Comparing changes in regional response to orbital forcing in the Equatorial Pacific and Atlantic during the Miocene

中新世是距今533万年至2303万年的地球历史时期，伴随着全球海洋化学和大陆气候的根本变化，现代海洋热盐环流开始演变。当时赤道太平洋和赤道大西洋中上层沉积物序列的特征是碳酸钙含量急剧和反复减少。大气中的二氧化碳与今天的相似。在中新世气候最佳期（13.9 ~ 17 Ma），如果不减少温室气体排放，二氧化碳水平甚至会暂时达到2100年的预测水平。尽管进行了大量的研究，但中新世赤道太平洋和赤道大西洋之间事件的确切顺序以及它们之间的因果关系却知之甚少。造成这种困境的原因是缺乏一个同步的高度精确的天文年龄模型。在这个项目中，我们打算通过生成一个天文校准的高分辨率深海底栖生物同位素参考曲线来改变这种情况，该曲线是在海洋钻探计划（ODP）第154条（Leg 154）期间从Ceara Rise获取的沉积物中获得的，时间跨度为5至23 Ma。将完成赤道太平洋底栖生物稳定同位素记录（IODP Exp. 320/321），然后与提出的整个中新世的Ceara Rise底栖生物参考曲线同步。同步底栖生物稳定同位素记录结合该项目生成的Ceara Rise沉积物的x射线荧光岩心扫描数据，将使我们能够前所未有地详细了解赤道太平洋和赤道大西洋之间碳酸盐岩聚集变化与现代海洋环流模式演变的关系。特别是，通过本项目的新数据，我们将能够解决太平洋和大西洋碳酸盐岩聚集的剧烈变化是否同步，是否存在领先和滞后，哪个轨道周期在哪个时期占主导地位，两个地区碳酸盐岩质量聚集速率的变化是否有联系，以及赤道太平洋和大西洋之间米兰科维奇时间尺度上碳酸盐岩补偿深度的变化是同相还是反相的问题。

During the Miocene, the period in Earth's history from 5.33 to 23.03 million years ago, the modern ocean thermohaline circulation evolved accompanied by fundamental changes in global ocean chemistry and continental climate. Drastic and repeated reductions of calcium carbonate contents characterize pelagic sediment sequences in the equatorial Pacific and equatorial Atlantic at that time. Atmospheric CO2 was similar to today. Temporarily, during the Miocene Climate Optimum (13.9 to 17 Ma), CO2 levels were even as high as predicted for the Year 2100 if greenhouse gas emissions will not be reduced. Despite numerous studies the exact sequence of events in the Miocene between equatorial Pacific and equatorial Atlantic as well as their causal relationship is poorly understood. Reason for this dilemma is the lack of a synchronized highly accurate astronomical age model for both regions. In this project, we intend to change this situation by generating an astronomically calibrated high-resolution deep-sea benthic isotope reference curve for the equatorial Atlantic on sediments retrieved from Ceara Rise during Ocean Drilling Program (ODP) Leg 154 spanning the interval from 5 to 23 Ma. Benthic stable isotope records from the equatorial Pacific (IODP Exp. 320/321) will be completed and then synchronized with the proposed Ceara Rise benthic reference curve for the entire Miocene. Synchronized benthic stable isotope records combined with X-ray fluorescence core scanning data generated in this project for Ceara Rise sediments will allow an unprecedented detailed view on changes in carbonate accumulation between equatorial Pacific and equatorial Atlantic in relation to the evolving modern ocean circulation pattern. In particular, with the new data of this project we will be able to solve the questions if drastic changes in carbonate accumulation in the Pacific and Atlantic are synchronous, if there are leads and lags, which orbital cycles dominate in what period, if changes in carbonate mass accumulation rates in both regions are connected, and if changes in the Carbonate Compensation Deep on Milankovitch time scales are in-phased or anti-phase between equatorial Pacific and Atlantic.