Collaborative Research: Geological constraints on the disappearance of the Laurentide Ice Sheet

合作研究：劳伦泰德冰盖消失的地质限制

• 批准号: 1927153
• 负责人: Gifford Miller
• 金额: $ 27.5万
• 依托单位: University of Colorado at Boulder
• 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: 2020-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1927153&HistoricalAwards=false
• 关键词: Collaborative; Research; Geological; constraints; disappearance

The Laurentide Ice Sheet (LIS) once covered much of the North American continent. It grows and expands during cold periods and contracts during warm periods in Earth's recent geological past. Today, the last remaining vestige of the LIS is the Barnes Ice Cap, located on central Baffin Island. While tracking the size of the LIS at times when it was significantly larger than today is relatively straightforward, constraining the size and frequency of LIS minima is much more challenging but can provide a long-term context in which to evaluate the current small state of the Barnes Ice Cap. For this project, the investigators will use new, cutting-edge geological techniques to piece together how often the LIS reaches its current dimensions. The team will be led by an early-career Hispanic geoscientist, and the project will train one doctoral and two undergraduate student. The investigators will participate in institutional open houses that are available to the public and recruit undergraduate student participation through institutional internship programs. Knowledge of past warm periods and their effect on the cryopshere can help place modern warming and glacier demise in a longer-term context. LIS is Earth's most dynamic ice sheet having undergone repeated continental-scale expansions and contractions through the Quaternary. Evidence for past ice-sheet maxima is found in terrestrial and marine settings, yet the minimum extent of the LIS during interglaciations is largely unknown. The Barnes Ice Cap, the last remaining vestige of LIS, once covered much of the North American continent during the Last Glacial Maximum (~27-20 ka). The investigators will measure multiple cosmogenic nuclides (Beryllium-10, Carbon-14, Neon-21, Aluminum-26, and Chlorine-36) from recently exposed bedrock along the Barnes Ice Cap to quantify how frequently and for how long the LIS/Barnes Ice Cap achieves its modern dimensions during interglaciations. They will use a new field method that relies on shallow bedrock cores (rather than surface samples), which will be combined with the inventory of multiple cosmogenic nuclides with different half-lives, to quantify total Quaternary exposure and burial durations of bedrock surfaces just now being exposed by receding ice. Results will be compared to recent cosmogenic nuclide measurements from beneath the Greenland Ice Sheet Project 2 (GISP2) borehole that suggest the Greenland Ice Sheet nearly completely deglaciated on several occasions through the Quaternary.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.

劳伦德冰盖（LIS）曾经覆盖了北美大陆的大部分地区。它在寒冷的时期和契约期间在地球最近的地质过去的温暖时期内生长和扩展。如今，LI的最后剩下的痕迹是位于巴芬岛中部的Barnes冰盖。尽管在明显大于今天的LIS的大小相对直接的情况下，限制LIS Minima的大小和频率的情况更具挑战性，但可以提供长期的背景，以评估当前的Barnes冰盖状态小。对于这个项目，研究人员将使用新的，尖端的地质技术来拼凑出LIS的频率。该团队将由早期的西班牙裔地球科学家领导，该项目将培训一名博士学位和两个本科生。调查人员将参加公众可用的机构开放式房屋，并通过机构实习计划招募本科生参与。 对过去温暖时期及其对冷冻厂的影响的了解可以帮助在长期的背景下将现代变暖和冰川灭亡。 LIS是地球最具动态的冰盖，通过第四纪经过了反复的大陆规模扩张和收缩。在陆地和海洋环境中发现了过去的冰片最大值的证据，但是在固定间期间，LI的最小程度在很大程度上尚不清楚。 Barnes冰盖是LI的最后剩下的痕迹，曾经在最后一次冰川最大值（〜27-20 ka）中覆盖了北美大陆的大部分大陆。研究人员将测量来自最近暴露的沿Barnes冰盖的底石的多种宇宙核素（Beryllium-10，Carbon-14，Neon-21，Aluminum-26和氯-36），以量化LIS/BARNES冰盖在间隙期间实现其现代尺寸的频率和多长时间。他们将使用一种依赖浅基岩核心（而不是表面样品）的新田间方法，该方法将与具有不同半衰期的多个宇宙核素的清单相结合，以量化Quaternary的总暴露和基岩表面的埋葬持续时间。结果将与最新的宇宙核素测量结果进行比较，从格陵兰冰盖项目2（GISP2）钻孔下进行了比较，该钻孔表明，通过第四纪，几乎多次脱离了格陵兰冰盖。这奖反映了NSF的法规任务，并被认为是通过基金会的知识优点和广泛的Impactia的评估来进行评估。