ABSTRACT

Mineral distributions in surface sediments of the Arabian Sea (north of 5°N) reflect several sedimentary origins and processes. Smectite- and quartz-rich sediments occurring along the Indian margin have been derived from the western regions of peninsular India. In the northern- and western-most areas of the Arabian Sea, sediments probably have been derived from several sources: Indus River, Iran-Makran region, Arabian peninsula, and Somalia; these different sediment sources appear to have characteristically high amounts of quartz, illite, chlorite, or palygorskite. In addition, smectite becomes a significant component in the sediments off Somalia (Horn of Africa). The sediments derived from the peninsular India and Indus River may have been dispersed by prevailing surface oceanic irculation in the region. Sediments from other sources probably have been transported by wind. The sediments of the distal Indus Fan appear to be a mixture of sediments derived from the Indus River, Iran-Makran, and Arabia-Somalia regions. Palygorskite clays from the arid regions of Arabia-Somalia appear to have been transported by winds eastward to as far as the Indian continental margin. In the southernmost region of study, relatively high kaolinite, derived from the tropical soils of Africa, Madagascar, and southern India characterize the sediments.