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

1142162/石头该奖项支持一个项目，该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。实地工作将在靠近WAIS分水岭的惠特莫尔山脉以及从韦德尔海排水系统分水岭顺流而下的纳什和皮里特山进行。在每个地点，将绘制过去较高(和较低)冰层的地质指标图，并将记录冰下侵蚀或不存在的证据。将收集冰川高程断面和邻近基岩样本，以确定这些地点最近冰川消融的时间，并为未来冰下钻探获得的深度断面材料的类似测量提供补充。在每个地点，基岩脊将通过近距离的冰穿透雷达测量追踪到地下，使用仪器和频率的组合，使用合成孔径技术获得米级的表面细节。总体而言，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利用从此类采样中获得的潜在信息。该项目的学术价值在于，对冰川下基岩中宇宙成因核素的测量有望解决以下问题：西南极冰盖过去是否完全崩溃，它是否容易反复发生大规模冰川消融，如果是，它们的规模和频率是多少。这样的研究将需要仔细选择目标，以确定基岩地质有利的地点，宇宙成因的核素记录可能受到冰下侵蚀的保护，并且当地的冰面反应表明大规模的冰盖行为。这项工作的更广泛影响包括帮助确定南极洲西部的冰下表面是否曾暴露于宇宙射线，这将为过去支持或反对较小的冰盖提供明确的证据。这是朝着确定WAIS未来是否容易崩溃迈出的重要一步，最终将有助于解决预测海平面变化的不确定性问题。这些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，并将帮助研究人员使用这些模型来确定导致WAIS冰川消融的古气候条件。对学生(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、具有技术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通报结果。

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.