Collaborative Research: Constraining West Antarctic Ice Sheet Elevation during the last Interglacial

合作研究：限制末次间冰期期间南极西部冰盖的海拔

• 批准号: 1745015
• 负责人: Matthew Zimmerer
• 金额: $ 30.85万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1745015&HistoricalAwards=false
• 关键词: Collaborative; Research; Constraining; West; Antarctic

This study will collect a novel dataset to determine how the West Antarctic Ice Sheet (WAIS) responded to a warmer climate during the last interglacial period (~125,000 years ago) by reconstructing the glacial history at the Mt. Waesche volcano. Reconstructing WAIS geometry when the ice sheet was smaller than present is difficult and data are lacking because the evidence lies beneath the present ice sheet. This study will drill through the ice sheet and recover bedrock that can be analyzed for its surface exposure history to help determine when the surface became overridden by the ice sheet. This study will provide constraints on the past maximum and minimum spatial extent of WAIS during the last glacial-interglacial cycle. Understanding the geometry of a reduced WAIS during intervals when the planet was warmer than present may provide a possible analogue for future environmental conditions given predicted temperature trends. A reduction of WAIS results in rising sea levels which threatens coastal communities across the globe. The data will help improve numerical ice sheet models to better predict WAIS response to current and future climate trends. The project supports a teacher educational workshop and the training of graduate and undergraduate students.The goal of this project is to obtain rock samples from beneath the WAIS through shallow (80 m) drilling at Mt. Waesche, a volcano in Marie Byrd Land, near an ice dome of WAIS (2000 m elevation). The lithologies of lava flows exposed on the flank of the volcano are well-suited for cosmogenic 3He and 36Cl as well as 40Ar/39Ar measurements which will establish eruption and exposure age. Existing 40Ar/39Ar data indicate basaltic lava flows on the volcano flank as young as 350 ka. Thus, measured cosmogenic nuclides measured in rock cores from beneath the ice surface will be indicative of relatively recent exposure during periods of reduced ice elevation, most likely, during the last interglacial. The first field season is focused on identifying appropriate locations for drilling and a ground penetrating radar (GPR) survey of the subglacial topography 100m under the blue ice area. Mapping and dating the adjacent exposed lava flows will allow tracing of lava flows of known age and composition below the ice margin that will be targeted for drilling the following year. The second field season activities include drilling 8 boreholes (two transects) through blue ice with the Winkie drill near the ice margin to 80 m depth to obtain rock cores from the sub-ice lava flows. 3He exposure ages will constrain the duration and minimum extent of past surface lowering of the WAIS in Marie Byrd Land. Deeper GPR imaging (up to 700 m) will hope to reveal additional evidence of lava/ice interactions that would independently place constraints on lower ice levels during past eruptions. Results from this study will be compared with the modeled ice elevation histories at Mt. Waesche to validate ice sheet modeling efforts.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.

这项研究将收集一个新的数据集，以确定在最后一次冰河间（〜125，000年前）如何通过重建Waesche火山山的冰川历史来确定西南极冰盖（WAIS）如何应对温暖的气候。重建WAIS几何形状时，当冰盖小于现在很困难并且缺乏数据，因为证据位于当前的冰盖下。这项研究将钻探冰盖并恢复基岩，该基石可以分析其表面暴露病史，以帮助确定何时被冰盖覆盖。这项研究将在最后一个冰川间冰周期内对过去的最大和最小空间范围提供限制。在行星温暖的时间比现在的时间温暖时，了解降低的宽度的几何形状可能为预测的温度趋势提供了可能的类似物。 WAIS的减少导致海平面上升，威胁着全球沿海社区。数据将有助于改善数值冰盖模型，以更好地预测WAI对当前和未来气候趋势的反应。该项目支持一个教师教育研讨会和研究生和本科生的培训。该项目的目的是通过在玛丽·伯德（Marie Byrd Land）的火山（2000 m海角）的玛丽·伯德（Marie Byrd Land）的火山（2000 m海拔）的玛丽·伯德（Marie Byrd Land）的火山（2000 m的冰圆顶）中，从伊斯（Wais）的浅层（80 m）钻探从伊斯（Wais）下方获取岩石样品。在火山侧面暴露的熔岩流的岩性非常适合宇宙基因3HE和36Cl，以及40AR/39AR测量值，这些测量将建立喷发和暴露年龄。现有的40AR/39AR数据表明火山侧面的玄武岩熔岩流量年仅350 ka。因此，在冰面下方测得的岩体中测得的宇宙核素将表明在冰升高时期降低的时期，最有可能在最后一次冰上冰层。第一个野外季节的重点是确定适当的钻孔位置，并在蓝冰区域对100m的冰川地形进行钻井雷达（GPR）调查。映射和约会相邻裸露的熔岩流将允许追踪已知年龄的熔岩流和冰缘以下的熔岩流，这些熔岩流将于第二年进行钻探。第二个现场季节活动包括通过蓝色冰钻8个钻孔（两个样带），冰缘附近的Winkie钻头至80 m的深度，以从亚冰熔岩流中获得岩石岩心。 3HE暴露年龄将限制玛丽·伯德（Marie Byrd）土地上瓦斯（Wais）的持续时间和最小程度。更深层次的GPR成像（高达700 m）将希望揭示出熔岩/冰相互作用的其他证据，这些证据将在过去喷发期间独立地对较低的冰层施加限制。这项研究的结果将与Waesche山的建模冰升级历史进行比较，以验证冰盖建模工作。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估评估的评估来支持的。