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: 2209537
• 负责人: Claire Todd
• 金额: $ 12.57万
• 依托单位: University Enterprises Corporation at CSUSB
• 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: 2021-10-01 至 2024-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2209537&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.

该项目的目标是通过直接的地质证据，确定南极东部海洋盆地是否在过去的温暖气候时期发生了完全的冰川消融。关于南极冰盖是否对过去的气候变化做出灾难性反应的直接地质信息对于评估非常重要。研究小组将通过对目前埋在冰盖下的基岩进行宇宙成因核素测量来评估实现这一目标的可能性。勘察和现场调查，以确定潜在的钻探地点，随后可以使用冰下基岩暴露测年来测试当地球上次经历当前二氧化碳水平（大约 3.0 至 330 万年前）时，这些地点的冰是否不存在。该项目将寻找潜在地点，以解决东南极洲沿海冰下盆地的完全消融是否发生在过去的温暖气候时期，例如大约在上新世中期的温暖时期3.0-3.3 Ma。冰盖模型模拟已确定海洋冰缘不稳定是这一时期海平面上升的可能原因。一般来说，很难获得直接且明确的地质证据来证明冰盖较小。过去，因为如果存在这样的证据，那么解决这个问题的一种方法很可能是在当前冰盖下方的基岩表面中寻找高浓度的宇宙射线产生的放射性核素。只有在表面无冰的情况下才能产生这样的浓度，因此显着的宇宙成因核素浓度将提供无可争议的证据，证明冰盖过去较小，此外，还可以提供有关何时发生这种情况的信息。 - 上新世冰川消融的薄片模型模拟，以确定威尔克斯冰下盆地完全消融将导致基岩暴露程度发生重大变化的区域，该团队将收集地球物理和地球化学数据，以识别和评估地点该奖项反映了 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。