Unlocking the Glacial History of the McMurdo Dry Valleys, Antarctica by Fingerprinting Glacial Tills with Detrital Zircon U-Pb Age Populations

通过用碎屑锆石 U-Pb 年龄种群对冰川碴进行指纹识别，解开南极洲麦克默多干谷的冰川历史

• 批准号: 1842542
• 负责人: Daniel Morgan
• 金额: $ 42.74万
• 依托单位: Vanderbilt University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1842542&HistoricalAwards=false
• 关键词: Unlocking; Glacial; History; McMurdo; Dry

The goal of this study is to identify and distinguish different source areas of glacial sediment in the McMurdo Dry Valleys, Antarctica to determine past glacial flow direction. Understanding ice flow is critical for determining how the Antarctic Ice Sheets have behaved in the past. Such insight is fundamental for allowing scientists to predict how the Antarctic Ice Sheets will evolve and, in turn, forecast how much and how fast sea level may rise. The project study site, the McMurdo Dry Valleys, contain a tremendous record of glacial deposits on land that extends back at least 14 million years. Chemistry of the rocks within the glacial deposits hold clues to the sources of ice that deposited the material. The chemical analyses of the glacial deposits will allow mapping of the former extent of glaciations providing a better understand of ice flow history. The mapping of the largest ice sheet expansion of the past 14 million years in the McMurdo Dry Valleys is of broad interest to the global climate change community. Undergraduate students comprise the majority of the field teams and will be responsible for sample preparation and analysis in the laboratory. This project utilizes new geochemical techniques to test hypotheses about the source, extent, and flow patterns of the glacier ice that deposited glacial tills in the McMurdo Dry Valleys, Antarctica (MDV). The MDV contain an unparalleled terrestrial archive of glacial deposits, which record multiple sources of ice that deposited them. These include the northeast flowing ice that overrode the Transantarctic Mountains, the eastward expansion of the East Antarctic Ice Sheet, the westward extension of the Ross Ice Shelf representing an expansion of the West Antarctic Ice Sheet, and the growth of local alpine glaciers. The glacial tills and drifts in the Antarctic are typically isolated in patches or disjointed outcrop patterns making it difficult to correlate tills and determine their source. This project will undertake a systematic study of the tills in the McMurdo Dry Valleys to determine their provenance with a variety of geochemical techniques including major and minor element analyses with X-ray fluorescence, heavy mineral composition, soil salt concentration, and determining the uranium-lead (U-Pb) ages of zircon sands contained in these tills. The primary tool will be the age distribution of the population of detrital zircon in a glacial drift because it reflects the source of the tills and provides a unique geochemical "fingerprint" used to distinguish source areas while correlating units across different sites. A deliverable from this project will be a community available library of zircon fingerprints for mapped glacial tills from archived samples at the Polar Rock Repository and the systematic collection of samples in the MDV.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项研究的目的是识别和区分南极麦克默多干谷中冰川沉积物的不同来源区域，以确定过去的冰川流动方向。了解冰流对于确定过去的南极冰盖表现至关重要。这种洞察力是允许科学家预测南极冰盖如何发展的基础，进而预测海平面的速度和速度可能会升高。项目研究地点McMurdo Dry Valleys在土地上包含冰川沉积物的巨大记录，至少可以追溯到1400万年。冰川沉积物内的岩石的化学含量为沉积材料的冰源提供了线索。对冰川沉积物的化学分析将允许绘制以前的冰川范围，从而更好地了解冰流史。在麦克穆尔多（McMurdo）干山谷中，过去1400万年中最大的冰盖扩展的映射吸引了全球气候变化社区。本科生组成了大多数现场团队，并将负责实验室的样本准备和分析。该项目利用新的地球化学技术来测试有关冰川冰的来源，范围和流动模式，这些假设沉积了冰川till，在McMurdo Dry Valleys，Antarctica（MDV）中。 MDV包含冰川沉积物的无与伦比的陆地档案，记录了沉积它们的多种冰来源。其中包括覆盖跨焦山脉的东北流动冰，东南极冰盖的向东膨胀，罗斯冰架的向西延伸，代表南极西部冰盖的扩展以及当地高山冰川的生长。南极中的冰川耕种和漂移通常在斑块中分离出来或脱节的露头模式，从而难以将耕tills关联并确定其来源。该项目将对McMurdo Dry Valleys中的耕种进行系统的研究，以通过各种地球化学技术来确定其出处，包括X射线荧光，重型矿物质成分，土壤盐浓度，并确定这些尿元（U-PB）含量包含的Zircon sands sands中的Zircon Sands。主要工具将是冰川漂移中碎屑锆石种群的年龄分布，因为它反映了耕种的来源，并提供了一种独特的地球化学“指纹”，用于区分源区域，同时在不同地点关联单位。该项目的可交付能力将是一个可用的锆石指纹库，用于映射的冰川耕种，来自Polar Rock存储库中归档样品的冰川耕种，并在MDV中进行了系统的样本集合。该奖项反映了NSF的法定任务，并通过基金会的知识效果和广泛的影响来评估NSF的法定任务。