Paleo-environmental effects of the mid-pleistocene transition in the tropical Atlantic and equatorial Africa

Abstract

This thesis describes the environmental changes in the eastern tropical Atlantic and equatorial Africa during the Mid-Pleistocene Transition (MPT) as revealed by analyses of lipid biomarkers and their stable carbon isotope compositions. The MPT was the start of the Late Pleistocene ice ages, with an enlarged mean global ice volume varying in a predominant 100-kyr cyclicity. Before the MPT, global ice volume was, on average, smaller and had a prevalent 41-kyr cyclicity. The increase in mean global ice mass around 920 kyr BP significantly preceded the establishment of the 100-kyr cycle at 640 kyr 8P. A pronounced effect of the MPT was the temporary severe decrease of the Atlantic deepwater ventilation, caused by the strongest reductions of North Atlantic Deep-Water formation in the last 2.5 million years.