The impact of the Miocene Carbonate Crash in the Atlantic and Pacific: Evidence from carbonate budgets and silt grain size studies

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In the current project causes, development, evolution and termination of the Middle to Late Miocene carbonate crash events in the Atlantic and Pacific will be studied comparatively. Different hypothesis to explain these events were postulated, e.g. (1) changes in deep water circulation connected with the Initiation and/or strengthening of NADW formation and subsequent shifts in its production modes, (2) changes in overall terrigenous sediment supply to the ocean caused by the uplift of high mountain ranges and the development of huge river drainage Systems, (3) perturbations of the oceanic carbonate System induced by the Initiation of the continental margin upwelling Systems and the resultant expansion of deserts on the African continent, and (4) changes in the ecologic conditions and/or the evolution of the phytoand Zooplankton during the Middle Miocene to Pliocene that were responsible for shifts in the carbonate concentrations and for variable contributions of coccoliths and planktic foraminifers. To test these different hypothesis of potential causes we study carbonate and terrigenous flux rates and determine carbonate preservation and paleo-bottom current intensities along depth traverses at Cearä Rise and compare the results with records from other key locations in the Atlantic and Pacific.