Abstract

The closing of the remnant ocean basin between India and Asia has produced the uplifted gneissic, sedimentary, and metasedimentary terrane of the western Himalayas. Sediment derived from this source is presently being deposited in the submarmefan and basin-plain complex of the Indus Cone and Arabian Abyssal Plain, the location of DSDP sites 221,222, and 224. Point-counts of 15 Cenozoic sand samples from these sites have mean QFL percentages of 43-30-27. The plagioclase/total-feldspar mean is 0.66. Lithic types are dominated by quartz-mica tectonite, argillite-shale, polycrystalline carbonate, and other sedimentary and metasedimentary varieties. Volcanic grains present are mainly felsic. These sands resemble those of the Bengal and Nicobar Fans, which were also derived from the Himalayas. These plus other sands derived from collision orogenic belts have a distinctive signature: P/F close to 0.66; Lv/L low, 0.10 or less; and Q dominant, with F and L subequal.

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