Collaborative Research: Potential Direct Geologic Constraint of Ice Sheet Thickness in the Central Transantarctic Mountains during the Pliocene Warm Period

合作研究：上新世温暖期横贯南极中部山脉冰盖厚度的潜在直接地质约束

• 批准号: 1443321
• 负责人: Gordon Bromley
• 金额: $ 29.16万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1443321&HistoricalAwards=false
• 关键词: Collaborative; Research; Potential; Direct; Geologic

This investigation will reconstruct past behavior of the East Antarctic Ice Sheet during periods of warmer-than-present climate, such as the Pliocene, in order to better project the likely response of Earth's largest ice sheet to anthropogenic warming. Containing the equivalent of ~55 m sea-level rise, the future evolution of the East Antarctic Ice Sheet has clear societal ramifications on a global scale as temperatures continue to rise. Therefore, determining ice-sheet sensitivity to climate on the scale predicted for the next two centuries is a matter of increasing urgency, particularly in light of evidence suggesting the East Antarctic Ice Sheet is more dynamic than previously thought. This research will provide a terrestrial geologic record of long-term ice-sheet behavior from sites immediately adjacent the East Antarctic Ice Sheet in the Transantarctic Mountains, with which the project will help ascertain how the ice sheet responded to past warm periods. The project will focus primarily on the Pliocene warm period, 5 to 3 million years ago, as this represents the closest analogue to 21st Century climate conditions.The proposed research will investigate glacial deposits corresponding to the East Antarctic Ice Sheet in the central Transantarctic Mountains in order to expand the geologic record of past ice-sheet behavior. The overarching research objectives are to improve understanding of the East Antarctic Ice Sheet's configuration during periods of warmer-than-present climate, such as the Pliocene warm period, and to determine whether the ice sheet underwent significant volume changes or remained relatively stable in response to warming. To address these goals, the investigation will map and date glacial deposits preserved at mountain sites immediately adjacent the ice sheet. Specifically, we will: (i) employ multiple cosmogenic nuclides (10Be, 26Al, 21Ne) to establish more fully ice-thickness histories for the upper Shackleton and Beardmore Glaciers, where they exit the ice sheet; (ii) use this record to identify periods during which the East Antarctic Ice Sheet was at least as extensive as today; and (iii) use these data to assess long-term ice-sheet variability in East Antarctica, with particular emphasis on Pliocene warm episodes. This research will require Antarctic fieldwork, glacial-geologic mapping, and cosmogenic surface-exposure dating.

这项调查将重建东南极冰盖在比现在温暖的气候时期（如上新世）的过去行为，以便更好地预测地球上最大的冰盖对人为变暖的可能反应。东南极冰盖的未来演变相当于海平面上升约55米，随着气温继续上升，它将在全球范围内产生明显的社会影响。因此，确定未来两个世纪冰盖对气候的敏感性是一个日益紧迫的问题，特别是考虑到有证据表明南极东部冰盖比以前认为的更具活力。这项研究将提供一个长期冰盖行为的陆地地质记录，这些记录来自横贯南极山脉的东南极冰盖附近的地点，该项目将有助于确定冰盖对过去温暖时期的反应。该项目将主要侧重于上新世温暖期，即500万至300万年前，因为这是最接近21世纪气候条件的时期，拟议的研究将调查与横贯南极山脉中部东南极冰盖相对应的冰川沉积物，以扩大过去冰盖行为的地质记录。总体研究目标是提高对南极东部冰盖在比现在温暖的气候时期（如上新世温暖时期）的结构的认识，并确定冰盖是否经历了重大的体积变化或保持相对稳定以应对变暖。为了实现这些目标，这项调查将绘制冰川沉积物的地图，并确定其保存在紧邻冰盖的山区的日期。具体而言，我们将：（i）使用多种宇宙成因核素（10 Be，26 Al，21 Ne）建立更完整的沙克尔顿冰川和比尔德摩尔冰川的冰厚度历史，在那里它们退出冰盖;（ii）使用这个记录来确定东南极冰盖至少和今天一样广泛的时期;和（iii）使用这些数据来评估南极洲东部冰盖的长期变化，特别强调上新世温暖的事件。这项研究将需要南极实地考察，冰川地质测绘和宇宙成因表面暴露年代测定。