Quaternary accumulation rates of biogenous and terrigenous components on the east Atlantic continental slope off NW Africa

Abstract

Accumulation rates of total sediment, CaCO 3, non-carbonaceous material, planktonic foraminifers, radiolarians, total benthos and five different benthonic components have been calculated for Holocene sections of fifteen cores from the east Atlantic continental slope off NW Africa. Würm and Eem accumulation rates were obtained from five cores. Accumulation rates of all components decrease with increasing water depth in a profile off the Sahara. Off Senegal, this is only true for benthonic foraminifers. The upper continental slope off the Sahara has higher accumulation rates of carbonate and of all biogenic particles than that off Senegal, probably due to stronger upwelling influence. Accumulation rates of total sediment and of insoluble material, however, are higher off Senegal because of supply of terrigenous mud from the Senegal river. During the Würm, accumulation rates of terrigenous material north of 20° N increased by a factor of 2–4, due to a change from arid to humid climate. Accumulation rates of CaCO 3 and planktonic foraminifers increased only slightly. An important increase was found for radiolarians and benthonic organisms in these cores, probably due to strongly increased upwelling influence during the Würm. Eem accumulation rates are similar to or slightly higher than those of the Holocene.