chondrites are
known to contain solar wind gases, the suggestion of Wieler
et al. (1985) that these two Reckling Peak specimens are paired
would appear very likely. However, RKPA80207 is probably
an H3 chondrite, as the great majority of its olivine grains
have compositions appropriate to equilibrated H chondrites
(Scott, 1984a). In RKPA79008, by contrast, most olivines
have compositions like those of equilbrated L chondrites. Since
chondrites having materials with the compositions of both
equilibrated H and L chondrites are not known, it is more likely
that these two specimens are not paired.
Pair Number 15.1
The presence of rather similar concentrations of spallogenic
and trapped noble gases in the LL3 chondrites, ALHA76004
and 81251, supports their pairing (Wieler et al., 1985).
Although petrographically similar, they have very different
degrees of weathering, unlike other paired specimens (Scott,
1984b).
ACKNOWLEDGMENTS.?I thank B. Mason, H.Y. McSween,
Jr., R.A. Score, P. Signer, R. Wieler, and other members of the
Meteorite Working Group for their helpful assistance. This
work was partly supported by NASA grant NAG-9-30 to K.
Keil.
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Memoirs of the National Institute of Polar Research (Japan), special
issue, 20:145-160.
Nautiyal, CM., J.T. Padia, M.N. Rao, T.R. Venkatesan, and J.N. Goswami
1982. Irradiation History of Antarctic Gas-Rich Meteorites. In Lunar and
Planetary Science XIII, pages 578-579. Houston: Lunar and
Planetary Institute.
Nishiizumi, K., J.R. Arnold, D. Elmore, X. Ma, D. Newman, and H.E. Gove
1983. ^Q and 53Mn in Antarctic Meteorites and 10Be-36Cl Dating of
Antarctic Ice. Earth and Planetary Science Letters, 62:407-417.
Prinz, M., M.K. Weisberg, C.E. Nehru, and J.S. Delaney
1985. ALHA81189, A Highly Unequilibrated Enstatite Chondrite: Evi-
dence for a Multistage History. Meteoritics, 20:731-732.
Sarafin R., and U. Herpers
1983. Spallogenic ^Al and 53Mn in Antarctic Meteorites and Determina-
tion of Exposure and Terrestrial Ages. Meteoritics, 18:392.
Sarafin, R., M. Bourot-Denise, G. Crozaz, U. Herpers, P. Pellas, L. Schultz,
and H.W. Weber
1985. Cosmic Ray Effects in the Antarctic Meteorite Allan Hills A78084.
Earth and Planetary Science Letters, 73:171-182.
Schultz, L.
1985. Terrestrial Ages of Antarctic Meteorites: Implications for Concen-
tration Mechanisms. In Abstracts for Workshop on Antarctic
Meteorites, pages 41?43. Houston: Lunar and Planetary Institute.
Score, R.
1980. Allan Hills 77216: A Petrologic and Mineralogic Description.
Meteoritics, 15:363.
1983. [Catalog description.] Antarctic Meteorite Newsletter, 6(2).
Score, R., T.V.V. King, CM. Schwarz, A.M. Reid, and B. Mason
1982. Descriptions of Stony Meteorites. In U.B. Marvin and B. Mason,
editors, Catalog of Meteorites from Victoria Land, Antarctica,
1978?1980. Smithsonian Contributions to the Earth Sciences,
24:19-48.
Score, R., CM. Schwarz, T.V.V. King, B. Mason, D.D. Bogard, and E.M.
Gabel
1981. Antarctic Meteorite Descriptions 1976-1977-1978-1979. Curato-
rial Branch Publication 54, JSC 17076. 144 pages. Houston:
Johnson Space Center.
Score, R., CM. Schwarz, and B. Mason
1984. Descriptions of Stony Meteorites. In U.B. Marvin and B. Mason,
editors, Field and Laboratory Investigations of Meteorites from
Victoria Land, Antarctica. Smithsonian Contributions to the Earth
Sciences, 26:23^17.
Score, R., CM. Schwarz, B. Mason, and D.D. Bogard
1982. Antarctic Meteorite Descriptions 1980. Curatorial Branch Publica-
tion 60, JSC 18170. 55 pages. Houston: Johnson Space Center.
Scott, E.R.D.
1984a. Classification, Metamorphism, and Brecciation of Type 3 Chon-
drites from Antarctica. In U.B. Marvin and B. Mason, editors. Field
and Laboratory Investigations of Meteorites from Victoria Land,
Antarctica. Smithsonian Contributions to the Earth Sciences,
26:73-94.
1984b. Pairing of Meteorites Found in Victoria Land, Antarctica. Memoirs
of the National Institute of Polar Research (Japan), special issue,
35:102-125.
Signer, P., H. Baur, Ph. Etique, and R. Wieler
1983. Light Noble Gases in 15 Meteorites. Meteoritics, 18:399.
Vogt, St., U. Herpers, R. Sarafin, P. Signer, R. Wieler, M. Suter, and W. Wolfli
1985. Cosmic Ray Records in Antarctic Meteorites. In Abstracts for
Workshop on Antarctic Meteorites, pages 55-57. Houston: Lunar
and Planetary Institute.
Wasson, J.T.
1974. Meteorites?Classification and Properties. 316 pages. Heidelberg:
Springer-Verlag.
Weber, H.W, and L. Schultz
1980. Noble Gases in Ten Stone Meteorites from Antarctica. Zeitschrift
fur Naturforschung, 35a:44?49.
Wieler, R., H. Baur, Th. Graf, and P. Signer
1985. He, Ne, and Ar in Antarctic Meteorites: Solar Noble Gases in an
Enstatite Chondrite. In Lunar and Planetary Science XVI, pages
902-903. Houston: Lunar and Planetary Institute.
Yanai, K.
1982. Antarctic Meteorite Distribution Map of Allan Hills Victoria Land,
Antarctica?Allan Hills-76, -77 and -78 Meteorites. Tokyo:
National Institute of Polar Research.
1984. Locality Map Series of Antarctic Meteorites, Sheet 1, Allan Hills:
Explanatory Text of Local Map of Allan Hills-76, Allan Hills-77
and Allan Hills-78 Meteorites. Tokyo: National Institute of Polar
Research.
14. Meteorite Distributions at the Allan Hills Main Icefield
and the Pairing Problem
Ursula B. Marvin
Paired meteorite specimens are fragments of a single body
that exploded during flight through the atmosphere and fell to
Earth as two or more pieces. All fragments, which may number
in the thousands, of the same body are cataloged as a single
meteorite. Observations in many parts of the world have shown
that fragments from a given meteorite shower fall over an
elliptical area in which the largest and heaviest specimens
travel farthest along the line of flight to the outer limit of a
so-called strewnfield. Outside Antarctica, specimens belonging
to the same class of meteorite found in a well-defined
strewnfield can be paired with confidence. On the Antarctic
stranding surfaces, however, strewnfields emerged from depth
will be compressed and deformed to some degree and their
specimens mixed with those from other falls. The extent to
which distribution patterns can aid in pairing specimens of a
given meteorite class on the Antarctic icefields has not
previously been investigated.
My approach to this problem was to plot the locations of
meteorite fragments on a composite map representing six
seasons of collecting on the Allan Hills Main Icefield. I also
examined thin sections of tentatively paired specimens and
combed the literature on pairing. I found that only on rare
occasions is pairing easy in Antarctica. When two or more
fragments fit together like pieces of a jigsaw puzzle, as was the
case with the pieces in Figure 14-1, they are paired in the field
and assigned the same specimen number. Specimens are
sometimes paired in the field if they look similar and lie within
a few meters of one another without actually fitting together.
In general, however, the pairing of Antarctic specimens is
fraught with uncertainty. Distribution patterns facilitate pairing
mainly by indicating which groups of specimens should be
scrutinized for similarities in petrography, trace element
compositions, solar flare tracks, or other diagnostic features.
Frequently, such scrutiny indicates that specimens found lying
side by side are not members of the same shower. In at least
one case, however, the opposite proved true: the location of a
Ursula B. Marvin, Smithsonian Astrophysical Observatory, 60 Garden
Street, Cambridge, Massachusetts 02138.
specimen led to its reclassification as a member of a paired
group.
Field Maps
Perhaps the main difficulty in mapping specimen distribu-
tion patterns on the Allan Hills Main Icefield, is the lack of a
single, accurate base map. For the present study, I compiled
distributions from two maps. The first map was published by
Yanai (1982) with an explanatory text by Yanai (1984). Yanai
plotted approximate specimen locations, from field notes made
during the 1976-1977, 1977-1978, and 1978-1979 seasons,
on a base prepared from an enlarged satellite photograph of the
Allan Hills region. The second base map was an unpublished
chart, 1.6 meters long with a scale of about 1:8000, prepared
by John O. Annexstad and John W. Schutt to show specimen
locations of the 1979-1980, 1980-1981, and 1981-1982
seasons. They measured angular directions from each specimen
to flags in the geodetic network described by Annexstad and
Annexstad (Chapter 4), and measured distances on snowmobile
odometers. Together, the maps of Yanai and of Annexstad and
Schutt show the locations of about 900 meteorites on the Main
Icefield, a number fully adequate for testing the usefulness of
distribution patterns.
Unfortunately, the two maps have no common reference
point that can be used to superimpose them precisely. Yanai
marked latitudes and longitudes on his map but Annexstad and
Schutt did not. The latter authors based their map on a
coordinate system measured in meters from geodetic network
Stations 1 and 2, which were anchored in bedrock and tied by
triangulation to peaks in the Allan Hills. They used a satellite
photograph, different from Yanai's, to draw in the outlines of
the Allan Hills. Both maps show distortion due to the
obliqueness of the satellite photographs. After photocopying
the two maps to the same scale, I tested several methods of
superimposing them and selected the one that produced the
least distortion in the southern and central part of the Main
Icefield. These regions are shown in Figures 14-2 to 14-6. In
those figures on which all specimens are plotted from either
113
114 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 14-1.?Meteorite fragments paired in the field. The two pieces of Allan Hills 81029, a 153 gram L6
chondrite, fitted tightly together along a fractured surface.
Yanai's map or the one by Annexstad and Schutt, the location
of each specimen is probably accurate to within a radius of
about 100 meters. On those with specimen locations taken from
both maps the uncertainty may well involve a radius of up to
2 kilometers. Even with errors of that magnitude, however, it
is possible in most cases to see which meteorite fragments
occur in clusters and which lie far apart. Figures 14-2 to 14-6
illustrate the distribution patterns of eucrites, ureilites, irons,
L3, and L6 chondrites on the Main Icefield, and Figure 14-7
shows that of three mesosiderites found on the Near Western
Icefield. Various proposed pairing schemes are indicated and
referenced.
Meteorite Distributions
EUCRITES
Beginning in the 1976-1977 season with the discovery of
ALHA76005, a 1.4 kg polymict eucrite, a total of 16 eucrite
specimens were collected within an area of only about 3.5 x
4.5 kilometers on the Main Icefield (Figure 14-2). Their
distribution suggests that all of these fragments belong to the
same fall. Some petrologic studies tend to support this
interpretation. Delaney, Takeda, and Prinz (1983) tentatively
paired 12 of the 16 specimens as polymict eucrites (containing
90% or more of eucritic components) belonging to a group
they designated as Allan Hills I. Their second group, Allan
Hills II, consisted solely of 78006, a howardite in which no
single component makes up 90% j)f the breccia. Further
petrographic analyses led Delaney, Prinz, and Stokes (1984)
to designate a third group, Allan Hills III, made up of 81006,
81007, and 81008, specimens they found to contain less
feldspar and more pyroxene than they observed in the other
members of Group I, and lithic clasts of an apparent pigeonite
cumulate not observed in any other eucrites.
Score, Schwarz, and Mason (1984) listed 12 of the 16
specimens as polymict eucrites and paired them on the basis
of external appearance and thin section petrography. They
tentatively designated 81009 and 81012 as a separate pair
because they differ from the other 12 specimens in the range
NUMBER 28 115
EUCRITES \ 78006 u
\
A
\
'S ?
78158 pljs 96 other
178165** Meteorites
\ at this site
\
\
\
.--#-\ 76?42
81010 \
i?\8IOO7.-i- V __b 81008 j?V
..8OIO2'?eioO6
o
78132
79017?O
N \
's \
eiooi^ \
0.5 I kn
J_J |
KEY;
O Meteorites collected 1976-1978 (from YANAI MAP)
? Meteorites collected 1979-1981 (from ANNEXSTAD-SCHUTT MAP)
ICE- FIRN BOUNDARY (from YANAI MAP)
ICE-FIRN BOUNDARY (from ANNEXSTAD-SCHUTT MAP)
XJ-" EAST-FACING SLOPE OF MONOCLINE (ANNEXSTAD-SCHUTT MAP)
:".'...'.'.'? PROPOSED PAIRINGS
? ? METEORITES SINGLED OUT AS UNPAIRED
FIGURE 14-2.?The distribution of 16 eucrite specimens and one howardite
(78006) on the Main Icefield. Areas outlined by dots include tentatively paired
specimens; the shapes of the areas are of no other significance. Pair "a" was
proposed by Score, Schwarz, and Mason (1984); pair "b" was proposed by
Delaney, Prinz, and Stokes (1984), but later incorporated by Delaney, Prinz,
and Takeda (1984) into Allan Hills Group I, which includes all specimens on
this map except 81001, the felty glass, and 78006, the howardite. Many
specimens belonging to other meteorite classes were also found in this area.
For example, the arrow at upper right indicates a site where two eucrites and
96 other stones were collected.
and distribution of their pyroxene compositions. The same
authors listed 81001 as anomalous, and 81011 (the location of
which was not mapped) as a eucritic breccia. They described
the anomalous stone, 81001, as consisting of smoky gray glass
crowded with felty pyroxene prisms (Score, Schwarz, and
Mason, 1984:44, and their figure 49a). The bulk composition
resembles that of an average eucrite, but no other eucrite has
such a texture. However, small clasts of similar material are
found within some polymict eucrites. The other unusual stone,
81011, has eucritic clasts up to 1 cm long embedded in a matrix
of dark glass and finely crushed plagioclase and pyroxene. The
stone looks polymict, but uniform compositions of the
plagioclase and pyroxene suggest that it is monomict.
After reviewing the evidence, Delaney, Prinz, and Takeda
(1984) concluded that all but two of the eucrites at the Allan
Hills probably belong to Group I, a heterogeneous suite in
which they included 81009 and 81012 and to which they
reassigned 81006, 81007, and 81008. They excluded only the
78019
ICE
\?''.
/
i
\
\
?
?
?
*
*
77257Q
i > 11 ii i
1 km
LJ
CO
0
m
FIRN
\^\
\
\
\
*
UREILITES
\ \ 76?42
\
\
\
\
\
)
78262\O * \
\
\
\
\
\
\
\
\
81101^ \
s
\
FIGURE 14-3.?Locations of four Allan Hills ureilites. The two closest stones,
77257 and 78262, have not been paired, but 78019 and 78262 were paired by
Score et al. (1981). This pairing is disputed by Berkley and Jones (1982). If it
is invalid, all four specimens represent separate falls.
glassy stone, 81001, and the breccia, 81011. Possibly even
81001 should be paired with the main group; its glassy texture
may simply represent the chilled margin of a flow or layered
body from which the other eucrites originally crystallized.
UREILITES
Four ureilite specimens were found on the Main Icefield
by the end of the 1981-1982 season. Without knowledge of
their field occurrence, Score et al. (1981) designated 77257 and
78262 as separate falls and paired 78262 with 78019 on the
basis of similar external appearance, textures, and olivine and
116 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
RONS O77250 ICE / FIRN/
:O
77289
77263
:O 77283
77290
o
\
"*?? ?>6002
\ 76?45/S
\
\
\
\
O78252 0.5 I I
i.i.l I
N
FIGURE 14-4.?Locations of seven iron meteorite specimens. All except 78252
were paired in the field by Cassidy (1980) and later proved to be coarse
octahedrites of group IA. Clarke et al. (1980) paired the five irons within the
dotted area but separated out 77283 because, although it belongs to the same
chemical group, it contains clumps of shock-produced diamond and lonsdaleite.
ALHA78252 is a group IVA iron.
pyroxene compositions. Figure 14-3 shows that the first two
were found only 1.5 kilometers apart, although in different
seasons, and the paired stones were found nearly 5.8 kilometers
apart in the same season. Pair 78262 and 78019 is listed in
Appendix C, but Berkley and Jones (1982) disputed its validity,
arguing that the olivines and pyroxenes in the two stones differ
slightly but consistently, and that diamond occurs in 78262
but not in 78019. Petrographic differences between the other
stones indicate that, if these two are not paired, then all four
ureilites represent individual falls?a surprising situation for
such unusual meteorites on a small area of the Icefield, when
only about 20 other ureilites have been found throughout the
world. Field distribution was of no aid in this case where, if
any stones are paired, they are not the two found closest
together.
/
? o77'7^
X(g)77l76
X ?77I78
X
\
r\ ^
Vi>8IO24 \
\
X
ICE /| FIRN
(i
77197? \ f
?77031 \j78015 /.
, - 7 71-17/1, A
L3 CHONDRITES
78015 ,,
77I7O>"'^77034 |\ f-*
77043O o I \ / /
77033 \ V.S
I \78I88
I O+X ?V \
\\
77036 N
? 96 other
Meteorites
at this site
O 77115 A
/
2#
81145*
Q'77140 \
' .81069 \
80133 \v._8IO87
77047OO 77049 XI8I085
a77050
8I065/66*
? ?
81053
76?42'S
^8
? 81156
?7705277214 O 77241
^78038'i\ \
77I66O
79022^ *79045 \
7400.? 8f2|\?
77165?
?,? 77160V
772I\ 77274798O5"? ^
77260?\... 77QII ~ (9J\ /0 O
O 7721177303-77244*
77215 ?/-...9=77252 /
77216 /
?77015
/
FIGURE 14-5.?The distribution of L3 chondrites on the central and southern
portion of the Main Icefield. Other L3 specimens lay farther north, off this
map. Unpaired specimens are indicated by extra rings; all others are paired
(and designated as the 77011 shower) except for the four specimens lying
within the dotted area at lower right, which differ from the others
petrographically (Score, 1980; Score et al., 1981) and in containing solar flare
tracks (Nautiyal et al., 1982).
octahedrites belonging to chemical group IA, but Clarke et al.
(1980), paired only the five specimens outlined in Figure 14-5,
on the basis of identical textures and compositions. The
adjacent unpaired specimen, 77283, contains masses of minute
shock-produced diamonds admixed with lonsdaleite. The only
other iron meteorite known to contain diamonds is Canyon
Diablo, a huge body that impacted northern Arizona with
sufficient energy to excavate a crater 1.4 kilometers in
diameter. The Allan Hills iron, in contrast, is a 10-gram
specimen with a thin surficial, heat-altered zone, which shows
that it entered the atmosphere as a small body that would have
made a soft landing. The diamonds must have formed during
a preterrestrial collision in space.
The seventh specimen, 78252, is a group IVA iron. The
distribution of these iron meteorites suggested a pairing scheme
close to, but not identical with, the one indicated by
compositions and textures.
IRONS
Seven specimens of irons were found within the 1.5 x 4.5
km area shown in Figure 14-4. Cassidy (1980) tentatively
paired six of them (all except 78252, which lay farthest south)
on the basis of their field locations. All of the six are coarse
L3 CHONDRITES
Seventy-five L3 chondrite specimens (56 mapped finds and
19 unmapped pebbles) were collected within a 6 x 3 km ellipse
on the Main Icefield. The larger fragments were clustered near
the southern end of the ellipse and smaller pieces lay at the
NUMBER 28
L6 CHONDRITES
O76003
O76007
O78I30
^ O76009
/
/
/
/
/
1V
\
\
\
\ \
\
\
\
78105 v.
???9.-' ^
78103
0.5 1 km
1 i i i i 1 1
78050
/
78043-. / 77
d ?-;?-:/
780459-;" ?x?
ICE / FIRN
/
1
284
QO77270
781271
X77269 i
78042Q
78104-
77277 o
? o ??
76001 '?
- ?
UJ
~bCM
I59C
78II4O
77155
0???..?7728!
c??'?.
78106 o''". ''
(
\
\
?^
?""" ICE "\ FIRN
18 SPECIMENS
??? INS'ET A
\
\
\
\
\
\
\76O45/S
\
\
\
'??. :'77280"-.
'?-. O-. ':
b ^41.'.:Q: :'
77272Vp-o'i;
7723'f"'\77273
\
\
\
\ /
V /
L6
INSET A
1
80107* *8OIO8
.80125
? 80119
#80ll4
? 80113
80110
^80120
8I262# *8OII6 ?81107
?^ 81017* ?SO"7
? 80115
80112 ?? 80103
8OIOI##8OIO5
100 M
117
FIGURE 14-6.?The distribution of 44 L6 chondrite specimens that were collected on the central and southern
portion of the Main Icefield. Several (but not all) of the proposed pairing schemes are shown. Pair "a" consists
of four specimens, 77231, 77273, 77272, and 77280, tentatively paired in the field by Cassidy. All were rather
large specimens lying near one another. Pair "b" was separated out on the basis of similar petrography and
concentrations of cosmogenic nuclides by Nishiizumi (1984). Specimens 77231 and 77280 differ in nuclide
concentrations and cannot be paired with 77272 and 77273; however, Goswami and Nishiizumi (1983) proposed
pair "c," 77280 and 77282. Pair "d" was proposed by Score et al. (1981) on petrographic similarities. Pair "e,"
78103 and 78105, were found close together in a remote location and they have similar concentrations of ^Al
(Evans, Reeves, and Rancitelli, 1982). Inset A shows the location of 18 specimens collected in 1980 and 1981
beyond the southern edge of the Main Icefield. All were classified on petrographic evidence as L6 chondrites,
except 81017 (arrow), which was first classed as an L5 and later reclassified as an L6.
ice-firn border at the northern end. This size distribution
suggested a strewnfield created by a southbound fireball;
however, as noted by Scott (1984) it is more likely that the
small fragments were blown to the northern edge of the Icefield
by the powerful katabatic winds that course down the surface
of the ice sheet from the southern reaches of the polar plateau.
The great majority of these L3 chondrites, large and small,
contain distinctive graphite-magnetite aggregates and so were
paired by McKinley et al. (1981). However, within a group of
nine relatively large specimens lying within an area only 500
meters across, four were shown to belong to a separate fall on
the basis of petrography (Score, 1980), and the presence of
solar flare tracks (Nautiyal, et al., 1982). Specimen distribu-
tions would never suggest the existence of this separate fall
(Figure 14-5). Several distinctive, unpaired L3 specimens lie
scattered amid the large group.
L6 CHONDRITES
Eighty-five L6 chondrites were collected during the first six
seasons on the Main Icefield. Numerous pairing schemes have
been proposed and almost all of them are disputed. The map
118 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
/ / /
/ ''? .^.81059
I i i i i I
500 M
81098 \
\
\
UJ
"in
S
MESOSIDERITES
Near Western Icefield
\
^ 76?44'S
\ \
\
\
\
\ \
77219 (^"\
FIGURE 14-7.?The only mesosiderites found in the Allan Hills region lay
within 2.25 kilometers of each other on the Near Western Icefield. 81098
consisted of two adjacent pieces that were paired in the field; 81059 was added
to the pair after laboratory examination. Although mesosiderites tend to be
markedly inhomogeneous, 77219 is regarded as a separate fall.
in Figure l4-6a, which includes only the area toward the
southern end of the field, shows find locations of 44 specimens
and five of the proposed pairings. The four specimens (77272,
77273, 77231, and 77280) at the southeastern part of the field
were tentatively paired in the field by Cassidy (1980). Six
others (77282, 77269, 77270, 77277, 77281, and 77284) were
paired with these four in the Antarctic Meteorite Newsletter,
7(1) (1984). Two specimens (77272 and 77273) of Cassidy's
original four are still accepted as a pair, but differences in 53Mn
concentrations and cosmic-ray track densities, measured by
Goswami and Nishiizumi (1983), indicate that 77273 and
77280 cannot be paired with each other even though they were
found only 200 meters apart. Without being aware of the field
distribution, the same authors using the same criteria paired
77280 with 77282, which were separated by a distance of
nearly three kilometers. This leaves one of Cassidy's original
four, 77231, unpaired. Two other specimens, 78043 and 78045,
were paired on petrographic evidence by Score et al. (1981),
and 78103 and 78105, which were were found only about 100
meters apart in a remote part of the field, were paired in the
Antarctic Meteorite Newsletter (1984). For evaluations of other
proposed pairings, see Scott (1984, and Chapter 13).
At the southern extremity of the map, separated from the
Main Icefield by a wide band of snow, a group of specimens
occupied an area about 500 meters long and 200 meters wide
(see Inset A, Figure 14-6). Fifteen specimens were collected
there in 1980 and identified as L6 chondrites by Score et al.
(1982), who, with no knowledge of their field occurrence,
paired them on the basis of identical textures, mineralogy, and
degrees of weathering. Three more specimens were picked up
in 1981. When thin sections of these were studied, again
without knowledge of their field locations, 81107 and 81262
were classed as L6, but 81017 was classed as an L5 chondrite.
The anomalous presence of an L5 in this tight cluster of L6
specimens, prompted me to request a reexamination of the thin
section of 81017. Mason (personal communication) complied,
and shortly afterward reported that he had originally classed
the specimen as an L5 because he had noted no plagioclase in
the section. On the second examination he found traces of
plagioclase and, as the difference between classes 5 and 6 is
often very uncertain, he reclassified 81017 as an L6 chondrite
belonging with the rest of the group. L6 chondrites are actually
so much alike that a case might be made for pairing these 18
specimens with the main group lying farther north. However,
the tightly clustered field distribution provides strong evidence
of a separate fall of L6 fragments.
MESOSIDERITES
Three mesosiderite specimens have been found in the Allan
Hills region, all of them on the Near Western Icefield (Figure
14-7), which lies about 15 kilometers from the Main Icefield.
Specimen 77219 was found during a brief helicopter reconais-
sance in the 1977 season; the other two, 81059 and 81098,
were collected on snowmobile traverses in the 1981 season.
Specimen 81098 actually consisted of two fragments that were
paired in the field. Clarke (1984) suggested pairing 81059 and
81098 on the basis of their mineralogy, texture, and degree of
weathering, but he regarded 77219 as a separate fall. Inasmuch
as mesosiderites are among the rarest of meteorites (stony-irons
of all types make up only 1.5% of falls), the occurrence of these
three specimens within 2.5 kilometers of each other at one end
of the small Near Western Icefield would suggest a common
source. Their distribution alone would not be sufficient for
pairing them, but analyses of their isotopic or trace element
content or particle track densities might yield conclusive
evidence for or against pairing.
Conclusions
This study shows that distribution patterns of specimens on
the Antarctic ice sheet can be a helpful guide to meteorite
pairings, but one that always must be used in conjunction with
other types of evidence. Laboratory examinations confirmed
the main outlines of field pairings for some of the seven
meteorite classes discussed herein, but produced numerous
surprises when adjacent specimens proved not to belong to the
same fall and widely separated ones showed strong evidence
that they did belong together. Meteorites that fall close together
are, in general, expected to remain close together while being
transported within a large ice sheet. Confusion begins when
they emerge from the ice and and are mixed with other
meteorites on stranding surfaces that are compressed against
mountain barriers by the persistent push of the oncoming sheet.
Furthermore, the powerful storm winds of Antarctica can send
specimens up to cobble size?and probably boulder size?
skittering across the ice to new locations, and drifts of snow
NUMBER 28 119
cover and uncover different groups of specimens from season
to season. Despite all the factors that disturb the orderly
patterns of strewnfields, specimen distributions are of sufficient
aid in pairing to make mapping worth the effort.
Since the 1982-1983 season, mapping techniques have been
speeded up and made more accurate by use of an infrared
distance measuring device to determine geodetic positions of
meteorite specimens relative to known points. There will be
no further need for painstaking attempts like this one to
superimpose maps in order to locate find sites. However, the
first six seasons at the Allan Hills Main Icefield yielded a
unique body of data that demanded analysis.
ACKNOWLEDGEMENTS.?I wish to thank John Annexstad
and John Schutt for kindly furnishing me with their map of
meteorite distributions on the Allan Hills Main Ice Field, and
Robbie Score and Ed Scott for critical readings of this
manuscript. This work was supported in part by NASA Grant
NAG 9-29 and in part by SAO allocation 86400040-P12P11-
4P50.
Literature Cited
Antarctic Meteorite Newsletter, 7(1), 1984.
Berkley, J.L., and J.H. Jones
1982. Primary Igneous Carbon in Ureilites: Petrological Implications.
Journal of Geophysical Research, 87 (supplement):A353-A364.
Cassidy, William A.
1980. list of Possible Pairings of ALHA77 Meteorites. In U.B. Marvin
and B. Mason, editors, Catalog of Antarctic Meteorites, 1977-1978.
Smithsonian Contributions to the Earth Sciences, 23:44-46.
Clarke, Roy S., Jr.,
1984. Descriptions of Iron Meteorites and Mesosiderites. In U.B. Marvin
and B. Mason, editors, Field and Laboratory Investigations of
Meteorites from Victoria Land, Antarctica. Smithsonian Contribu-
tions to the Earth Sciences, 26:49-53.
Clarke, R.S., Jr., E. Jarosewich, J.I. Goldstein, and P.A. Baedecker
1980. Antarctic Iron Meteorites from Allan Hills and Purgatory Peak.
Meteor itics, 15:273-274.
Delaney, J.S., M. Prinz, and C.P. Stokes
1984. The Allan Hills 81-series of Polymict Eucrites. In Lunar and
Planetary Science XV, pages 214-215. Houston: Lunar and
Planetary Institute.
Delaney, J.S., M. Prinz, and H. Takeda
1984. The Polymict Eucrites. Journal of Geophysical Research, 89
(supplement):C251-C288.
Delaney, J.S., H. Takeda, and M. Prinz
1983. Modal Comparison of Yamato and Allan Hills Polymict Eucrites.
Memoirs of the National Institute of Polar Research (Japan), special
issue, 30:206-223.
Evans, J.C., J.H. Reeves, and L.A. Rancitelli
1982. Aluminum-26 Survey of Victoria Land Meteorites. In U.B. Marvin
and B. Mason, editors, Smithsonian Contributions to the Earth
Sciences, 24:70-74.
Goswami, N.N., and K. Nishiizumi
1983. Cosmogenic Records in Antarctic Meteorites. Earth and Planetary
Science Letters, 64:1-8.
McKinley, S.G., E.R.D. Scott, GJ. Taylor, and K. Keil
1981. A Unique Type 3 Ordinary Chondrite Containing Graphite-
Magnetite Aggregates?Allan Hills A77011. In Proceedings of the
Twelfth Lunar and Planetary Science Conference, pages 1039-1048.
New York: Pergamon Press.
Nautiyal, CM., J.T. Padia, M.N. Rao, T.R. Venkatesan, and J.N. Goswami
1982. Irradiation History of Antarctic Gas-Rich Meteorites. In Lunar and
Planetary Science XIII, pages 578-579. Houston: Lunar and
Planetary Institute.
Nishiizumi, K.
1984. Cosmic-ray Produced Nuclides in Victoria Land Meteorites. In
U.B. Marvin and B. Mason, editors, Smithsonian Contributions to
the Earth Sciences, 26:105-109.
Score, R.
1980. Allan Hills 77216: A Petrologic and Mineralogic Description.
[Abstract.] Meteoritics, 15:363.
Score, R., CM. Schwarz, T.V.V. King, B. Mason, D.D. Bogard, and E. M.
Gabel
1981. Antarctic Meteorite Descriptions 1976-1977-1978-1979. Curato-
rial Branch Publication, 54, JSC 17076. 144 pages. Houston:
Johnson Space Center.
Score, R., T.V.V. King, CM. Schwarz, A.M. Reid, and B. Mason
1982. Descriptions of Stony Meteorites. In U.B. Marvin and B. Mason,
editors, Catalog of Meteorites from Victoria Land, Antarctica,
1978-1980. Smithsonian Contributions to the Earth Sciences,
24:19^8.
Score, R., CM. Schwarz, and B. Mason
1984. Descriptions of Stony Meteorites. In U.B. Marvin and B. Mason,
editors, Field and Laboratory Investigations of Meteorites from
Victoria Land, Antarctica. Smithsonian Contributions to the Earth
Sciences, 26:23-47.
Scott, E.R.D.
1984. Pairing of Meteorites Found in Victoria Land, Antarctica. Proceed-
ings of the Ninth Symposium on Antarctic Meteorites. Memoirs of
National Institute of Polar Research, special issue, 35:102-125.
Yanai, K.
1982. Antarctic Meteorite Distribution Map of Allan Hills, Victoria Land,
Antarctica?Allan Hills-76, -77, -78 Meteorites. Tokyo: National
Institute of Polar Research.
1984. Locality Map Series of Antarctic Meteorites, Sheet 1 Allan Hills:
Explanatory Text of Locality Map of Allan Hills-76, Allan Hills-77,
and Allan Hills-78 Meteorites. Tokyo: National Institute of Polar
Research.
Appendix
Tables of ANSMET Meteorites
Terminology
Class and type: A = achondrite, unique; Au = aubrite; C = carbonaceous chondrite;
Di = diogenite; E = enstatite chondrite; EH = enstatite high-iron chondrite; Eu = eucrite;
Ho = howardite; H = high-iron chondrite; I = iron (IA, IIA, I IB, IVA = iron groups);
L = low-iron chondrite; LL = low-iron low-metal chondrite; M = mesosiderite; Sh =
shergottite; Ur = ureilite. Chondrite petrologic type is indicated by digit following the
abbreviation.
Olivine composition in mole percent Fe2Si04 (Fa).
Pyroxene (orthopyroxene or low-Ca clinopyroxene) composition in mole percent
FeSiO3 (Fs).
Degree of weathering: A = minor; metal flecks have inconspicuous rust haloes, oxide
stain along cracks is minor. B = moderate; metal flecks show large rust haloes, internal
cracks show extensive oxide stain. C = severe; specimen is uniformly stained brown, no
metal survives.
Degree of fracturing: A = slight; specimen has few or no cracks and none penetrate the
entire specimen. B = moderate; several cracks extend across the specimen, which can be
readily broken along the fractures. C = severe; specimen has many extensive cracks and
readily crumbles.
Locations: ALH = Allan Hills; BTN = Bates Nunatak; DRP = Derrick Peak; EET =
Elephant Moraine; ILD = Inland Forts; MBR = Mount Baldr; MET = Meteorite Hills;
OTT = Outpost Nunatak; PCA = Pecora Escarpment; PGP = Purgatory Peak; RKP =
Reckling Peak; TIL = Thiel Mountains; TYR = Taylor Glacier.
Classification by S.J.B. Reed and S.O. Agrell (*); by S.G. McKinley and K. Kiel (f);
by C.B. Moore (+).
Abbreviations: n.d. = no data.
NOTE: The following meteorites were characterized after the manuscript had been
submitted:
H5 META78009,010,011,012,018
H6 META78006,007, 013,014,016, 017,019, 020,022, 023, 024,025,026, 027
L6 META78002, 003, 004, 005, 021, 028
The possibility of pairings within each group should be considered. Classifications by
Brian Mason.
121
122 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE A.?Meteorites listed by source area in numerical sequence (fractions of grams in weight dropped unless
total weight is less than 1 gram).
Specimen
number
ALH
76001
76003
76004
76002
76005
76006
76007
76008
76009
77001
77002
77003
77004
77005
77007f
77008t
77009
77010
77011
77012
77013f
77014
77015
77016f
77017f
77018f
77019t
77021
77022f
77023t
77025
77026f
77027f
77029f
7703If
77033
77034f
77036f
77038f
770391
7704If
77042f
77043f
77045f
770461
77047f
77049f
77050f
7705If
77052t
77054t
77056t
77058t
77060t
Weight
(g)
20151
10495
53
307
317
271
79
281
3950
252
235
780
2230
483
99
93
236
296
292
180
23
309
411
78
78
52
60
17
16
21
19
20
4
1
0.5
9
2
8
19
8
17
20
11
18
8
20
7
84
15
112
10
12
4
64
Class
and
type
L6
L6
LL3
I
Eu
H6
L6
H6
L6
L6
L5
C3O
H4
Sh
H5
L6
H4
H4
L3
H5
L3
H5
L3
H5
H5
H5
L6
H5
H5
H5
H5
L6
L6
C3O
L3
L3
L3
L3
H5
H5
LL6
H5
L3
H5
H6
L3
L3
L3
H5
L3
H5
H4
H5
LL5
%Fain
olivine
25
25
0-34
37-57
18
24
19
24
25
25
4-48
17-20
28
19.1
24.6
18
18
4-36
18
9-28
18
1-21
18.6
18.8
19.0
24.9
18
19.1
19.1
18
24.3
25.0
23.0
n.d.
8-38
n.d.
n.d.
19.0
18.5
30.7
19.0
1-37
18.7
19.0
n.d.
n.d.
n.d.
18.8
n.d.
18.5
18.8
18.8
28.1
% Fs in
pyroxene
21
21
0-53
16
21
17
21
21
22
2-25
15-27
23
16.7
20.6
16
15-18
1-33
16
1-35
17
4-24
17.1
16.3
17.0
21.4
17
17.0
16.8
17
20.7
21.5
2.6
n.d.
8-9
n.d.
n.d.
17.1
16.3
25.1
16.6
1-28
17.0
16.7
n.d.
n.d.
n.d.
16.5
n.d.
16.9
16.3
16.1
23.2
Degree
of
weathering
A
A
A
A
C
B
B/C
B
B
B
A
C
A
B
A
C
C
C
C
B
C
C
B
B
B/C
B/C
C
A
B
C
B/C
B/C
A/B
B/C
C
B/C
B
A/B
A/B
A
A/B
B/C
A
A/B
C
B/C
B/C
A
B/C
B
A/B
B
A
Specimen
number
77061
77062
77063t
77064
77066t
77069t
77070t
77071
77073t
77074
77076t
77078t
77079t
77081
77082t
77084t
77085t
77086
77087t
77088
77089t
7709It
77092t
77094t
77096f
77098t
77100t
771011
77102
77104t
77106t
77108t
771111
77112t
77113t
77114t
77115t
77117f
77118
77119
77120t
77122t
77124
77125t
77126t
77127t
77129t
77130t
77131t
77132t
77133t
77134t
77136t
77138t
77140
Weight
(g)
13
17
3
6
5
0.8
18
11
10
12
2
24
8
9
12
44
46
19
31
51
8
4
45
7
2
8
18
4
12
6
8
0.7
52
22
2
45
154
21
8
6
4
5
4
19
25
4
2
25
26
115
19
19
4
2
79
Class
and
type
H5
H5
H5
H5
H5
L6
H5
H5
H5
H5
H5
H5
H5
"H(?)"<
%Fain
olivine
18
18
18.0
18
19.0
25.4
18.4
18
18.8
18
19.5
19.5
18.2
? 11
* (Acapulco-like)
H5
H5
H5
H5
H5
H5
L6
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H6
H5
H5
H5
L3
L5
H5
H5
H5
H5
H5
H5
H5
L5
H5
H5
H6
H5
H6
H6
H5
H5
L3
19.3
18.8
18.8
19
19.0
19
25.5
18.9
18.5
18.5
18.7
18.7
19.2
18.6
19
18.9
18.8
18.5
19.0
18.7
18.7
19.6
n.d.
24.4
19
18
18.5
19.1
19
17.2
18.3
25.0
18.9
18.9
19.2
19.0
19.0
18.9
19.1
19.2
8^4
%Fsin
pyroxene
17
17
16.8
17
17.4
21.4
16.8
17
17.7
17
16.1
16.7
15.8
11
16.5
16.8
17.6
17
16.7
17
21.4
16.1
16.5
16.2
17.1
16.7
16.4
17.0
15
16.9
16.5
15.9
16.6
16.7
17.2
17.2
n.d.
21.0
17
17
16.0
16.8
17
15.5
16.2
21.1
16.6
16.5
16.8
16.9
17.0
16.7
16.4
17.0
2-17
Degree
of
weathering
B
B
B
B
A
B/C
B
B
A/B
B
B
B
A
B
A/B
A/B
B
C
B
C
B
B/C
A
B
A
B
A/B
B
B
A
A/B
A/B
A/B
A
B
B
B/C
A/B
C
C
A/B
B
C
A/B
A/B
B
B
A
A/B
A/B
A
A
A/B
A
B
NUMBER 28 123
TABLE A.?Continued.
Specimen
number
77142f
77143f
77144
77146f
77147f
77148"
77149f
77150
77151f
77152t
77153f
77155
77156f
77157f
77158f
77159f
77160
77161f
77162f
77163f
77164
77165
77166f
77167
77168f
77170f
77171f
77173f
77174f
77175f
77176f
77177
77178f
77180
77181f
77182
77183
77184f
77185f
77186f
77187f
77188f
77190
77191
77192
77193f
77195f
77197f
77198f
77200f
77201f
77202f
77205f
77207f
77208
Weight
(g)
3
39
8
18
19
13
26
58
17
18
12
305
18
88
20
17
70
6
29
24
38
31
139
611
25
12
24
26
32
23
55
368
6
191
33
1135
288
128
28
122
52
109
387
642
845
7
5
20
7
0.9
15
3
3
5
1733
Class
and
type
H5
H5
H6
H6
H6
H6
H6
L6
H5
H5
H5
L6
EH4
H6
H5
L6
L3
H5
L6
L3
L3
L3
L3
L3
H5
L3
H5
H5
H5
L3
L3
H5
L3
L6
H5
H5
H6
H5
L3
H5
H5
H5
H4
H4
H4
H5
H5
L3
L6
H6
H5
H5
H5
H5
H4
%Fain
olivine
18.9
18.7
19
18.9
19.0
18
19.1
25
18.9
18.7
19.2
24
0.8
18.6
18.9
24.4
3^16
19.3
25.3
n.d.
6-39
8-33
n.d.
2-41
19.0
n.d.
18.9
19.1
18.3
n.d.
0.3-34
18
1-36
24
20.0
19
19
17.8
n.d.
18.8
18.1
18.1
17-19
16-18
16-18
19.0
18.9
10-27
24.4
19.7
18.8
18.6
18.8
17.8
17
%Fsin
pyroxene
17.1
16.2
17
16.9
16.6
16
16.9
22
16.4
16.9
16.7
20
1.5
15.7
16.9
20.8
6-40
17.1
20.9
n.d.
3?41
6-35
n.d.
3-17
16.5
n.d.
17.0
17.0
16.0
n.d.
1-37
16
2^0
20
17.3
17
16
15.9
n.d.
16.0
16.3
16.1
15-22
14-16
15-21
15.7
16.4
4-21
20.6
17.6
15.3
16.6
16.7
16.7
14
Degree
of
weathering
A/B
A/B
B
A/B
A/B
C
A/B
C
A
A
A
A/B
B
A/B
B
A/B
C
B
A
B/C
C
cc
cB
B/C
A/B
B
A
B/C
B
C
B/C
C
B
C
C
B
A/B
A/B
A/B
A/B
C
C
c
A
A
A/B
B
C
A
B
B
A/B
C
Specimen
number
77209f
7721If
77212t
77213t
77214
77215
77216
77217
77218t
77219
77220t
77221
77222t
77223
77224
77225
77226
77227t
77228t
77230
77231
77232
77233
77235t
77237t
77239t
77240t
77241t
77242t
77244t
77245t
77246t
77247t
77248t
77249
77250
77251t
77252
77253t
77254
77255
77256
77257
77258
77259
77260
77261
77262
77263
77264
77265t
77266t
77267t
77268
77269
Weight
(g)
32
27
17
8
2111
820
1470
413
45
637
69
229
125
208
787
5878
15323
16
19
2473
9270
6494
4087
5
4
19
25
144
56
40
33
42
44
96
504
10555
69
343
24
246
765
676
1996
597
294
744
412
862
1669
11
18
108
104
272
1045
Class
and
type
H6
L3
H6
H5
L3
L3
L3
L3
L5
M
H5
H4
H4
H4
H4
H4
H4
H5
H5
L4
L6
H4
H4
H5
H5
H6
H5
L3
H5
L3
H5
H6
H5
H6
L3
I
L6
L3
H5
L5
I
Di
Ur
H6
H5
L3
L6
H4
I
H5
H5
H5
L5
H5
L6
%Fain
olivine
18.8
n.d.
18.9
18.6
1-49
22-26
15-35
17-25
23.4
26
17.7
15
18.0
17
19
17
18
18.9
18.5
22-25
24
17
14-21
18.9
18.5
18.7
18.8
n.d.
18.8
n.d.
19.2
19.2
18.8
18.7
7-35
25.0
22-28
19.2
23
13
18
18
7-23
24
15-19
19
17.6
19.6
24.7
18
24
%Fsin
pyroxene
16.4
n.d.
17.0
16.5
4-23
9-21
14-23
9-26
19.1
24-28
16.0
13-15
15.3
15-23
17
16
16
16.6
16.3
18-29
21
15
15-17
16.7
15.8
15.9
16.0
n.d.
16.2
n.d.
17.2
16.5
16.4
16.7
2-25
21.3
2-22
16.9
20
23
12
16
15
1-28
21
13-16
16
15.9
17.7
20.9
16
22
Degree
of
weathering
B
B/C
A/B
A
C
B
A/B
B
A
B
B
C
A/B
C
C
cc
A
B
C
A/B
C
C
A/B
A
B
A
C
B
B/C
A/B
B
A/B
B/C
C
B
B
A/B
A/B
A/B
A
B/C
C
C
B
B/C
A/B
B
B
A
C
B
124 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE A.?Continued.
Specimen
number
77270
11211
77272
77273
77274
77275f
77277
1121%
77279f
77280
77281
77282
77283
77284
77285
77286
77287
77288
77289
77290
7729It
77292
77293f
77294
77295f
77296
77297
77299
77300
7730If
77302
77303t
77304
77305
77306
77307
78001+
78002+
78003
78004*
78005+
78006
78008
78010+
78012
78013
78015*
78017+
78018+
78019
78021
78023
78025+
78027*
Weight
(g)
589
610
674
492
288
25
143
313
175
3226
1231
4127
10510
376
271
246
230
1880
2186
3784
6
200
110
1351
141
963
952
261
235
55
236
79
650
6444
20
181
85
11
125
36
28
8
7
1
38
4
35
3
18
30
17
10
8
29
Class
and
type
L6
H6
L6
L6
H5
H5
L6
LL3
H5
L6
L6
L6
I
L6
H6
H4
H5
H6
I
I
H5
L6
L6
H5
EH4
L6
L6
H3
H5
L6
Eu
L3
L4
L6
C2
C3
H5
H6
L6
H5
H5
Ho
H5
H5
H5
L3
LL(?L)3
L3
H5
Ur
H5
H5
H5
H5
% Fa in
olivine
24
18
24
24
18
18.3
24
11-29
18.8
24
24
24
25
18
17
18
19
18.9
24
24.7
17
0.8
24
24
11-21
18
24.9
n.d.
18-27
24
1-45
1-30
18.6
19.0
24
19.2
19.3
18
19.4
18
11-45
8-35
3-43
19.2
22
18
18
18.9
19.3
% Fs in
pyroxene
21
16
20
20
16
15.6
20
9-21
17.1
21
20
20
21
16
12-16
16
17
15.9
20
20.9
15
1.7
21
20
15-20
16
20.9
37-64
n.d.
13-19
21
1
1-12
20
25-61
16
16
1-31
18
16
16
Degree
of
weathering
A/B
C
B/C
B
C
A
A/B
A
A
B
B
B
A/B
C
C
cc
A
B
B
A
B
A/B
A
A
C
A
A
B/C
B
B/C
A
A
B
A
C
B
A
B
B
F
B/C
A
Specimen
number
78028
78029+
78031
78033+
78035
78037+
78038
78039
78040
78041+
78042
78043
78044
78045
78046
78047*
78048
78049+
78050
78051
78052*
78053
78055+
78057
78059+
78062
78063+
78065+
78067
78069+
78070
78074
78075
78076
78077
78078
78079
78080
78081*
78082+
78084
78085
78086*
78088*
78090*
78092*
78094*
78096*
78098*
78100
78101
78102
78103
78104
78105
Weight
(g)
4
4
5
5
2
0.5
363
299
212
118
214
680
164
397
70
130
191
96
1045
120
97
179
14
9
9
11
77
7
8
4
10
200
281
276
331
290
5
25
18
24
14280
219
9
5
8
16
4
7
2
85
121
337
590
672
942
Class
and
type
H5
H4
H5
H4
H6
L3
L3
L6
Eu
L3
L6
L6
L4
L6
L3
H5
L6
H5
L6
H4
H5
H4
L6
H4
L6
LL6
LL6
H6
H6
H6
L4
L6
H5
H6
H4
L6
H5
H5
H5
LL6
H4
H5
H6
H5
H5
H5
H5
H5
H5
I
L6
H5
L6
L6
L6
% Fa in
olivine
18
19.2
18
19.2
18
7-38
4-42
24
0-41
24
25
23-25
25
8-25
18.8
24
19.4
23
18
17.9
17
25.5
18
21.5
29
29.1
18.0
18
19.1
23
24
18
18
19
24
18
18
19.1
27.7
18
18
19.0
18.8
18.7
19.0
19.1
18.9
18.9
24
18
24
24
23
% Fs in
pyroxene
16
16
16
2-19
21
33-52
20
21
19-24
21
8-20
21
20
15-18
16
16
24
16
13-25
21
16
16
15-18
20
16
16
8-24
16
21
17
20
20
20
Degree
of
weathering
B
B
B
C
B
A
B
B
B
B/C
B/C
B
A/B
B
B
C
C
B
B
A
B
B
B
B/C
B
C
A/B
A
B/C
B
B/C
B
B
B
NUMBER 28 125
TABLE A.?Continued.
Specimen
number
78106
78107
78108
78109
78110
78111
78112
78113
78114
78115
78116*
78117+
78119+
78120
78121*
78122
78123+
78124
78125*
78126
78127
78128
78129+
78130
78131
78132
78133
78134
78135*
78136+
78137
78138+
78139*
78140+
78141
78142*
78145+
78146
78147*
78149+
78150
78152
78153
78154+
78156
78157+
78158
78159
78160*
78162+
78163+
78164
78165
78168+
78169+
Weight
(8)
465
198
173
233
161
127
2485
299
808
848
128
4
103
44
30
5
18
28
19
607
195
155
128
2733
269
656
60
458
131
52
70
11
17
17
24
32
34
17
31
23
16
5
152
12
9
63
15
23
16
33
10
25
21
34
22
Class
and
type
L6
H5
H5
LL5
H5
H5
L6
Au
L6
H6
H5
H5
L3
H4
H5
H6
H5
H6
L6
L6
L6
H5
H5
L6
L6
Eu
L3
H4
H6
H5
H6
LL3
H5
H4
H5
L5
H6
H5
H5.6
L3
H5
H6
LL6
H5
L6
H4
Eu
H5
H5
L3
H5
H5
Eu
H4
H6
% Fa in
olivine
24
18
18
28
18
18
25
25
18
18.7
18.5
0-28
18
19.2
19
19.3
17
25.0
25
24
19
19.4
25
25
1-34
18
19.0
19.1
17
0-35
19.3
18.4
18
24.2
19.6
18
19.4
18-31
18
18
29
19.3
24
19.0
18
19.3
2-30
18.7
18
19.2
19.2
% Fs in,
pyroxene
20
17
16
23
16
16
20
20
16
16
17
15
21
20
17
21
21
40-458
1-16
15-20
15
16
16
16
16
24
21
40-68
16
16
37-61
Degree
of
weathering
A/B
C
B
A/B
B/C
B/C
B
A/B
B/C
B
B
A
A
B
B
B
B/C
C
B
B/C
B/C
A
B/C
B
A
B
B
A
B
B/C
B
B
A
B
B
A
B
B
Specimen
number
78170+
78171+
78172+
78173+
78174+
78176+
78178+
78180+
78182
78184
78186
78188
78189
78190
78191
78193
78194
78196
78197
78199
78201
78203
78205
78207
78209
78211
78213
78215
78217+
78219+
78221
78223
78225
78227
78229
78231
78233
78235+
78236
78238
78239+
78241
78243
78245
78247
78249
78251
78252
78253+
78255+
78257+
78259+
78261
78262
Weight
(g)
21
23
29
20
13
8
7
8
10
8
3
0.9
23
20
20
13
25
11
20
13
10
11
9
8
12
11
10
6
8
8
5
6
5
2
2
2
1
19
14
10
16
7
2
4
3
4
1312
2789
7
3
2
6
5
26
Class
and
type
H3
L6
H4
H5
H5
L3
H5
L3
H5
H6
L3
L3
H6
H5
H6
H4
H5
H4
H5
H5
H5
H5
H5
H6
H5
H6
H6
H6
H5
H5
H5
H4
H5
H5
H6
H6
H5
L3
L3
L3
L3
H5
L3
H5
H5
H6
L6
I
H5
H5
H5
H5
C2
Ur
%Fain
olivine
3-36
25.4
19.7
19.7
18.2
8-26
19.0
2-33
18
18
3-36
1-34
18
18
18
18
18
18
18
18
18
18
18
19
18
18
18
18
18.8
19.4
18
18
18
18
18
18
18
8-28
2-37
2-34
1-34
18
1-36
18
18
18
23
18.9
19.4
19.2
19.7
0-50
22
% Fs in
pyroxene
16
16
3-24
5-29
16
16
16
16
16
16
16
16
16
16
16
17
15
16
15
16
16
16
16
16
15
16
16
3-26
3-21
16
3-30
16
16
16
20
1-8
19
Degree
of
weathering
B
B
B
B
B
B
B
B
C
B/C
B/C
B/C
B
B
B/C
B
B
B
B
B
B/C
B
B/C
B/C
B
B
B
B
A
B
A
A
B/C
126 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE A.?Continued.
Specimen
number
79001
79002
79003
79004
79005
79006
79007
79008
79009
79010
79011
79012
79013
79014
79015
79016
79017
79018
79019
79020
79021
79022
79023
79024
79025
79026
79027
79028
79029
79031
79032
79033
79034
79035
79036
79037
79038
79039
79040
79041
79042
79043
79045
79046
79047
79048
79049
79050
79051
79052
79053
79054
79055
80101
Weight
(g)
32
223
5
35
60
41
142
12
76
25
14
192
28
11
64
1146
310
121
12
4
29
31
68
22
1208
572
133
16
506
3
3
281
13
38
20
15
50
108
13
20
11
62
115
90
19
37
54
27
24
23
86
36
15
8725
Class
and
type
L3
H6
LL3
H5
H6
H5
L6
H5
H5
H5
H5
H5
H5
H5
H5
H6
Eu
L6
H6
H6
H5
L3.4
H4
H6
H5
H5
L6
H6
H5
H5
H5
L6
H6
H4
H5
H6
H5
H4
H5
H5
H5
L6
L3
H5
H5
H5
H6
H5
H5
L6
H5
H5
H6
L6
% Fa in
olivine
6-39
16
10-38
16
18
18
23
17
18
17
18
17
18
18
17
17
28-53
23
17
17
18
1-28
17
17
17
18
24
18
18
16
16
24
18
17
18
18
17
16
18
18
18
23
2-38
18
18
18
18
18
18
23
17
18
18
24
%Fsin
pyroxene
2-31
18
5-26
14
16
15
19
15
15
15
16
15
16
16
15
15
20
15
15
17
9-22
14-17
15
15
16
20
16
16
14
14
20
16
14-18
16
16
15
15
15
16
16
20
2-29
15
15
16
16
15
15
20
15
16
16
20
Degree
of
weathering
C
C
B
B/C
B
B/C
A/B
B
C
B/C
B/C
C
c
B
B
B/C
A
B/C
B
B/C
B
A/B
B/C
C
C
B
B
B
C
C
C
B
B
B
B
B
C
B
B
B
B
C
C
B
B
B
C
C
C
B/C
B/C
B
B/C
B
Specimen
number
80102
80103
80104
80105
80106
80107
80108
80110
80111
80112
80113
80114
80115
80116
80117
80118
80119
80120
80121
80122
80123
80124
80125
80126
80127
80128
80129
80130
80131
80132
80133
81001
81002
81003
81004
81005
81006
81007
81008
81009
81010
81011
81012
81013
81014
81015
81016
81017
81018
81019
81020
81021
81022
81023
Weight
(g)
471
536
882
445
432
178
125
168
42
331
313
233
306
191
89
2
34
60
39
50
28
12
139
35
47
138
93
5
20
153
4
53
14
10
5
31
255
164
44
229
219
406
37
Mill
188
5489
3850
1434
2237
1051
1353
695
913
418
Class
and
type
Eu
L6
I
L6
H4
L6
L6
L6
H5
L6
L6
L6
L6
L6
L6
H6
L6
L6
H4
H6
H5
H5
L6
H6
H5
H4
H5
H6
H4
H5
L3
Eu
C2
C3V
C2
A
Eu
Eu
Eu
Eu
Eu
Eu
Eu
I
I
H5
L6
L5
L5
H5
H5
E6
H4
L5
%Fain
olivine
24
24
19
24
24
24
18
24
24
24
24
24
24
17
24
24
19
18
18
18
24
19
18
18
18
18
19
18
1-35
0-52
0-60
0-52
11-40
19
25
25
24
19
19
19
25
% Fs in
pyroxene
34-52
20
20
16-19
20
20
20
16
20
20
20
20
20
20
15
20
20
17
16
16
16
20
17
16
15-20
15
16
16-22
16
5-30
59
0-2
1
0-2
7-47
35-60
38-55
32-59
30-63
31-57
33-60
33-62
16
21
21
21
16
16
0-1
17
21
Degree
of
weathering
A
B
B
C
B
B
B
B
B
B
B
B
B/C
B
B
B
B
B/C
B/C
C
B
B/C
A/B
B
B
B
B/C
B
B
B
A
A
A/B
A/B
A/B
A
A/B
A/B
A
A
A/B
A/B
B
B
B
B
B/C
B
A
B/C
B
NUMBER 28 127
TABLE A.?Continued.
Specimen
number
81024
81025
81026
81027
81028
81029
81030
81031
81032
81033
81034
81035
81036
81037
81038
81039
81040
81041
81042
81043
81044
81045
81046
81047
81048
81049
81050
81051
81052
81053
81054
81055
81056
81057
81058
81059
81060
81061
81062
81063
81064
81065
81066
81067
81068
81069
81070
81071
81072
81073
81074
81075
81076
81077
81078
Weight
(g)
798
379
516
3835
80
153
1852
1595
111
252
255
256
252
320
229
206
195
729
534
106
387
90
17
82
191
9
26
43
29
3
2
5
1
8
66
540
28
24
0.5
5
191
13
9
228
24
7
4
2
3
3
8
16
10
4
6
Class
and
type
L3
L3
L6
L6
L6
L6
L3
L3
L3
H5
H5
H6
H5
H6
H6
H5
L4
H4
H5
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
L3
H6
H6
H4
H4
H4
M
L3
L3
H5
H5
H5
L3
L3
H5
H4
L3
H5
H5
H5
H4
H4
H5
H6
H5
H6
% Fa in
olivine
3-28
1-41
25
25
25
25
1-49
1-43
0-42
18
19
19
19
20
19
19
25
18
19
18
18
18
18
18
18
18
18
18
18
1-29
19
19
19
19
18
28
2-28
3-33
18
18
18
10-41
1-44
19
19
4-38
19
19
19
19
19
19
19
19
19
%Fsin
pyroxene
2-24
3-40
21
21
21
21
5-33
3-35
2-14
16
17
17
17
17
17
17
21
15-23
17
15
16
16
16
16
16
16
16
16
16
I^t2
17
16
17
13-21
15
25-32
5-27
5-27
16
16
15
5-24
1-25
17
16
1-31
17
17
17
8-18
16
17
16
17
16
Degree
of
weathering
C
C
B
C
B
C
B/C
C
cc
B
C
C
B
C
A/B
B/C
C
C
B/C
C
cc
B/C
B/C
B/C
C
B/C
C
C
B
B
B
B
C
C
C
B/C
C
B/C
C
B/C
C
C
B
B/C
B/C
B
B/C
B/C
B
B
B
B
B/C
Specimen
number
81079
81080
81081
81082
81083
81084
81085
81086
81087
81088
81089
81090
81091
81092
81093
81094
81095
81096
81097
81098
81099
81100
81101
81102
81103
81104
81105
81106
81107
81108
81109
81110
81111
81112
81113
81114
81115
81116
81117
81118
81119
81120
81121
81122
81123
81124
81125
81126
81127
81128
81129
81130
81131
81132
81133
Weight
(g)
7
17
5
6
7
16
16
6
8
4
11
10
12
16
271
152
59
83
80
71
152
155
119
196
136
184
93
48
140
69
1
3
210
150
111
79
155
2
33
85
107
14
88
21
2
9
10
22
15
16
32
30
13
5
21
Class
and
type
H6
H5
H5
H5
H5
H5
L3
H6
L3
H5
H5
H5
H5
H4
H6
H6
H4
H6
H4
M
L6
H5
Ur
H6
H6
H4
H4
L6
L6
H5
H4
H5
H6
H6
H5
H4
H5
H5
H4
H5
L4
H5
L3
L6
LL6
H5
H5
H5
H6
H5
H5
H5
L6
H5
H5
%Fain
olivine
19
19
19
19
19
19
1-39
19
2-29
19
19
19
19
19
20
19
18
19
18
25
19
10-22
19
19
19
18
24
24
18
19
19
19
19
18
18
19
19
18
19
24
18
8-40
25
30
19
19
19
19
19
18
18
25
18
18
% Fs in
pyroxene
16
17
17
17
16
16
2-25
16
3-31
17
17
16
16
17
17
16
16
17
16
28
21
17
17
17
17
16
20
21
16
17
17
17
17
16
16
17
17
14-21
16
21
16
1-24
21
25
17
17
16
17
17
16
16
22
16
16
Degree
of
weathering
C
A/B
B
B
B
B
C
B
B/C
B
B
B
B
B
A/B
C
B/C
B
B
C
A/B
B
A/B
B/C
B/C
C
cB
B
B
B
B/C
B/C
B/C
B/C
B/C
C
B
B
B/C
B
B/C
B
B
B
B
B
B
B/C
B/C
A/B
B
A/B
B
B
128 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE A.?Continued.
Specimen
number
81134
81135
81136
81137
81138
81139
81140
81141
81142
81143
81144
81145
81146
81147
81148
81149
81150
81151
81152
81153
81154
81155
81156
81157
81158
81159
81160
81161
81162
81163
81164
81165
81166
81167
81168
81169
81170
81171
81172
81173
81174
81175
81176
81177
81178
81179
81180
81181
81182
81183
81184
81185
81186
81187
81188
Weight
(g)
15
10
1
9
4
7
14
1
1
13
3
21
24
2
13
9
2
5
10
4
1
5
20
12
2
10
12
122
59
82
20
6
26
59
8
6
59
24
33
26
33
13
95
17
30
14
17
15
5
104
17
65
23
40
9
Class
and
type
H6
H5
H5
H6
H5
H5
H4
H5
H4
H5
H5
L3
H6
H4
H5
H4
L6
LL5
H5
L5
H6
H5
L3
H4
H5
L6
H6
H5
L3
H5
H5
H5
H5
L6
H5
H5
H5
H5
L6
H5
H5
H5
H5
H4
H5
H5
H6
L6
H5
H5
L4
LL6
H5
A
H5
% Fa in
olivine
18
19
20
19
19
19
19
19
18
18
19
5-40
18
19
19
19
25
28
18
24
19
19
4-42
19
19
25
19
19
1-40
19
18
19
19
25
19
18
19
19
24
19
19
19
19
19
19
19
18
25
18
17
24
30
18
4
19
%Fsin
pyroxene
16
16
17
17
17
17
17
17
16
16
16
3-23
16
16
17
16
22
23
16
21
17
17
1-30
17
17
21
17
16
4-20
17
16
16
16
22
17
16
17
17
21
16
17
17
17
16
17
17
16
22
16
15
20
25
16
6.5
17
Degree
of
weathering
B/C
B
B
B/C
B
B/C
B/C
B/C
B/C
B/C
B
B
C
B
B
B
C
B/C
B
B
B
A/B
B/C
B/C
B/C
B/C
C
C
C
C
B
B
B
B/C
C
B
B
B/C
C
A/B
B
A/B
B
B/C
B/C
B
C
B
B
C
A/B
A/B
B
B/C
A/B
Specimen
number
81189
81190
81191
81192
81193
81194
81195
81196
81197
81198
81199
81200
81201
81202
81203
81204
81205
81206
81207
81208
81209
81210
81211
81212
81213
81214
81215
81216
81217
81218
81219
81220
81221
81223
81224
81225
81226
81227
81228
81229
81230
81231
81232
81233
81234
81235
81236
81237
81238
81239
81240
81241
81242
81243
81244
Weight
(g)
3
48
30
9
13
17
5
9
68
0.9
16
9
7
5
4
7
3
4
14
2
14
0.6
7
11
3
4
11
2
5
6
24
3
9
10
14
14
3
11
8
40
13
9
5
25
5
7
41
27
24
32
41
34
20
15
5
Class
and
type
E4
L3
L3
H5
H6
H5
H5
H6
H5
L5
H4
H4
H5
H5
L6
H6
L6
H4
H5
Di/M
H5
H6
H5
H4
H5
L3
H5
H5
L6
H5
H5
H5
L6
H6
H6
H6
H5
H5
H5
L3
H5
H4
H5
H5
H4
L6
H5
H5
H5
H5
H5
H5
H5
L3
H5
% Fa in
olivine
2
0.3-32
2-29
19
18
19
18
18
17
24
19
19
18
19
25
18
25
18
18
18
19
18
18
19
0.2-38
18
18
24
19
19
18
25
18
19
19
19
19
18
7-32
18
19
18
19
18
25
18
18
19
19
19
17
18
5-44
19
%Fs in
pyroxene
3
4-28
1-30
16
16
16
16
16
15
21
16
17
16
17
21
16
23
15-21
16
25
16
17
16
16
17
0.1-45
16
17
20
16
17
16
21
16
17
17
17
17
16
2-30
16
16
16
17
16
21
16
16
16
17
18
14
17
6-31
17
Degree
of
weathering
C
C
cA/B
B
B
B
B
B/C
B/C
C
B/C
B/C
C
C
B
B
B/C
C
C
B/C
B
B
B/C
B/C
B/C
A
C
C
C
B
B/C
C
A/B
B/C
B
C
B
B/C
C
B
B/C
B
C
C
C
A/B
B
C
B
C
B
B/C
C
B
NUMBER 28 129
TABLE A.?Continued.
Specimen
number
81245
81246
81247
81248
81249
81250
81251
81252
81253
81254
81255
81256
81257
81258
81259
81260
81261
81262
81263
81265
81266
81267
81268
81269
81270
81271
81272
81273
81274
81275
81276
81277
81278
81279
81280
81281
81282
81283
81284
81285
81286
81287
81288
81289
81290
81291
81292
81293
81294
81295
81296
81297
81298
81299
Weight
(g)
4
3
104
5
10
17
158
2
10
9
12
28
29
1
10
124
12
55
6
8
12
27
18
5
4
28
23
43
19
11
42
7
1
27
55
46
31
0.6
10
20
28
78
20
4
2
4
13
2
9
105
13
20
16
0.5
Class
and
type
H5
H5
L6
H6
H5
H6
LL3
H5
H6
H6
H5
H5
L6
C3V
L3
E6
-H(?r
%Fain
olivine
19
19
25
18
18
18
1-29
18
18
18
18
18
24
0-28
0-22
* 11
* (Acapulco-like)
L6
H5
H5
L6
H4
H6
H5
H5
H6
L3
H6
H5
H5
H5
H5
L6
H4
L3
H5
L6
H5
H5
LL6
H5
H5
H6
L6
H4
H6
L3
H5
H5
H5
H5
H5
H6
L3
25
18
19
24
18
18
18
18
18
2-36
19
18
18
18
18
24
17
1-32
18
24
18
19
27
19
17
18
24
18
18
11-34
18
18
19
17
18
19
1-37
%Fsin
pyroxene
17
17
21
16
17
16
2-28
16
16
16
16
15
21
0-1
0-29
0.3
11
21
16
17
21
15-22
16
16
16
16
3-22
17
16
16
16
16
21
16
2-24
16
21
16
17
23
17
15
16
21
17
16
2-31
16
16
16
15
16
17
2-16
Degree
of
weathering
B/C
C
A/B
C
B/C
B
B/C
B
A/B
C
B
C
B
B
C
A/B
A/B
A/B
B
B/C
A/B
C
C
B/C
C
B
C
C
A/B
B
C
B
B
C
C
B
A/B
B/C
B/C
C
B
C
B
A
B
B
C
B
B
C
B/C
B
B
C
Specimen
number
81300
81301
81302
81303
81304
81305
81306
81307
81308
81309
81310
81311
81312
81313
81314
81315
82100
82101
82102
82103
82104
82105
82106
82107
82108
82109
82110
82111
82112
82113
82114
82115
82116
82117
82118
82119
82120
82121
82122
82123
82124
82125
82126
82127
82128
82129
82130
82131
82132
82133
82134
82135
82136
Weight
(g)
10
12
4
4
42
1
7
57
19
0.6
0.7
0.9
0.7
0.5
3
2
24
29
48
2529
399
363
35
9
14
47
39
63
28
61
41
48
18
4
111
24
7
2
142
111
26
178
140
5
15
14
45
1
6
20
28
12
4
Class
and
type
H5
H5
H5
H6
L6
H5
H5
L6
H5
H4
H6
L6
C2
Eu(?)
H5
"H(?r
%Fain
olivine
19
19
18
18
24
18
19
24
18
18
19
24
1-35
18
* 11
* (Acapulco-like)
C2
C30
H5
H5
L5
L6
Ur
L5
H5
H5
H3
US
H5
H6
H5
H5
H6
L5
US
H5
H5
L6
H5
L6
H6
L6
H4
H6
H4
H5
Ur
C2
E4
H4
H5
C4
H4
1-47
1-50
18
17
25
24
3
22
18
18
1-24
24
17
18
17
18
18
25
24
18
19
24
18
25
18
24
18
18
18
18
3
0.3
18
16
27
18
% Fs in
pyroxene
16
16
16
16
21
16
17
21
16
16
17
21
1-31
38
16
11
1-2
1-10
16
16
21
21
4
19
16
16
4-27
21
16
16
15
16
16
22
20
16
17
20
16
20
16
20
15
16
16
17
4
0.4
16
15
24
5-20
Degree
of
weathering
A/B
B/C
B/C
B/C
A/B
B/C
B
B
B/C
C
B
B
A
B
A/B
A
A
B/C
B
A
A/B
B
B/C
B/C
B/C
B/C
A/B
C
A/B
A/B
A/B
B
B
A/B
B/C
B
A
B
B
C
C
B/C
A/B
B/C
B/C
B
A
C
B/C
B/C
A
B
130 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE A.?Continued.
Specimen
number
82137
82138
82139
82140
82141
82142
82143
82144
83001
83009
83010
83014
83015
83016
83100
83101
83102
84001
84004
84006
84007
84008
84011
84025
84027
84028
84029
84030
84031
84032
84033
84034
84042
84044
BTNA
78001
78002
78004
DRPA
78001
78002
78003
78004
78005
78006
78007
78008
78009
EETA
79001
79002
Weight
(g)
11
5
0.2
0.3
0.6
20
3
7
1569
2
395
1
3
4
863
639
1241
1931
9000
16000
706
302
138
5
8
736
120
6
12
8
60
44
51
147
161
4301
1079
15200
7188
144
134
18600
389
11800
59400
138100
7942
2843
Class
and
type
L5
H6
L6
L6
H5
L6
H6
H5
L4
Au
L3
Ur
Au
C2
C2
L6
C2
Di
H4
H4.5
Au
Au
Au
A
LL7(?)
C3V
C2
C2
C2
C2
C2
C2
C2
C2
L6
L6
LL6
I
I
I
I
I
I
I
I
I
Sh
Di
% Fa in
olivine
23
19
24
25
19
25
18
19
23-28
4-31
18
0.3-30
25
0-2
17-18
18
32-33
27
0-50
0-2
0-2
0-2
0-2
0-1
0-2
0-2
0-2
24
24
30
23-27
24-25
% Fs in
pyroxene
20
17
20
20
17
21
16
17
20-32
2-28
15
0-1
23
27
16-19
17-18
11
23
2
2
2
21
20
24
16-67
22
Degree
of
weathering
B
B
B
C
C
C
C
B
B
A/B
B
B
A/B
A/B
B
A
B/C
A/B
B
B/C
A
A/B
A
A/B
B
A
A
A
A
A
A
A
A
A
B
B
B
A
B
Specimen
number
79003
79004
79005
79006
79007
79009
79010
79011
EET
82600
82601
82602
82603
82604
82605
82606
82607
82608
82609
82610
82611
82612
82613
82614
82615
82616
83200
83201
83202
83203
83204
83205
83206
83207
83208
83209
83210
83211
83212
83213
83214
83215
83224
83225
83226
83227
83228
83229
83230
83231
83232
83234
83235
83236
Weight
(g)
436
390
451
716
200
140
287
86
247
150
1824
8210
1571
625
982
165
95
326
42
13
32
4
8
29
2
779
1060
1213
546
377
471
462
1238
263
520
426
543
402
2727
1398
510
9
44
33
1973
1206
313
530
66
211
181
255
6
Class
and
type
L6
Eu
Eu
Ho
H5
L5
L6
Eu
Ho
L3
H4
H5
H5
L6
L6
L6
LL6
H4
H6
L4
L6
L4
H5
H6
H4
H5
H6
L6
H5
LL6
L6
L6
H4
H5
L6
L6
H4
Eu
L3
L6
H6
C2
Ur
C2
Eu
Eu
Eu
I
Eu
Eu
Eu
Eu
Eu
%Fain
olivine
24
18
24
24
2-39
19
19
19
25
25
23
28
18
19
24
25
24
18
19
18
17-18
18-20
24-25
20
29-31
25
24
18
17-19
25
24-25
18-20
13-30
24-25
18
0.2-41
0.5-69
% Fs in
pyroxene
20
30-61
30-61
19-57
16
20
20
30-61
22-53
1-35
16
17
16
21
21
20
23
17
17
21
21
20
16
17
16
17-19
18
22-23
18-21
27
22
22
16-18
16-17
22-23
22
16-20
3-26
22-24
19
0-1
0.6-10
Degree
of
weathering
B
B
A
B
B
B
B
B
A
B/C
B
B
B/C
B
B
B/C
A/B
B/C
B
B
A
B
A/B
B
B/C
B/C
B/C
A/B
B/C
A
A/B
B
B
B/C
B/C
A/B
B/C
B
B
B
B/C
A/B
B/C
A/B
B
B
B
B
B
B
B
B
NUMBER 28 131
TABLE A.?Continued.
Specimen
number
83237
83245
83246
83247
83250
83251
83283
ILD
83500
MBRA
76001
76002
META
78001
78002
78003
78005
78006
78007
78010
78028
OTTA
80301
PCA
82500
82501
82502
82503
82504
82505
82506
82507
82508
82509
82510
82511
82512
82513
82514
82515
82516
82517
82518
82519
82520
82521
82522
82523
82524
82525
Weight
(g)
883
59
48
22
11
261
57
2523
1096
13773
624
542
1726
172
410
175
234
20657
36
91
54
890
8308
3094
3086
5316
480
389
286
254
149
55
239
130
7
16
41
22
125
23
1
46
11
114
40
Class
and
type
L6
I
Di
Di
C2
Eu
Eu
I
H6
H6
H4
L6
L6
L6
H6
H6
H5
L6
H3
C4
Eu
Eu
L6
L5
L5
Ur
LL6
L6
L6
L5
H4
H6
L5
L4
H4
H6
H5
E4
L5
H3
H5
H5
H6
H4
L6
%Fain
olivine
25-26
0.3-22
18
18
17
23
24
24
18
19
19
25
17-19
31
24
23
23
21
30
23
25
24
17
18
24
23
17
18
19
0.8
24
15-22
18
18
19
18
24
% Fs in
pyroxene
23-25
2-14
16
16
14-21
20
21
20
15
17
17
21
4-19
41-57
36-61
20
20
20
18
25
20
21
20
14
16
20
11-22
14
16
17
21
2-19
16
16
16
16
20
Degree
of
weathering
B
A/B
B/C
B
B
B
B
B
B/C
B
B
B
C
B/C
B
B
B/C
B
A
A
A
A/B
B
A/B
A
A/B
B
A
B
B
A/B
B
B
B/C
B/C
B
B
B/C
C
B/C
A
A/B
B
Specimen
number
82526
82527
82528
PGPA
77006
RKPA
78001
78002
78003
78004
79001
79002
79003
79004
79008
79009
79012
79013
79014
79015
80201
80202
80203
80204
80205
80206
80207
80208
80209
80210
80211
80213
80214
80215
80216
80217
80218
80219
80220
80221
80222
80223
80224
80225
80226
80227
80228
80229
80230
80231
80232
Weight
(g)
25
3
51
19068
235
8483
1276
167
3006
204
182
371
73
55
13
11
78
10022
813
545
4
15
54
47
18
10
10
11
2
19
5
9
44
8
7
21
124
52
7
25
8
8
160
8
11
14
58
238
80
Class
and
type
H6
H6
L6
I
L6
H4
L6
H4
L6
L6
H6
H5
L3
H6
H6
L5
H5
M
H6
US
H6
Eu
H3
H6
L3
H6
L5
H5
H6
H6
H6
L6
L4
H5
H5
L6
H5
H6
LL6
H5
Eu
L6
I
H5
L5
M
H5
H6
H4
%Fain
olivine
18
18
25
23
18
23
17
23
24
18
18
1-29
18
18
23
18
19
24
19
17-20
19
15-29
19
25
19
19
19
19
24
23
18
18
25
18
19
28
18
54
25
19
23
18
18
18
% Fs in
pyroxene
16
16
21
20
15
20
14-21
20
20
16
16
2-28
16
16
20
16
24
16
20
17
52-57
5-13
17
6-28
17
21
16
17
17
17
20
20
15
15
21
16
17
23
16
21
16
19
24
16
16
16
Degree
of
weathering
B
A
B/C
C
B
C
A
B
B
B
B/C
B
C
B
B/C
B/C
A/B
B
B
C
A
B
C
C
B
C
B/C
C
B/C
C
C
B
C
C
B
B/C
C
B
C
A/B
C
B/C
C
C
B
C
B
132 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE A.?Continued.
Specimen
number
80233
80234
80235
80236
80237
80238
80239
80240
80241
80242
80243
80244
80245
80246
80247
80248
80249
80250
80251
80252
80253
80254
80255
80256
80257
80258
80259
80260
80261
Weight
(g)
414
136
261
16
22
18
6
61
0.6
7
3
14
37
6
1
11
10
4
29
11
5
68
7
153
9
4
20
8
62
Class
and
type
H5
LL5
LL6
H5
H4
LL6
Ur
H5
C3V
L4
H5
H5
H5
M
H5
LL6
H5
H5
H5
L6
LL5
H6
H6
L3
H5
M
E5
H5
L6
% Fa in
olivine
18
26
30
18
18
28
16
18
1-6
22
18
18
18
18
27
17
17
17
24
27
19
19
20-25
17
18
24
% Fs in
pyroxene
16
22
24
16
16
23
15
16
1-8
19
16
16
16
24
16
23
15
15
15
20
22
17
17
10-26
15
17-21
0-1
16
20
Degree
of
weathering
B/C
B
A/B
B/C
C
A/B
B
C
B
B/C
C
C
B/C
C
c
A/B
B/C
B/C
B
A/B
A/B
C
C
B
B/C
B/C
B/C
C
B
Specimen
number
80262
80263
80264
80265
80266
80267
80268
TIL
82400
82401
82402
82403
82404
82405
82406
82407
82408
82409
82410
82411
82412
82413
82414
82415
TYR
82700
Weight
(g)
32
17
24
8
10
24
3
221
282
476
50
322
1116
152
221
80
231
19
180
35
18
15
70
892
Class
and
type
H6
M
L6
H6
H6
H4
L5
L5
L6
LL6
Eu
L4
H6
L4
L4
LL3
H5
Di
L4
H5
H5
H5
H5
L4
%Fain
olivine
19
24
19
19
19
24
25
25
29
23
19
23
23
1-29
18
24
17
17
17
17
24
% Fs in
pyroxene
17
24
20
17
17
16
20
21
21
24
43-58
20
17
19
20
2-21
16
24
21
16
16
15
15
15-23
Degree
of
weathering
C
C
B
C
B/C
C
B/C
A/B
A/B
A/B
A
B
B
B
B/C
B
B
A
A/B
C
C
B
A/B
B
NUMBER 28 133
TABLE B.?Meteorites listed by class and source area in numerical sequence (fractions of grams in weight
dropped unless total weight is less than 1 gram).
Specimen
number
ALHA77306
ALHA78261
ALHA81002
ALHA81004
ALHA81312
ALH 82100
ALH 82131
ALH 83016
ALH 83100
ALH 83102
ALH 84029
ALH 84030
ALH 84031
ALH 84032
ALH 84033
ALH 84034
ALH 84042
ALH 84044
EET 83224
EET 83226
EET 83250
ALHA77307
ALHA77003
ALHA77029f
ALH 82101
ALHA81OO3
ALHA81258
ALH 84028
RKPA 80241
ALH 82135
PCA 82500
ALHA81189
ALH 82132
PCA 82518
ALHA77156f
ALHA77295f
RKPA80259
ALH A81021
ALHA81260
ALHA77299
ALHA78170+
ALH 82110
OTTA80301
PCA 82520
RKPA80205
ALHA77004
ALHA77009
ALHA77010
Weight
(g)
20
5
14
5
0.7
24
1
4
863
1241
120
6
12
8
60
44
51
147
9
33
11
181
780
1
29
10
1
736
0.6
12
91
3
6
22
18
141
20
695
124
261
21
39
36
23
54
2230
236
296
Class
and
type
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C3
C3O
C3O
C3O
C3V
C3V
C3V
C3V
C4
C4
E4
E4
E4
EH4
EH4
E5
E6
E6
H3
H3
H3
H3
H3
H3
H4
H4
H4
Degree of
weathering
A
A
A
A/B
A
A
A
A/B
B
B/C
A
A
A
A
A
A
A
A
A/B
A/B
B
A
A
A/B
A
A/B
B
A
B
A
B
C
C
B
B/C
A
A/B
A
B
B/C
B/C
B/C
B
C
C
C
fracturing
CHOIN
A
A
B
A
A
A
B
B/C
B/C
C
B
B/C
B
A
B
A
B
B
B
B
C
A
A
A/B
A/B
A/B
A
B
A
C
B
B/C
A
B
B
B
B
A/B
A
B
B
A/B
B
C
A
A
Specimen
number
rDRITES
ALHA77056f
ALHA77190
ALHA77191
ALHA77192
ALHA77208
ALHA77221
ALHA77222f
ALHA77223
ALHA77224
ALHA77225
ALHA77226
ALHA77232
ALHA77233
ALHA77262
ALHA77286
ALHA78029+
ALHA78033+
ALHA78051
ALHA78053
ALHA78057
ALHA78077
ALHA78084
ALHA78120
ALHA78134
ALHA78140+
ALHA78157+
ALHA78168+
ALHA78172+
ALHA78193
ALHA78196
ALHA78223
ALHA79023
ALHA79035
ALHA79039
ALHA80106
ALHA80121
ALHA80128
ALHA80131
ALHA81022
ALHA81041
ALHA81043
ALHA81044
ALH A81045
ALHA81046
ALHA81047
ALHA81048
ALHA81049
ALHA81050
ALHA81051
ALHA81052
ALHA81056
ALHA81057
ALHA81058
ALHA81068
ALHA81073
ALHA81074
ALHA81092
ALHA81095
Weight
(g)
12
387
642
845
1733
229
125
208
787
5878
15323
6494
4087
862
246
4
5
120
179
9
331
14280
44
458
17
63
34
29
13
11
6
68
38
108
432
39
138
20
913
729
106
387
90
17
82
191
9
26
43
29
1
8
66
24
3
8
16
59
Class
and
type
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
Degree of
weathering
A/B
C
C
cc
c
A/B
cc
cc
cc
B/C
C
B
B
C
C
B/C
B/C
B
B
B
B
B/C
B/C
B
B/C
B
B
C
B/C
B
B
B/C
C
B/C
C
C
C
B/C
B/C
B/C
C
B/C
C
B
B
C
B
B/C
B
B
B/C
fracturing
C
B/C
C
cA
C
C
C
C
C
B
B
B
B
B
B
B/C
A
B
B
C
B
B
B
C
B/C
B
A
C
C
C
B/C
B/C
B/C
B/C
B
C
B
B
A
A
C
A
A
B
A
C
134 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE B.?Continued.
Specimen
number
ALHA81097
ALHA81104
ALHA81105
ALHA81109
ALHA81114
ALHA81117
ALHA81140
ALHA81142
ALHA81147
ALHA81149
ALHA81157
ALHA81177
ALHA81199
ALHA81200
ALHA81206
ALHA81212
ALHA81231
ALHA81234
ALHA81267
ALHA81279
ALHA81290
ALHA813O9
ALH 82126
ALH 82128
ALH 82133
ALH 82136
ALH 84004
EET 82602
EET 82609
EET 82616
EET 83207
EET 83211
META78001
PCA 82511
PCA 82515
PCA 82524
RKPA78002
RKPA78004
RKPA80232
RKPA80237
RKPA 80267
ALH 84006
ALHA77007f
ALHA77012
ALHA77014
ALHA77016f
ALHA77017f
ALHA77018f
ALHA77021
ALHA77022f
ALHA77023f
ALHA77025
ALHA77038f
ALHA77039t
ALHA77042f
ALHA77045f
ALHA77051t
Weight
(g)
80
184
93
1
79
33
14
1
2
9
12
17
16
9
4
11
9
5
27
27
2
0.6
140
15
20
4
9000
1824
326
2
1238
543
624
149
7
114
8483
167
80
22
24
16000
99
180
309
78
78
52
17
16
21
19
19
8
20
18
15
Class
and
type
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4
H4.5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
weathering
B
C
C
B
B/C
B
B/C
B/C
B
B
B/C
B/C
C
B/C
B/C
B/C
B/C
C
C
C
B
C
B/C
B/C
B/C
B
B
B/C
B/C
B
B/C
B/C
B
B
A/B
B
A
B
C
C
B/C
B
C
C
B
B
B/C
C
A
B
C
A/B
A/B
A/B
A
A
?ree of
fracturing
A
C
B/C
A
B/C
B/C
A
B/C
A
B
B
B
B
A
A
B
B
A
B/C
B/C
A
A
A
A
A/B
B
B
B
A/B
A
B
B/C
B
B
A/B
B
A/B
A
A
B
A
B
A
B/C
A
B
Specimen
number
ALHA77054f
ALHA77058f
ALHA77061
ALHA77062
ALHA77063f
ALHA77064
ALHA77066f
ALHA77070f
ALHA77071
ALHA77073f
ALHA77074
ALHA77076f
ALHA77078f
ALHA77079t
ALHA77082f
ALHA77084f
ALHA77085f
ALHA77086
ALHA77087f
ALHA77088
ALHA77091f
ALHA77092t
ALHA77094f
ALHA77096f
ALHA77098f
ALH A77100t
ALHA77101f
ALHA77102
ALHA77104f
ALHA77106f
ALHA77108f
ALHA77112f
ALHA77113f
ALHA77114f
ALHA77118
ALHA77119
ALHA77120f
ALHA77122f
ALHA77124
ALHA77125f
ALHA77126f
ALHA77129f
ALHA77130f
ALHA77132f
ALHA77136f
ALHA77138f
ALHA77139f
ALHA77142f
ALHA77143f
ALHA77151f
ALHA77152t
ALHA77153f
ALHA77158f
ALHA77161f
ALHA77168f
ALHA77171f
ALHA77173f
ALHA77174f
ALHA77177
Weight
(8)
10
4
13
17
3
6
5
18
11
10
12
2
24
8
12
44
46
19
31
51
4
45
7
2
8
18
4
12
6
8
0.7
22
2
45
8
6
4
5
4
19
25
2
25
115
4
2
66
3
39
17
18
12
20
6
25
24
26
32
368
Class
and
type
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
Degree of
weathering
B
B
B
B
B
B
A
B
B
A/B
B
B
B
A
A/B
A/B
B
C
B
C
B/C
A
B
A
B
A/B
B
B
A
A/B
A/B
A
B
B
C
C
A/B
B
C
A/B
A/B
B
A
A/B
A/B
A
A/B
A/B
A/B
A
A
A
B
B
B
A/B
B
A
C
fracturing
A
B
B
B
B
B
B
B
B
B
A
A
NUMBER 28 135
TABLE B.?Continued.
Specimen
number
ALHA77181f
ALHA77182
ALHA77184f
ALHA77186f
ALHA77187f
ALHA77188f
ALHA77193f
ALHA77195t
ALHA77201f
ALHA77202f
ALHA77205f
ALHA77207f
ALHA77213f
ALHA77220f
ALHA77227f
ALHA77228f
ALHA77235f
ALHA77237f
ALHA77240f
ALHA77242I
ALHA77245f
ALHA77247f
ALHA77253f
ALHA77259
ALHA77264
ALHA77265f
ALHA77266f
ALHA77268
ALHA77274
ALHA77275f
ALHA77279f
ALHA77287
ALHA77291f
ALHA77294
ALHA77300
ALHA78001+
ALHA78004*
ALHA78005+
ALHA78008
ALHA78010+
ALHA78012
ALHA78018+
ALHA78021
ALHA78023
ALHA78025+
ALHA78027*
ALHA78028
ALHA78031
ALHA78047*
ALHA78049+
ALHA78052*
ALHA78075
ALHA78079
ALHA78080
ALHA78081*
ALHA78085
ALHA78088*
ALHA78090*
ALHA78092*
Weight
(g)
33
1135
128
122
52
109
7
5
15
3
3
5
8
69
16
19
5
4
25
56
33
44
24
294
11
18
108
272
288
25
175
230
6
1351
235
85
36
28
7
1
38
18
17
10
8
29
4
5
130
96
97
281
5
25
18
219
5
8
16
Class
and
type
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
Degree of
weathering
B
C
B
A/B
A/B
A/B
A
A
A
B
B
A/B
A
B
A
B
A/B
A
A
B
A/B
A/B
A/B
C
A/B
B
B
C
C
A
A
C
A
A
C
B
B
B
B
A
B
B
C
B/C
B
fracturing
B
B
A
C
A
A
A
B
B
B
B
B
Specimen
number
ALHA78094*
ALHA78096*
ALHA78098*
ALHA78102
ALHA78107
ALHA78108
ALHA78110
ALHA78111
ALHA78116*
ALHA78117+
ALHA78121*
ALHA78123+
ALHA78128
ALHA78129+
ALHA78136+
ALHA78139*
ALHA78141
ALHA78146
ALHA78150
ALHA78154+
ALHA78159
ALHA78160*
ALHA78163+
ALHA78164
ALHA78173+
ALHA78174+
ALHA78178+
ALHA78182
ALHA78190
ALHA78194
ALHA78197
ALHA78199
ALHA78201
ALHA78203
ALHA78205
ALHA78209
ALHA78217+
ALHA78219+
ALHA78221
ALHA78225
ALHA78227
ALHA78233
ALHA78241
ALHA78245
ALHA78247
ALHA78253+
ALHA78255+
ALHA78257+
ALHA78259+
ALHA79004
ALHA79006
ALHA79OO8
ALHA79009
ALHA79010
ALHA79011
ALHA79012
ALHA79013
ALHA79014
ALHA79015
Weight
(g)
4
7
2
337
198
173
161
127
128
4
30
18
155
128
52
17
24
17
16
12
23
16
10
25
20
13
7
10
20
25
20
13
10
11
9
12
8
8
5
5
2
1
7
4
3
7
3
2
6
35
41
12
76
25
14
192
28
11
64
Class
and
type
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
Degree of
weathering
B/C
C
B
B/C
B/C
B
A
B
C
B
A
B
B
B
B
B
B/C
B
B
B
B
B/C
B/C
B
A
B
A
B/C
B/C
B
C
B/C
B/C
C
cB
B
fracturing
B
A
B
B
A
B
B/C
B
A
A
B
B
B
B
B
A
B
A
B
B
A
B
136 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE B.?Continued.
Specimen
number
ALHA79021
ALHA79025
ALHA79026
ALHA79029
ALHA79031
ALHA79032
ALHA79036
ALHA79O38
ALHA79040
ALHA79041
ALHA79042
ALHA79046
ALHA79047
ALHA79048
ALHA79050
ALHA79051
ALHA79053
ALHA79054
ALHA80111
ALHA80123
ALHA80124
ALHA80127
ALHA80129
ALHA80132
ALHA81015
ALHA81019
ALHA81020
ALHA81033
ALHA81034
ALHA81036
ALHA81039
ALHA81042
ALHA81062
ALHA81063
ALHA81064
ALHA81067
ALHA81070
ALHA81071
ALHA81072
ALHA81075
ALHA81077
ALHA81080
ALHA81O81
ALHA81082
ALHA81083
ALHA81084
ALHA81088
ALHA81089
ALHA81090
ALHA81091
ALHA81100
ALHA81108
ALHA81110
ALHA81113
ALHA81115
ALHA81116
ALHA81118
ALHA81120
ALHA81124
Weight
(g)
29
1208
572
506
3
3
20
50
13
20
11
90
19
37
27
24
86
36
42
28
12
47
93
153
5489
1051
1353
252
255
252
206
534
0.5
5
191
228
4
2
3
16
4
17
5
6
7
16
4
11
10
12
155
69
3
111
155
2
85
14
9
Class
and
type
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
De$
weathering
B
C
B
C
C
C
B
C
B
B
B
B
B
B
C
C
B/C
B
B
C
B
B
B
B
B
B/C
B
C
B
C
A/B
C
C
B/C
C
cB/C
B
B/C
B
B
A/B
B
B
B
B
B
B
B
B
B
B
B/C
B/C
C
B
B/C
B/C
B
?ree of
fracturing
A
A
B
B/C
B
B
B
B
A
B
A
B
B
B
B
A
B
A
A
A
B
A
A
B
B
B
A
C
B
A
B
C
A
B
A/B
B
A
A
A
A
A
A
A
A
A
A
A
A
A
B
A
B
A
C
A/B
A
A
B
A
Specimen
number
ALHA81125
ALHA81126
ALHA81128
ALHA81129
ALHA8113O
ALHA81132
ALHA81133
ALHA81135
ALHA81136
ALHA81138
ALHA81139
ALHA81141
ALHA81143
ALHA81144
ALHA81148
ALHA81152
ALHA81155
ALHA81158
ALHA81161
ALHA81163
ALHA81164
ALHA81165
ALHA81166
ALHA81168
ALHA81169
ALHA81170
ALHA81171
ALHA81173
ALHA81175
ALHA81176
ALHA81178
ALHA81179
ALHA81182
ALHA81183
ALHA81186
ALHA81188
ALHA81192
ALHA81194
ALHA81195
ALHA81197
ALHA81201
ALHA81202
ALHA81207
ALHA81209
ALHA81211
ALHA81213
ALHA81215
ALHA81216
ALHA81218
ALHA81219
ALHA81220
ALHA81226
ALHA81227
ALHA81228
ALHA81230
ALHA81232
ALHA81233
ALHA81236
ALHA81237
Weight
(g)
10
22
16
32
30
5
21
10
1
4
7
1
13
3
13
10
5
2
122
82
20
6
26
8
6
59
24
26
13
95
30
14
5
104
23
9
9
17
5
68
7
5
14
14
7
3
11
2
6
24
3
3
11
8
13
5
25
41
27
Class
and
type
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
Degree of
weathering
B
B
B/C
A/B
B
B
B
B
B
B
B/C
B/C
B/C
B
B
B
A/B
B/C
C
C
B
B
B
C
B
B
B/C
A/B
A/B
B
B/C
B
B
C
B
A/B
A/B
B
B
B/C
B/C
C
C
B/C
B
B/C
A
C
C
B
B/C
C
B
B/C
B
B
C
A/B
B
fracturing
A
A
A
A
B
A
A
A
A/B
A
B
B
A
A
A
A
A
A
C
B/C
A
A
A
B
B
A/B
B
A
B
A
B/C
A
A/B
B/C
A/B
A
A
B
A/B
B/C
A
A
B
A
A
A
A
A
B
A
A/B
A
B
A
B
A/B
B/C
A/B
B
NUMBER 28 137
TABLE B.?Continued.
Specimen
number
ALHA81238
ALHA81239
ALHA81240
ALHA81241
ALHA81242
ALHA81244
ALHA81245
ALHA81246
ALHA81249
ALHA81252
ALHA81255
ALHA81256
ALHA81263
ALHA81265
ALHA81269
ALHA81270
ALHA81274
ALHA81275
ALHA81276
ALHA81277
ALHA81281
ALHA81283
ALHA81284
ALHA81286
ALHA81287
ALHA81293
ALHA81294
ALHA81295
ALHA81296
ALH A81297
ALHA813OO
ALHA813O1
ALHA81302
ALHA81305
ALHA81306
ALHA81308
ALHA81314
ALH 82102
ALH 82103
ALH 82108
ALH 82109
ALH 82112
ALH 82114
ALH 82115
ALH 82119
ALH 82120
ALH 82122
ALH 82129
ALH 82134
ALH 82141
ALH 82144
EETA79OO7
EET 82603
EET 82604
EET 82614
EET 83200
EET 83203
EET 83208
META78010
Weight
(g)
24
32
41
34
20
5
4
3
10
2
12
28
6
8
5
4
19
11
42
7
46
0.6
10
28
78
2
9
105
13
20
10
12
4
1
7
19
3
48
2529
14
47
28
41
48
24
7
142
14
28
0.6
7
200
8210
1571
8
779
546
263
234
Class
and
type
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
Degree of
weathering
C
B
C
B
B/C
B
B/C
C
B/C
B
B
C
B
B/C
B/C
C
A/B
B
C
B
B
B/C
B/C
B
C
B
B
C
B/C
B
A/B
B/C
B/C
B/C
B
B/C
B
B/C
B
B/C
B/C
C
A/B
A/B
B/C
B
B
B/C
B/C
C
B
B
B
B/C
A/B
B/C
B/C
B/C
B
fracturing
B
B
C
A/B
A
A
A/B
A
A
A
B
A
B
A
A
A/B
A
A
B
A
B
A
A
B
B/C
A/B
A
B/C
B
A
A
A
A
A
A
B
A
A
B
A
A/B
A
A
A
B
A
A
A
A
A
A
B
A
B
A
B
B/C
B
A
Specimen
number
PCA 82517
PC A 82521
PCA 82522
RKPA79004
RKPA79014
RKPA80210
RKPA80217
RKPA80218
RKPA80220
RKPA 80223
RKPA 80227
RKPA 80230
RKPA 80233
RKPA80236
RKPA 80240
RKPA 80243
RKPA 80244
RKPA80245
RKPA 80247
RKPA80249
RKPA 80250
RKPA 80251
RKPA 80257
RKPA80260
TIL 82409
TIL 82412
TIL 82413
TIL 82414
TIL 82415
ALHA78147*
ALHA76006
ALHA76008
ALHA77046f
ALHA77111t
ALHA77131t
ALHA77133f
ALHA77134f
ALHA77144
ALHA77146f
ALHA77147f
ALHA77148
ALHA77149f
ALHA77157f
ALHA77183
ALHA77200f
ALHA77209t
ALHA77212f
ALHA77239t
ALHA77246f
ALHA77248f
ALHA77258
ALHA77271
ALHA77285
ALHA77288
ALHA78002+
ALHA78035
ALHA78065+
Weight
(g)
41
1
46
371
78
11
8
7
124
25
8
58
414
16
61
3
14
37
1
10
4
29
9
8
231
35
18
15
70
31
271
281
8
52
26
19
19
8
18
19
13
26
88
288
0.9
32
17
19
42
96
597
610
271
1880
11
2
7
Class
and
type
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5
H5.6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
Degree of
weathering
B/C
C
B/C
B/C
B/C
B/C
C
cB/C
c
B/C
B
B/C
B/C
C
cc
B/C
C
B/C
B/C
B
B/C
C
B
C
C
B
A/B
C
B/C
A/B
A/B
A/B
A
A
B
A/B
A/B
C
A/B
A/B
C
C
B
A/B
B
B
B/C
B/C
C
cc
A
B
fracturing
B
A
B
B
B
B
A
A
B/C
B
A
B
B
B
A
A
B
B
B
A
A
B
B
B
A
B
B
A
A
B
B
A
B
A
A/B
A
B
B
138 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE B.?Continued.
Specimen
number
ALHA78067
ALHA78069+
ALHA78076
ALHA78086*
ALHA78115
ALHA78122
ALHA78124
ALHA78135*
ALHA78137
ALHA78145+
ALHA78152
ALHA78169+
ALHA78184
ALHA78189
ALHA78191
ALHA78207
ALHA78211
ALHA78213
ALHA78215
ALHA78229
ALHA78231
ALHA78249
ALHA79002
ALHA79005
ALHA79016
ALHA79019
ALHA79020
ALHA79024
ALHA79028
ALHA79034
ALHA79037
ALHA79049
ALHA79055
ALHA8O118
ALHA80122
ALHA80126
ALHA8O13O
ALHA81035
ALHA81037
ALHA81O38
ALHA81054
ALHA81055
ALHA81076
ALHA81078
ALHA81079
ALHA81086
ALHA81093
ALHA81094
ALHA81096
ALHA81102
ALHA81103
ALHA81111
ALHA81112
ALHA81127
ALHA81134
ALHA81137
ALHA81146
ALHA81154
Weight
(g)
8
4
276
9
848
5
28
131
70
34
5
22
8
23
20
8
11
10
6
2
2
4
223
60
1146
12
4
22
16
13
15
54
15
2
50
35
5
256
320
229
2
5
10
6
7
6
271
152
83
196
136
210
150
15
15
9
24
1
Class
and
type
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
Degree of
weathering
B
B
B
B
A
B
B
B
B/C
B
B/C
C
B
B/C
B
B/C
C
B
B
B
C
B/C
B
B/C
A/B
B/C
C
B
C
B
B
B
B/C
C
B
A/B
C
B
B/C
B/C
B/C
B/C
B/C
B/C
B/C
C
B
fracturing
B
A
B
B
B
B
B
B
B
B
B
A
B
B
B
A
B
B
B
A
B
A
A
A/B
A
B
B
A
A
B
A
B
A/B
B
B
A/B
B/C
B
A
B
B
A/B
B
B
Specimen
number
ALHA81160
ALHA81180
ALHA81193
ALHA81196
ALHA81204
ALHA81210
ALHA81223
ALHA81224
ALHA81225
ALHA81248
ALHA81250
ALHA81253
ALHA81254
ALHA81268
ALHA81271
ALHA81273
ALHA81288
ALHA81291
ALHA81298
ALHA81303
ALHA81310
ALH 82113
ALH 82116
ALH 82124
ALH 82127
ALH 82138
ALH 82143
EET 82610
EET 82615
EET 83201
EET 83215
MBRA76001
MBRA76002
META78006
META78007
PCA 82512
PCA 82516
PCA 82523
PCA 82526
PCA 82527
RKPA79003
RKPA79009
RKPA79012
RKPA 80201
RKPA80203
RKPA80206
RKPA80208
RKPA 80211
RKPA 80213
RKPA 80214
RKPA80221
RKPA 80231
RKPA 80254
RKPA80255
RKPA80262
RKPA80265
RKPA80266
TIL 82405
Weight
(g)
12
17
13
9
7
0.6
10
14
14
5
17
10
9
18
28
43
20
4
16
4
0.7
61
18
26
5
5
3
42
29
1060
510
1096
13773
410
.175
55
16
11
25
3
182
55
13
813
4
47
10
2
19
5
52
238
68
7
32
8
10
1116
Class
and
type
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
H6
Degree of
weathering
C
C
B
B
B
B
A/B
B/C
B
C
B
A/B
C
C
B
C
B
B
B
B/C
B
A/B
B
C
A/B
B
C
B
B
B/C
B/C
B
B
C
B/C
B
B/C
A
B
A
B
C
B
B
C
C
B
C
B/C
C
cc
cc
cc
B/C
B
fracturing
B
B
A
A
A
A
A
A
A
A/B
B
B
A
B/C
B
B/C
A
A
B
A
A
A
B
A/B
A
A/B
A/B
A
A
A
C
B
B
B
B
A
B
B
A
A
A
B
B
A
A
B
A
B
B
B
B/C
B/C
B/C
B
B
B
B
A
NUMBER 28 139
TABLE B.?Continued.
Specimen
number
ALHA81174
ALHA77081
ALHA81261
ALHA81315
ALHA77011
ALHA77013f
ALHA77015
ALHA77031f
ALHA77033
ALHA77034f
ALHA77036f
ALHA77043f
ALHA77047f
ALHA77049f
ALHA77050f
ALHA77052f
ALHA77115f
ALHA77140
ALHA77160
ALHA77163I
ALHA77164
ALHA77165
ALHA77166f
ALHA77167
ALHA77170f
ALHA77175f
ALHA77176f
ALHA77178f
ALHA77185f
ALHA77197J
ALHA77211t
ALHA77214
ALHA77215
ALHA77216
ALHA77217
ALHA77241t
ALHA77244f
ALHA77249
ALHA77252
ALHA77260
ALHA77303f
ALHA78013
ALHA78017+
ALHA78037+
ALHA78038
ALHA78041+
ALHA78046
ALHA78119+
ALHA78133
ALHA78149+
ALHA78162+
ALHA78176+
ALHA7818O+
ALHA78186
ALHA78188
ALHA78235+
ALHA78236
ALHA78238
Weight
(g)
33
U
292
23
411
0.5
9
2
8
11
20
7
84
112
154
79
70
24
38
31
139
611
12
23
55
6
28
20
27
2111
820
1470
413
144
40
504
343
744
79
4
3
0.5
363
118
70
103
60
23
33
8
8
3
0.9
19
14
10
Class
and
type
H
"H(?)"
(Acapulco-
like)
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
Degree of
weathering
B
B
A/B
A/B
C
B
C
B/C
C
B/C
B
B/C
C
B/C
B/C
B/C
B/C
C
C
B/C
C
C
C
c
B/C
B/C
B
B/C
A/B
A/B
B/C
C
B
A/B
B
C
B/C
C
B
C
B/C
B
B
C
B
A
B
B
B
B
C
B
fracturing
B/C
A
A
A
A
B
B
B
B
C
C
B/C
C
B/C
B/C
B/C
C
C
c
c
B
Specimen
number
ALHA78239+
ALHA78243
ALHA79001
ALHA79045
ALHA80133
ALHA81024
ALHA81025
ALHA81O3O
ALHA81031
ALHA81032
ALHA81053
ALHA81060
ALHA81061
ALHA81065
ALHA81066
ALHA81069
ALHA81085
ALHA81087
ALHA81121
ALHA81145
ALHA81156
ALHA81162
ALHA81190
ALHA81191
ALHA81214
ALHA81229
ALHA81243
ALHA81259
ALHA81272
ALHA81280
ALHA81292
ALHA81299
ALH83010
EET 82601
EET 83213
RKPA79008
RKPA80207
RKPA80256
ALHA79022
ALHA77230
ALHA77304
ALHA78044
ALHA78070
ALHA81040
ALHA81119
ALHA81184
ALH 83001
EET 82611
EET 82613
PCA 82514
RKPA80216
RKPA80242
TIL 82404
TIL 82406
TIL 82407
TIL 82411
TYR 82700
Weight
(8)
16
2
32
115
4
798
379
1852
1595
111
3
28
24
13
9
7
16
8
88
21
20
59
48
30
4
40
15
10
23
55
13
0.5
395
150
2727
73
18
153
31
2473
650
164
10
195
107
17
1569
13
4
130
44
7
322
152
221
180
892
Class
and
type
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3
L3.4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
L4
Degree of
weathering
B
C
C
B
C
C
B/C
C
C
C
C
B/C
B/C
C
B/C
C
B/C
B
B
B/C
C
cc
B/C
cc
cc
cc
cB
B/C
B
B
C
B
A/B
C
B
B/C
B/C
B
A/B
B
B
B
B
B
B/C
B
B
B/C
A/B
B
fracturing
A
B
B
B
B
B/C
B/C
A
B
B
A
B
B
A
B
B
B
B
B/C
C
A/B
B/C
A
B/C
B
B
B
B
A/B
A/B
A
A
A
B
B
A
B
B
B
B
A
B
A
A
B
A
A
B
B
B
A
A
A
A
140 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE B.?Continued.
Specimen
number
ALHA77002
ALHA77117f
ALHA77127f
ALHA77218f
ALHA77254
ALHA77267f
ALHA78142*
ALHA81017
ALHA81018
ALHA81023
ALHA81153
ALHA81198
ALH 82104
ALH 82107
ALH 82117
ALH 82137
EETA79009
PCA 82504
PCA 82505
PCA 82510
PCA 82513
PCA 82519
RKPA79013
RKPA 80209
RKPA 80228
RKPA80268
TIL 82400
ALHA76001
ALHA76003
ALHA76007
ALHA76009
ALHA77001
ALHA77008f
ALHA77019t
ALHA77026f
ALHA77027f
ALHA77089t
ALHA77150
ALHA77155
ALHA77l59f
ALHA77162f
ALHA77180
ALHA77198f
ALHA77231
ALHA77251f
ALHA77261
ALHA77269
ALHA77270
ALHA77272
ALHA77273
ALHA77277
ALHA77280
ALHA77281
ALHA77282
ALHA77284
ALHA77292
ALHA77293t
Weight
(g)
235
21
4
45
246
104
32
1434
2237
418
4
0.9
399
9
4
11
140
3094
3086
254
239
125
11
10
11
3
221
20151
10495
79
3950
252
93
60
20
4
8
58
305
17
29
191
7
9270
69
412
1045
589
674
492
143
3226
1231
4127
376
200
110
Class
and
type
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L5
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
Degree of
weathering
B
A/B
B
A
A/B
A
B
B
B
B
B/C
A
B/C
B
B
B
A/B
B
A
A/B
B
B/C
C
cB/C
A/B
A
A
B
B
B
A
B/C
B/C
B/C
B
C
A/B
A/B
A
C
B
A/B
B
B
B
A/B
B/C
B
A/B
B
B
B
A/B
B
B
fracturing
A/B
A
A
B
A/B
A
A
A/B
A
B
A
B
B
B
A
A
A
B
B
B
B
B
A
A
A
B
B
B
A
A
A/B
B
A
B
B
B
A
B/C
B
B
B
A
Specimen
number
ALHA77296
ALHA77297
ALHA77301f
ALHA77305
ALHA78003
ALHA78039
ALHA78042
ALHA78043
ALHA78045
ALHA78048
ALHA78050
ALHA78055+
ALHA78059+
ALHA78074
ALHA78078
ALHA78101
ALHA781O3
ALHA78104
ALHA78105
ALHA78106
ALHA78112
ALHA78114
ALHA78125*
ALHA78126
ALHA78127
ALHA78130
ALHA78131
ALHA78156
ALHA78171+
ALHA78251
ALHA79007
ALHA79018
ALHA79027
ALHA79033
ALHA79043
ALHA79052
ALHA80101
ALHA8O1O3
ALHA80105
ALHA80107
ALHA8O1O8
ALHA80110
ALHA80112
ALHA8O113
ALHA80114
ALHA80115
ALHA80116
ALHA80117
ALHA80119
ALHA80120
ALHA80125
ALHA81016
ALHA81026
ALHA81027
ALHA81028
ALHA81029
ALHA81099
ALHA81106
ALHA81107
Weight
(g)
963
952
55
6444
125
299
214
680
39
191
1045
14
9
200
290
121
590
672
942
465
2485
808
19
607
195
2733
269
9
23
1312
142
121
133
281
62
23
8725
536
445
178
125
168
331
313
233
306
191
89
34
60
139
3850
516
3835
80
153
152
48
140
Class
and
type
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
Degree of
weathering
A/B
A
A
B/C
C
B
B
B
B/C
A/B
B
B
B
B
A/B
B
B
B
A/B
B
B/C
B
B
B/C
B/C
B/C
B
B
A/B
B/C
B
B
C
B/C
B
B
B
B
B
B
B
B
B
B
B/C
B
B
B
B/C
B
B
C
B
C
A/B
B
B
fracturing
A
B
B
B
B
A
B
B
B
B
B
A
B
A
A
A
B
B
B
B
B
B
A
A
B
A/B
A
A
B
B
B
A
B
B
B
B
B
B/C
B
A
B
A
B
B
B
A
A
A/B
B
A
A
B
A
NUMBER 28 141
TABLE B.?Continued.
Specimen
number
ALHA81122
ALHA81131
ALHA81150
ALHA81159
ALHA81167
ALHA81172
ALHA81181
ALHA81203
ALHA81205
ALHA81217
ALHA81221
ALHA81235
ALHA81247
ALHA81257
ALHA81262
ALHA81266
ALHA81278
ALHA81282
ALHA81289
ALHA81304
ALHA81307
ALHA81311
ALH 82105
ALH 82111
ALH 82118
ALH 82121
ALH 82123
ALH 82125
ALH 82139
ALH 82140
ALH 82142
ALH 83101
BTNA78001
BTNA78002
EETA79003
EETA79010
EET 82605
EET 82606
EET 82607
EET 82612
EET 83202
EET 83205
EET 83206
EET 83209
EET 83210
EET 83214
EET 83237
META78002
META78003
META78005
META78028
PCA 82503
Weight
(g)
21
13
2
10
59
33
15
4
3
5
9
7
104
29
55
12
1
31
4
42
57
0.9
363
63
111
2
111
178
0.2
0.3
20
639
161
4301
436
287
625
982
165
32
1213
471
462
520
426
1398
883
542
1726
172
20657
8308
Class
and
type
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
US
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
US
US
US
US
US
US
US
US
usus
usus
usus
usus
us
Degree of
weathering
B
A/B
C
B/C
B/C
C
B
C
B
C
C
C
A/B
B
A/B
A/B
B
A/B
A
A/B
B
B
A/B
A/B
A/B
A
B
C
B
C
C
A
B
B
B
B
B
B
B/C
A
A/B
A/B
B
B/C
A/B
B
B
B
B
B
B
A
fracturing
B
B
A
A
B
B
A
A
A
B/C
A/B
B
B
A
B
B
A
A
A
B
B/C
A
A
A
B
B
A
B
A
A
B/C
A
B
A
B
C
A
B
A
A
B
B
A
A
B
A
A/B
A
B
B
B
B
Specimen
number
PCA 82508
PCA 82509
PCA 82525
PCA 82528
RKPA78001
RKPA78003
RKPA79001
RKPA79002
RKPA80202
RKPA80215
RKPA80219
RKPA 80225
RKPA80252
RKPA80261
RKPA 80264
TIL 82401
ALHA78015*
ALHA76004
ALHA77278
ALHA78138+
ALHA79003
ALHA81251
TIL 82408
ALHA77060f
ALHA78109
ALHA81151
RKPA80234
RKPA 80253
ALHA77041f
ALHA78062
ALHA78063+
ALHA78082+
ALHA78153
ALHA81123
ALHA81185
ALHA81285
BTNA78004
EET 82608
EET 83204
PCA 82507
RKPA80222
RKPA80235
RKPA8O238
RKPA80248
TIL 82402
ALH 84027
Weight
(g)
389
286
40
51
235
1276
3006
204
545
9
21
8
11
62
24
282
35
53
313
11
5
158
80
64
233
5
136
5
17
11
77
24
152
2
65
20
1079
95
377
480
7
261
18
11
476
8
Class
and
type
L6
L6
L6
L6
US
US
US
US
US
US
US
L6
US
US
US
L6
LL(?L)3
LL3
LL3
LL3
LL3
LL3
LL3
LL5
LL5
LL5
LL5
LL5
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL6
LL7(?)
Degree of
weathering
A/B
B
B
B/C
C
C
B
B
B
C
B
C
A/B
B
B
A/B
A
A
B
B
B/C
B
A
A/B
B/C
B
A/B
A
A
A
B/C
B
A/B
C
B
A/B
A
A
B
A/B
A/B
A/B
A/B
B
fracturing
B
A
B
B
B
B
C
B
A
B
A
A
A
A
B
A
A
A
B
B
A/B
A
A
B
A
B
A
A/B
A
A
A
A
A/B
B
B
A
A
A
B
142 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE B.?Continued.
CHONDRITE subtotals: Class and type
C2
C3
C30
C3V
C4
E4
EH4
E5
E6
H3
H4
H4,5
H5
H5.6
H6
H
L3
L3.4
L4
L5
L6
LL(?L)3
LL3
LL5
LL6
LL7(?)
Total:
Class weight (g)
2680
181
810
748
103
31
159
20
819
433
83289
16000
42892
31
30305
33
23
19377
31
7149
12397
154434
35
619
443
3170
8
376220
Specimen ?
number
ALHA81187
ALH 84025
ALHA81005
ALHA78113
ALH 83009
ALH 83015
ALH 84007
ALH 84008
ALH 84011
EET 83235
ALHA77256
ALH 84001
EETA79002
EET 83246
EET 83247
TIL 82410
ALH A81208
ALHA76005
ALHA77302
ALHA78040
ALHA78132
Weight
(g)
40
5
31
299
2
3
706
302
138
255
676
1931
2843
48
22
19
2
317
236
212
656
Class
and
type
A (unique)
A (unique)
Anorthositic
breccia
Au
Au
Au
Au
Au
Au
Basaltic
achon.
Di
Di
Di
Di
Di
Di
Di/M
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Degree of
weathering
B/C
A/B
A/B
A/B
A/B
A/B
A
A/B
A
B
A/B
A/B
B
A/B
B/C
A
C
A
A
A
A
fracturing
ACHC
B
A
A
A
A
A
A/B
A
A/B
B
A
B
B
A/B
B
B
A
A
A
A
)N
Specimen
number
T3RITES
ALHA78158
ALHA78165
ALHA79017
ALHA80102
ALHA81001
ALHA81006
ALHA81007
ALHA81008
ALHA81OO9
ALHA81010
ALHA81011
ALHA81012
ALHA81313
EETA79004
EETA79005
EETA79011
EET 83212
EET 83227
EET 83228
EET 83229
EET 83231
EET 83232
EET 83234
EET 83236
EET 83251
EET 83283
PC A 82501
PCA 82502
RKPA80204
RKPA 80224
Weight
(g)
15
21
310
471
53
255
164
44
229
219
406
37
0.5
390
451
86
402
1973
1206
313
66
211
181
6
261
57
54
890
15
8
Class
and
type
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (anomalous)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu
Eu (polymict)
Eucritic breccia
Eu
Eu(?)
Eu
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu (polymict)
Eu
Eu (polymict)
Eu (polymict)
Eu (unbrecciated)
Eu (unbrecciated)
Eu
Eu (unbrecciated)
Degree of
weathering
A
A
A
A
A
A
A/B
A/B
A
A
A/B
A/B
B
A
B
B
B
B
B
B
B
B
B
B
B
A
A
A
A/B
fracturing
A
A
A
B
B
A/B
A
A/B
A
A
A
A
B
B
B
B
B
B
B
A/C
A/B
B
A
A/B
B
A
A
A
A
NUMBER 28 143
TABLE B.?Continued.
Specimen
number
RKPA 80224
TIL 82403
ALHA78006
EETA79006
EET 82600
ALHA77005
EETA79001
Weight
(8)
8
50
8
716
247
483
7942
Class
and
type
Eu (unbrecciated)
Eu (brecciated)
Ho
Ho
Ho
Sh
Sh
Degree of
weathering
A/B
A
A
B
A
A
A
fracturing
A
A
A
B
B
A
A
Specimen
number
ALHA77257
ALHA78019
ALHA78262
ALHA81101
ALH 82106
ALH 82130
ALH 83014
EET 83225
PCA 82506
RKPA 80239
Weight
(8)
1996
30
26
119
35
45
1
44
5316
6
Class
and
type
Ur
Ur
Ur
Ur
Ur
Ur
Ur
Ur
Ur
Ur
Degree of
weathering
A
B/C
B/C
A/B
B
B
B
B/C
A/B
B
fracturing
B
C
A
B
A
A
A
B
A
B
ACHONDRITE subtotals: Class and type
A (unique)
Anorthositic breccia
Aubrite
Basaltic breccia
Diogenite
Diogenite/Mesos.
Eucrite
Howardite
Shergottite
Ureilite
Total:
Class weight (g)
45
31
1449
255
5540
2
10266
971
8425
7618
34602
Total weight (g): 324743
Specimen
number
ALHA77255
ALHA80104
EET 83230
ILD 83500
ALHA81013
ALHA81014
EET 83245
RKPA80226
ALHA76002
ALHA77250
ALHA77263
ALHA77283
ALHA77289
Weight
(8)
765
882
530
2523
17727
188
59
160
307
10555
1669
10510
2186
Class
and
type
Ataxite (anom)
Ataxite
Ataxite
Ataxite
Hexahedrite
Octahedrite
Octahedrite
Octahedrite
IA
IA
IA
IA
IA
Degree of
weathering fracturing
I
Specimen
number
)NS
ALHA77290
PGPA77006
ALHA78100
DRPA78001
DRPA78002
DRPA78003
DRPA78OO4
DRPA78005
DRPA78006
DRPA78007
DRPA78008
DRPA78009
ALHA78252
Weight
(8)
3784
19068
85
15200
7188
144
134
18600
389
11800
59400
138100
2789
Class
and
type
IA
IA
IIA
IIB
IIB
IIB
IIB
IIB
IIB
IIB
IIB
IIB
IVA
Degree of
weathering fracturing
Specimen
number
ALHA77219
ALHA81O59
ALHA81098
RKPA79015
Weight
(8)
637
540
71
10022
Class
and
type
M
M
M
M
Degree of
weathering
B
C
C
A/B
fracturing
STOI
B
B/C
B/C
A
Specimen
number
r-lRON
RKPA 80229
RKPA80246
RKPA80258
RKPA80263
Total weight (g): 11311
Weight
(8)
14
6
4
17
Class
and
type
M
M
M
M
Degree of
weathering
C
C
B/C
C
fracturing
B/C
C
B
B
144 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE C.?Meteorites tentatively identified as paired specimens from common falls. Pairing criteria are field
relations (t), megascopic physical similarities (v), petrographic and mineral chemical similarities (w),
metallography (x), bulk chemistry (y), and trace element chemistry (z). This list is restricted to paired groups
listed in the Antarctic Meteorite Newsletters and which are assigned pairing confidence levels of over 50% by
Scott (Chapter 13). For a more comprehensive discussion of the pairing problem, and a more inclusive list of
pairings, see Scott (Chapter 13) and Scat (1984)*.
Pair no. Paired specimens Criteria
9
10
11
12
13
14
15
16
17
18
ALH83009, 83015
AUB RITES
EUCRITES
ALHA81009, 81012
ALHA76005, 77302, 78040, 78132, 78158, 78165, 79017, 80102
ALHA81006, 81007, 81008, 81010
EETA79004, 83228
v,w
v,w
v,w
v,w
w
EETA79006, 82600
ALHA78019, 78262
ALH82106, 82130
ALHA81002, 81004
ALH83100, 83102
ALHA77003, 82101
HOWARDITES
UREILITES
C2 CHONDRITES
C30 CHONDRITES
V,W
w
C3V CHONDRITES
ALHA81OO3, 81258 w
EH4 CHONDRITES
ALHA77156,77295 w
E6 CHONDRITES
ALHA81021, 81260 w
"H?" CHONDRITES (Acapulco-like)
ALHA77081,81261,81315 w
H4 CHONDRITES
ALHA77004, 77190, 77191, 77192, 77208, 77223, 77224, 77225, 77226, 77232, t.w
77233
ALHA78193, 78196, 78223 t,x
ALHA81041, 81043, 81044, 81045, 81046, 81047, 81048, 81049, 81050, 81051, w
81052
?Scott, E.R.D. 1984. Pairing of Meteorites Found in Victoria Land, Antarctica. Memoirs of the National
Institute of Polar Research (Japan), special issue, 35:102-125. Tokyo.
NUMBER 28 145
TABLE C.?Continued.
Pair no. Paired specimens Criteria
H5 CHONDRITES
ALHA77014, 77264
ALHA77021,77025,77061,77062,77064,77071, 77074,77086,77088
ALHA77118, 77119,77124
ALHA78209, 78221, 78225, 78227, 78233
ALHA79031,79032
ALHA80127, 80129, 80132
RKPA80217, 80218
RKPA80220, 80223
RKPA 80250, 80251
TIL82412, 82413
TIL82414, 82415
H6 CHONDRITES
MBRA76001,76002
ALHA77144, 77148
ALHA77271, 77288
ALHA78211, 78213, 78215, 78229, 78231
ALHA80122, 80126, 80130
ALHA81O35, 81038, 81103, 81112
RKPA80203, 80206, 80208, 80211, 80213, 80214, 80221, 80231, 80254, 80255,
80265, 80266
EET82610, 82615
PCA82526, 82527
L3 CHONDRITES
ALHA77011, 77015, 77031, 77033, 77034, 77036, 77043, 77047, 77049, 77050,
77052,77115,77140,77160,77163,77164,77165, 77166,77167,77170, 77175,
77178,77185, 77211,77214,77241, 77244,77249, 77260,77303,78013, 78038,
78186, 78188, 78236, 78238,78243, 79001, 79045, 80133, 81025, 81030, 81031,
81032, 81053, 81060, 81061, 81065, 81066, 81069, 81085, 81087, 81121, 81145,
81156, 81162, 81190, 81191, 81214
ALHA77215, 77216, 77217, 77252
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
RKPA80216, 80242
ALHA81017, 81018, 81023
PCA82504, 82505
L4 CHONDRITES
L5 CHONDRITES
L6 CHONDRITES
ALHA77001, 77292, 77293, 77296, 77297
ALHA78043,78045
ALHA78103, 78105
ALHA80101, 80103, 80105, 80107, 80108, 80110, 80112, 80113, 80114, 80115,
80116, 80117, 80119, 80120, 80125
ALHA81027, 81028, 81029
BTNA78001, 78002
RKPA78001, 78003
RKPA79001, 79002, 80202, 80219, 80225, 80252, 80261, 80264
EET82605, 82606
t
t,w
t
t,x
w
w
w
w
w
w
w
w
t
t
t,x
w
t.v.w
t,v,w
w
t,w
v,w
w
v,w
146 SMITHSONIAN CONTRIBUTIONS TO TH E EARTH SCIENCES
TABLE C.?Continued.
Pair no. Paired specimens Criteria
LL3 CHONDRITES
53 ALHA76004,81251 w
LL6 CHONDRITES
54 RKPA80222,80238,80248 w
MESOSIDERITES
55 RKPA79015,80229, 80246,80263 w
56 ALHA81059,81098 w
IRONS
57 ALHA76002,77250,77263,77289,77290 t,x,y,z
58 DRPA78001,78002, 78003, 78004, 78005, 78006, 78007, 78008,78009t t,v,x,y
tSeven additional specimens (DRPA78010-78016), collected at the same time from the same small area,
are believed by all workers to be included in this pairing even though they have not been studied in detail. See
Scott (Chapter 13) and Clarke, R.S., Jr. 1982. The Derrick Peak, Antarctica, Iron Meteorites. Meteoritics,
17:129-134.
. GOVERNMENT PRINTING OFFICE: 1989-181-717/60033