Collaborative Research: EAGER: Dating Glacier Retreat and Readvance near Mount Waesche, West Antarctica

合作研究：EAGER：约会南极洲西部韦什山附近的冰川退缩和雷德万斯

• 批准号: 2210093
• 负责人: Matthew Zimmerer
• 金额: $ 2.09万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2210093&HistoricalAwards=false
• 关键词: Collaborative; Research; EAGER; Dating; Glacier

Obtaining glaciological and geologic data on the size of the West Antarctic Ice Sheet between the last two glacial periods (125,000 years ago), when global temperatures and sea level were higher than today, provides direct constraints on the ice sheet’s response to warmer climate. These data also provide validation points for ice-sheet models used to project future sea level. However, obtaining these data is difficult as the evidence for between glacial period ice extent lies below the present ice surface. A key location for determining this ice extent is Mount Waesche, a volcano that rises above the ice surface near the dome of the ice sheet. In preparation for drilling through the ice to obtain rock cores from lava flows that extend under the ice sheet, the team previously used ground-penetrating radar to map the sub-ice topography and internal glacial layering. These radar profiles revealed discontinuities within the ice that represent lower ice levels that may have occurred during the last between glacial periods. The ice-core work to be added through this award aims to enhance the team’s rock core drilling program at Mount Waesche by dating the discontinuities in the ice. Knowing the age of the discontinuities would provide independent evidence for past ice levels. Similar internal glacial discontinuities have been observed in radar profiles elsewhere in Antarctica; if the team is successful dating them at Mount Waesche, the technique could have wider application for constraining lower ice-sheet levels across Antarctica.To maximize scientific return from the rock-drilling portion of the project, the team will collect and analyze ice samples to constrain the ages of englacial unconformities. Specifically, the team will obtain vertical ice cores that include the englacial unconformities using the Eclipse Drill and surface horizontal cores that sample exposed englacial tephra stratigraphy extending back to 118,000 years before present using a horizontal ice trencher. The team will extrapolate the resulting surface chronology to subsurface depths using radar, providing lateral depth-age constraints of stratigraphy. Isotopic and tephra analysis will be used to provide age constraints on the ice cores. These data will be correlated with other, well-dated West Antarctic ice cores to obtain a local chronology and date the unconformities. The goal of this exploratory work is to provide data that complement the results from subglacial rock cores to better constrain surface-elevation change, including both retreat and readvance, since the last interglacial.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.

获得关于最后两个冰期(12.5万年前)之间南极西部冰盖大小的冰川学和地质数据，当时全球气温和海平面高于今天，这为冰盖对气候变暖的反应提供了直接的限制。这些数据还为用于预测未来海平面的冰盖模型提供了验证点。然而，获取这些数据是困难的，因为冰川时期之间冰川范围的证据位于现在的冰面之下。确定冰层范围的一个关键位置是威斯切山，这是一座火山，位于冰盖圆顶附近的冰面上方。为了准备钻穿冰层，从延伸到冰盖下的熔岩流中获取岩芯，该团队之前使用了探地雷达来绘制冰下地形和内部冰川分层的地图。这些雷达轮廓揭示了冰层内的不连续，这代表了较低的冰层水平，可能发生在上一次冰川时期之间。通过该奖项增加的冰芯工作旨在通过测定冰层中的不连续面来加强该团队在芒特威斯切山的岩心钻探计划。知道断裂面的年龄将为过去的冰层水平提供独立的证据。在南极洲其他地方的雷达剖面中也观察到了类似的内部冰川不连续；如果团队成功地在威斯切山测年，这项技术可能会在限制整个南极洲较低的冰盖水平方面得到更广泛的应用。为了最大限度地从项目的岩石钻探部分获得科学回报，团队将收集和分析冰样，以限制冰川不整合的年龄。具体地说，该团队将使用日食钻头获取包括冰盖不整合在内的垂直冰芯，以及使用水平冰沟对暴露的冰盖岩层进行采样的地表水平冰芯，这些地层可以追溯到11.8万年前。该小组将使用雷达将由此产生的地表年代学推断到地下深度，从而提供地层学的横向深度-年龄限制。将使用同位素和Tephra分析来提供冰芯的年龄限制。这些数据将与其他年代良好的西南极冰芯进行关联，以获得当地的年代学并确定不整合的日期。这项探索性工作的目标是提供补充冰下岩石岩芯结果的数据，以更好地限制自上一次间冰期以来的地表海拔变化，包括退缩和回升。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。