Cosmogenic surface exposure dating of Arctic NW Laurentide ice-sheet deglaciation: implications for abrupt climate change

北极西北劳伦泰德冰盖消融的宇宙成因表面暴露测年：对气候突变的影响

• 批准号: 1834667
• 负责人: Anders Carlson
• 金额: $ 34.96万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1834667&HistoricalAwards=false
• 关键词: Cosmogenic; surface; exposure; dating; Arctic

The objective of this project is to date the retreat of the Keewatin Dome of the Arctic NW Laurentide ice sheet (LIS) during the last deglaciation and test the relationship among the timing and rate of ice retreat, discharge of meltwater to the Arctic Ocean, and abrupt climate change. The study will also document how meltwater associated with Arctic NW LIS retreat may have contributed to deglacial sea level rise. The investigator will measure the cosmogenic nuclide beryllium-10 from 80 boulders at 11 sites along a 1000 km east-west transect. The project will support two undergraduate students who will be trained in glacial geology, geochronology, paleoclimatology, and Arctic fieldwork. Public outreach is planned for Da Vinci Days and a farmers' market in Corvallis, Oregon, as well as to northern communities and local geoscientists through the annual Yellowknife Geoscience Forum. This project will provide new understanding of the relationship among Arctic ice-sheet retreat, Atlantic meridional overturning circulation, and climate change. Retreat of the Arctic NW Laurentide ice sheet (LIS) will be dated using beryllium-10 surface exposure ages for more than 80 boulders at 11 sites along a 1000 km long transect perpendicular to LIS retreat at 65 degrees North. Sampling density will be 100 km, resolvable by ice sheet models. The investigator will address two primary questions: 1) What are the spatiotemporal patterns of Arctic NW LIS deglaciation and was retreat monotonic or were their periods of accelerated retreat? And 2) Do Arctic NW LIS retreat-rate changes correspond with deglacial periods of Northern Hemisphere abrupt climate change, such as the Younger Dryas? The first question will be answered using beryllium ages, with the sampling approach able to resolve century-scale changes in ice-margin retreat. The second question will be addressed by comparing the timing of Arctic NW LIS retreat at the 11 sampling locations to abrupt climate events of the last deglaciation. To convert the ice-margin retreat record into changes in ice volume and meltwater discharge, the investigator will use the chronology to filter Bayesian deglacial LIS-model simulations, which will force sea-level/earth models and be compared to deglacial climate simulations.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.

该项目的目标是确定北极西北劳伦泰德冰盖 (LIS) 基瓦廷圆顶 (LIS) 在末次冰消期期间退缩的日期，并测试冰退缩的时间和速度、向北冰洋排放融水以及冰消退之间的关系。气候突然变化。该研究还将记录与北极西北 LIS 退缩相关的融水如何导致冰消海平面上升。研究人员将从沿 1000 公里东西向横断面 11 个地点的 80 块巨石中测量宇宙成因核素铍 10。该项目将支持两名本科生，他们将接受冰川地质学、地质年代学、古气候学和北极实地考察方面的培训。计划在达芬奇日和俄勒冈州科瓦利斯的农贸市场进行公众宣传，并通过年度黄刀地球科学论坛向北部社区和当地地球科学家进行宣传。该项目将为北极冰盖退缩、大西洋经向翻转环流和气候变化之间的关系提供新的认识。北极西北劳伦泰冰盖 (LIS) 的退缩将使用铍 10 表面暴露年龄来测定，该年龄位于北纬 65 度垂直于 LIS 退缩的 1000 公里长横断面的 11 个地点的 80 多个巨石上。采样密度为 100 公里，可通过冰盖模型解析。研究者将解决两个主要问题：1）北极西北 LIS 冰消的时空模式是什么？是单调退缩还是加速退缩期？ 2）北极西北 LIS 退缩率变化是否与北半球气候突变的冰消期（例如新仙女木期）相对应？第一个问题将使用铍年龄来回答，采样方法能够解决冰缘退缩的世纪尺度变化。第二个问题将通过将 11 个采样点的北极西北 LIS 退缩时间与上次冰消期的突变气候事件进行比较来解决。为了将冰缘退缩记录转换为冰量和融水排放的变化，研究人员将使用年代学来过滤贝叶斯冰消期LIS模型模拟，这将迫使海平面/地球模型并与冰消期气候模拟进行比较。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。