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数据的响应。还为用于预测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，因为冰河时期冰范围的证据位于当前冰面以下。确定这一冰层范围的是瓦埃什山，这座火山位于冰盖圆顶附近的冰面上方。为了准备钻探冰层，从延伸到冰盖下的熔岩流中获取岩芯，该团队之前使用了地面。 - 绘制冰下地形和内部冰川分层的穿透雷达这些雷达剖面揭示了冰内的不连续性，这些不连续性代表了最后一个冰期期间可能发生的较低冰层。旨在通过确定冰层不连续性的年代来加强该团队在瓦埃什山的岩芯钻探计划，如果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，那么该研究将提供有关过去冰层水平的独立证据。该团队在韦舍山成功地对它们进行了年代测定，该技术可以在限制整个南极洲冰盖水平较低方面有更广泛的应用。项目中，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 钻头获得包括冰川不整合面的垂直冰芯，以及对暴露的冰川火山灰地层进行采样的地表水平冰芯。该团队将使用水平冰挖沟机将所得到的表面年代学推断到地下深度，从而提供横向深度年龄限制。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南极西部冰芯相关联，以获得当地的年代学并确定不整合面的年代。提供补充冰下岩芯结果的数据，以更好地限制自上次间冰期以来地表高程变化，包括后退和再前进。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。