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

南极西部冰盖（WAIS）的崩塌可能使全球海平面以每世纪高达1米的速度上升3米，从而产生重大的社会影响。该项目的目标是确定最近是否发生过这样的崩溃。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在过去温暖时期的行为。研究小组将进行的主要活动是：1)表征从WAIS不同部分排放的沉积物的化学和磁性，并利用这些特性来“指纹”。来自非洲大陆不同来源的投入；2)在海洋沉积物岩心中测量这些相同的特性，以记录过去15万年中WAIS的主要变化。确定WAIS最近是否崩溃，可以提供关于WAIS未来可能变得不稳定的重要信息。然后，在这里开发的工具可以用于WAIS周围的旧记录，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物源替代物，以追踪南极西部冰盖（WAIS）向大陆隆起排放的沉积物的来源。具体问题有：1)不同WAIS地体沉积物的地球化学和磁分异程度；2)地表物源指标对晚第四纪WAIS崩塌的探测能力。WAIS侵蚀了来自南极西部各种地质地体的沉积物，这些沉积物沉积在邻近的漂流地点。漂移沉积物的地球化学特征和磁性特征反映了其源区的构造和变质史。在WAIS坍塌过程中，地表的消冰作用应该通过地表的损失来检测。陆起碎屑沉积物的地球化学和磁性特征。来自目前WAIS磨砂线附近的大陆架晚全新世沉积物将被分析淤泥和粘土大小的Sr-Nd-Pb同位素、磁性和主要微量元素。这组岩心包括罗斯海东部到南极半岛北端，并将建立玛丽伯德地的罗斯和阿蒙森省、松岛湾、瑟斯顿岛/八海岸块、埃尔斯沃斯-惠特莫尔地壳块和南极半岛地体的物源特征。其中许多地体具有相似的构造和变质史，但碎屑沉积物的Sr-Nd同位素数据表明至少有3种不同的物源特征。将对别令斯豪森海的海洋钻探计划1096地点进行初步的下岩心研究，以检测WAIS在最后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.