Oceanic circulation modes of the Glacial-Interglacial cycle - high resolution measurements of Neodymium isotopes on Atlantic IODP/ODP sediment cores.

冰期-间冰期循环的海洋环流模式 - 大西洋 IODP/ODP 沉积物核心上的钕同位素的高分辨率测量。

基本信息

批准号：
242773409
负责人：
Professor Dr. Norbert Frank
金额：
--
依托单位：
Institut für Umweltphysik
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/242773409?language=en
关键词：
Oceanic circulation modes Glacial Interglacial

项目摘要

It is supposed that in the global interplay of hemispheres either the deep water production in the North or in the South Atlantic dominated, having direct and significant influence on the heat budget of the respective hemisphere. Although great efforts have been undertaken in order to reconstruct the past of the extremely climate relevant Atlantic Ocean, it has so far not been possible to identify the role of the ocean circulation as cause or consequence of the in part dramatic climate fluctuations which have taken place in the past 100,000 years. The branch of research considering these questions, the palaeoceanography, faces two essential problems here: On the one hand , the methods used often have weaknesses and limited applicability, especially tracers which take part in the nutrient cycle and are subject to diagenetic processes. On the other hand the temporal and spacial coverage of existing measurements allows only for limited conclusions which may deliver local information which cannot be extrapolated to a global scale. In order to come to reliable results about the oceanic past of heat transport and the distribution of carbon and nutrients it is necessary to collect a high amount of data. The material provided from the IODP/ODP core repositories represents a unique fundament for this work. In the younger past the measurement of the neodymium isotope ratio 143Nd/144Nd emerged as method of choice. The distinct isotopic signatures of water masses originating in the Pacific and the North Atlantic Deep Water render neodymium a unique tracer for the ocean circulation in the Atlantic. The neodymium signature and with it the mixing ratio of the prominent water masses in the past is preserved in ferromanganese accretions in the sediment. The appraoch of careful separation of these accrections from the bulk sediment and the subsequent measurement of their neodymium isotopy serves as a methodology which is, applied on a large scale, uttermost promising. It is applicable wherever there are cores available, it is reliably measurable with modern standard mass spectrometers and the chemical treatment of the sample material is relatively fast and cost-efficient, if the respective experience and the knowledge of the chemical work steps exist. Therefore, using selected IODP/ODP cores the question of the timings of water mass transitions in the Atlantic shall be pursued. It shall be clarified how fast these transitions took place and in which global climatological phase which circulation pattern was prominent. With the aid of box models and the comparison with further tracers (231Pa/230Th, d13C) a comprehensive image of the past glacial-interglacial cycle shall be drawn, allowing inference of the crucial feedback effects and interactions in the climate system, which are directly necessary for the improvement and validation of climate models.

据认为，在半球的全球相互作用中，北部或南大西洋的深水产量占主导地位，对各个半球的热预算有直接而重大影响。尽管为了重建极度气候相关的大西洋的过去而付出了巨大的努力，但到目前为止，迄今无法将海洋循环的作用确定为过去100,000年发生的戏剧性气候波动的部分原因或结果。考虑这些问题的研究分支，古生物学，在这里面临两个基本问题：一方面，所使用的方法通常具有弱点和有限的适用性，尤其是参与营养循环并受到成岩化过程的示踪剂。另一方面，现有测量值的时间和空间覆盖范围仅允许有限的结论，这些结论可能会提供无法推断到全球规模的本地信息。为了获得有关热传输的海洋过去以及碳和养分的分布的可靠结果，有必要收集大量数据。 IODP/ODP核心存储库提供的材料代表了这项工作的独特基本原理。在过去的年轻人中，同位素比率143/144nd的测量成为选择方法。源自太平洋和北大西洋深水的水质的独特同位素特征，使近代成为大西洋海洋循环的独特示踪剂。过去的临后象征及其过去的混合比在沉积物中的铁龙甘甘群积聚中保存。仔细分离这些收入与散装沉积物的评估以及随后的肾上飞机同位素的测量方法是一种方法，该方法是在大规模上应用的，最有前途的方法。它适用于有核心的任何可用核心，可以可靠地测量现代标准质谱仪，如果相应的经验和化学工作步骤的知识，则样品材料的化学处理相对较快且具有成本效益。因此，应使用选定的IODP/ODP核心提出大西洋水质量过渡时机的问题。应阐明这些过渡发生的速度以及在哪个全球气候阶段，哪些循环模式突出。借助框模型以及与其他示踪剂（231Pa/230th，d13c）的比较，应绘制过去的冰川间间流循环的全面图像，从而推断气候系统中关键的反馈效果和相互作用的推断，这是气候模型的改进和验证气候模型所必需的。