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

比较中新世期间赤道太平洋和大西洋对轨道强迫的区域响应变化

• 批准号: 446583469
• 负责人: Dr. Thomas Westerhold
• 金额: --
• 依托单位: College of Earth, Ocean, and Atmospheric Sciences
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/446583469?language=en
• 关键词: Comparing; changes; regional; response; orbital

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.

在中新世，即533万年前至2303万年前的地球历史时期，现代海洋温盐环流伴随着全球海洋化学和大陆气候的根本变化而演变。 当时赤道太平洋和赤道大西洋的中上层沉积序列的特点是碳酸钙含量的急剧和反复减少。大气中的二氧化碳含量与今天相似。 暂时而言，在中新世气候最佳时期（13.9至17 Ma），如果温室气体排放量不减少，CO2水平甚至与2100年的预测一样高。 尽管有许多研究，赤道太平洋和赤道大西洋之间的中新世事件的确切顺序以及它们之间的因果关系仍然知之甚少。 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为这两个地区。 在这个项目中，我们打算改变这种情况，通过生成一个天文校准的高分辨率深海海底同位素参考曲线的赤道大西洋的沉积物检索从塞阿拉上升在大洋钻探计划（ODP）腿154跨度从5到23马。 赤道太平洋海底稳定同位素记录（IODP Exp. 320/321），然后与整个中新世拟议的塞阿拉海隆海底参考曲线同步。 同步的海底稳定同位素记录结合X射线荧光岩心扫描数据在这个项目中产生的塞阿拉隆起沉积物将允许一个前所未有的详细了解之间的变化，在赤道太平洋和赤道大西洋之间的碳酸盐积累与不断演变的现代海洋环流模式。 特别是，通过该项目的新数据，我们将能够解决太平洋和大西洋碳酸盐积累的剧烈变化是否同步的问题，是否有超前和滞后，哪个轨道周期在哪个时期占主导地位，如果两个地区碳酸盐质量积累率的变化是相关的，在米兰科维奇时间尺度上，赤道太平洋和大西洋碳酸盐补偿深度的变化是否同相或反相。