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

拟议项目的目的是重建新生代期间南大西洋东部深水和底层水团的循环。将特别注意在极端气候情况下的深水质量的性质和行为，并对他们的反应，在古新世晚期至始新世早期突然的环境和气候变化。这一时间间隔的特点是短期的气候波动压倒了长期的变暖趋势。极端气候对海洋产生了重大影响，例如，在沃尔维斯海岭地区古新世/始新世界线，方解石补偿深度变浅，超过2 000米。在OOP Leg 208在沃尔维斯岭恢复的古近纪沉积物允许详细的时间和强度的扰动和重组的深和底层水体超过2000米的paleodepth范围。在我们的研究中，我们将结合联合收割机沉积学和粘土矿物学的调查。目前的预先调查旨在重建海洋环流发展的长期趋势。他们将提供背景资料的变化与过渡从中期古近纪气候始新世温室，随后冷却到渐新世冰库和中新世冷却事件，以评估在古近纪早期观察到的极端气候事件的意义。

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.