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Distinctive Properties of Turbiditic and Hemipelagic Mud Layers in the Algéro-Balearic Basin, Western Mediterranean Sea

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dc.contributor.author Rupke, Nicolaas A. en_US
dc.contributor.author Stanley, Daniel Jean en_US
dc.date.accessioned 2006-11-15T20:23:53Z en_US
dc.date.accessioned 2011-03-21T19:47:08Z
dc.date.available 2006-11-15T20:23:53Z en_US
dc.date.available 2011-03-21T19:47:08Z
dc.date.issued 1974-09-10 en_US
dc.identifier.citation Smithsonian Contributions to the Earth Sciences; 13 en_US
dc.identifier.issn 0081-0274
dc.identifier.uri http://hdl.handle.net/10088/829 en_US
dc.description.abstract Two types of mud layers alternate in dominantly muddy cores of the southern Balearic Basin. Type A muds (a few cm to over 50 cm thick), macroscopically homogeneous, occur above turbidite sands or silt laminae. Type B muds (imperceptible to about 50 cm thick), comparatively coarse due to interspersed microskeletons, occur below turbidite sands or silt laminae, and lie above type A muds. The two types are distinguished in X-radiographs on the basis of texture and sedimentary structures. Type A and B mud layers in six cores were sampled at 1 to 8 cm intervals. Type A muds are distribution graded (upward shift of the entire size distribution to finer sizes), continuing the upward grading of the underlying sand turbidites. A granulometric change occurs at the boundary with type B muds which contain sand (to 16 percent), largely tests of forams and pteropod shells. The sand fraction of type A muds (d" 1 percent) differs from that of type B in the proportion of terrigenous constituents and in remains of pelagic forams and of pteropods. Type B muds are not graded; their grain-size distribution is uniform. They have a higher (26 to 46 percent) carbonate content than type A (16 to 39 percent). In some instances, peak-height ratios of clay minerals change across the boundary between type A and type B mud layers. It is concluded that type A muds are turbiditic (deposited instantaneously), while B muds are hemipelagic deposits. Carbon-14 ages were determined on the carbonate sand fraction of type B layers. The ages were plotted against the total sediment thickness above the dated samples in each core. A statistically significant correlation exists. However, when the turbiditic sand and mud layers are omitted and the ages are plotted only against the combined thicknesses of the hemipelagic type B layers, an even stronger correlation is obtained. The hemipelagic rate of sedimentation during the past 16,000 years approximates 10 cm/1000 years. The frequency of turbidity current incursions at a particular core location averages 3 per 2000 years. en_US
dc.format.extent 7802903 bytes en_US
dc.format.mimetype application/pdf en_US
dc.title Distinctive Properties of Turbiditic and Hemipelagic Mud Layers in the Algéro-Balearic Basin, Western Mediterranean Sea en_US
dc.identifier.srbnumber 113536
dc.identifier.doi 10.5479/si.00810274.13.1

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