COLLABORATIVE RESEARCH - Relationship between subglacial geology and glacial processes in West Antarctica: Petrological and geochemical analyses of subglacial and basal sediments

合作研究 - 南极洲西部冰下地质与冰川过程之间的关系：冰下和基底沉积物的岩石学和地球化学分析

• 批准号: 0087486
• 负责人: Slawek Tulaczyk
• 金额: $ 9.54万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0087486&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Relationship; between; subglacial

0087486TulaczykThis award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a collaborative research project between the University of California-Santa Cruz, the University of Texas-Austin, and the Ohio State University to investigate sediment samples recovered from the base of the West Antarctic Ice Sheet (WAIS). West Antarctica is a remote polar region but its dynamic ice sheet, complicated tectonic history, and the sedimentary record of Cenozoic glaciation make it of particular interest to glaciologists and geologists. Glaciologists are concerned with the possibility of significant near-future changes in mass balance of the WAIS that may contribute to the ongoing global sea level rise. Geologists are investigating in West Antarctica the fundamental process of continental extension and are constructing models of a polar marine depositional system using this region as the prime modern example. The subglacial part of West Antarctica has escaped direct geological investigations and all that is known about subglacial geology comes from geophysical remote sensing. Recent acquisitions of new, high-quality geophysical data have led to generation of several enticing models. For instance, subglacial presence of high-magnitude, short-wavelength magnetic anomalies has prompted the proposition that there may be voluminous (1 million cubic km), Late Cenozoic flood basalts beneath the ice sheet. Another important model suggests that the patterns of fast ice streaming (~100 meters/year) and slow ice motion (~1-10 meters/year) observed within the WAIS are controlled by subglacial distribution of sedimentary basins and resistant bedrock. These new geophysics-based models should be tested with direct observations because they are of such great importance to our understanding of the West Antarctic tectonic history and to our ability to predict the future behavior of the WAIS.This research is designed as a pilot study to provide new geologic data, which may help to test the recent models inferred from geophysical observations. The new constraints on subglacial geology and on its interactions with the WAIS will be obtained through petrological and geochemical analyses of basal and subglacial sediments collected previously from seven localities. This investigation will take place in the context of testing the following three hypotheses: (A) the provenance of bedrock clasts in the glacial sediment samples is primarily from West Antarctica, (B) some clasts and muds from the West Antarctic subglacial sediments have been derived by erosion of the (inferred) subglacial Late Cenozoic flood basalts, and (C) the sediments underlying the West Antarctic ice streams were generated by glacial erosion of preglacial sedimentary basins but the sediments recovered from beneath the slow-moving parts of the WAIS were produced through erosion of resistant bedrock.The individual hypotheses will be tested by collecting data on: (A) petrology, geochemistry and age of granitoid clasts, (B) petrology, geochemistry and age of basaltic clasts combined with mud geochemistry, and (C) clay mineralogy/paragenesis combined with textural maturity of sand and silt grains. The results of these tests will help evaluate the interesting possibility that subglacial geology may have first-order control on the patterns of fast ice flow within the WAIS. The new data will also help to determine whether the subglacial portion of West Antarctica is a Late Cenozoic flood basalt province. By combining glaciological and geological aspects of West Antarctic research the proposed collaborative project will add to the ongoing U.S. effort to create a multidisciplinary understanding of this polar region.

该奖项由极地计划办公室南极地质和地球物理计划提供，支持加州大学圣克鲁斯分校、德克萨斯大学奥斯汀分校和俄亥俄州立大学之间的一个合作研究项目，以调查从西南极冰盖(WAIS)底部恢复的沉积物样本。西南极是一个偏远的极地地区，但其动态的冰盖、复杂的构造历史和新生代冰川的沉积记录使其受到冰川学家和地质学家的特别关注。冰川学家担心，在不久的将来，WAIS的物质平衡可能会发生重大变化，这可能会导致全球海平面持续上升。地质学家们正在南极洲西部研究大陆伸展的基本过程，并正在以该地区为主要的现代例子来构建极地海洋沉积体系的模型。西南极的冰下部分没有进行直接的地质调查，所有关于冰下地质的知识都来自地球物理遥感。最近对新的高质量地球物理数据的获取导致了几个诱人的模型的产生。例如，冰层下存在高震级、短波长磁异常，这促使人们提出冰盖下可能存在大量(100万立方公里)晚新生代洪泛玄武岩的命题。另一个重要的模型表明，在WAIS内观测到的快速冰流(~100米/年)和慢冰运动(~1~10米/年)的模式受沉积盆地和阻力基岩的冰下分布控制。这些新的基于地球物理的模型应该通过直接观测进行测试，因为它们对于我们理解南极西部构造历史和预测WAIS未来行为的能力非常重要。这项研究旨在提供新的地质数据，这可能有助于测试最近从地球物理观测中推断出的模型。将通过对先前从七个地点收集的冰底和冰下沉积物进行岩石学和地球化学分析，获得冰下地质及其与世界冰川研究所相互作用的新制约因素。这项调查将在检验以下三个假设的背景下进行：(A)冰川沉积物样品中基岩碎屑的来源主要来自南极西部，(B)来自西南极冰下沉积物的一些碎屑和泥浆是由(推断的)冰下晚新生代洪水玄武岩的侵蚀而产生的，以及(C)西南极冰川下的沉积物是由冰前沉积盆地的冰川侵蚀产生的，但从WAIS缓慢运动部分的沉积物是通过侵蚀抵抗的基岩而产生的。将通过收集以下数据来检验个别的假设：(A)花岗岩碎屑的岩石学、地球化学和年龄(B)玄武岩碎屑的岩石学、地球化学和年龄与泥浆地球化学相结合；(C)粘土矿物学/共生作用与砂粒和粉砂颗粒的结构成熟度相结合。这些测试的结果将有助于评估有趣的可能性，即冰下地质可能对WAIS内的快速冰流模式进行一级控制。新的数据还将有助于确定西南极的冰下部分是否为晚新生代洪水玄武岩省。通过将西南极冰川学和地质学方面的研究结合起来，拟议中的合作项目将有助于美国正在进行的努力，以建立对这一极地地区的多学科了解。