Mid to Late Pleistocene variations of marine productivity in and terrigenous input to the southeast Atlantic.

Abstract

During Ocean Drilling Program (ODP) Leg 175, the Sites 1075, 1077, and 1082 were drilled off the westem coast of Africa (Congo and Namibia). The goal was to reconstruct the Pleistocene history of theAngola-Benguela Current system (ABC-system) between about 5°S and 22°S. The investigated area is one of the five largest continental margin upwelling systems in the world, with analogues off Peru, California, northwest Africa and in the northeastem Arabian Sea. The ABC-system is characterized by organic-rich sediments that yield an outstanding record of productivity history. One major goal of the present work is to document fluctuations in marine productivity and terrigenous input in relationship to large-scale climate changes within the Pleistocene, including the onset of the mid-Pleistocene Revolution (MPR) associated to Northern Hemisphere glaciation. The MPR covers the transition from the dominant 41 k.y.-cycle of obliquity during the mid-Pleistocene to the dominant 100-k.y. cycle of eccentricity during the late Pleistocene, that has been observed in many marine paleoclimatic records.