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.

中新世，即距今5.33至2303万年的地球历史时期，现代海洋温盐环流的演变伴随着全球海洋化学和大陆气候的根本变化。 碳酸钙含量急剧且反复减少是当时赤道太平洋和赤道大西洋中上层沉积物序列的特征。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），如果不减少温室气体排放，二氧化碳水平甚至与 2100 年的预测一样高。 尽管进行了大量研究，但人们对中新世赤道太平洋和赤道大西洋之间事件的确切顺序及其因果关系知之甚少。 造成这种困境的原因是这两个地区缺乏同步的高精度天文年龄模型。 在本项目中，我们打算通过在海洋钻探计划 (ODP) 第 154 段期间从 Ceara Rise 取回的沉积物生成天文校准的赤道大西洋高分辨率深海底栖同位素参考曲线来改变这种情况，跨越从 5 到23马。 来自赤道太平洋的底栖稳定同位素记录（IODP Exp. 320/321）将完成，然后与拟议的整个中新世 Ceara Rise 底栖参考曲线同步。 同步底栖稳定同位素记录与该项目中为塞阿拉海隆沉积物生成的 X 射线荧光岩心扫描数据相结合，将能够对赤道太平洋和赤道大西洋之间碳酸盐积累的变化与不断演变的现代海洋环流模式的关系获得前所未有的详细了解。 特别是，利用该项目的新数据，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、是否存在超前和滞后、哪个轨道周期在什么时期占主导地位、如果变化是否同步等问题。两个区域的碳酸盐质量积累速率是相关的，并且米兰科维奇时间尺度上碳酸盐补偿深部的变化在赤道太平洋和大西洋之间是同相还是反相。