Collaborative Research: Development of a Suite of Proxies to Detect Past Collapse of the West Antarctic Ice Sheet

西南极冰盖(WAIS)的崩塌可能会使全球海平面以每世纪约1米的速度上升3米，产生重大的社会影响。这个项目的目标是确定这种坍塌是否发生在最近的过去。这将包括开发新的地球化学工具来评估WAIS周围的沉积地质记录，以评估WAIS在过去暖期的行为。研究小组将开展的主要活动是：1)表征从WAIS不同部分排放的沉积物的化学和磁性，并利用这些性质来提取指纹？来自大陆不同来源的输入；2)测量海洋沉积物岩芯中的这些相同特性，以记录过去150,000年来WAIS的重大变化。确定WAIS在最近的过去是否崩溃，可以提供关于WAIS未来可能变得不稳定的重要信息。然后，这里将要开发的工具可以用于WAIS周围的较旧记录，以检查过去冰盖不稳定的频率。该项目将支持一名博士后研究员和本科生。该项目将开发沉积物来源代理，以追踪从西南极冰盖(WAIS)排放到大陆隆起的沉积物来源。需要解决的具体问题是：1)不同WAIS地体的沉积物可以在多大程度上进行地球化学和磁分异；2)地体物源代理探测WAIS晚第四纪坍塌的能力。WAIS侵蚀了来自各种西南极地质地体的沉积物，这些沉积物沉积在邻近的漂移地点。漂移沉积物的地球化学和磁学性质反映了其源岩的构造和变质历史。大陆隆起碎屑沉积中的S地体的地球化学和磁学特征的丧失，应该可以检测到大陆隆起崩塌过程中地体的解冰作用。来自当前WAIS基准线附近的大陆架晚全新世沉积物将被分析粉砂和粘土大小的锶-钕-铅同位素、磁性和主要微量元素。这套岩心包括罗斯海东部到南极半岛北端，并将建立罗斯省和阿蒙森省玛丽·伯德陆地、松岛湾、瑟斯顿岛/八海岸地块、埃尔斯沃斯-惠特莫尔地壳地块和南极半岛地体的物源特征。这些地体中的许多具有相似的构造和变质历史，但来自碎屑沉积物的锶-钕同位素数据表明，至少有3个明显的物源特征。将对位于别林豪森海的大洋钻探计划地点1096进行初步岩心研究，以检测WAIS在上一次间冰期是否不稳定。

Collapse of the West Antarctic ice sheet (WAIS) could raise global sea level by up to 3 meters, at a rate of up to ~1 meter per century, yielding major societal impacts. The goal of this project is to determine if such a collapse occurred in the recent past. This will include development of new geochemical tools to evaluate the sedimentary geologic record around the WAIS to evaluate WAIS behavior during past warm periods. The primary activities to be carried out by the research team are to: 1) characterize the chemistry and magnetic properties of sediments being discharged from different portions of the WAIS and use these properties to ?fingerprint? inputs from different sources on the continent; 2) measure these same properties in a marine sediment core to document major changes in the WAIS over the last 150,000 years. Determining if the WAIS has collapsed in the recent past can provide important information on WAIS potential to grow unstable in the future. The tools to be developed here can then be used on older records around the WAIS to examine the frequency of ice sheet instability in the past. The project will support a postdoctoral researcher as well as undergraduate students. This project will develop sediment provenance proxies to trace the sources of sediment discharged by the West Antarctic Ice Sheet (WAIS) to the continental rise. Specific questions to be addressed are: 1) the degree that sediment from different WAIS terranes can be geochemically and magnetically differentiated; 2) the ability of terrane provenance proxies to detect WAIS collapse in the late Quaternary. The WAIS erodes sediments from various West Antarctic geologic terranes that are deposited in adjacent drift sites. The geochemistry and magnetic properties of drift sediments reflect the tectonic and metamorphic history of their source terranes. Deglaciation of a terrane during WAIS collapse should be detectable by the loss of the terrane?s geochemical and magnetic signature in continental-rise detrital sediments. Continental shelf late-Holocene sediments from near the current WAIS groundling line will be analyzed for silt- and clay-size Sr-Nd-Pb isotopes, magnetic properties, and major-trace elements. The suite of cores includes the eastern Ross Sea to the northern tip of the Antarctic Peninsula and will establish provenance signatures of the Ross and Amundsen Provinces of Marie Byrd Land, Pine Island Bay, Thurston Island/Eight Coast Block, Ellsworth-Whitmore Crustal Block, and Antarctic Peninsula terranes. Many of these terranes have similar tectonic and metamorphic histories but Sr-Nd isotope data from detrital sediments suggest at least 3 distinct provenance signatures. An initial down core study of Ocean Drilling Program Site 1096 in the Bellingshausen Sea will be conducted to detect if the WAIS was unstable during the last interglacial period.