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: 2210092
• 负责人: Seth Campbell
• 金额: $ 7.79万
• 依托单位: University of Maine
• 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=2210092&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.

在过去两个冰川时期（125，000年前）之间获得有关西南极冰盖大小的冰川和地质数据，当时全球温度和海平面高于今天，这对冰盖对温暖气候的反应提供了直接限制。这些数据还为用于投影未来海平面的冰盖模型提供了验证点。但是，获得这些数据很困难，因为冰川周期之间的证据位于当前冰表面以下。确定此冰范围的关键位置是瓦斯山（Mount Waesche），这是一座火山，它在冰盖圆顶附近的冰面上升起。为了准备通过冰钻探以从冰盖下延伸的熔岩流中获得岩石岩心，该团队先前使用地面穿透辐射射线来绘制亚冰的地形和内部冰川分层。这些雷达轮廓揭示了冰内的不连续性，这些不连续性代表了冰川时期最后一次可能发生的较低的冰层。通过该奖项添加的冰核工作旨在通过约会冰上的不连续性来增强球队在Waesche的摇滚核心钻探计划。了解不连续性的年龄将为过去的冰层提供独立的证据。在南极其他地方的雷达轮廓中也观察到了类似的内部冰川不连续性。如果团队成功地在Waesche约会了他们，该技术可能会更广泛地限制整个南极的冰层水平较低的水平。为了最大程度地利用该项目的岩石钻孔部分的科学回报，团队将收集和分析冰样品，将冰层限制以限制工程师的层次，包括练习型钢铁架的训练式训练型培训，这些训练的训练是驱动的。裸露的工程师Tephra层学层次摄影层使用水平冰沟延长至118,000年。该团队将使用RADIAR推断出所得的表面年表到地下深度，从而提供层次造影的横向深度约束。同位素和TEPHRA分析将用于在冰芯上提供年龄限制。这些数据将与其他年代良好的西南极冰芯相关，以获得局部年表并日期不整合。这项探索性工作的目的是提供补充冰川岩岩的结果以更好地限制表面脉冲变化的数据，包括撤退和阅读，这是因为上次冰川造成的。这项奖项反映了NSF的法定任务，并通过使用该基金会的智力功能和广泛影响来评估NSF的法定任务，并被认为是珍贵的支持。