Collaborative Research: Resolving Earth Structure Influence on Ice-Sheet Stability in the Wilkes Subglacial Basin (RESISSt)

合作研究：解决地球结构对威尔克斯冰下盆地冰盖稳定性的影响 (RESISSt)

• 批准号: 1914668
• 负责人: Andy Aschwanden
• 金额: $ 14.09万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1914668&HistoricalAwards=false
• 关键词: Collaborative; Research; Resolving; Earth; Structure

Part I: NontechnicalEarths warming climate has the potential to drive widespread collapse of glaciers and ice sheets across the planet, driving global sea-level rise. Understanding both the rate and magnitude of such changes is essential for predicting future sea-level and how it will impact infrastructure and property. Collapse of the ice sheets of Antarctica has the potential to raise global sea-level by up to 60 meters. However, not all regions of Antarctica are equally suspectable to collapse. One area with potential for collapse is the Wilkes Subglacial Basin in East Antarctica, a region twice the size of California's Central Valley. Geologic evidence indicates that the ice-sheet in this region has retreated significantly in response to past global warming events. While the geologic record clearly indicates ice-sheets in this area are vulnerable, the rate and magnitude of any future retreat will be influenced significantly by geology of the region. In particular, ice-sheets sitting above warm Earth will collapse more quickly during warming climate. Constraining the geologic controls on the stability of the ice-sheets of the Wilkes Subglacial Basin remains challenging since the ice-sheet hides the geology beneath kilometers of ice. As a step in understanding the potential for future ice loss in the Wilkes Subglacial Basin this project will conduct geophysical analysis of existing data to better constrain the geology of the region. These results will constrain new models designed to understand the tectonics that control the behavior of the ice-sheets in the region. These new models will highlight the geological properties that exert the most significant control on the future of the ice-sheets of the Wilkes Subglacial Basin. Such insights are critical to guide future efforts aimed at collecting in-situ observations needed to more fully constrain Antarctica's potential for future sea-level. Part II: Technical DescriptionIn polar environments, inward-sloping marine basins are susceptible to an effect known as the marine ice-sheet instability (MISI): run-away ice stream drainage caused by warm ocean water eroding the ice shelf from below. The magnitude and time-scale of the ice-sheet response strongly depend on the physical conditions along the ice-bed interface, which are, to a first order, controlled by the tectonic evolution of the basin. Topography, sedimentology, geothermal heat flux, and mantle viscosity all play critical roles in ice-sheet stability. However, in most cases, these solid-Earth parameters for regions susceptible to the MISI are largely unknown. One region with potential susceptibility to MISI is the Wilkes Subglacial Basin of East Antarctica. The project will provide an integrated investigation of the Wilkes Subglacial Basin, combining geophysical analyses with both mantle flow and ice-sheet modeling to understand the stability of the ice sheet in this region, and the associated potential sea level rise. The work will be focused on four primary objectives: (1) to develop an improved tectonic model for the region based on existing seismic observations as well as existing geophysical and geological data; (2) to use the new tectonic model and seismic data to estimate the thermal, density, and viscosity structure of the upper mantle and to develop a heat flow map for the WSB; (3) to simulate mantle flow and to assess paleotopography based on our density and viscosity constraints; and (4) to assess ice-sheet behavior by modeling (a) past ice-sheet stability using our paleotopography estimates and (b) future ice-sheet stability using our heat flow and mantle viscosity estimates. Ultimately, the project will generate improved images of the geophysical structure beneath the WSB that will allow us to assess the geodynamic origin for this region and to assess the influence of geologic parameters on past, current, and future ice-sheet behavior. These efforts will then highlight areas and geophysical properties that should be the focus of future geophysical deployments.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.

第一部分：非技术性地球变暖的气候有可能导致全球冰川和冰盖的广泛崩溃，导致全球海平面上升。了解这种变化的速度和幅度对于预测未来海平面以及它将如何影响基础设施和财产至关重要。南极洲冰盖的崩溃有可能使全球海平面上升60米。然而，并非南极洲的所有地区都同样有可能崩溃。南极洲东部的威尔克斯冰下盆地是一个有可能崩溃的地区，这个地区的面积是加州中央谷的两倍。地质学证据表明，该地区的冰盖在过去的全球变暖事件中显著退缩。虽然地质记录清楚地表明该地区的冰盖是脆弱的，但未来任何退缩的速度和幅度都将受到该地区地质的显著影响。特别是，在气候变暖期间，位于温暖地球上方的冰盖将更快地崩溃。限制地质对威尔克斯冰下盆地冰盖稳定性的控制仍然具有挑战性，因为冰盖将地质隐藏在数公里厚的冰层之下。作为了解威尔克斯冰下盆地未来冰损失潜力的一步，该项目将对现有数据进行地球物理分析，以更好地约束该地区的地质。这些结果将限制旨在了解控制该地区冰盖行为的构造的新模型。这些新模型将突出对威尔克斯冰下盆地冰盖的未来施加最重要控制的地质特性。这些见解对于指导今后收集更充分限制南极洲未来海平面上升潜力所需的实地观测资料的工作至关重要。 第二部分：技术描述在极地环境中，向内倾斜的海洋盆地容易受到称为海洋冰盖不稳定性（MISI）的影响：温暖的海水从下面侵蚀冰架造成的冰流流失。冰盖响应的大小和时间尺度强烈地依赖于沿沿着冰床界面的物理条件，而这些物理条件在一级上受盆地构造演化的控制。地形学、沉积学、地热通量和地幔粘性都对冰盖的稳定性起着关键作用。然而，在大多数情况下，易受MISI影响的地区的这些固体地球参数在很大程度上是未知的。南极洲东部的威尔克斯冰下盆地是一个可能易受MISI影响的地区。该项目将对威尔克斯冰下盆地进行综合调查，将地球物理分析与地幔流和冰盖建模相结合，以了解该地区冰盖的稳定性以及相关的潜在海平面上升。这项工作将集中在四个主要目标上：（1）根据现有的地震观测以及现有的地球物理和地质数据，为该地区建立一个改进的构造模型;（2）利用新的构造模型和地震数据，估计上地幔的热、密度和粘度结构，并为西太平洋板块绘制热流图;（3）模拟地幔流并根据我们的密度和粘度约束评估古地形;（4）通过模拟（a）使用我们的古地形估计的过去冰盖稳定性和（B）使用我们的热流和地幔粘度估计的未来冰盖稳定性来评估冰盖行为。 最终，该项目将生成WSB下方地球物理结构的改进图像，这将使我们能够评估该地区的地球动力学起源，并评估地质参数对过去，当前和未来冰盖行为的影响。这些努力将突出未来地球物理部署的重点领域和地球物理特性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。