Wind-Borne Deposits in the Northwestern Indian Ocean: Record of Holocene Sediments Versus Modern Satellite Data

Abstract

A study of deep sea cores shows that eolian dust plumes from Arabia dominate the Holocene non-turbiditic lithogenic sedimentation in the northwestern Indian Ocean; fluvial supply controls only the proximal deposition near India, off Kenya, and off Oman, where also the suspension load of the intermediate water from the Persian Gulf is added. A survey of modern dust outbreaks as depicted on satellite images from 1979 was used to calibrate the paleoclimatic and paleometeorological record of lithogenic sediment accumulation in the deep sea. Dolomite, chlorite and illite-rich sediments mark the dispersal of Shamal wind-borne dust from the Persian Gulf and Gulf of Oman. Palygorskite and kaolinite are linked to the dust outbreaks from and near the Gulf of Aden. The outer margin of the steep gradient of dust accumulation rates, which runs from the Horn of Africa to India near 20 o N, parallels the position of the southwesterly low-level Somali Jet. The average of annual dust accumulation in the Arabian Sea during the last 8000 years amounted to about 100 *10 6 t y-l. This number compares well with a transcoastal dust flux of 115 to 215 *10 6 t y-l derived for 1979 from satellite images.