Establishing the Pattern of Holocene-LGM Changes in Sediment Contributions from Antarctica to the Southern Ocean

0088054戈尔茨坦该奖项由极地项目办公室南极地质和地球物理项目提供，支持一个调查南大洋沉积物岩心进行古环境研究的项目。极地地区易受气候变化的影响最大，也是地球上最难进入的地方之一。目前对南极西部冰盖不稳定性的关注提高了人们对极地地区脆弱性的认识。该提案旨在基本了解全新世和末次盛冰期来自南极洲的陆源沉积物来源的同位素特征及其向南大洋的扩散。陆源碎屑沉积物通过河流、冰和风从大陆源带到海洋，并通过表层和深层洋流分布在海洋中。目前，除了大西洋部分的一些锶（Sr）同位素比值外，几乎没有关于环极碎屑的同位素数据。该项目将填补部分空白。从南极洲地壳区地质年龄的大幅度变化，我们可以预测，大陆周围的碎屑有很大的同位素差异。主要目的是（1）表征锶钕铅氩合金（2）通过对南极沉积物中角闪石和长石的单颗粒分析，结合体相同位素分析，确定主要冰筏碎屑（IRD）的组成和物源年龄;（3）全新世和末次盛冰期沉积物向南极绕极流（ACC）扩散的追踪研究。因此，它将为未来的研究提供一个基本的数据库。尽管如此，仍有一些重要的假设驱动的问题将在这一初级阶段得到解决。北大西洋IRD研究中的经验教训能否应用于了解南极冰盖的历史？南极边缘周围的巨大地质变化是否可以被视为一系列注入ACC的天然示踪剂，从而描述其轨迹，速度以及与当今和过去其他电流系统的相互作用？这项研究的动机是一组令人兴奋的结果，从南大西洋，碎屑锶同位素比值是一个敏感的电流示踪剂在该地区。如果使用长寿命放射性同位素（Sr-Nd-Pb-Ar）作为海洋沉积物来源的示踪剂成功地阐明了与气候条件变化有关的过程，这项研究应满足许多地球科学学科的基本需要。这项研究的结果将填补我们对地球上一个重要区域的认识的基本空白。与此同时，它将为在LGM期间尝试重建ACC以及未来研究南极地质，冰盖历史和南大洋环流提供必要的基础。

0088054GoldsteinThis award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a project to investigate the sediment core from the Southern Ocean for paleoenvironmental research. The polar regions are susceptible to the largest changes in climate and are among the least accessible places on Earth. Current concern about the instability of the West Antarctic Ice Sheet has heightened awareness of the vulnerability of polar regions. This proposal seeks to gain a basic understanding of the isotopic characteristics of terrigenous sediment sources derived from Antarctica in the Holocene and Last Glacial Maximum, and their dispersal into the Southern Ocean. Terrigenous clastic sediments are brought to the ocean from continental sources via rivers, ice and wind, and distributed within the ocean by surface and deep currents. At present there are virtually no isotopic data on circumpolar detritus, save a few strontium (Sr) isotopic ratios in the Atlantic sector. This project will fill part of this gap. From the large range in geological ages of crustal provinces of Antarctica, we would predict that there are large isotopic differences in detritus around the continent. The main objectives are to (1) characterize the strontium-neodymium-lead-argon (Sr-Nd-Pb-Ar) isotope compositions of sediment sources derived from Antarctica, (2) to identify the composition and source ages of major ice rafted detritus (IRD) contributions by analyzing individual grains of hornblende and feldspar in conjunction with bulk isotopic analysis, and (3) track sediment dispersal into the Antarctic Circumpolar Current (ACC) during the Holocene and Last Glacial Maximum.Because of the paucity of circumpolar data, this research necessarily has a large exploratory component. Consequently, it will provide a basic database for future studies. Nevertheless there are important hypothesis-driven questions that will be addressed in this primary pass. Can lessons learned in North Atlantic IRD studies be applied toward understanding the history of Antarctic ice sheets? Can the large geological variability around the Antarctic margin be treated as a series of natural tracer injections into the ACC, and thus characterize its trajectory, speed, and interaction with other current systems today and in the past? The proposed study is motivated by an exciting set of results from the South Atlantic, showing that detrital Sr isotope ratios are a sensitive current tracer in that region. This research should serve a basic need across many Earth Science disciplines if the use of long-lived radiogenic isotopes (Sr-Nd-Pb-Ar) as tracers of marine sediment sources is successful in elucidating processes related to changing climatic conditions. The results of this study will fill a basic gap in our knowledge of an important region of the Earth. At the same time, it will provide an essential basis for attempting reconstruction of the ACC during the LGM, as well as for future studies of Antarctic geology, ice sheet history, and the Southern Ocean circulation.