COLLABORATIVE RESEARCH: Site Survey for Subglacial Bedrock Exposure Dating at the Margin of the Wilkes Basin in Northern Victoria Land

合作研究：维多利亚州北部威尔克斯盆地边缘冰下基岩暴露年代测定现场调查

• 批准号: 1744850
• 负责人: Claire Todd
• 金额: $ 12.57万
• 依托单位: Pacific Lutheran University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2022-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744850&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Site; Survey; Subglacial

The goal of this project is to establish, through direct geological evidence, whether complete deglaciation of East Antarctic marine basins took place during past warm-climate periods. Direct geological information about whether the Antarctic Ice Sheet responded catastrophically to past climate changes is important to evaluating the likelihood of significant ice-sheet response to future climate change. The team will assess the feasibility of achieving this goal using cosmogenic-nuclide measurements on bedrock that is currently buried under the ice sheet. They will conduct a reconnaissance and site survey to identify potential drill sites where subglacial bedrock-exposure dating could subsequently be used to test whether ice at those sites was absent when the Earth last experienced current levels of carbon dioxide—at approximately 3.0 to 3.3 million years ago.This project will seek out potential sites that can address whether total deglaciation of subglacial basins in coastal East Antarctica took place during past warm-climate periods like the middle Pliocene warm period at circa 3.0-3.3 Ma. Ice-sheet model simulations have identified marine ice-margin instability as a possible cause for higher eustatic sea level during this period. In general, it is difficult to obtain direct and unambiguous geological evidence that an ice sheet was smaller in the past because if such evidence exists it is most likely inaccessible beneath the present ice sheet. One means of overcoming this problem is to search for significant concentrations of cosmic-ray-produced radionuclides in bedrock surfaces beneath the present ice sheet. Such concentrations can only be produced if the surface is ice-free, so significant cosmogenic-nuclide concentrations would provide incontrovertible evidence that the ice sheet was smaller in the past, and, in addition, can provide information about when this occurred. Guided by ice-sheet model simulations of Pliocene deglaciation to identify areas where complete deglaciation of the Wilkes subglacial basin would cause substantial changes in the extent of bedrock exposure, the team will collect geophysical and geochemical data to identify and evaluate sites with potential for future bedrock recovery.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.

该项目的目的是通过直接的地质证据来确定南极海洋贝斯的完全脱水是否在过去的温暖气候期间发生。直接的地质信息有关南极冰盖是否对过去气候变化有灾难性反应对于评估对未来气候变化的重大冰期反应的可能性很重要。该团队将使用目前在冰盖下建造的基岩上的宇宙基因核测量值来评估实现这一目标的可行性。他们将进行侦察和现场调查，以确定潜在的钻探地点，在该地点下，可以使用地球上最后一次经历当前当前二氧化碳水平的冰层（大约3.0至3300万年前）的潜在地点的潜在地点，是否可以在近地区进行临时近距离近距离替代地位，以便在地球上次经历当前二氧化碳的当前水平时是否缺乏ICE来测试是否缺乏ICE。诸如大约3.0-3.3 ma的上新世暖时期。冰盖模型模拟已经确定海洋冰块不稳定性是在此期间较高层状海平面的可能原因。通常，很难获得直接和明确的地质证据，表明过去的冰盖较小，因为如果存在这种证据，则在当前的冰盖下很可能是无法进入的。克服这个问题的一种方法是在当前的冰盖下方的基岩表面中寻找大量宇宙射线产生的放射线。只有在表面无冰的情况下才能产生这种浓度，因此明显的宇宙基因核浓度将提供无可争议的证据，证明过去冰盖较小，而且还可以提供有关发生这种情况的信息。在冰原模型模型模型的指导下，确定威尔克斯底部盆地完全脱位的区域，将在基岩暴露范围内导致实质性变化，团队将收集地球物理和地球化学数据，以识别和评估其在未来的基础上，以表现出质量依据，并反映了NSF的授权，并以此为基础。更广泛的影响审查标准。