SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES ? NUMBER 15
Sands in the Alboran Sea:
A Model of Input in a
Deep Marine Basin
Daniel Jean Stanley, Gilbert Kelling,
Juan-Antonio Vera, and Harrison Sheng
SMITHSONIAN INSTITUTION PRESS
City of Washington
1975
ABSTRACT
Stanley, Daniel Jean, Gilbert Kelling, Juan-Antonio Vera, and Harrison Sheng.
Sands in the Alboran Sea: A Model of Input in a Deep Marine Basin. Smith-
sonian Contributions to the Earth Sciences, number 15, 51 pages, 23 figures,
8 tables, 1975.?The Alboran Sea, an almost totally land-enclosed, mountain-
bounded (Rif, Betic ranges) basin, lies east of Gilbraltar in the westernmost
Mediterranean. A petrologic study of the sand fraction in river, river mouth,
and beach samples collected on the coast of the Alboran Sea defines the compo-
sition and distribution of the principal light and heavy mineral groups along
its margins. The investigation details 20 mineralogical provinces on the southern
Iberian and northern Moroccan margins and the Strait of Gibraltar sector and
identifies the major source terrains and fluvial and marine point sources of
terrigenous sediment entering the basin.
Significant sample-to-sample changes in the proportion of mineralogical com-
ponents are attributed to marine processes, particularly nearshore currents,
which move sands laterally along the coast and, while so doing, modify the
proportions of light and heavy mineral components. Lateral trends observed
within Moroccan and Spanish mineralogical provinces provide evidence on the
actual sense of nearshore sediment dispersal. Marine transport agents have a
more pronounced effect on the light mineral fraction, while even unstable heavy
mineral species appear to suffer less modification as a result of the transport in
the marine environment. The paths followed by the sands between source ter-
rain and final depositional site in deepwater environments are complex ones.
A comparison of mineral assemblages in coastal sands and in sands in deep-sea
cores shows a provenance from the Serrania de Ronda complex in the Betic
range west of Malaga. After initial deposition on the coast, these river-borne
sediments are transported in a southwestward direction toward Gibraltar and
then eventually are funneled downslope in a southeastward direction toward
the Western Alboran Basin through the Gibraltar Canyon and submarine valley.
In geological terms, the Alboran Sea study can serve as a model for sedimen-
tation in one type of elongate enclosed basin bounded by regions of high relief.
Although the geographic and geologic configuration of the Alboran Sea and
contiguous land conforms to a multisource basin model, the transport paths of
sediment since the late Quaternary have been essentially longitudinal. This
longitudinal input, with filling as a result of currents primarily from the Strait
of Gibraltar sector, is independent of a major delta source and is thus unlike
many elongate, deep-sea basins examined in present oceans and troughs (includ-
ing fiysch) mapped in the ancient rock record.
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded
in the Institution's annual report, Smithsonian Year. SI PRESS NUMBER 5251. SERIES COVER DESIGN:Aerial view of Ulawun Volcano, New Britain.
Library of Congress Cataloging in Publication Data
Stanley, Daniel J.Sands in the Alboran Sea.
(Smithsonian contributions to the earth sciences, no. 15)
Supt. of Docs, no.: SI 1.26:15
1. Sand?Alboran Sea. 2. Sedimentation and deposition. I. Kelling, Gilbert, joint author.II. Vera, Juan-Antonio, joint author. III. Title. IV. Series: Smithsonian Institution. Smith-
sonian contributions to the earth sciences, no. 15.
QE1.S227 no. 15 [GC389] 550'.8s [551.4'62'1] 74-20880
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Contents
Page
Introduction 1
General Considerations 2
Sampling and Methodology 3
Definition of Mineralogic Provinces 9
General 9
Spanish River Samples 12
Iberian Coast 13
Moroccan Margin 19
Strait of Gibraltar Region 23
Alboran Sea 26
Provenance of Sediments on Alboran Sea Margins 27
General 27
Origin of Selected Spanish River Sediments 28
Origin of Spanish Margin Sediments?Light Minerals 28
Origin of Spanish Margin Sediments?Heavy Minerals 29
Origin of Moroccan Margin Sediments?Light Minerals 30
Origin of Moroccan Margin Sediments?Heavy Minerals 31
Mineralogical Modification by Coastal Processes 32
Dispersal of Marginal Sands to the Western Alboran Basin 38
Summary 46
Appendix: Brief Summary of the Betic Cordillera Source Terrains 47
Literature Cited 49
Sands in the Alboran Sea:
A Model of Input in a
Deep Marine Basin
Daniel Jean Stanley, Gilbert Kelling,
Juan-Antonio Vera, and Harrison Sheng
Introduction
This investigation, an outgrowth of sedimento-
logical and oceanographic surveys of the Alboran
Sea between Morocco and Spain, summarizes the
results of a mineralogic analysis of coastal samples
collected along the southern Spanish margin and
the northern coast of Morocco in the westernmost
Mediterranean Sea. The primary purpose of the
study was to identify the principal source terrains
of the sediments derived from the adjacent moun-
tainous sectors into this almost totally enclosed sea
(Figure 1). To date, little is known concerning the
mineralogy and distribution of sediments along
the margins of the Alboran Sea. This study is in-
tended to define the major point sources of terrige-
nous sands entering the Western Alboran Sea from
the Strait of Gibraltar and the Moroccan and Span-
ish sectors. In turn, this involves both determina-
tion of the predominant direction of sediment
movement along the coast and the identification of
the major transport paths from the coast seaward
into the deeper regions of the Western Alboran
Sea. The relative efficacy of heavy and light min-
Daniel Jean Stanley and Harrison Sheng, Division of Sedi-
mentology, Smithsonian Institution, Washington, D.C. 20560.
Gilbert Kelling, Department of Geology and Oceanography,
University of Wales, Swansea, Great Britain. Juan-Antonio
Vera, Departamento de Estratigrafia, Universidad de Granada,
Granada, Spain.
erals in the context of provenance and dispersal
is also investigated.
Another purpose of this study was to better
evaluate the factors influencing provenance and
dispersal in analogous ancient marine basins whose
sediments are preserved in the fossil record. The
similarity between the sediments in the Western
Alboran Basin plain, a flat, deep (just over 1500
m) oval (24 by 37 km) basin, and some ancient
flysch deposits has been noted elsewhere (Stanley
et al., 1970; Stanley and Unrug, 1972). The min-
eralogical study in the Alboran Sea is of potential
value geologically because it enables the sand-sized
sediments, materials initially transported by rivers
to the coast and subsequently modified by marine
coastal agents, to be traced downslope to deeper
environments in an almost completely enclosed
system. Thus, the Alboran case can serve as a
model for a type of multisource dispersal system
possibly applicable to some ancient basins, includ-
ing flysch troughs (Stanley and Unrug, 1972, figs.
37-40).
ACKNOWLEDGMENTS.?We are indebted to Mr. N.
Cano and Mr. F. de Castillejo, both of the Spanish
Institute of Oceanography, Malaga, and to Profes-
sor D. V. Ager and Dr. N. Fry, University of Wales,
Swansea, for their help in the collection of samples
along the Spanish margin. Particular thanks are
expressed to Mr. A. Giiven, University of Wales,
Swansea, for assistance with the mineralogic analy-
30'
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
4* 30' 3*
ALBORAN BE
CORE LOCATIONS
FIGURE 1.?Chart showing core localities and major geographic features in the Alboran Sea and
Strait of Gibraltar region. Details on cores available in Huang and Stanley (1972). (Geographic
names cited in the text are shown here and on Figures 2 and 3.)
sis, and to Professor J. F. Fontbote, University of
Granada, for providing us with valuable regional
data, maps, and references, and for his review of
the text. The 3.5 kHz subbottom records were col-
lected on 1972 cruises of the USNS Lynch, and
aerial photographs were supplied by the Defense
Intelligence Agency, Washington, D. C. Dr. A.
Maldonado, University of Barcelona, also reviewed
the manuscript.
Funds for this study, part of the Mediterranean
Basin Project, including travel to Spain and Mo-
rocco and the collecting and processing of samples,
were provided to one of us (D. J. S.) by Smithso-
nian Research Foundation grants (FY 1971) 472350
and (FY 1972) 430035. Support was also provided
(G. K.) by the United Kingdom Natural Eviron-
ment Research Council and the Royal Society of
London.
General Considerations
The southern flank of the Betic Cordillera bor-
dering the southern Spanish margin (elevations to
over 3000 m) and the northern flank of the Rif
(maximum elevations in excess of 2000 m) are cut
by numerous seasonally active rivers (or oueds)
NUMBER 15
and torrents capable of carrying material of mud
to boulder size directly to the coast. The study was
planned so that sand-size material collected in
these rivers and along the coast of both margins
eventually could be compared to sand collected
offshore in cores from the deeper Alboran Sea.
A review of the major geologic units that pro-
vide sedimentary material is necessary to properly
interpret the provenance of coastal samples. The
major stratigraphic-structural units mapped in the
Betic Cordillera and the Rif chains are depicted in
Figures 2 and 3. Each of these units can be distin-
guished on the basis of gross lithology and miner-
alogy, which permits the composition of river
mouth and coastal sands to be identified with out-
crops of specific units.
The major stratotectonic units comprising the
Betic Cordillera source terrains (Figure 2) are
defined on the basis of investigations of many
workers. Among the more recently published re-
gional studies pertinent to the Iberian margin, we
can cite the following: Kockel (1963), Mollat
(1965), Diirr (1967), Hernandez-Pacheco (1967),
Boulin (1968), Durand-Delga (1968), Hoppe
(1968), Aldaya (1969), Egeler and Simon (1969),
Jacquin (1970), Aldaya and Vera (1971), Font-
bote (1971), Gonzalez-Donoso et al. (1971), Orozco
(1971), Puga (1971), and Loomis (1972). A sum-
mary of the major units providing sediments to the
Spanish coast is presented in the Appendix.
The general geology of the Moroccan margin
illustrated in Figure 3 is based on the published
maps of the Service G^ologique du Maroc, together
with more detailed discussions by Fallot (1937),
Fallot and Marin (1952), Milliard (1959), and
Durand-Delga and Kornprobst (1963).
Sampling and Methodology
Samples on the Iberian margin were collected
at the mouths of major rivers and on beaches be-
tween the Strait of Gibraltar and Adra (i.e., from
3? to 5?37'W longitude) in the region popularly
called the Costa del Sol. Sampling here is facili-
tated by the presence of a major coastal road
(Spanish highway no. 340) that follows the shore-
line along much of this area. The spacing between
Spanish coastal samples ranges from 2 to 6 km;
the average distance between stations is 3 to 4 km
(position given in Table 1; see also Figure 2). The
major rivers, principal fluvial drainage basins, and
sample localities are shown in Figures 2 and 4. The
name of each drainage basin is derived from the
principal river. Several of the smaller morpho-
logical basins without major rivers bear no name.
It is useful to compare the mineralogy of river-
borne material and that of sediment at the same
river mouths along the coast. In this respect, six
sample stations were occupied between the Calena
(near Marbella) and the Genal-Guadiaro rivers
west of Marbella. The rivers sampled include, from
east to west, the Calena, Guadaiza, Guadalmansa,
Padron, Enmedia, and Genal-Guadiaro (rivers be-
tween 7 and 4 on Figure 4); sampling stations were
made close to where Highway 340 crosses the
rivers. Two samples were collected about 100 m
apart at each of the six stations. The results are
listed in Tables 4 and 5 and illustrated in Figures
5 and 6.
In similar fashion, samples were collected in the
major rivers and river mouths and along the coast
on the Moroccan margin between Cap Spartel and
Al Hoceima (also known as Al Hucemas) from
4? 10' to 5?50'W longitude (Figure 3, Table 2).
However, the coastal area of northern Morocco
remains considerably less accessible than that of
Spain, and as a consequence the sampling is neither
as regular or as complete, although we believe that
it provides representative data.
The grain size of the 113 Spanish and 38 Moroc-
can river and littoral samples examined varies
from muddy sand to granule grade. Consequently,
only the 0.062 to 0.25 mm fraction (very fine to
fine sand) was selected for petrologic study in
order to minimize size-sorting problems and thus
to provide a better evaluation of regional changes
in mineralogy.
It is in this fraction that the heavy minerals,
sensitive indicators of provenance, are generally
concentrated. The granules and pebbles, common
in most of the samples, include a wide variety of
metamorphic as well as carbonate rock types; the
petrology of these coarse fractions is not examined
in the present study.
Heavy minerals were separated by the standard
heavy liquid method and their percent (by weight)
calculated. Light minerals were mounted on glass
slides, ground and stained according to the method
of Hayes and Klugman (1959), in order to identify
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
NUMBER 15
FIGURE 2.?Geological map of the southern coast of Spain
between Adra and the Strait of Gibraltar showing the major
tectonic-stratigraphic (including lithologic) units in the
Betic Cordillera. The map is based on geologic maps pub-
lished by the Instituto Geol6gico y Minero de Espana at a
scale of 1:200,000 and modified by J. M. Fontbote and J.-A.
Vera. Lithology of the different units are described in the
Appendix. Coastal and river sample localities are also shown
(see Table 1). [Broken line = Boundary between the major
Atlantic and Mediterranean drainage systems. Dotted line =
Boundary delineating the principal Mediterranean fluvial
basins in the study area; the basins are named after the
major rivers flowing southward toward the Mediterranean
Sea; those basins with rivers and torrents of only minor im-
portance remain unnamed. Internal Zones: 1, Peridotite
(ultrabasic) Complex; 2, Nevado-Filabride Complex, meta-
morphic rocks; (3-7, Alpujarride Complex, eastern sector);
3, Paleozoic, with prevailing dolomite and marble; 4, Paleo-
zoic, with prevailing micaschist and quartzite; 5, Permian-
Werfenian, phyllite and quartzite; 6, Middle and Upper
Triassic, limestone and/or dolomite; 7, Permo-Trias, undif-
ferentiated (5) and (6); 8, Malaguide Complex, Pre-Cambrian
(?), miscaschist and gneiss; 9, Sierra Blanca Unit; 10, Casares
Unit (Alpujarride Complex, western sector); 11, Las Nieves
Unit; 12, Malaguide Complex, Paleozoic (also includes,
locally, a thin Mesozoic-Tertiary cover). External Zones: 13,
Triassic ("Germanic fades"); 14, Jurassic, limestone and
marly limestone; 15, Cretaceous-Paleogene-lower Miocene,
mainly marl and marly limestone; also sandstone and lime-
stone. Posl-Orogenic Sequences: 16, Neogene-Quaternary,
mainly detrital sedimentary rocks and sediments.]
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 1.?Sediment sample localities on the southern Mediterranean coast of
Spain and vicinity of the Strait of Gibraltar, from west to east (see Figure 2)
Sample
Number
(On Fig. 2)
Dir ctio
General Description of Sample Locality on Southern Spanish Coast and Gibraltar (October 1970)
Dominant Beach
Lithology
Pebble
Sandy
Pebbly
Sand
Pebble
Pebbly
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Sandy
Pebbly
Pebbly
s and larger
pebbly
s and larger
sand
sand
sand
sand
sand
sand
sand
cobble (>10 cm)
sand
sand
Pebbly sand
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Sand
Sand
Sand
Shelly
Shelly
Shelly
Sand
Pebbly
Shelly
Sand
Sand
Pebbly
Pebbly
Pebbly
Pebbly
Sandy
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Sandy
Sand
Sandy
Pebble
Pebbly
Pebbly
sand
sand
sand
sand
sand
pebbly sand
pebbly sand
sand
sand
pebbly sand
sand
sand
sand
sand
pebbly
sand
sand
sand
sand
sand
pebbly
pebbly
s and larger
Pebbly and coarser
Pebbly
Pebbly
Pebbly
Sandy
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Pebbly
Sandy
Sandy
Sandy ;
Pebbly
sand
and coarser
and coarser
pebbly
and coarser
and coarser
and coarser
and coarser
and coarser
and coarser
pebbly
pebbly
pebbly
sand
Pebbly sand
S 1
S 2
S 7
S 8
S 9
S10
Sll
SI 2
SI 3
SI 4
S15
S16
G 4
G 2
G 5
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
S29
S30
S31
S32
S33
S34
S35
S36
S37
S38
S39
S40
S41
S42
S43
S44
S45
S46
S47
S48
S49
S50
S51
S52
S53
S54
S55
S56
S57
S58
S59
S60
S61
S62
S63
S64
S65
S66
S67
S68
S69
S70
S71
S72
S73
S74
S76
S78
S79
S80
S81
S82
S83
S84
Rocky beach east of Tarifa along rugged coastline; rocky offshore
Beach at base of mountainous coast near Arroyo Vifias about 4 km east o
Tarifa; rocky offshore
Coast near Punta del Carnero (a mountainous cape), near old destroyed
jetty
Ensenada de Getares, near mouth of Arroyo del Lobo, small delta
Just north of Punta de San Garcia, Algeciras Bay, same latitude
as Europa Point
Algeciras, south of jettys
Beach at base of hill, just north of Algeciras
Mouth of Palmones River, Algeciras Bay
Beach between Palmones and Guadarranque rivers, Algeciras Bay
Mouth of Guadarranque River, Algeciras Bay
Northern Algeciras Bay, near large petroleum refinery; near Arroyo de
los Lecheros
Northern Algeciras Bay near El Campamento; low coastal plain
Northeast Algeciras Bay near La Lfnea; low coastal plain
Camp Bay, southwest side of Gibraltar, northwest of Europa Point
Beach from Sandy Bay, east side of Gibraltar
Dune sand (Pleistocene?), just south of Catalan Bay, east side of
Gibraltar
Beach at southern end of Catalan Village Bay, east side of Gibraltar
Eastern Beach, east side of Gibraltar, south of La Lfnea
North of La Llnea, near Torre de Senales; dunes along coast
Beach at base of hills, Punta Carbonera
Dunes along coast just south, Guadiaro River
Mouth of Guadiaro River
Beach north of Guadiaro River; low deltaic coastal plain
Playa del Negro, north of Punta Chullera
Beach near mouth of Rio de Manilva; coastal plain below hills
West of Estepona, near Arroyo de Guadalobon
Estepona, near port
Narrow rocky beach west of Rfo del Padr6n
Mouth of Rfo del Padron; small water bodies present
Near Rfo del Castor; semi-desert physiography
San Pedro de Alcantara, east of Rio Guadalmansa
Arroyo de Dos Hermanas, west of Rio Guadalmina
Mouth of Rfo Guadalmina; river sediments form delta
Beach near Arroyo del Chopo
Beach near mouth of Rfo Verde, west of Marbella
On Ensenada de Marbella, west of Marbella; near Arroyo de Nagueles
Beach east of Marbella, near Rfo Real
Beach near Chalets Costa Bella
Beach near Punta Ladrones
Beach near Torre de Calahonda
Beach at Ensenada de Cala del Moral
Cabo de Calaburra, west of Rfo de Fuengirola
Beach at Fuengirola, west of Arroyo Real
Beach near Arroyo de Presas, Torre Blanca del Sol
Beach near Torre Benalmadena
Arroyo de la Miel, west of Torremolinos
Beach at Torremolinos, Playa de la Carihuela
Beach west of Guadalhorce River, on delta
Beach east of Guadalhorce River, on delta; west of Malaga (industrial
zone)
Beach west of Malaga, west of Guadalmedina River
Mouth of Guadalmedina River, Malaga
East of Malaga, Malaga Bay
Near El Palo, Malaga Bay, at mouth of dry torrent
Beach west of La Victoria, Malaga Bay
Beach near Cala del Moral, Malaga Bay
Beach at La Victoria, Malaga Bay
Beach near Estacion Benagalbin
Beach off plain, east of Torre Moya
Beach, west of Rio Velez
Mouth of Rfo Velez, on small delta west of Torre del Mar
Torre del Mar, east of Rfo Velez
Beach east of Torre del Mar and west of La Caleta
Narrow beach east of Rfo de Algarrobo
Beach west of Morche
Beach on delta, west of Rio de Torrox
Mouth of Rfo de Torrox, on small delta
Beach east of Rfo de Torrox
Beach east of Punta de Torrox
Mouth of Rfo Higuerdn, on small delta
Beach east of Nerja, south of Maro
Beach off rocky high terrain, east of Maro
Beach on rocky point west of La Herradura
Beach at La Herradura
Beach east of Punta de la Mona and west of Rio Verde
Beach east of Rfo Verde and Almunecar
Small river south of Taramay
Beach west of Salobrena and La Caleta
Beach on delta of Rio Guadalfeo, south of Salobrena
Beach at mouth of Rio Guadalfeo
Beach at mouth of Rio Guadalfeo, on delta
Beach on eastern part of Rfo Guadalfeo delta
130?
105?
125
95?
115?
130?
160?
150?
85?
110?
180?
180?
180?
170?
170?
175?
175?
130?
130?
130?
130?
160?
140?
130?
120?
140?
140?
150?
150?
125?
180?
190?
160?
175?
170?
170?
175?
120?
120?
110?
115?
150?
210?
190?
180?
170?
165?
190?
190?
200?
190?
190?
200?
220?
250?
230?
220?
220?
200?
210?
220?
240?
250?
150?
140?
140?
160?
155?
170?
165?
170?
NUMBER 15
TABLE 1.? (Continued)
Sample Locality Spanish Coast and Gibraltar
Direction
(October 1970) Lithology
S 85
S 86
S 87
S 88
S 89
S 90
S 91
S 93
S 94
S 95
S 96
S 97
S 98
S 99
SI 00
S101
S102
?103
S104
H at the Port of Motril
on Cabo Sacratif, near light house
on Cabo Sacratif, off flat plain
at Calahonda, at mouth of small river
east of Calahonda along rough coastlin
at Castell de Ferro, near Rambla Gualc
east of Castell de Ferro, along rough
i beach east of La Hamola
at La Rabita, at mouth of small river
beach east of El Pozuelo
;jes t of La Alcazaba
at Cainos Bajos
rfest of Adra, near small port
east of Adra
on delta, west of Rio Chico (R. Adra)
outh of Rfo Chico (R. Adra), on delta
145
155?
160?
180?
140?
125?
170?
120?
150?
120?
115?
150?
140?
130?
135?
160?
145?
140?
130?
Sandy pebblv
Sand
Sandy pebbly
Pebbly sand
Sandy pebbly
Pebbly and c
Pebbly and c
Pebbly and c
Sandy pebbly
Pebbly sand
Pebbly and c
Pebbly sand
Pebbly sand
Pebbly sand
Sandy pebbly
Pebbly and c
Pebbly sand
Pebbly sand
Sandy pebbly
STRAIT OF GIBRALTAR
TANGER
8
KILOMETERS
FIGURE 3.?Geological map of the northern margin of Morocco showing major stratigraphic
sequences (based on maps by Fallot, 1937; Fallot and Marin, 1952; and others). Coastal and
river sample localities also shown (see Table 2). Note that for clarity, the submarine outcrops
of basic/ultrabasic rocks around Cabo Negro deduced by Milliard (1959) and others are also
shown as occupying the peninsula.
GUADALQUIVIR BASIN
MEDITERRANEAN SEA
ALGECIRAS
1.
2.
3.
4.
5.
6.
7.
R. de las Canas
R. Guadarranque
R. Hozgarganta
R. Guadiaro
R. Genal
R. Guadalevin
R. Verde
8.
9.
10.
11.
12.
13.
14.
R. Fuengirola
R. Grande
R. Turon
R. Guadalhorce
R. de las Campanillas
R. Guadalmedina
R. Velez
15.
16.
17.
18.
19.
20.
21.
R. Algarrobo
R. Torrox
R. Verde
R. Guadalfeo
R. Izbor
R. de Lanjaron
R. Poqeria
22.
23.
24.
25.
26.
27.
28.
R.
R.
R.
R.
R.
R.
R.
Yator
Ujijar
Bayarcal
Adra
Chi co
Andarax
Nacimento
FIGURE 4.?Map showing distribution of rivers on the southern Iberian margin. (Black triangles
denote stations occupied by the Centro de Estudios Hidrograficos (1966); river flow data listed
in Table 3.)
and distinguish different types of feldspar grains.
A total of about 300 light mineral grains and 200
transparent, heavy mineral grains were counted
and relative percentages calculated. Opaque min-
erals were also counted. Mica flakes occur in both
heavy and light mineral concentrations; in this
study, the micas have been assigned for quantita-
tive purposes to the light mineral fraction.
A total of 23 mineral species were identified in
the heavy fractions, many of them occurring in
trace amounts or in only a few samples. Only the
dozen or so nonopaque mineral species which ap-
pear with reasonable consistency in a large number
of samples have been distinguished and plotted
in Figures 7 and 9. Moreover, for purposes of quan-
titative comparison the related mineral species
have been grouped together in a manner reflect-
ing their provenance characteristics and assigned
to 10 categories (including opaque minerals and
"others"). Similarly, light minerals were assigned
to eight groups, together with two ratios (total
quartz to total feldspar, and igneous quartz to
metamorphic quartz). Certain categories of light
minerals, notable rock fragments and glauconite,
although locally common, are not sufficiently wide-
spread in their occurrence to justify the erection
of additional compositional groups.
Inspection of the compositional data from indi-
vidual samples (Figures 7 to 10) revealed signifi-
cant geographic variations, which enabled the
Spanish and Moroccan samples to be assigned to
provinces (i.e., regions characterized by sands of
comparable composition). In most cases, the prov-
ince boundaries can be drawn solely on the basis of
marked changes in the relative abundance of sev-
eral of the heavy or light mineral groups. How-
ever, in a few instances, there is a more gradual
change in composition, and the province boundary
is then more arbitrarily defined, usually on the
basis of some geographic feature such as a major
river or prominent cape.
This original compositional data was subse-
quently compared with data previously obtained
from deep-sea samples in the Strait of Gibraltar
NUMBER 15
TABLE 2.?Sediment sample localities on the north-
ern Mediterranean coast of Morocco, from west to
east (see Figure 3)
SAMPLE
NUMBER MOROCCAN SAMPLE LOCALITY
M 8 Mouth of Oued el Herradou, approx. 4 km west of Tangier town
M 1 Beach at mouth of Oued Chall, just east of Tangier
M 2 Oued approx. 4 km south of Cap Malabata on Route S7O4, about
2 km from coast
M 3 Beach at mouth of Oued Sfisifa, near Pointe Kankouch
M 4 Oued el Lgam, along Route S704, near Pointe Bou Maaza
M 5 Oued el Razor, at Ksar-es-Seghir, along Route S704
M 6 Beach at Benzou, about 10 km west of Ceuta
M 7 Beach about 6 km southwest of Ceuta, near junction of Routes
P28 and 8303
M 20 Small oued at Riffien, north of Oued Negron, Route P28
M 21 Mouth of Oued Negron, north of Restinga, Route P28
M 22 Dune sand in Restinga-Smir area, 16 km south of Ceuta,
Route P28
M 19 Near mouth of Oued Smir, along Route P28, 3 km north of M'Diq
M 23 Oued ed Siador, along Route P28, 3 km south of Cabo Negro
M 9 Rio Martin, just south of Tetouan
M 18 Oued just north of Cap Mazari, approx. 13 km southeast of
Tetouan, Route S608
M 17 Oued Emsa, south of Cap Mazari and west of Cap Timousourga,
Route S608
M 16 Oued on southeast flank of Cap Akaili, Route S608
M 15 Oued northwest (approx. 4 km) of Cap Menkal, Route S608
M 14 Oued Laou, near Es Sebt, Route S608
M 13 Oued Akheron, near El Arba, Route S608
M 12 Mouth of Oued Targa, at Targa, Route S608
M 11 Oued, near Asenli, approx. 5 km southeast of Targa, Route S608
M 10 Junction of Oued el Had and Oued Bouchia at town of Bou-Hamed,
Route S608
M 24 Mouth of Oued Ouringa, approx. 1 km west of Pointe des Pecheurs
M 25 Mouth of small Oued, Pointe des Pecheurs
M 28 Junction of Oued Mestasa and Oued Bi Chetouan, near village
of Mastassa
M 27 Mouth of Oued 0.5 km east of Cala Iris beach
M 26 Mouth of Oued Bou Frah, near Torres-de-Alcala
M 29 Oued Bades, north of Arba-Snada, on Route S610
M 30 Oued approx. 4 km east of El Hader Rouadi, on Route S610
M 31 Oued Merelia, west of Ait-Kamara, on Route S610
M 35 Mouth of Oued Boussikour, approx. 12 km west of Al Hoceima
M 36 Oued east of Pointe Boussikour, approx. 7 km west of
Al Hoceima
M 37 Small Oued approx. 3 km west of Al Hoceima, on Piste 8506
M 38 Beach below Mohammed V Hotel, Al Hoceima (no Oued)
M 34 Beach at Plage Espalmadero, 4.5 km southeast of Al Hoceima
on Route P39A
M 33 Oued Rhis, approx. 12 km southeast of Al Hoceima, on Route P39
M 32 Oued Nekor, approx. 6 km south of Al Hoceima Bay, on Piste S604
TABLE 3.?River flow data collected on the south-
ern Iberian margin (see Figure 4); sample stations
occupied by the Centro de Estudios Hidrogrdficos
(1966)
RIVER
Guadarranque
Guadiaro
Guadalhorce
Guadalmina
Velez
Algarrobo
Guadalfeo
Adra
SAMPLE STATION
CODE (FIG. 4)
A
B
C
D
E
F
G
H,I,J,K
LITERS/SECOND
17.2
19.4
4.73
8.17
5.65
5.49
3.47
2.13
(average)
MONTHS DRY
July, August
July, August
None
July, August
July, August
(almost dry)
June, July,
August
August
July, August
(almost dry)
region and the western Alboran Basin (Kelling
and Stanley, 1972; Huang and Stanley, 1972), reas-
signed as far as possible to the same mineralogic
groupings (Table 8).
A survey of selected aerial photographs, collected
at altitudes of from 5,000 to 14,000 m, was made
in order to provide information on short- and
long-term coastal sedimentation and littoral drift
patterns on both the Moroccan and Spanish mar-
gins. Predominant near-shore current drift paths
(cf., Figures 12 to 14) are defined on the basis of
beach-groin patterns, delta shapes and river out-
flow, and suspended sediment lobe distribution.
Particular attention has also been paid to pub-
lished data of river flow and rain data (cf., Figures
4 and 20) on the Spanish margin (Centro de
Estudios Hidrograficos, 1966, 1970) and to offshore
surface drift data in the Alboran Sea (Gaibar-
Puertas, 1967; Lanoix, 1974).
Definition of Mineralogic Provinces
GENERAL
Both heavy and light minerals are utilized in
denning the various mineralogic provinces in the
study area. The light mineral fraction in the very
fine to fine sand-size range accounts for the bulk
(usually 90 to 95% or more) of the total material
present. In most instances, approximately 2 to 11
samples comprise the regional mean.
Thirteen zones have been established on the
southern Iberian margin between Tarifa and Adra
and seven on the Moroccan coast from Cap Spartel
to the mouth of the Oued Nekor. In addition,
assemblages already established for the sublittoral
portions of the Strait of Gibraltar Submarine
Valley and the Western Alboran Basin (Kelling
and Stanley, 1972a, b; Huang and Stanley, 1972)
were reexamined in the light of this new data.
The abundance of individual light and heavy
mineral species may differ appreciably from sample
to sample (see Figures 7 to 10), but it is seldom
feasible to utilize the presence or absence of specific
minerals to define geographic associations. We have
found it more useful to assign the dominant heavy
mineral species to ten groups (cf., Tables 5, 7, and
8), which are defined primarily on the basis of prob-
able provenance. Seven light mineral groups are
recognized in this study. In addition, two compo-
sitional ratios (igneous quartz/metamorphic
quartz and total quartz /feldspar) help define
mineralogic provinces.
10 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
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12 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 4.?Mineral provinces for Spanish coastal and river samples (see Figures
5 to 8)
Province
Designation Geographic Limits of Province Sample Numbers
COASTAL SAMPLES
larifa to Punta San Garcfa (Algeciras
Bay)
Punta San Garcfa (north side) to Rfo
Guadarranque mouth
Rfo Guadarranque mouth to Europa Point,
Gibraltar
Europa Point, Gibraltar (east side) to
La Lfnea (eastern beach)
La Lfnea to Guadiaro River mouth
Guadiaro River mouth to Rfo Verde mouth
(Marbella)
Rfo Verde mouth to Torrente Calaburra
Torrente Calaburra to Rio Guadalhorce
mouth (Malaga)
Rfo Guadalhorce mouth to Rfo Velez mouth
Rfo Velez mouth to Rfo Higueron mouth
(Nerja)
Rfo Higuer6n mouth to Rfo Guadalfeo delta
Rfo Guadalfeo delta to Calahonda
Calahonda to Adra
SI,2,6,
S9-13
S14-16,
Gl,2,3,
S20-23
S24-36
S37-43
S44-50
S51-60
S61-70
S71-74,
S82-91,
S94-104
7,8
G4
5; S19
76,78-81
93
No heavy mineral
from sample S6
No heavy mineral
from samples S25,
No heavy mineral
from samples S62,
No heavy mineral
from samples S82,
No heavy mineral
from samples S96.
fractions
fractions
28, 30
fractions
67
fractions
90-93
fractions
101,104
RIVER SAMPLES
I
II
III
IV/V
VI
Rfo de Calena
Rfo Guadaiza
Rfo Guadalmansa
Rfo Padron and Rio Enmedia
Rfo Guadiaro-Genal
IA, IB
IIA, IIB
IIIA, IIIB
IVA, IVB, VA, VB
VIA, VIB
Province boundaries were established primarily
on the basis of marked changes in either qualita-
tive or quantitative character of the mineral con-
tent of the samples, and were further denned in
light of geographic factors (presence of major
rivers, promontories and capes, etc.).
SPANISH RIVER SAMPLES
The river samples constitute five associations
which are distinguishable on both heavy and light
mineral components (Figures 5 and 6). These will
be discussed in sequence from west to east.
GUADIARO-GENAL ASSEMBLAGE (VI).?This heavy
mineral suite is characterized by moderate amounts
of orthopyroxene and clinopyroxene, together with
a relatively high proportion of metamorphic group
minerals (mainly andalusite) and opaque grains.
The content of ZTR (zircon, tourmaline, rutile)
is higher than in any other Spanish rivers. The
total quartz abundance also attains its highest
value in this river, while total feldspar is present
in minimal quantities.
ENMEDIA-PADRON ASSEMBLAGE (IV-V).?These
two rivers furnish closely similar, heavy mineral
assemblages which display the highest values of
orthopyroxenes, clinopyroxenes, and amphiboles
encountered in the Spanish rivers and exceeded by
only two coastal samples. Opaque grains and the
ZTR group are deficient. There is a more con-
spicuous difference between the two rivers in terms
of light minerals, the Enmedia being substantially
richer in quartz and poorer in feldspar content
than the Padron.
GUADALMANSA ASSEMBLAGE (III).?This assem-
blage is distinguished from the neighboring rivers
on the basis of its greatly enhanced garnet and
olivine plus spinel. The light mineral assemblage
NUMBER 15 13
is broadly similar to that of the Padron River.
GUADAIZA ASSEMBLAGE (II).?The heavy mineral
assemblage is distinguished by the highest propor-
tions of metamorphic group minerals (mainly
staurolite), olivine and spinel, and contains the
lowest proportions of garnet. The light mineral
assemblage is characterized by a high quartz to
feldspar ratio, together with a greatly increased
content of mica.
Rio DE CALENA ASSEMBLAGE (I).?This assem-
blage is notably deficient in pyroxenes and amphi-
boles but relatively enriched in opaque minerals
and garnet. Carbonate minerals predominate in
the light mineral assemblage, but quartz substan-
tially exceeds feldspars in abundance.
IBERIAN COAST
PROVINCE A.?This province extends from Tarifa
to Punta San Garcia, in the southwest part of
Algeciras Bay (Figures 7 and 8). No major rivers
traverse this rocky coast. The heavy assemblage is
dominated by the opaque minerals, although the
proportion of ZTR minerals reaches its maximum
for the Iberian coastal samples. The percentage
of opaque and ZTR minerals increases eastward,
whereas that of garnet, epidote, and olivine actu-
ally decreases. All other heavy mineral groups are
equally deficient. The total content of quartz is
comparable to values obtained in other samples
from the southern Iberian margin but considerably
lower than the immediately adjacent provinces.
However, the ratio of igneous to metamorphic
quartz is comparable to that measured in the neigh-
boring regions. The total feldspar percentage for
this province readies a maximum for these Iberian
samples, and as a consequence the quartz/felds-
par ratio is minimal.
PROVINCE B.?This province includes samples on
the west side of Algeciras Bay, from Algeciras to
the mouth of the Rio Guadarranque. The major
rivers are the Palmones and Guadarranque. The
heavy assemblage is characterized by a reduced
proportion of opaque minerals and a greatly en-
hanced content of pyroxenes. The opaque minerals
TABLE 5.?Mineralogic composition of Spanish coastal and river samples-
province means (see Figures 5 and 6)
PROVINCE
Opaque Minerals
Zircon + Tourmaline
+ Rutile (ZTK)
Orthopyroxenes
Clinopyroxenes
Amphi boles
Metamorphic Group"
Garnets
Olivine + Spinel
Epidote Croup
Others'
Igneous Quartz5
Metamorphic Quartz4
Total Quartz
Quartz Ratio
Potash Feldspar
Plagioclase
Total Feldspar
Quartz/Feldspar
Ratio
Micas + Chlorite
Carbonates
Others6
NO. OF SAMPLES
79
2
2
0
1
1
5
0
3
2
12
19
31
0
1
56
57
0
0
4
5
A
.9
.3
.5
.5
.9
.0
.0
. 7
. 6
.6
. 1
.7
.8
.61
. 4
.0
.4
.55
.8
.4
.3
/37
B
25.6
1.3
34.2
4.8
5.0
5.1
4.7
3.7
12.5
3. 1
25.2
45.7
70.9
0.55
-
10.0
10.0
7.09
3.9
5. 7
9.2
5/1
C
21.6
1.5
27.8
8. 3
3.2
4.4
12.6
2.3
15.1
3.2
20.6
31.5
52.1
0.65
8.1
22.6
30.7
1.69
0.8
10.7
5.7
4/2
D
19.0
tr.5
38.6
6.5
2.4
4.8
15.6
1.5
9.7
1.6
29.6
33.3
62.9
0.88
0.6
21.2
21.8
2.88
2.7
7.0
5.6
5/4
E
33.9
tr.
18.4
8.9
8.7
5.1
7.3
2.6
11.4
3.3
8.1
41.5
49.6
0.19
1.4
30.1
31.5
1.57
1.1
4.5
13.0
4/1
F
17.1
0.5
26.9
10.3
3.9
2.7
9.7
7.5
16.7
4.7
2.8
31.7
34.5
0.08
2.6
34.1
36.7
0.94
1.3
9.6
17.6
10/2
G
27.0
1.4
20.0
3.2
7.4
3.2
11.5
5.6
14.9
5.8
2.4
28.5
30.9
0.08
1.2
37.9
38.1
0.81
0.8
12.2
17.7
111
H
30.
1.
12.
3.
7.
3.
22.
3.
12.
2.
4.
22.
27.
0.
tr
37.
37.
0.
-
14.
20.
3
3
7
8
5
0
8
1
8
7
2
8
0
18
0
3
72
6
0
7/1
I
42.6
0.6
10.5
0.6
9.4
5.0
9.9
1.2
17.4
2.8
10.9
21.3
32.2
0.51
1.0
43.0
44.0
0.73
1.5
6.9
14.6
10/5
J
30.0
1.0
9.1
5.6
8.3
9.0
11.5
1.1
22.6
1.8
7.8
25.4
33.2
0.30
0.8
28.8
29.6
1.12
5.5
8.1
24.0
8/2
K
29.9
0.9
8.9
1.6
18.0
7.9
6.4
1.0
22.5
1.9
14.2
15.0
29.2
0.94
1.1
38.2
39.3
0.74
11.8
3.5
16.1
9/1
L
39.7
1.1
1.1
0.6
4.1
1.0
40.6
2.0
8.9
0.9
10.8
20.0
30.8
0.54
1.5
29.2
30.7
1.00
1.7
18.5
18.0
7/2
M
43.4
0.8
0.7
0.5
3.2
0.9
38.6
1.0
8.1
2.8
9.7
30.3
40.0
0.32
tr.
28.0
28.4
1.40
1.5
7.9
22.0
8/2
I
46.5
1.7
10.9
5.8
5.8
3.2
13.8
8.7
1.8
1.8
24.5
8.5
2.88
3.0
64.0
2/2
II
20.4
tr.
33.4
4.5
7.1
7.7
0.8
10.1
4.7
0.9
62.0
9.5
6.53
26.5
2.0
2/2
III
11.
0.
32.
13.
7.
2.
16.
12.
2.
1.
60.
15.
4.
12.
3.
0
7
5
6
2
2
1
4
8
5
5
3
54
1
1
2/2
7
0
44
21
13
1
2
6
2
54
24
2
10
11
IV
.5
.7
.2
.1
.6
.1
.8
.7
.3
-
.6
.6
.22
.5
.0
2/2
10
45
19
12
2
2
4
1
1
79
8
9
8
4
V
.8
_
.5
.2
.8
.2
.8
.8
.4
.9
.5
.4
.46
.0
.0
111
VI
28.
2.
30.
5
3
0
12.8
5.
6.
7.
3.
1.
2.
85.
3.
24.
6.
4.
2
9
3
2
1
7
7
5
5
3
1
2/2
2. Mainly Apatite,
3. Simple, unstra:
4. Composite and f
te, Staurolite, Slllimanite, Andalusite and Chiastolite
Sphene, Anatase, Monazite, Corundum and Topaz
5.6.
7.
tr.Mai
Fir
sec
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16 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
NUMBER 15 17
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18 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
decrease northward paralleling the increase of py-
roxenes. The light assemblage comprises the high-
est total quartz, the lowest amounts of feldspar, and
one of the higher proportions of micas encoun-
tered in the southern Iberian coastal samples.
PROVINCE C.?This province extends from north-
ern Algeciras Bay near Arroyo de los Lecheros to
Europa Point on the southern tip of Gibraltar.
There are no major rivers in this region. The
heavy assemblage includes enhanced proportions
of garnet and clinopyroxene and slightly higher
epidote. The southernmost sample (G4) is some-
what anomalous in this group, displaying a con-
siderably increased quantity of opaque and ZTR
minerals and a deficiency of ferromagnesian
minerals. There is a slight decrease in clinopyrox-
enes toward the south, whereas the orthopyroxenes
increase as far as La Linea. The light assemblage
is characterized by the highest proportion of
potash feldspar sampled anywhere on the Iberian
coast. The proportion of total quartz, although less
than adjacent provinces, is still relatively high,
and the igneous to metamorphic quartz ratio is
similar to that of provinces A and B. Mica content
is diminished.
PROVINCE D.?This province lies on the eastern
flank of Gibraltar from Sandy Bay to La Linea.
There are no rivers in this region. The heavy frac-
tion is distinguished by the highest mean value of
orthopyroxene encountered in the coastal samples.
Epidotes show a regular decrease northward as far
as La Linea, and garnet increases northward to a
maximum near the Gibraltar airfield and then de-
clines. Quartz dominates the light mineral assem-
blage with the second highest mean value of Iberi-
an coastal samples measured. Metamorphic quartz
exceeds igneous quartz. The total amount of quartz
decreases rather steadily from this province east-
ward as far as Province H, while the total feldspar
content displays a corresponding increase.
PROVINCE E.?This province extends from north
of La Linea to the mouth of the Guadiaro River,
the only major river in this sector. The heavy
fraction in this province contains somewhat en-
riched opaque minerals, amphiboles, and meta-
morphics, together with diminished amounts of
orthopyroxenes. There is a notable increase in the
proportion of opaques northward, accompanied by
a decrease in clinopyroxenes. The proportion of
quartz with respect to feldspar is diminished, and
the igneous to metamorphic quartz ratio is sub-
stantially reduced compared to the previously
described provinces.
PROVINCE F.?This province extends from north
of the mouth of the Guadiaro River to near the
mouth of the Rio Verde west of Marbella. This
sector includes numerous other rivers, such as the
Manilva, Padron, Guadalmansa, Guadalmina, and
Guadaiza. The heavy assemblage is distinguished
by the highest mean values of clinopyroxene and
olivine with spinel and the lowest values of opaque
minerals. Amphiboles and metamorphic minerals
are somewhat diminished with respect to the ad-
jacent provinces. There is a general increase in
opaque minerals toward the northeast. The high-
est value of olivine in the Iberian coastal samples
occurs at the mouth of Arroyo dos Hermanas
(sample 33). There is an irregular decrease north-
ward in proportion of clinopyroxenes. The decline
in the total quartz content observed in Province E
is continued into Province F and is accompanied
by a corresponding increase in the total amount of
feldspar (largely plagioclase), which in fact slightly
predominates. Curiously, the ratio of igneous to
metamorphic quartz reaches a minimum value in
Provinces F and G.
PROVINCE G.?This province extends from 3 km
west of Marbella to the Torrente Calaburra. Rivers
include the Arroyo de Calena, Rio Real, Arroyo
de Siete Revueltas, and Arroyo de Cala del Moral.
The heavy fraction is distinguished by a slightly
enhanced proportion of opaque and ZTR min-
erals and a decreased amount of pyroxenes. There
is an irregular increase in garnet toward the east.
The light fraction is broadly similar to that in
Province F, but it has a slightly higher proportion
of feldspar to quartz and a higher proportion of
detrital carbonate.
PROVINCE H.?This province extends from the
Rio Fuengirola to the Guadalhorce River, west of
Malaga, the major river in this sector. The heavy
fraction is distinguished by an enhanced propor-
tion of garnet and diminished pyroxene and oli-
vine content. There is an irregular decrease in
metamorphic minerals toward the northeast. The
total quartz reaches a minimal value for the coastal
samples, whereas the total feldspar content is com-
parable to that of Province G. The proportion of
detrital carbonate is again increased.
PROVINCE I.?This province extends from west of
NUMBER 15 19
Malaga to west of the Rio Velez. The Guadalme-
dina is the most important river in this sector.
The heavy fraction is distinguished by high mean
proportions of opaque minerals and epidotes and
decreased amounts of pyroxene (especially clino-
pyroxene) and garnet. Very high values of amphi-
boles are localized at the mouth of the Guadal-
medina River and beach to the southwest (samples
52 and 51). There is an increase in epidote east-
ward toward Estacion Benagalbon. The light as-
semblage has the second highest total feldspar con-
tent and a somewhat enhanced proportion of
igneous quartz.
PROVINCE J.?This province extends from the
mouth of the Rio V^lez to the mouth of the Rio
Higueron. Important rivers include the V?lez,
Algarrobo, Torrox, and Chillar. The heavy frac-
tion includes somewhat enhanced proportions of
clinopyroxene, metamorphic group minerals, and
epidote. There is a slight but regular decrease in
the opaque minerals eastward. There is also a
marked and regular decrease in amphiboles east-
ward from east of the Rio Velez delta, but a not-
able increase in amphibole is observed at the
mouth of the Rio Chillar. The total quartz content
and the ratio of igneous to metamorphic quartz
are similar to values encountered in Province I,
but the total feldspar content is substantially re-
duced. The percentage of micas and chlorite also
increases significantly with respect to Province I.
PROVINCE K.?This province extends from east of
Nerja to west of the mouth of the Rio Guadalfeo.
The Rio Verde is the most important river in
this sector. The heavies are characterized by a
marked increase in the amphibole content and
decrease in the clinopyroxene and garnet. The
proportions of amphiboles are substantially higher
in the samples west of the Rio Verde (nos. 72-76),
whereas the proportions of opaque minerals and
epidotes are substantially greater to the east of the
Rio Verde. In the light fraction, the total quartz
content remains relatively low, although it is note-
worthy that the proportions of igneous and meta-
morphic quartz are nearly identical in sharp con-
trast to adjacent provinces. The highest values of
micas and chlorite in the Iberian coastal samples
occur in this province.
PROVINCE L.?This province extends from the
delta of the Rio Guadalfeo to west of Calahonda.
The Guadalfeo is the only major river in this sec-
tor. The heavy fraction is dominated by garnet,
and there is a decrease in almost all other mineral
groups except the opaques. The major break in
trend of proportion of garnet occurs on both sides
of the mouth of the Guadalfeo. The proportion of
epidote also decreases noticeably east of the mouth
of the Guadalfeo. It is noteworthy that in the
region of El Varadero (sample 86), there is a
dramatic change in the amphibole and epidote
content and a corresponding decrease in garnet.
The light assemblage is essentially similar to Prov-
ince K except that the proportion of metamorphic
quartz is again higher, while the micas and chlorite
revert to a low value. The carbonate content is
also substantially higher than in the neighboring
provinces.
PROVINCE M.?This province extends from Castell
de Ferro to east of Adra. The major river is the
Chico (Rio Adra). The heavy assemblage is dis-
tinguished by garnet and opaques and a slightly
diminished olivine content. Garnet content in-
creases toward the east from Punta Negra, and the
epidote decreases eastward from this point as well.
The major break in mineral trends is localized at
the delta of the Rio Chico, just west of its mouth,
where proportion of amphiboles and opaque min-
erals increase substantially, accompanied by a very
marked decrease in garnet content. The light frac-
tion is marked by a substantial increase in total
quartz content and a slight decrease in total feld-
spar and micas. The proportion of detrital car-
bonates is also significantly reduced compared with
Province L.
MOROCCAN MARGIN
PROVINCE N.?The area included in this province
extends from Cap Spartel west of Tangier to west
of Ceuta along the south flank of the Strait of
Gibraltar (Figures 9 and 10). As in all seven Mo-
roccan provinces, opaque grains comprise the most
abundant single group of the heavy minerals. The
ZTR group is dominant among the nonopaque
minerals, closely followed by garnet and the meta-
morphic group. The proportion of garnet in-
creases toward the east, while zircon tends to de-
crease in the same direction. Significantly, ortho-
pyroxene and olivine occur only in the beach sam-
ples from the western sector of the Strait. Andalu-
site is the dominant metamorphic mineral, but
20 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
NUMBER 15 21
*o "5b
5? a
&
IS
W)
22 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
staurolite also occurs in all samples. Dolomite
rhombs are abundant in samples M8 (west of
Tangier) and M6 (below Djebel Moussa near
Ceuta). Quartz dominates the light mineral assem-
blage with the igneous variety generally in excess
of metamorphic quartz. The average total feld-
spar content is the lowest observed in the Moroc-
can samples.
PROVINCE O.?This province extends from the
south side of Ceuta peninsula to Cap Mazari. The
major river in this sector is the Rio Martin. This
association contains substantially higher propor-
TABLE 6.?Mineral provinces for Moroccan coastal and river samples (see
Figures 5, 6, 9, 10)
Province
Designation
a
0
P
Q
R
S
T
Geographic Limits of Province
Cap Spartel to Ceuta (north side)
Ceuta (south side) to Cap Mazari
Cap Mazari (south side) to Targa
Targa to Bou Haned (Oued El Had)
Oued Ouringa mouth to Pointe des
Pecheurs
Oued Mestasa to Al Hoceima (western
side)
Al Hoceima (eastern side) to Oued
Nekor
Sample
Ml-6,8
M7,9,1
Ml 2-17
M10.11
M2U,25
M26-31
Numbe rs
8-23
, 35-37
, 38
Romarks
M1,3,6,8 are coastal
samples.
M7,19,20-22 are coastal
samples
M2U is a coastal sample
M35 is a coastal sample
M38 is a coastal sample
TABLE 7.?Mineralogic composition of Moroccan samples-province means (see
Figures 5 and 6)
PROVINCE
Opaque Minerals
Zircon + Tourmaline + Rutile (ZTR)
Orthopyroxenes
Clinopyroxenes
Amphiboles
Metamorphic Group
Garnets
Olivine + Spinel
Epidote Group
Others2
Igneous Quart z-^
Metamorphic Quartz
Total Quartz
Igneous/Metam. Quartz Ratio
Potash Feldspar
Plagioclase
Total Feldspar
Quartz/Feldspar Ratio
Micas + Chlorite
Carbonates
Others6
NO. OF SAMPLES
N
41.3
18.4
0.6
tr.5
tr.
13.8
17.2
tr.
3.9
3.9
43.4
22.6
66.1
1.92
1.8
23.2
25.0
2.64
tr.5
8.0
tr.
7
0
29.1
5.8
15.1
5.8
2.3
15.1
13.9
8.1
2.2
2.6
32.2
19.5
51.8
1.65
2.7
37.1
39.8
1.30
0.9
6.2
1.3
8
P
70.2
8.1
1.3
tr.
tr.
4.0
6.7
2.7
1.8
4.9
3.7
13.8
17.5
0.26
0.6
65.8
66.4
0.26
1.-2
4.4
9.5
6
Q
22.9
5.7
9.2
8.0
4.6
12.6
18.4
9.2
6.1
4.3
7.8
11.7
19.5
0.67
4.7
71.2
75.0
0.26
tr.
tr.
5.0
2
R
80.0
3.6
tr.
4.9
-
8.3
1.5
-
3.1
-
0.5
29.3
29.8
0.01
1.7
43.3
45.0
0.66
0.5
4.7
19.9
2
S
63.1
20.8
tr.
1.0
2.0
10.9
1.1
0.6
1.7
-
37.9
13.6
51.5
2.79
1.9
41.2
42.1
1.22
tr.
4.5
1.7
9
T
63.6
4.5
-
3.0
15.2
4.5
1.5
-
6.2
1.5
14.1
6.1
20.2
2.31
2.1
54.1
56.3
0.36
0.5
22.0
1.0
4
1. Comprises Kyanite, Staurolite, Sillimanite, Andalusite and Chiastolite
2. Mainly Apatite, Sphene, Anatase, Monazite, Corundum, Topaz
3. Simple, unstrained quartz
4. Composite and strained quartz
5. tr. = trace (< 0.5%)
6. Mainly rock-fragments and carbonaceous debris
NUMBER 15
tions of orthopyroxenes, clinopyroxenes, olivine,
spinel and amphibole, and diminished ZTR and
garnet. Amphiboles increase toward the south,
while the metamorphic species decrease toward the
south. A high proportion of dolomite rhombs oc-
curs in sample M9 from the Rio Martin. Feldspar
increases in relation to quartz, and there is a slightly
higher proportion of metamorphic quartz.
PROVINCE P.?This province extends from the
south side of Cap Mazari to Targa. Important
rivers in this region include Oued Emsa and Oued
Laou. This region is characterized by an abun-
dance of opaque and ZTR minerals. Both olivines
and pyroxenes increase in the southern samples.
High proportions of dolomite rhombs occur in
sample M16 (near Cap Akaili) and M14 (Oued
Laou). The total quartz content is minimal in
samples taken north of the Oued Laou, while
feldspar reaches a maximum value in the same
samples. The ratio of igneous to metamorphic
quartz increases substantially to the south of the
Oued Laou.
PROVINCE Q.?This province extends from Targa
to Bou Hamed and includes the Oued el Had.
The heavy mineral assemblage here is similar to
that of Province O, but it includes a slightly de-
creased proportion of orthopyroxene and increased
amount of garnet. Olivines and both pyroxenes
tend to increase northward. There is a dominance
of the metamorphic quartz variety, and the ratio
of quartz to feldspar is similar to that in Province
P.
PROVINCE R.?This province includes the region
adjacent to Pointe des Pecheurs and includes the
Oued Ouringa. The heavy mineral assemblage con-
tains the highest proportion of opaque grains in
the Moroccan samples. The metamorphic minerals
(especially andalusite and kyanite) represent the
most abundant nonopaque group. Orthopyroxenes,
garnets, and olivines are notably deficient. Samples
24 and 25 contain high proportions of rhombic
dolomite. The ratio of igneous to metamorphic
quartz decreases considerably from that of Province
Q, and the ratio of quartz to feldspar increases as
a result of a significant diminution in the total
feldspar content as compared with Province Q.
PROVINCE S.?This province extends from Oued
Mastasa to just west of Al Hoceima (Al Hucemas).
The most important rivers include the Oued Mas-
tasa, Oued Bou Frah, Oued Bades, and Oued
Boussikour. The dominant nonopaque heavy min-
eral group is the ZTR suite, which here attains
its maximum abundance for Moroccan samples,
especially in the Bou Frah-Mestasa drainage basin.
The metamorphic minerals are also important,
especially andalusite. Amphiboles are also present
and increase conspicuously in the eastern samples.
Dolomite rhombs are locally important, particu-
larly in the Oued Bou Frah. The proportion of
igneous to metamorphic quartz in this region
reaches its highest level in the Moroccan samples,
and the proportion of quartz to feldspar continues
to increase.
PROVINCE T.?This province includes the west
side of Al Hoceima Bay and extends to the Oued
Nekor. The Rhis and Nekor comprise the two
main drainage systems. Amphiboles are the domi-
nant, nonopaque mineral group and include sub-
stantial proportions of actinolite, rare elsewhere
in the Moroccan assemblages. The amphibole per-
centages decrease toward the west of Oued Nekor.
An increase in the proportion of epidote is accom-
panied by a decrease in metamorphic minerals.
Epidotes decrease eastward from Al Hoceima. Dol-
omite proportions are universally high and reach
a maximum value in sample M33 (Oued Rhis).
There is a notable decrease in the quartz to feld-
spar ratio as compared to Province S and R and a
slight decline in the ratio of igneous to metamor-
phic quartz.
STRAIT OF GIBRALTAR REGION
STRAIT CHANNEL, NORTH PROVINCE.?The mate-
rial examined lies in the northern of the two deep
channels, passing through the Strait of Gibraltar
(Kelling and Stanley, 1972a, b). The heavy frac-
tion is distinguished by relatively high values of
pyroxenes and garnet and low values of ZTR and
amphibole. The mean total quartz and potash
feldspar values are the highest noted in the Strait
region. There is a considerable excess of igneous
over metamorphic quartz, as in all the Strait prov-
inces. Mica content is minimal.
STRAIT CHANNEL, SOUTH PROVINCE.?These sam-
ples were obtained in the South Channel sector
of the Strait proper. The heavy mineral assem-
blage is characterized by high values of opaque
minerals and the maximum ZTR and clinopyrox-
enes. Garnet, metamorphic minerals, and ortho-

cu
a
?3 8
26 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
pyroxenes are minimal. Garnets and orthopyroxenes
increase from west to east, while the clinopyroxenes,
epidotes, and amphiboles show a broad reverse
trend. The light fraction is distinguished by mini-
mal values of total quartz and feldspar, together
with a low proportion of mica and chlorite. Car-
bonates (mainly shell debris) are the dominant
light component.
GIBRALTAR CANYON PROVINCE.?The samples were
obtained from the Gibraltar Canyon, both in the
axial region and on the adjacent flanks between
the northern portion of Algeciras Bay and the zone
of confluence at the eastern end of the Strait (see
Kelling and Stanley, 1972b, fig. 14). The heavy
fraction comprises the highest mean values of
metamorphic minerals and amphiboles, together
with a considerable amount of orthopyroxenes.
Opaque minerals occur in amounts similar to
those in the North Channel, while the mean clino-
pyroxene value is the lowest encountered in the
Strait region samples. The proportion of amphi-
boles broadly decreases down-canyon until the flat
east sector of the Strait and then increases slightly.
The light fraction is characterized by the highest
proportion of igneous to metamorphic quartz, total
feldspar and plagioclase, and mica in the Strait
region; the lowest values of carbonate (shell de-
bris) are noted here.
CEUTA CANYON PROVINCE.?The samples were col-
lected from the axial region of the Ceuta Canyon
to the southern flat region of confluence at the
eastern end of the Strait (Kelling and Stanley,
1972b, fig. 14). Heavy minerals in this region are
characterized by the highest mean value of garnet,
epidote, and olivine in the Strait region. Garnet
increases down-canyon, while orthopyroxenes de-
crease in the same direction. The light fraction is
distinguished by the highest quartz to feldspar
ratio in the Strait region.
ALBORAN SEA
GIBRALTAR VALLEY-MALAGA LOW PROVINCE.?
Samples in this province were derived from core
TABLE 8.?Mineralogic composition of Alboran deep-sea samples-province and
core means (see Figures 5 and 6)
PROVINCE OR CORE
Opaque Minerals
Zircon + Tourmaline +
Rutile (ZTR)
Orthopyroxenes
Clinopyroxenes
Amphiboles
Metamorphic Group1
Garnets
Olivine + Spinel
Epidote Group
Others2
Igneous Quartz
Metamorphic Quartz
Total Quartz
Igneous/Metamorphic
Quartz Ratio
Potash Feldspar
Plagioclase
Total Feldspar
Quartz/Feldspar Ratio
Micas + Chlorite
Carbonates
Others5
NO. OF SAMPLES
GC
11.4
7.0
28.4
3.4
6.7
18.6
16.7
3.2
2.2
2.4
34.0
10.6
44.6
3.21
0.8
7.0
7.8
6.56
5.4
25.4
16.8
5
CC
20.0
6.8
17.4
6.5
4.7
12.9
22.1
3.9
3.6
2.1
30.0
12.9
42.9
2.33
1.6
3.6
5.2
8.20
4.5
28.2
19.2
3
SS
27.8
7.3
15.9
12.3
5.6
10.1
11.6
3.8
3.5
2.1
21.1
8.3
29.4
2.54
2.6
1.5
4.1
7.17
1.6
57.8
7.1
4
SN
10.9
2.0
35.1
8.1
2.7
14.4
21.9
2.0
1.4
1.5
41.3
13.8
55.1
2.99
3.4
3.8
7.2
7.65
1.0
29.7
7.0 .
2
91
17.7
5.1
35.86
2.5
5.1
9.4
tr.7
20.8
3.2
17.8
0.8
44.5
20.5
51.4
9.5
2
92
22.5
5.4
35.1
3.6
6.4
16.3
-
9.9
0.8
52.2
2.0
26.1
18.2
26.9
0.7
3
93
20.9
3.7
40.6
2.5
4.8
10.8
tr.
15.8
-
35.0
0.5
70.0
14.8
51.8
-
2
97
27.0
2.9
41.3
2.2
3.6
4.4
tr.
12.9
5.7
24.9
tr.
-
18.4
48.9
7.8
2
98
28.0
1.8
43.3
4.3
4.9
4.9
-
10.4
2.4
31.3
1.9
15.6
14.1
40.6
12.1
2
101
28.8
2.2
39.3
2.6
3.3
4.0
-
15.7
4.1
28.8
1.4
20.6
11.5
54.3
4.0
3
107
15.6
6.2
38.5
7.5
4.2
11.7
-
13.8
2.5
44.0
2.2
20.0
9.7
39.1
5.0
5
108
12.9
5.2
42.0
4.6
9.7
9.3
-
12.7
3.6
51.3
2.2
23.3
10.4
33.0
3.1
3
1-4. (as on other tables)
5. Mainly rock-fragments and carbonac
6. Total pyroxenes, undifferentiated
7. tr. = trace (< 0.5%)
GC = Gibraltar Canyon; CC = Ceu
SS = Strait of Gibraltar, southe
SN = Strait of Gibraltar, northe
NUMBER 15 27
108 in the Gibraltar Submarine Valley and core
107 from the Malaga Low, north of the Western
Alboran Basin (Figures 1, 5, and 6). One graded
sand layer in core 108 and two in core 107 were
analyzed (Huang and Stanley, 1972). The heavy
mineral assemblage is characterized by substantial
amounts of pyroxenes, amphiboles, and ZTR and
relatively low values of opaque minerals and
garnet. Olivine was not encountered. The light
fraction has a very low proportion of feldspar, and
quartz accounts for approximately half of the light
assemblage. The high carbonate values are largely
attributable to concentrations of foraminifera.
WESTERN ALBORAN BASIN PROVINCE.?Samples
were collected from the same sand layer (Lower
sand-and-silt layer) from six cores in cores 91, 92,
93, 97, 98, and 101 (Huang and Stanley, 1972, figs.
7, 8) in the flat plain of the Western Alboran
Basin. An average grouping of all sample data
examined shows a heavy mineral assemblage, which
is dominated by pyroxenes and epidote with high
values of ZTR. Quartz accounts for about one-
third of the light fraction, and the carbonates
(mainly planktonic foraminifera) constitute about
the same proportion. Feldspars are notably defi-
cient. A subtle regional trend can be discovered
on both sides of an east-west line bisecting the
basin plain. Samples to the south (cores 91, 92, 93)
contain somewhat higher values of ZTR, garnet,
epidote, total quartz, and mica, whereas those to
the north (cores 97, 98, 101) contain slightly en-
hanced amounts of opaque minerals, pyroxenes,
and carbonates.
Provenance of Sediments on Alboran Sea Margins
GENERAL
The regional distribution of mineral groups on
the southern Iberian and Moroccan margins is de-
fined in terms of 20 light and heavy mineral prov-
inces as described in the previous sections. The
position of these mineral provinces (Figures 5 and
6) is broadly concordant with the seaward limits
of the major drainage basins (Figures 2 and 3).
This emphasizes the close relationship which exists
between the varied lithology of the mountainous
margins of the Iberian Peninsula and North Africa
and the mineralogical composition of sediments
along the adjacent coast. The following section
details the manner in which the composition of
coastal and fluvial samples can be related to specific
source terrains in the Betic Cordillera and the Rif.
Essentially, two major mineralogical sectors are
recognized on the Spanish margin: one to the east,
extending from Velez-Malaga toward Adra, influ-
enced by the Nevado-Filabride and Alpujarride
complexes, and the other, west of Malaga, draining
the ultrabasic rocks of the Peridotite Complex.
In the former region, the Adra and Guadalfeo
rivers, as well as smaller intervening rivers, carry,
among others, the following minerals: sodic pla-
gioclase (albite, oligoclase), quartz, carbonates,
mica, garnet (very abundant), epidote, amphibole,
orthopyroxene, and opaque minerals.
In the western region, peridotites are among the
significant lithologies that crop out in basins of
the Guadalhorce, Fuengirola, and Verde rivers
and smaller basins between Malaga and Estepona.
These rivers carry the following: calcic plagioclase
(or calco-sodic varieties), mica, olivine, amphibole,
orthopyroxene, clinopyroxene, garnet, epidote,
and opaque minerals.
On the Moroccan margin, two major minera-
logical sectors are also recognized: one to the east,
extending from the Beni Bouchera ultrabasic com-
plex, influenced essentially by Paleozoic, Mesozoic,
and Tertiary sediments, and the other, north and
west of the ultrabasic complex, draining Paleozoic
sediments, metamorphic rocks, and basic or ultra-
basic intrusives.
In the former, rivers such as the Nekor and
Ouringa convey sodic plagioclase, both igneous and
metamorphic quartz, carbonates, and opaque
heavy minerals (very abundant). In the north-
western region, rivers such as the Oued Laou and
Martin carry more calcic plagioclase and a high
proportion of metamorphic quartz, together with
garnet, orthopyroxene, and olivine.
A study of minerals in coastal sediments from
the Spanish margin east of Malaga by P?rez-
Mateos et al. (1973) provides results which differ
in some major respects from those of this investi-
gation. These authors show substantially higher
values of minerals such as andalusite, staurolite,
and quartz and much lower values of pyroxene,
epidote, and feldspar than analyzed here. Further-
more, they recognize three provinces (I, II, III)
between Malaga and the Cabo de Gata as com-
pared to five defined by us along the same sector
28 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
(Provinces I to M). A point of resemblance, how-
ever, is that the dramatic increase in the propor-
tion of garnet to the east of Motril (Rio Guadal-
feo) (Figure 7) is also recorded by Perez-Mateos
and others (1973).
ORIGIN OF SELECTED SPANISH RIVER SEDIMENTS
Two samples from each of six rivers in the
western sector of the Iberian margin (west of Mar-
bella) were examined: Calena (I), Guadaiza (II),
Guadalmansa (III), Padron (IV), Enmedia (V),
and the Genal-Guadiaro (VI). These rivers fall
within the coastal mineral provinces G, F, and E,
from east to west respectively.
At each of the river localities the sample pairs
show similar heavy mineral associations, and con-
sequently an average value is supplied for each
river (Table 5). Each river sample closely reflects
the lithology of the terrain traversed. Thus, the
main variations from river to river are most readily
ascribed to differences in lithology of the terrains
cut by the six rivers (cf., Figure 2). The notable
increase in quartz and mica and orthopyroxene,
amphibole, olivine, and metamorphic minerals and
the concurrent decrease of carbonate, garnet and
opaque minerals, from the Calena to the neighbor-
ing Guadaiza river, are explained by the fact that
the first river cuts carbonate-rich rocks, while the
second (Guadaiza) cuts across peridotites as well
as metamorphic terrains. The westernmost river,
the Genal-Guadiaro, carries an assemblage that is
more similar to that of the Guadaiza River than
the intervening rivers. The headwaters of the
Genal-Guadiaro also erode peridotites and meta-
morphic lithologies.
The percentage of total quartz increases sub-
stantially to the west, reflecting the westward pre-
dominance of source terrains of Cretaceous, Paleo-
gene, and Miocene sediments.
Samples collected from these rivers are broadly
comparable in composition to the samples col-
lected on the coast adjacent to the appropriate
river mouth. However, with the exception of epi-
dote, which appears to be consistently more com-
mon in the coastal samples, there is little change
downstream. As a general rule, coastal samples con-
tain higher values of opaque minerals and lower
values of orthopyroxenes. Moreover, the river
samples in aggregate generally contain more quartz
and mica and less feldspar than most of the coastal
sands (Table 5, Figure 6).
These differences in composition between fluvial
and coastal samples may be partly a function of
the relative efficacy of the differing hydraulic proc-
esses affecting these two environments, but the in-
fluence of grain-size factor cannot be excluded
(despite the restrictions of analyses to the same
grades, as indicated earlier, page 3).
ORIGIN OF SPANISH MARGIN SEDIMENTS?
LIGHT MINERALS
Quartz is marginally the most abundant min-
eral, ranging from 29% to 71% of the total light
mineral fraction (the average content approxi-
mates 40%). Metamorphic quartz is more abun-
dant than quartz of igneous origin. The former
originates in metamorphic terrains that abound
in the study area. Quartz of igneous origin is de-
rived from several sources: the acid volcanics of
the Cabo de Gata region, hydrothermal veins in
the different complexes, and reworked older sands
and sandstones, particularly those in the External
Zone. Plagioclase generally constitutes between
10% and 56% of the light mineral fraction, aver-
aging about 35%. Both sodic and calcic plagio-
clases display distinct regional distributions. Sodic
plagioclase (albite and oligoclase) is predominant
east of Malaga; calcic species abound between
Estepona and Malaga. As would be expected, the
relation between plagioclase assemblages and river
supply is a direct one. For instance, sodic plagio-
clases are common in the rocks of the Nevado-
Filabride and Alpujarride complexes, i.e., sequences
that crop out in the fluvial basins east of Malaga.
An important source of calcic feldspars, on the
other hand, is the Peridotite Complex that crops
out in basins between Malaga and Estepona. Be-
tween Estepona and Tarifa, farther to the west,
both sodic and calcic varieties occur.
The lower relative percentages of potassic feld-
spars (generally less than 2%) in all coastal sam-
ples examined can be related to their generally
low abundance in most rock types of the different
stratigraphic-tectonic units cropping out in the
various drainage basins. An exception is Province
C, on the eastern side of Algeciras Bay, where the
increased quantity (to 8%) may reflect the im-
portance of sedimentary sources conveyed into
NUMBER 15 29
the northern part of the Bay from the Rio
Guadarranque.
Carbonate, including dolomite rhombs, and
lithic fragments are commonly present and in
many cases can be related to specific carbonate rock
types cropping out in the drainage basins. The
highest percentages occur in Province L, which is
bounded by cliffs of Middle to Upper Triassic
shaly limestones and dolomites. High values are
also encountered in Provinces G and H and appear
to represent fluvial supply from the Sierra Blanca
unit, which includes marbles and gneisses.
Glauconite, essentially of detrital origin, is ob-
served in some samples. Most of the detrital glau-
conite originates in the sandstones of Cretaceous,
Paleogene, and lower Miocene age in the External
Zone and in sands and sandstones of postorogenic
sequences (especially the Miocene).
The percentage of mica is variable, but is gener-
ally quite low (less than 2%). Muscovite and par-
ticularly biotite abound in most of the metamor-
phic sequences of the Internal Zone. The highest
mica values (12%) occur in Province K east of
Nerja, west of Motril, where Paleozoic micaschists
and quartzites crop out in the coastal ranges. Cer-
tain other coastal samples contain a notably high
percentage of mica. An example in point are those
in the Bay of Algeciras which, interestingly enough,
are fed by rivers that cut metamorphic units not
particularly rich in mica. This suggests that en-
riched mica content may also be related to factors
other than provenance (see following section).
ORIGIN OF SPANISH MARGIN SEDIMENTS?
HEAVY MINERALS
Garnets occur at all sample stations along the
Spanish margin (Figure 7), and a large fraction
of these undoubtedly are derived from the Nevado-
Filabride Complex. In addition, garnets are sup-
plied from certain Alpujarride Complex sequences,
from basal units of the Malaguide Complex, and
from the Casares Unit. The highest percentages of
garnet occur in samples from the sector between
the mouths of the Adra and Gualdalfeo rivers.
These rivers traverse extensive outcrops of the
Nevado-Filabride Complex (Figure 2). Other areas
where high amounts of garnet occur include
coastal sections near the mouths of the Guadal-
horce and Fuengirola rivers, where garnetiferous
sequences of the Malaguide Complex crop out.
High values of epidote occur along the coast,
and the highest concentrations are found in the
region between Malaga and Motril, and in some
sectors to the west of Adra. This mineral has dif-
ferent possible origins that include the Nevado-
Filabride and Alpujarride Complexes as well as
certain sequences of the Malaguide Complex.
Pyroxenes are abundant west of Motril. Per-
centages of orthopyroxenes are higher than those
of clinopyroxenes except in certain isolated cases
(sample stations 2, 20, 35 and 74). Provenance of
pyroxenes (ortho- as well as clinopyroxenes) is
closely related to the Peridotite Complex. Some
clinopyroxenes are derived from the amphibolites
of the Alpujarride Complex that are intercalated
in the Paleozoic dolomites exposed west of Motril.
Amphiboles are present in all samples in vari-
able amounts. In some sectors, such as near Nerja,
it is the most important mineral in the heavy frac-
tion in some samples. Here, its origin lies in the
amphibolites of the Paleozoic sequences of the
Alpujarride Complex that crop out extensively
north of the coast between Nerja and Motril.
Olivine is derived in large part from the Perido-
tite Complex, and the highest percentages observed
in coastal samples occur between Estepona and
Marbella, where rivers eroding this complex reach
the sea. Olivine is abundant from Algeciras to
Malaga; this in part explained by the load carried
by the various rivers (Guadalhorce, Fuengirola,
Verde) cutting this complex and is also due to
coastal currents carrying olivine-bearing sediments
toward the west (see next chapter). At the mouth
of the Guadalfeo River there is an anomalously
high percentage of olivine; this can be interpreted
as originating in the "rocas verdes" (altered basic
igneous rocks) facies of the Nevado-Filabride and
Alpujarride complex that crop out in the drainage
basin of this river.
Significant percentages of apatite occur only in
samples collected in the vicinity of the Strait of
Gibraltar. Apatite, derived in large part from
igneous rocks, is transported by currents from
source terrains that are exposed along this coastal
sector. There is no primary source for this mineral
in the fluvial basins north of this area. The pres-
ence of very rounded grains does suggest that
apatite is reworked, at least in part, from older
apatite-bearing sandstones.
30 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Tourmaline is derived from the Nevado-
Filabride Complex, phyllites of the Alpujarride
Complex and the Casares Unit, and the amphi-
bolites of diverse units. The total ZTR content
ranges up to 2.3% and is more abundant in the
coastal samples from the Strait of Gibraltar re-
gion, tending to decrease eastward from this area.
This change results from the diminished impor-
tance of sedimentary terrains east of Gibraltar.
Kyanite is associated with certain lithologic sec-
tions (micaschists) of the Nevado-Filabride Com-
plex. Sillimanite originates in rocks, including
micaschists, of possible pre-Cambrian age in the
Malaguide Complex and the Sierra Blanca Unit.
Andalusite is derived from several units: micaschist
of the Alpujarride Complex, lower sequences of
the Paleozoic Malaguide Unit, the Casares Unit,
and the Sierra Blanca Unit. The percentages are
noteworthy along the coast from Nerja toward the
west.
Opaque minerals are present, generally in high
percentages. Particularly significant are coastal
samples containing large amounts of opaques
(45% to 60%) between Malaga and the Motril-
Adra sector and the Strait of Gibraltar sector. Of
these minerals, magnetite is very abundant in the
fine sands of this coast (beaches such as the Playa
de Carchuna near Motril). Magnetite has several
possible origins and can be found in diverse strati-
graphic sections of sedimentary and metamorphic
as well as ultrabasic rocks.
ORIGIN OF MOROCCAN MARGIN SEDIMENTS?
LIGHT MINERALS
Feldspar, particularly plagioclase, is the most
abundant mineral, ranging from 25% to 75% of
the total light mineral fraction (the average con-
tent approximates 43%). Plagioclase generally con-
stitutes between 27 and 71%, and calcic varieties
predominate, particularly in the central sectors
(Provinces O, P, Q, and R). High values of calcic
plagioclase in the sediments of Provinces P and Q
reflect a source terrain which includes bodies of
ultrabasic rock (Beni Bouchera). Individual coastal
samples from the vicinity of Cabo Negro in Prov-
ince O also contain enhanced proportions of
calcic plagioclase, probably derived from the peri-
dotite bodies intruded into the Paleozoic meta-
morphic rocks of this region (Figure 3). High
values of more sodic plagioclase are encountered
in the sediments of Province T and probably de-
rive, directly or indirectly, from isolated outcrops
of Paleozoic metamorphic rocks in the drainage
basin of the Oued Nekor.
Total quartz, ranging from 17% to 66%, is most
abundant in the western sectors (Provinces N and
O) and also in Province S, west of Al Hoceima (to
52%). These areas drain essentially sedimentary
terrains. The igneous quartz variety predominates
over the metamorphic type in those provinces cited
above which contain abundant total quartz of
presumably sedimentary origin, whereas the meta-
morphic quartz is dominant in Provinces such as
P, Q, and R, receiving material largely from Pale-
ozoic metamorphic sources. The dominance of
igneous quartz in Province T probably reflects
the derivation of material from acid and inter-
mediate volcanic rocks of late Mesozoic and Ter-
tiary age including the Cap Quilates Complex.
Carbonate content generally ranges between 4%
and 8%, but reaches the exceptionally high mean
value of 22% in Province T east of Al Hoceima.
Dolomite rhombs constitute an important part of
the carbonate fraction and reach their peak abun-
dance in samples from the Oued Nekor drainage
basin. Such carbonate components derive largely
from Mesozoic limestone and dolomite sequences,
particularly those of Triassic and early Jurassic
age, most commonly exposed in the eastern part of
the study area. High values of carbonate in indi-
vidual samples (Figure 6) which occur in Prov-
inces N, O, and P may be ascribed to a similar
provenance, although some may also be derived
from smaller bodies of marble developed in the
Paleozoic terrains between Ceuta and Bouhamed.
Glauconite is generally rare in the Moroccan
samples except in a sample (no. 3) east of Tangier
in the Strait of Gibraltar (Figure 10), whose origin
lies in the adjacent terrain of Cretaceous/Tertiary
sandstones.
Rock fragments account for only a minor pro-
portion of the light fraction except in sample 6
just west of Cueta, where they consist mainly of
slate.
Mica percentages are generally low and consist
predominantly of biotite. The highest values, en-
countered in Province P, are attributable to the
adjacent Paleozoic sediments.
NUMBER 15 31
ORIGIN OF MOROCCAN MARGIN SEDIMENTS?
HEAVY MINERALS
In general, garnets account for the highest per-
centage of transparent heavy mineral fraction but
vary considerably in abundance (1.1% to 18.4%).
The highest values occur in river sediment samples
from the Province Q (Bouhamed) region and in
coastal samples from the Strait of Gibraltar and
the region south of Ceuta (Provinces N and O).
Paleozoic metamorphic rocks represent the pri-
mary source of this mineral and account for its
abundance in the Bouhamed region. However, the
abundance of garnet in the coastal sediments may
be attributed either to reworking of younger sedi-
mentary rocks or to preferential concentration by
littoral processes.
The ZTR group is generally an important con-
stituent of most of the Moroccan heavy fraction
(4% to 18% mean values), and varieties of zircon
tend to dominate the group. Exceptionally high
values of ZTR occur in samples from Province S
(west of Al Hoceima) and from the Strait of Gi-
braltar region. These enhanced proportions clearly
indicate the increased importance of sedimentary
rocks in the source terrains.
Minerals assigned to the metamorphic group
(andalusite, kyanite, staurolite, and sillimanite)
are also abundant in the heavy mineral assem-
blages from the Moroccan margin, ranging from
4% to 15% mean values. This group attains its
maximum abundance in the region south of
Ceuta (Province O), although high mean values
also occur in the Bouhamed area (Province Q)
adjacent to extensive outcrops of metamorphosed
Paleozoic rocks. High values in the Strait of Gi-
braltar (Province N) are mainly observed in the
littoral samples and probably reflect the increased
resistance of certain members of this group, not-
ably staurolite. Staurolite constitutes 12.2% of the
nonopaque fraction in individual samples but is
almost confined to Provinces N and O in the
western portion of the study area. This mineral
recurs in lesser abundance in the samples from the
Bouhamed metamorphic area (Province Q, Figure
5). Andalusite is common, but exceptionally large
values are noted in individual samples from Prov-
inces R, S, and T near Al Hoceima. They are
evidently reworked from Mesozoic and Tertiary
sediments, an origin confirmed by the well-rounded
character of these grains. Large relative values of
kyanite are also noted in the same samples. How-
ever, angular grains of kyanite are consistently
abundant in samples from Provinces O and Q
(south of Ceuta and Bouhamed) where such grains
may be more confidently attributed to the sur-
rounding metamorphic rocks.
Orthopyroxenes are highly variable in abun-
dance (up to 24% in individual samples) and are
almost confined to Provinces O and Q. The en-
hanced content of the orthopyroxene in these re-
gions reflects the presence of ultrabasic bodies
occurring in the vicinity. Clinopyroxene is more
widespread than the orthopyroxene but is almost
always lower in value. The highest percentages of
clinopyroxene are found in Provinces O and Q.
Somewhat enhanced proportions of clinopyroxene
occur in coastal samples from the Pointe de
Pecheurs area (Province R) and here may be de-
rived from the basic or ultrabasic intrusives near-
by. A sample from the Oued Nekor provides the
highest individual value of clinopyroxene, which
probably originates from igneous or metamorphic
rocks that crop out in small areas near the source
of this river.
Province T, in the Oued Nekor drainage basin,
also provides the consistently highest content of
amphibole minerals, including substantial amounts
of actinolite, which is typical of the amphibolite
metamorphic facies. The minor amounts of am-
phibole encountered in the more westerly regions
(especially Province Q) are dominated by brown
and green hornblende, together with some glau-
cophane. These minerals probably originated in
the Paleozoic metasediments.
Olivine and spinel (mainly picotite) are con-
sidered together because these minerals are de-
rived largely from basic and ultrabasic rocks in
which these two species are intimately associated.
The distribution of olivine and spinel closely
parallels the distribution of orthopyroxene, con-
firming the basic or ultrabasic provenance of these
minerals. The maximum values for this group
occur in the region between Pointe Targa and
Bouhamed, reflecting the influence of the Beni
Bouchera igneous mass.
Epidote attains maximum abundance in Prov-
inces Q and T, areas rich in metamorphic source
terrains.
Apatite is relatively uncommon on the Moroccan
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
margin but attains appreciable abundance (up to
4.7%) in individual samples from the Strait of
Gibraltar beaches. Grains are well rounded and,
in part, may be reworked from older sedimentary
terrains.
Opaque minerals comprise the most important
component of the heavy mineral fraction, with
mean values ranging from 23% to 80% and aver-
aging approximately 45%. The highest mean
values occur in rivers and beaches in the more
easterly provinces (R, S and T), together with
Province P (Cap Mazari area). Opaques are prob-
ably derived from sedimentary and metasedimen-
tary rocks, although this provenance is diverse and
subsequent concentration by both fluvial and
coastal processes has also occurred.
Mineralogical Modification by Coastal Processes
Although the similarity of heavy and light min-
eral assemblages in river and adjacent coastal sam-
ples attests to the virtually direct transport of sedi-
ment from source to sea on all margins of the
Alboran Sea, several features indicate that some
modification of mineralogy does occur while mate-
rial is held in the littoral and nearshore zone. The
nature of these modifications may be used to inter-
pret the effects of coastal processes and the conse-
quent dispersal pattern on both Iberian and Mo-
roccan margins.
The most compelling evidence for modification
by coastal processes derives from the nonconcord-
ance in detail of mineral province boundaries
30'
30'
FIGURE 11.?Predominant movement of coastal and nearshore currents based primarily on aerial
photographic analysis (cf. Figures 12-14).
NUMBER 15 33
/.-?
CURRENT PATTERN
SAMPLE LOCALITY
FI'GURE 12.?Aerial photographic coverage of selected portions of the southern Iberian margin
(arrows denote major current pattern). Upper: Malaga Bay (altitude approximately 7000 m;
R. Ghor = Rio Guadalhorce; R. Gmed = Rio Guadalmedina; Mai = Malaga; El P = El Palo;
Vic = La Victoria). Lower: Strait of Gibraltar (altitude approximately 7000 m; R. Ve ? Rio
de la Vega; Tar = Tarifa).
with the adjacent drainage basin boundaries, de-
spite the broad parallelism already noted. Impor-
tant and abrupt variations in the mineralogy of
the coastal sands are related to the supply at a
river mouth or to the presence of coastal outcrops
directly supplying material to the adjacent beach.
However, where examined in detail (see previous
section), the mineralogical variation from river
to river is greater than that observed along the
intervening stretch of coast near the river mouths.
An example of this effect is shown by the com-
parison of coastal and fluvial materials on the
Spanish margin between the Calena and Genal-
Guadiaro rivers. Here, coastal stations 27 to 30
(Figure 2) display a greater increase in the per-
centage of garnet than is observed between the
supplying rivers (Enmedia and Padron).' Stations
22 to 29 contain appreciably enhanced proportions
of olivine as compared to adjacent rivers, and
both clinopyroxene and amphibole are less abun-
dant in samples from the corresponding rivers
than in the sands from coastal stations 27 to 36.
There is, in addition, a much higher content of
orthopyroxene observed in all the coastal samples
as compared with the fluvial sediments. Thus, river
samples, as would be expected, reflect more directly
the mineralogy of the terrains crossed by the flu-
vial flow, while the greater sample-to-sample simi-
larity along the coast indicates that at least some
mixing and dilution of individual river supply
34 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FK.I'KK 13.?Aerial photographic coverage of Algeciras Bay. (Altitude
approximately 7000 in; PSG = Punta tie San Garcia: Alg = Algeciras;
RPa = Rio Palinones; RGuad = Rio Guadarran(|iie: (Jib = Gibral-
tar; EP ?? Europa Point; La I.i = La Linea. Allows denote major
current pattern.)
NUMBER 15 35
FICURE 14.?Aerial photographic coverage of selected portions of the Spanish margin east of
Malaga (altitude approximately 5000 m; arrows denote major current pattern). Upper: area
near Castell de Ferro (= Ca Fe; RaGua = Rio Gualchos). Lower: area near Calahonda ( =
Cal; Fa = Faro, light house; B.R. = beach ridges).
has occurred at the coast as a result of wave and
longshore current transport.
This example demonstrates that the coastal
modification processes are not solely concerned
with enhancement of the more stable or resistant
mineral species. For example, the increased pro-
portions of pyroxenes in the coastal sands west of
Marbella (Figure 7) indicate some increment in
these relatively unstable minerals from sources
other than the adjacent rivers, presumably through
littoral drift from more distant fluvial or coastal
sources.
Evidence concerning the actual sense of near-
shore sediment transport is provided by the lat-
eral trends observed within both Moroccan and
Spanish coastal mineral provinces. Such trends
involve distinct, regular diminution or augmenta-
tion of the relative proportions of certain mineral
species, which may be assigned to supply from a
given river or coastal outcrop. For example, in
the region of Malaga, samples 48 to 52 show a
steady southward decrease in the abundance of
amphibole and a concurrent increase in the pro-
portion of garnet and olivine (Figure 7). The
implication of this trend is that this stretch of
coast is subject to an essentially southwestward
longshore movement of sediment by coastal cur-
rents. This conclusion is substantiated by an inde-
pendent appraisal of coastal current motion and
long-term sediment drift patterns observed from
36 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
aerial photographs and large-scale charts (Figures
11 and 12).
The coastal current map suggests a predomi-
nance of westerly trending transport along the
Spanish coast from Malaga to the Strait of Gibral-
tar. Surface drift surveys (Gaibar-Puertas, 1967)
also reveal a similar pattern. Such transport would
help account for the observation that the highest
percentage of the main mineral species generally
occurs in samples taken immediately west of the
river delivering it to the sea (note changes on
heavy mineral bar graphs, Figure 7). This south-
westward transport is further attested by the re-
markably high concentrations of orthopyroxene,
amphibole, and olivine in the region of the Strait
of Gibraltar, a region isolated from direct fluvial
or coastal supply of these minerals.
The distribution of minerals in the coastal sand
of the Bay of Algeciras poses some problems in
that the mineral assemblages are rich in metamor-
phic species, pyroxenes and olivine, although the
rivers that flow into the Bay do not cross meta-
morphic or ultrabasic terrains. It is significant,
therefore, that the Bay assemblage is similar to
assemblages outside of the Bay and east of Gibral-
tar (Kelling and Stanley, 1972a). There are sev-
eral possible interpretations: (a) currents from
the east, moving around the peninsula of Gibral-
tar, enter the Bay carrying with them sediments
from La Li'nea and farther east; (b) the sands are
eroded from Tertiary-Quaternary sediments that
bear this particular suite of minerals and that are
exposed near the Bay; (c) or the present peninsula
forming the "rock" of Gibraltar was an island
4?-- "??-'??-
?si
FIGURE 15.?Photographs showing strong coastal currents in the Strait of Gibraltar region.
Upper left: ship heading west across Algeciras Bay toward Algeciras. Lower left: view from the
Rock of Gibraltar across Algeciras Bay toward the Strait (to the southwest). Right: view showing
east side of the Rock and coastline north of Gibraltar. (Note current patterns parallel to the
straight coastline off La Linea-Gibraltar region. Large structure in foreground is a water catch-
ment above Catalan Bay.)
\
NUMBER 15 37
FICURE 16.?Photographs showing evidence of strong coastal currents. Upper: currents oft Morocco
between Cap Mazari and Cabo Negro. Lower: view east toward the plain of Carchuna from
Cape Sacratif (southeast of Motril, Spain).
38 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
during the recent past, and the coast line along
which minerals moved originally lay north of the
"rock" (i.e., in the low area close to the Gibraltar
air strip and the Gibraltar-Spanish border); (d)
or, still, a fourth possibility is that the Guadiaro
River in the past occupied the present lower valley
of the Guadarranque River; subsequently, the
Guadiaro River was captured and occupied its
present position east of Gibraltar. Thus, if hy-
potheses (b), (c), or (d) are valid, some of the
Algeciras Bay coastal sands would be essentially
relict in origin.
In any event, the present distribution of miner-
als in the Bay sediments conforms closely to the
predicted counterclockwise transport path (Fig-
ures 13 and 15). Note for example the southward
diminution of pyroxene in the western part of
the Bay (samples 13 to 8) and the northward de-
crease in orthopyroxene from Europa Point toward
La Linea on the eastern side of the Bay.
Although some workers (Perez-Mateos et al.,
1973), using size parameters, have deduced a
predominant eastward transport of the coastal
sediments in the region east of Malaga, the min-
eralogic trends between Malaga and Adra observed
in this study are generally less regular in sense
or in degree. This variability may be partly a func-
tion of the increased contributions from coastal
outcrops and partly attributable to the less con-
stant coastal drift patterns revealed by independent
analysis of the aerial photographs (Figures 11 and
14)\Similar effects of nearshore transport have been
identified on the Moroccan margin. Coastal sam-
ples from the western part of the Moroccan shore
of the Strait of Gibraltar contain substantial
quantities of minerals, such as orthopyroxene and
olivine, which are virtually absent from the adja-
cent river sediments. The source of these minerals
lies in ultrabasic intrusives exposed on the coast
around Ceuta, and their presence in this western
region implies a net westward transport of detritus
along this portion of the Strait (Figure 11).
As in the region west of Malaga, the predomi-
nant nearshore sediment drift, as revealed by
aerial photo survey, is essentially toward west and
north, in the region from Melilla to Cap Negro
(Figures 11 and 16). The region between Cap
Negro and Ceuta appears to be one of converging
flow (to the south from Ceuta, and to the north
from Cap Negro). The mineral distribution in
this coastal region is significant (samples 7, 19-22,
Figures 9 and 10). Here, the orthopyroxene de-
rived respectively from ultrabasic bodies outcrop-
ping at Ceuta and at Cap Negro (Milliard, 1959)
decreases away from these sources to a minimum
in the central region near the mouth of the Oued
Negron. These decreasing trends parallel the cur-
rent convergence (Figure 11).
Two other factors, in addition to nearshore
currents, influence the distribution of mineral
assemblages. These are (a) coastal morphology
(i.e., embayments and sheltered areas that serve
to trap selected minerals such as micas versus long,
open straight coastlines that are prone to more
intense wave attack with resulting concentration
of heavy mineral lag deposits; the orientation of
beaches that may be more or less prone to erosion
by wave and coastal currents, etc.) and (b) mete-
orological conditions including rainfall, snow-melt,
water, and wind patterns that vary seasonally. A
case in point is the region of Gibraltar where
highly contrasted coastal regimes occur on either
side of the Rock. East of Gibraltar, the long
straight beaches are exposed to strong attack by
waves as well as longshore currents, with the con-
sequence that these eastern sands contain very high
proportions of heavy minerals (up to 71% in sam-
ples from Eastern Beach near La Linea). On the
other hand, the Bay of Algeciras, west of Gibraltar,
is a region of lower energy where deposition pre-
vails, resulting in the enhanced proportions of
mica.
It is apparent, therefore, that the abundance of
individual mineral species is not solely dependent
on provenance but is subject to modification by
processes active in the coastal zone. Such processes
operate chiefly to concentrate or dissipate specific
minerals of differing size, density, or physical
durability.
Dispersal of Marginal Sands to the
Western Alboran Basin
The evidence cited in the previous section dem-
onstrates that sediment transported by rivers from
both the Iberian and Moroccan highlands main-
tain, at least in a general manner, their mineralogi-
cal integrity along well-defined coastal sectors. This
NUMBER 15 39
fact should enable the provenance of sands in more
offshore environments to be identified.
Earlier studies have shown that sand is actively
being conveyed into deeper marine environments
both to the west and east of the Strait of Gibraltar
(Heezen and Johnson, 1969; Kelling and Stanley,
1972a, b). These investigations indicated that
coarse sediment is principally being transferred
from the Ceuta-Cabo Negro and the Gibraltar-
Algeciras regions to the eastern end of the Strait
through two major canyons, Ceuta and Gibraltar
canyons. From the canyons, this material is trans-
ported to a zone of canyon confluence in a rela-
tively flat sector at the eastern end of the Strait
(Figure 17) and subsequently is shifted pre-
dominantly in a westward direction under the
influence of the strong deep Mediterranean under-
current (Kelling and Stanley, 1972b, figs. 15, 16).
The results of the present study provide inde-
pendent evidence for this westward transport, since
coastal and fluvial samples from both the Spanish
and Moroccan borders of the Strait show little
mineralogical resemblance to samples from the
adjacent deep floor of the Strait (Figures 5 and 6).
Significantly, the latter bear a closer mineralogical
resemblance to coastal samples obtained farther
to the east.
However, there is some evidence that part of
the canyon-fed sediment load reaching the zone
of confluence is conveyed eastward and may reach
the Western Alboran Basin plain via the large
Gibraltar Submarine Valley (Figure 18; cf., Kel-
ling and Stanley, 1972b:518). This eastward trans-
port of sand is substantiated by the results of a
detailed high-resolution subbottom survey (Stanley
et al., 1970; Bartolini et al., 1972) showing the
distribution of sand layers in the Western Alboran
Basin. The number and thickness of these sand
layers provide a means of determining the gross
dispersal pattern of late Pleistocene-Holocene
elastics within the Basin. These earlier surveys
showed that sands were primarily transported from
the west and north.
Further confirmation of this mode of filling has
EAST
FIGURE 17.?Two east-west high resolution subbottom profiles (3.5 kHz) at the eastern end of
the Strait of Gilbraltar showing the zone of confluence, a flat area between Gibraltar and Ceuta.
Profiles cross Ceuta Ridge bounding the eastern margin of Ceuta Canyon (see Figure 1). (Spac-
ing between horizontal lines is 20 fm (37 m).)
40 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
been provided by compositional studies of the sand
layers in numerous cores from the western Alboran
Basin plain and surrounding area (Bartolini et al.,
1972; Huang and Stanley, 1972). Material from
several turbidites was attributed to a source area
in the region of the Serrania de Ronda west of
Malaga and at the eastern end of the Strait of
Gibraltar.
A closer evaluation enables us to identify more
precisely the immediate and ultimate sources of
the late Quaternary and Holocene sands in the
deep-sea cores. It is evident that the heavy mineral
assemblages are more valuable for this purpose
than the light fraction, partly because of the addi-
tion of biogenic carbonate (largely planktonic
foraminifera and some shell debris) and mica, and
partly because of size-sorting effects. The data of
Huang and Stanley (1972, table 5) pertaining to
the Upper sand turbidite layer (dated at about
10,000 years B.P.) and to the Lower sand turbidite
layer (emplaced subsequently to about 12*500
years B.P.) in six cores (91, 92, 93, 97, 98, and 101)
was re-expressed in order to achieve mineral pro-
portions compatible with those of the shallower
regions.
The Western Alboran Basin heavy mineral suite
is consistent from core to core and is dominated by
pyroxenes and opaque minerals, with substantial
proportions of epidote, garnet, and ZTR. On the
basis of the mean values of the heavy minerals,
the deep-sea sands most closely resemble those of
coastal sands in the vicinity of Gibraltar (Provinces
B, C, and D). The high proportion of pyroxene
precludes derivation of the Alboran Basin sands
from coastal areas east of Marbella on the Spanish
margin. No assemblage resembling these deep-sea
sands occurs on the Moroccan margin (low py-
roxene and low epidote).
The ultimate derivation of the Lower sand
layer may lie in the Serrania de Ronda as sug-
gested by Bartolini et al. (1972) on the basis of
abundant enstatite and also indicated by river
NORTHWEST
IcEUTA RIDGE
600 fm
SOUTHEAST
FIGURE 18.?High resolution subbottom profile (3.5 kHz) extending from the Ceuta Ridge near
the Strait of Gibraltar downslope across the Alboran Basin. Traverse cuts diagonally across
Gibraltar Submarine Valley, Malaga Low, and Alboran Trough (see Figure 1). (Spacing between
horizontal lines is 20 fm (37 m).)
NUMBER 15 41
samples from this region. Tenuous evidence of
more direct derivation from the north (region of
Malaga-Marbella) is provided by the sands of core
107 collected south of Malaga in the Malaga Low
(north of the Western Alboran Basin). The sands
in this core display mineralogic attributes closely
comparable to those in rivers draining the region
north of coastal provinces F and G (Figure 5). It
34"N
3"W
FIGURE 19.?General geology of region surrounding the
Alboran Sea-Strait of Gibraltar region. Note general sym-
metric distribution of stratigraphic terrains around the Al-
boran Basin, including position of ultramafic rocks (Ronda
and Beni Bouchera) on opposite margins. (1, Predominantly
Paleozoic sedimentary, granitic, and metamorphic terrain of
the Meseta. 2, Mesozoic and Tertiary zones of transitional
depth clastic and carbonate deposition. 3, Mesozoic subbetic
deep water carbonate, marl, and volcanic rocks; intrarif sandy
flysch. 4, Spanish Rondaides and Moroccan Chaine Calcaire-
Mesozoic carbonate rocks with Alpine-type facies in the
Triassic. 5, Cretaceous and Tertiary sandy flysch. 6, Spanish
Betic and Moroccan Paleozoic zones; Paleozoic geosynclinal
clastic and thin Mesozoic carbonate rocks. 7, Andalusite-
sillimanite low-pressure metamorphic sequences. 8, Ultramafic
rock, including an outcrop near Ceuta. High-pressure meta-
morphic rock with kyanite is exposed in the Sierra Nevada
uplift. Figure and legend after Loomis, 1972, fig. 1.)
is conceivable that these sands may have been con-
veyed directly offshore to this locale during periods
of eustatic low sea level stands in the late Quater-
nary (Huang et al., 1972).
However, our analysis of the modern coastal
sands demonstrates that a predominant transport
from the Serrania de Ronda complex and adjacent
regions directly to the deep sea is unlikely. Our
evidence favors the transfer of Serrania de Ronda
detritus southwestward toward Gibraltar and sub-
sequent funneling to the Western Alboran Basin
through the Gibraltar Canyon and Submarine
Valley (Figure 23), a hypothesis suggested earlier
by Huang and Stanley (1972). The trace of this
transport path is recorded by sands of core 108
(lying 28 km southeast of Europa Point close to
the Gibraltar Submarine Valley) that bear a
marked mineralogic resemblance to the Alboran
Basin sands on the one hand and the coastal sands
of Province D (eastern shore of Gibraltar) on
the other (Figure 5).
It should be noted that other source terrains
and dispersal paths cannot be excluded for the
older, deeper Western Alboran Basin sands. Thus,
derivation from the north African margin and
from the region east of Malaga during earlier
geological periods remains a possibility which
would require further examination and could now
be identified on the basis of mineralogy. We can,
however, exclude as a possible source area the Mo-
roccan margin south of the NE-SW trending
morphological barrier created by the Xauen-
Tofino-Alboran Ridge (Milliman et al., 1972).
In the broader context, the asymmetry of prov-
enance of recent sands of the Western Alboran
Basin plain indicated in this survey is a feature
which at first sight would have been difficult to
predict in view of the marked similarity of the
opposite margins. The relief (Houston, 1964) as
well as the geology of both margins are compar-
able and in certain respects mirror one another
(Figure 19). Both areas are drained by relatively
short, steep rivers flowing seasonally, and the spac-
ing of these streams is similar on both the Spanish
and Moroccan borders. Climatic conditions are
comparable with rain concentrated during the
winter months with 300 to 1400 mm per year on
the Iberian margin (Figure 20) and 400 to 1400
mm per year on the Moroccan side (Jackson,
1961). Rainfall on both margins decreases toward
42 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
GUADALQUIVIR BASIN
MEDITERRANEAN SEA
FIGURE 20.?Map showing rainfall distribution on the southern Spanish margin (contour inter-
val, 100 mm/year). Maximum rainfall (1400 mm/year) occurs in the Sierra de Grazalema
(headwater of the Guadiaro River) and in the Sierra Nevada (1000 mm/year). (Data after
Centro de Estudios Hidrograficos, 1970.)
the east and in zones of lower elevations. It appears
that intensity or river flow, at least on the Iberian
margin, increases substantially toward the west,
suggesting increased fluvial input of sediment in
this sector. Although some major rivers are peren-
nial, the majority are dry during much of the
year (Figure 21). Snow melt derived from moun-
tainous regions of the Sierra Nevada and the Rif
may provide additional increments of sediment
during the late winter and spring. Winds also are
seasonally variable in both intensity and direction,
but the strongest and most persistent aeolian trans-
port is to be anticipated from the Sirocco, which
is known to convey particles up to sand size (Fig-
ure 22) well offshore from the Moroccan coast
(Ericksson, 1961).
The morphological symmetry of both margins
of this part of the Mediterranean is further re-
flected in the submarine topography; narrow
shelves (approximately 10 km wide to the 200 m
isobath) leading to relatively smooth slopes of
comparable gradients (less than 6?). Coastal cur-
rents also reflect this symmetry, showing a predomi-
nant westerly trend along both Moroccan and
Iberian coasts* (Figure 11).
Despite these resemblances, this mineralogical
study has enabled us to define the source and com-
plex dispersal path of a deep-sea turbidite sand
deposited in the intervening basin. The geometry
of this and older sand bodies in the Western Albo-
ran Basin plain, as determined by high-resolution
subbottom surveys, had previously been defined
(Bartolini et al., 1972) and a general input from
the northwest postulated (Stanley et al., 1970).
Moreover, a plausible source terrain of these sands,
the Serrania de Ronda lying to the northwest, has
* It is noteworthy that predominant nearshore currents
trend toward the west in the Western Alboran Sea in spite
of the fact that the main direction of surface flow is to the
east. This less saline surface and near-surface water mass,
originating in the Atlantic, apparently produces large-scale
jetlike eddies as it enters the Mediterranean east of Gibraltar
(Gaibar-Puertas, 1967; Lucayo, 1969; Lanoix, 1974). Our
study suggests that these eddies entrain a clockwise flow of
water along the Moroccan margin and a counterclockwise
movement along the Spanish coast.
NUMBER 15 43
FIGURE 21.?Photographs showing typical river beds which are dry during most of the year.
Upper: Rambla de Albunol, north of la Rabita and Punta Negra on the Spanish margin.
Lower: mouth of Oued Ouringa, at Pointe des Pecheurs on the Moroccan coast. (Note coarse
bed load moved during flood stage.)
44 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
been identified on mineralogical ground (Bartolini
et al., 1972; Huang and Stanley, 1972). The present
study has refined these earlier surveys by enabling
the complex transport path from source terrain to
coast, through the nearshore zone and thence to
the deep basin, to be defined by means of sediment
composition.
Most previous heavy mineral studies of modern
sediments in enclosed marine basins have been
concerned either with relatively shallow areas, in
which depositional processes differ greatly from
those operative in the Alboran Sea (van Andel
and Postma, 1954), or with deeper basins differing
in important morphological respects from the
present study area. Certain of the latter category
differ in possessing bordering areas of low relief
(Baak, 1936; Hsu, 1960; Davies and Moore, 1970),
while others, although bordered by mountainous
regions, receive an important part of their filling
sediment from one end of the elongate trough,
usually from a major deltaic source (van Andel,
1964; Pigorini, 1968).
Our study suggests that there exists yet another
type of elongate basin bounded by regions of high
relief which a priori could supply material of varied
source directly to the adjacent deeps, thus conform-
ing to a multisource basin model (Pettijohn, 1957;
Pettijohn et al., 1973). However, the evidence pre-
sented above suggests that during the recent geo-
logical past, the dispersal patterns within this
basin have been essentially longitudinal, i.e., input
from the western termination. In view of the pos-
sible reversal of currents on the Strait of Gibraltar
(with eastward flowing bottom currents below a
westward surface outflow), it is probable that this
longitudinal transport pattern was reinforced dur-
ing glacial lowstands of the Pleistocent (Huang et
al., 1972).
FIGURE 22.?Sirocco blowing silt and sand seaward on the Moroccan coast near Pointe des
Pecheurs (April 1973).
NUMBER 15 45
Elongate deep marine basins with predominant
longitudinal transport patterns are common in
the geological record. Various interpretations of
the dispersal systems in such troughs, including
elongate flysch basins, have been proposed
(Kuenen, 1958; Pryor, 1961). In geological terms,
our study demonstrates the importance of the
mineralogic changes produced by coastal processes
and the further modification, largely due to size-
sorting, which ensues from downslope transport
to the final site of deposition. Changes induced by
marine transportation appear to have a more pro-
nounced effect on the light mineral fraction, while
even relatively unstable heavy mineral species
(such as orthopyroxene) apparently suffer less
modification. This conclusion must be qualified
for geological purposes by the observation that
many heavy mineral species are susceptible to dia-
genetic alteration and removal (van Andel, 1959).
A further geological implication of our study is
ALBQRAN SEA
PROVENANCE OF
LOWER TURBIDITE SAND
-3d"
-3d1
Contour Interval- 50fm
3O* 5
FIGURE 23.?Summary diagram showing provenance and complex dispersal path of sands that
were deposited as the Lower sand-and-silt layer (Huang and Stanley, 1972) in the Western
Alboran Basin (dark pattern shows extent of this layer in the basin plain?after Bartolini et al.,
1972) at the end of the Pleistocene. These sediments, eroded from the Serrania de Ronda region,
were transported by rivers to the coast between Estepona and Marbella. The sands were
subsequently reworked to the southwest by coastal currents to the Strait of Gibraltar region,
and then downslope toward the southeast by turbidity current through the Gibraltar Submarine
Valley.
46 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
that the path taken by detritus from source terrain
to the final site of deposition may be highly com-
plex and is largely governed by processes active in
the coastal zone, a region seldom preserved in
ancient mobile belts.
Summary
1. This study defines the composition and re-
gional distribution of the major sand-sized light and
heavy mineral groups on the Iberian and Moroc-
can margins of the Alboran Sea, an almost totally
land-enclosed, mountain-bounded basin in the
western Mediterranean.
2. Twenty light and heavy mineral provinces are
identified along the basin margins and these are
broadly concordant with the limits of the major
drainage basins. The concordance emphasizes the
close relationship which exists between the varied
lithology of the mountainous Moroccan Rif and
the southern Iberian Betic margins, and the min-
eral ogical composition of sediments on the adja-
cent coast.
3. Sands in the coastal and fluvial samples can
be related to specific source terrains. Two major
mineralogical sectors (comprising 13 mineralogical
provinces) are recognized on the Spanish margin:
one between Velez-Malaga and Adra, influenced
by the Nevado-Filabride and Alpujarride com-
plexes; the other west of Malaga draining the
ultrabasic rocks of the Peridotite complex. Two
major mineralogical sectors (comprising 7 minera-
logical provinces) are also recognized on the Mo-
roccan margin: one from the Bteni Bouchera
ultrabasic complex to the east, influenced by
Paleozoic, Mesozoic, and Tertiary sediments; the
other north and west of the ultrabasic complex,
draining Paleozoic sediments, metamorphic rocks,
and basic or ultrabasic intrusives.
4. A special study of samples from six rivers in
the western sector of the Iberian margin west of
Marbella shows that river samples closely reflect
the lithology of the terrain traversed. River sam-
ples and samples collected on the coast adjacent
to the appropriate river mouth are broadly com-
parable in composition, attesting to the virtual
direct transport of sediment from source to sea on
aJ] margins oi the Alboran Sea. Differences between
fluvial and coastal samples may be a function of
differing hydraulic processes and also possibly
grain-size factors.
5. That modification of the mineralogy occurs
while the sediment is held in the littoral and near-
shore zone is demonstrated by the nonconcordance
in detail of mineral province boundaries with adja-
cent drainage basin boundaries. The mineralogical
variation from river to river is greater than along
the intervening stretch of coast near the river
mouths. The greater sample-to-sample similarity
along the coast indicates that at least some mixing
and dilution of river supply has occurred at the
coast as a result of longshore current transport.
6. The lateral trends observed within Moroccan
and Spanish coastal mineralogical provinces pro-
vide evidence on the actual sense of nearshore
sediment transport. The mineralogical trends sug-
gesting predominant nearshore transport direc-
tions (movement largely to the west along exten-
sive sectors of both the western Spanish and Mo-
roccan margins) are substantiated by independent
evaluation of coastal current motion and long-
term sediment drift patterns observed from aerial
photographs.
7. Lateral variations in mineralogical trends may
also be partly a function of the increased contri-
bution from coastal outcrops and partly to less
constant coastal drift patterns (area east of Malaga
for example). Furthermore, local coastal morpho-
logical factors and meteorological conditions that
vary seasonally influence the distribution of min-
eral assemblages. These factors, as well as near-
shore currents, operate to concentrate or dissipate
specific minerals of differing size, density, or phys-
ical durability.
8. Several possible interpretations are provided
for the origin of the mineral suites in the coastal
sands of the Bay of Algeciras. However, the present
mineralogic distribution within the Bay conforms
closely to predicted counterclockwise transport
paths.
9. This mineralogical study enables us to define
the source and dispersal of sands to the intervening
deep basin in spite of the geological and geo-
graphic similarities that characterize the opposite
margins of the Alboran Sea. A comparison of sands
collected in cores in the Western Alboran Basin
with sands on the Alboran coastal margins serves
to identify the ultimate source oi late Quaternary
and Holocene sands in the deep basin plain.
NUMBER 15 47
Sources east of Marbella on the Spanish margin
as well as on the Moroccan margin can be pre-
cluded. Heavy minerals indicate that the ultimate
derivation lies in the Serrania de Ronda complex
in the western Betic chain as postulated in earlier
studies.
10. The dispersal path of sands between the
Serrania de Ronda source to deep basin is a com-
plex one. We suggest that detritus was first trans-
ferred southwestward toward Gibraltar by coastal
agents and then subsequently was funneled to the
Western Alboran Basin through the Gibraltar Can-
yon and submarine valley.
11. It appears that mineralogical changes pro-
duced during dispersal by marine processes
have a more pronounced effect on the light
mineral fraction, while even relatively unstable
heavy mineral species apparently suffer less modi-
fication. The implication of this study is that
there is a marked mineralogical evolution of detri-
tus moving between source and deep basin, and
that these changes are largely governed by proc-
esses active in the coastal zone, a region seldom
preserved in ancient mobile belts.
12. In geological terms, the Alboran Sea can
serve as one type of model for sedimentaion in an
elongate, enclosed basin bounded by regions of
high relief. Although this region, a priori, would
conform to a multisource basin model, we show
that the dispersal pattern within the basin has
been essentially longitudinal. Unlike some elongate
basins in the geological record, filling from one
end has been from currents (input at the Strait of
Gibraltar) and not from a major delta point
source.
Appendix
Brief Summary of the Betic Cordillera Source Terrains
The Betic Cordillera, a highly complex moun-
tain chain, can be discussed most readily in terms
of major stratigraphic-structural units. Two major
zones are recognized, i.e., an Internal Zone and
an External Zone. The major units described in
the following sections are depicted in Figure 2.
Internal Zone
The major stratigraphic-tectonic units in the
Internal Zone include the Nevado-Fildbride Com-
plex (unit 2, Figure 2), Alpujdrride Complex,
eastern sector (units 3-7), Casares Unit, Alpujar-
ride, western sector (unit 10). The Maldguide
Complex (units 8 and 12)> Peridotite Complex
(unit 1), and two other units?Sierra Blanca Unit
(unit 9) and Las Nieves Unit (unit 11)?whose
attribution to a specific complex is not clear?are
also included in the Internal Zone.
Nevado-Fildbride Complex.?Rocks of this unit
crop out extensively in the Sierra Nevada and its
prolongation toward the east. It comprises three
tectonic-lithological units.
The Sierra Nevada Series.?Composed largely of
graphite-bearing micaschists (in large part garnetif-
erous) with intercalations of quartzites. Quartz,
sodic plagioclase, garnet, white micas, biotite, tour-
maline, zircon, rutile, and opaque minerals form
the predominant mineral assemblage. Locally,
amphibolites are present and these contain horn-
blende, actinolite, epidote, quartz, mica, and
tourmaline.
The Fildbride Series.?The Filabride Series,
more varied in composition than the one described
above, include micaschist, quartzite, marble, gneiss,
and amphibolite. The micaschists contain the same
minerals as in the Sierra Nevada Series as well as
staurolite, epidote, kyanite, and muscovite. Gneiss
includes quartz, albite, oligoclase, biotite, epidote,
garnet, and chlorite. Amphibolite contains various
amphibole minerals, chlorite, epidote, quartz, mica,
and clinopyroxene.
The Caldera Unit.?This unit contains similar
mineralogical assemblages as those in the Fila-
bride sequence listed above.
Alpujdrride Complex.?This complex includes
strata of Paleozoic and Triassic age. Four major
lithostratigraphic units are recognized.
The Paleozoic formations include micaschist
and quartzite (depicted as unit 3 on Figure 2);
these, in their lower part and toward the west,
change facies and become dolomitic marble with
lenses of amphibolite (unit 4). The micaschist
includes quartz, sodic plagioclase (albite-oligo-
48 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
cla.se), white micas, biotite, and locally (in some
stratigraphic-tectonic nappe units) andalusite,
staurolite, chlorite, chloritoid, garnet, and epidote
(pistacite and zoisite). Dolomitic marble as well
as dolomite include calcic amphiboles (tremolite
and actinolite), feldspars (albite, oligoclase), bio-
tite, muscovite, and phlogopite. Amphibolites,
which appear related to the recrystallized dolo-
mites, include minerals of the type found in the
amphibolites of the Nevado-Filabride Complex
(see above).
The Permo-Werfenian Formations (unit 5) in-
clude lower grade metamorphic phyllites and
quartzites. Quartz, albite, muscovite, chlorite,
tourmaline, and zircon are the most common
minerals.
The Middle and Upper Triassic formations
(limestone and dolomite, partly recrystallized but
without the metamorphic mineral suite (unit 6))
contain metallic sulfides and oxides related to
sedimentary or hydrothermal processes, or both.
Quartz, calcite, fluorite, epidote, and hematite
occur in hydrothermal veins.
Maldguide Complex.?Two lithostratigraphic
units are recognized: a lower one, distinctly meta-
morphic of possible pre-Cambrian age, and an
upper one, consisting of Paleozoic strata (locally,
with a poorly developed Mesozoic-Tertiary cover),
which is essentially sedimentary. The base of the
Pre-Cambrian (?) rocks consists of gneiss and
micaschist. Gneisses dominate the base of the se-
quence; they are leucocratic, containing quartz,
plagioclase, microperthite, microcline, and also
sillimanite, garnet, and low amounts of cordierite.
Above these are found micaschist and micaceous
gneiss with garnet, sillimanite, staurolite, plagio-
clase, and microcline.
The Paleozoic rocks (unit 12, Figure 2), region-
ally, are lithologically extremely variable. Rocks
displaying low-grade metamorphism (phyllites and
micaschists with quartz, white mica, biotite, garnet
and andalusite) occur at the base of the section.
The bulk of the unit comprises sedimentary series,
including flysch-type sequences that have under-
gone considerable diagenesis, but without the for-
mation of metamorphic minerals; interbedded
carbonates are also common. The Permian-Mesozoic-
Tertiary cover, which is only locally preserved,
includes limestone and sandstone.
Peridotite {ultrabasic) Complex.?Ultrabasic
plutonic rocks crop out extensively west of Malaga
and form the Peridotite Complex of the Serrania
de Ronda. In this region are found dunite and
harzburgite and, less frequently, pyroxenite, norite,
gabbro, lherzolite, and websterite. In many places,
these rock types have been partially, or totally,
serpentinized. Dominant minerals are olivine,
orthopyroxene, clinopyroxene, calcic and calco-
sodic plagioclase, apatite, spinel, and opaque
minerals.
Sierra Blanca Unit.?This group of rock types
(unit 9) has been affected by medium to high-
grade metamorphism and is in part similar to the
Casares Unit described below. Marble and gneiss
are dominant, and amphibolites are also locally
present. Marbles are to a large degree totally, or
partially, dolomitized. The biotite gneiss contains
sillimanite, cordierite, and/or andalusite, depend-
ing upon the locality.
Casares Unit.?This group of rock types (unit
10) of the Alpujarride Complex (western sector)
comprises essentially Paleozoic metamorphics
overlain by limestone and dolomite, marbleized,
of Triassic age. The base of this metamorphic
sequence is related to the Peridotite Complex,
their mutual contact being intrusive. From older
to younger, the following types occur: gneiss, rich
in feldspar, cordierite and, locally, garnet; mica-
schist with andalusite, which in its lowest parts con-
tains garnet, staurolite and biotite; phyllite and
quartzite, with similar minerals as those in the
Permo-Werfenian rocks of the Alpujarride Com-
plex (eastern sector); limestone and/or dolomite,
marbleized, similar to the Middle and Upper Tri-
assic of the Alpujarride Complex (eastern sector).
Nieves Unit.?Carbonates of the Upper Triassic
and Lias (unit 11) are assigned to the Internal
Zone by some authors and to the External Zone
by others. Limestone, partially dolomitized, is the
dominant lithology; abundant chert nodules are
present locally.
External Zone
A number of units including the Campo de
Gibraltar, "Flysch" de Colmenar, and the Subbetic
Zone are included in the External Zone. Each of
these sequences can be characterized by specific
lithological criteria; the age of each unit has also
been determined. Three major groups are differ-
NUMBER 15 49
entiated: a detrital red bed fades of Triassic age,
a Jurassic limestone-dominated facies, and a marl-
rich Cretaceous-Paleogene-Lower Miocene sequence.
Triassic Units.?The sediments comprising this
group (unit 13, Figure 2), very different from the
Triassic of the Internal Zone, display a "Germanic
facies" aspect. The predominant lithologies in-
clude variegated clay, marl, and sandstone. Locally
dolomite and ophite are exposed as well as evap-
orite (in particular gypsum and salt). These crop
out in numerous areas and are easily eroded.
Jurassic Units.?Sedimentary rocks of this group
(unit 14) include a highly variable suite of sedi-
ments, and show a great variability in thickness
(Gonzalez-Donoso et al., 1971). The dominant
lithologies include limestone of highly variable
texture and marls and petrologic transitions be-
tween the two. Very locally, there are notable out-
crops of radiolarites and submarine basic volcanics
(pillow lava) intercalated in the Jurassic series.
Cretaceous-Paleogene-Lower Miocene Units.?
This suite of sedimentary rocks (unit 15) includes,
for the most part, marl and marly limestone facies.
There are recognizable lithologic variations that
are related to differences in age, outcrop locality,
and tectonic grouping. A flyschoid facies with
sandstone (includes rocks of different ages) domi-
nates toward the west; toward the east, on the other
hand, marl and limestone intercalations are
common.
Post-Orogenic Sequences
The extensive outcrops of sediments of Neogene-
Quaternary age that fill postorogenic depressions
and recent alluvial basins are designated as Post-
Orogenic Sequences on the map (unit 16). The
most common lithologies of Neogene age are
conglomerates, sandstones, shales, and evaporites.
Limestone and bioclastic rocks also crop out lo-
cally. Quaternary sediments include large volumes
of detrital material of medium to coarse grain size.
Literature Cited
Aldaya, F.
1969. Los mantos alpujarrides al S. de Sierra Nevada. 527
pages. Thesis, University of Granada.
Aldaya, F., and J. A. Vera
1971. Mapa y memoria explicativa de la hoja 83
(Granada-Malaga), del mapa geoldgico 1:200.000 de
Espana. Instituto Geol6gico y Minero de Espafia.
van Andel, Tj. H.
1959. Reflections on the Interpretation of Heavy Mineral
Analyses. Journal of Sedimentary Petrology, 29:
153-163.
1964. Recent Marine Sediments of Gulf of California. In
van Andel, Tj. H., and G. G. Shor, Jr., editors,
Marine Geology of the Gulf of California. American
Association of Petroleum Geologists Memoir 3:216-
310.
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