The pre-PETM perspective of transient paleoceanographic events

古近纪早期，海洋生态系统受到了多次短暂的古环境事件（<200 ky）的严重干扰，其中最突出的是古新世-始新世热盛期（PETM，~56 Ma）。在这些事件中，同位素轻碳注入海洋/大气系统，导致每百万人中负碳同位素偏移>1，温度大幅上升，生物群和海洋化学发生变化。迄今为止，在深海中对最早的两个事件，“最新的达尼事件”（LDE，~ 61.75Ma）和“中古新世生物事件”（MPBE，58.9Ma）的研究很少。在这个项目中，我们研究了南极生态系统对这些扰动的响应。我们测试这些事件是否在全球范围内表示，如果它们可以在各种不同的环境设置中被跟踪。浮游有孔虫组合从几个ODP的网站，包括大西洋，太平洋和印度洋，以及在埃及大陆架沉积物进行定量评估和统计分析。动物群分析得到有孔虫稳定同位素研究（碳和氧同位素）的补充，以重建当时的古海洋学条件。这也将允许建立一个高分辨率的化学地层记录，补充生物地层的晚Danian到Selandian间隔。最后，粘土矿物学预计将表明气候驱动的风化条件在邻近大陆和无机地球化学的变化是用来详细的氧化还原状态的海洋伴随着研究的事件。该项目是与KU Leuven密切合作进行的，在那里对以底栖有孔虫为代表的底栖生态系统进行了相同样本的研究，以评估这些事件对整个水柱的影响。

The marine ecosystem has been severely disturbed by several transient paleoenvironmental events (<200 ky) during the early Paleogene, from which the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) is the most prominent one. During these events the injection of isotopically light carbon into the ocean/atmosphere system resulted in a >1 per mil negative carbon isotope excursion, a substantial temperature rise as well as changes of the biota and in ocean chemistry. Until now two of the earliest events, the "Latest Danian Event" (LDE, ~61.75 Ma) and the "Mid-Paleocene Biotic Event" (MPBE, 58.9 Ma) have rarely been studied in the deep-sea. In this project we investigate the response of the planktic ecosystem to these perturbations. We test if these events are represented on a global scale and if they can be traced in various distinct environmental settings. Planktic foraminiferal assemblages from several ODP sites covering the Atlantic, Pacific and Indian oceans as well as from shelf deposits in Egypt are quantitatively assessed and statistically analyzed. Faunal analyses are supplemented by foraminiferal stable isotope studies (carbon and oxygen isotopes) to reconstruct the prevailing paleoceanographic conditions. This will also allow for establishing a high-resolution chemostratigraphic record complementing the biostratigraphy for the late Danian to Selandian interval. Finally, clay mineralogy is expected to indicate climate driven changes in weathering conditions on the adjacent continent and inorganic geochemistry is used to detail changes in the redox state of the oceans accompanying the studied events. The project is carried out in close co-operation with the KU Leuven, where the benthic ecosystem as represented by benthic foraminifera is studied on the same samples to assess the impact of these events on the entire water column.