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

本项目将比较研究大西洋和太平洋地区中-晚中新世碳酸盐碰撞事件的成因、发展、演化和终止。提出了不同的假设来解释这些事件，例如：(1)与NADW形成的开始和/或加强以及随后的生产方式转变有关的深水循环的变化；(2)高山脉的隆起和巨大河流排水系统的发展引起的海洋陆源沉积物供应的总体变化；(3)大陆边缘上升流系统的启动和由此导致的非洲大陆沙漠扩张所引起的海洋碳酸盐系统的扰动；(4)中新世至上新世期间生态条件和/或浮游植物和动物的演化的变化，导致碳酸盐浓度的变化以及球岩体和浮游有孔虫的不同贡献。为了验证这些潜在原因的不同假设，我们研究了碳酸盐和陆源通量率，并确定了沿Cearä Rise深度穿越的碳酸盐保存和古底部电流强度，并将结果与大西洋和太平洋其他关键地点的记录进行了比较。

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.