Glacial-interglacial History of West Antarctic Nunataks and Site Reconnaissance for Subglacial Bedrock Sampling

西南极努纳塔克群岛的冰期-间冰期历史和冰下基岩采样现场勘察

• 批准号: 1142162
• 负责人: John Stone
• 金额: $ 34.97万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2015-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1142162&HistoricalAwards=false
• 关键词: Glacial; interglacial; History; West; Antarctic

1142162/StoneThis award supports a project to conduct a reconnaissance geological and radar-sounding study of promising sites in West Antarctica as a prelude to a future project to conduct subglacial cosmogenic nuclide measurements. Field work will take place in the Whitmore Mountains, close to the WAIS divide, and on the Nash and Pirrit Hills, downflow from the divide in the Weddell Sea drainage. At each site geological indicators of higher (and lower) ice levels in the past will be mapped and evidence of subglacial erosion or its absence will be documented. Elevation transects of both glacial erratics and adjacent bedrock samples will be collected to establish the timing of recent deglaciation at the sites and provide a complement to similar measurements on material from depth transects obtained by future subglacial drilling. At each site, bedrock ridges will be traced into the subsurface with closely-spaced ice-penetrating radar surveys, using a combination of instruments and frequencies to obtain meter-scale surface detail, using synthetic aperture techniques. Collectively the results will define prospective sites for subglacial sampling, and maximize the potential information to be obtained from such samples in future studies. The intellectual merit of this project is that measurements of cosmogenic nuclides in subglacial bedrock hold promise for resolving the questions of whether the West Antarctic ice sheet collapsed completely in the past, whether it is prone to repeated large deglaciations, and if so, what is their magnitude and frequency. Such studies will require careful choice of targets, to locate sites where bedrock geology is favorable, cosmogenic nuclide records are likely to have been protected from subglacial erosion, and the local ice-surface response is indicative of large-scale ice sheet behavior. The broader impacts of this work include helping to determine whether subglacial surfaces in West Antarctica were ever exposed to cosmic rays, which will provide unambiguous evidence for or against a smaller ice sheet in the past. This is an important step towards establishing whether the WAIS is vulnerable to collapse in future, and will ultimately help to address uncertainty in forecasting sea level change. The results will also provide ground truth for models of ice-sheet dynamics and long-term ice sheet evolution, and will help researchers use these models to identify paleoclimate conditions responsible for WAIS deglaciation. The education and training of students (both undergraduate and graduate students) will play an important role in the project, which will involve Antarctic fieldwork, technically challenging labwork, data collection and interpretation, and communication of the outcome to scientists and the general public.

1142162/Stone 该奖项支持一个项目，对南极洲西部有希望的地点进行勘察地质和雷达探测研究，作为未来进行冰下宇宙核素测量项目的前奏。现场工作将在靠近 WAIS 分水岭的惠特莫尔山脉以及威德尔海排水分水岭下游的纳什山和皮里特山进行。在每个地点，过去较高（和较低）冰层的地质指标将被绘制出来，并记录冰下侵蚀或不存在的证据。 将收集冰川不稳定物和邻近基岩样本的高程横断面，以确定该地点最近冰川消退的时间，并为未来冰下钻探获得的深度横断面材料的类似测量提供补充。 在每个地点，基岩山脊将通过紧密间隔的透冰雷达勘测追踪到地下，结合使用仪器和频率，利用合成孔径技术获得米级表面细节。总的来说，这些结果将确定冰下采样的预期地点，并在未来的研究中最大限度地从这些样本中获得潜在的信息。 该项目的智力价值在于，对冰下基岩中宇宙成因核素的测量有望解决以下问题：南极西部冰盖过去是否完全崩塌，是否容易发生重复的大规模冰川消融，如果是的话，其规模和频率是多少。此类研究需要仔细选择目标，以找到基岩地质条件有利、宇宙成因核素记录可能免受冰下侵蚀的地点，以及当地冰面响应表明大规模冰盖行为的地点。这项工作的更广泛影响包括帮助确定西南极洲的冰下表面是否曾经暴露于宇宙射线，这将为过去较小的冰盖提供明确的证据。这是确定 WAIS 未来是否容易崩溃的重要一步，并将最终有助于解决预测海平面变化的不确定性。研究结果还将为冰盖动力学和长期冰盖演化模型提供基础事实，并将帮助研究人员利用这些模型来确定导致 WAIS 冰川消融的古气候条件。 学生（本科生和研究生）的教育和培训将在该项目中发挥重要作用，该项目将涉及南极实地考察、技术上具有挑战性的实验室工作、数据收集和解释以及向科学家和公众传达结果。