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.

在最后两个冰川期（125,000 年前）期间（当时全球气温和海平面高于今天）获取有关西南极冰盖大小的冰川学和地质数据，可以直接限制冰盖对气候变暖的反应。 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，获得这些数据很困难，因为冰河时期冰范围的证据位于目前的冰面以下。确定冰范围的一个关键位置是韦什山，这是一座高出冰盖圆顶附近冰面上方的火山。 为了准备钻穿冰层，从冰盖下延伸的熔岩流中获取岩芯，该团队之前使用探地雷达来绘制冰下地形和内部冰川分层的地图。 这些雷达剖面揭示了冰层内部的不连续性，这些不连续性代表着冰层水平较低，可能发生在最后一个冰河期期间。 通过该奖项增加的冰芯工作旨在通过测定冰中不连续性的年代来加强团队在瓦埃什山的岩芯钻探计划。 了解不连续性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性；如果该团队在韦什山成功地对它们进行了年代测定，该技术可能会得到更广泛的应用，以限制整个南极洲的冰盖水平较低。为了最大限度地提高该项目凿岩部分的科学回报，该团队将收集和分析冰样本，以限制冰川不整合面的年龄。具体来说，该团队将使用 Eclipse 钻机获得包括冰川不整合面在内的垂直冰芯，并使用水平冰挖沟机对暴露的冰川火山灰地层进行采样，这些冰芯可以追溯到距今 118,000 年前。 该团队将使用雷达将所得的表面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。 同位素和火山灰分析将用于提供冰芯的年龄限制。这些数据将与其他已确定年代的西南极冰芯相关联，以获得当地的年表并确定不整合面的年代。这项探索性工作的目标是提供数据来补充冰下岩芯的结果，以更好地限制地表高程变化，包括自上次间冰期以来的后退和再前进。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。