Early Paleogene deep-water overturning in the South Atlantic - implications from the ODP Leg 208 Walvis Ridge depth transect

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The aim of the proposed project is to reconstruct the circulation of deep- and bottom-water masses in the eastern South Atlantic during the Cenozoic. Particular attention will be laid on the nature and behavior of the deep-water masses during extreme climatic situations and on their response to abrupt environmental and climatic changes in the late Paleocene to early Eocene. This time interval is characterized by short climatic excursions overriding a long-term warming trend. The climatic extremes had a significant impact on the oceans, e.g. a shoaling of the calcite compensation depth (CCD) of more than 2000 m at the Paleocene/Eocene boundary in the Walvis Ridge region. The Paleogene sediments recovered during OOP Leg 208 at Walvis Ridge allow detailed reconstructions of timing and intensity of such perturbations and reorganization of the deep- and bottom water masses over a paleodepth range of more than 2000 m. In our study we will combine sedimentological and clay mineralogical investigations. The current preinvestigations aim in a reconstruction of the long-term trend in the development of the oceanic circulation. They will provide background information on the changes associated with the transitions from an intermediate Paleogene climate to the Eocene greenhouse, the subsequent cooling into the Oligocene icehouse and Miocene cooling events to evaluate the significance of the observed extreme climatic events in the early Paleogene.