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.

该项目的目标是测定北极西北部劳伦蒂德冰盖(LIS)的Keewatin穹顶在最后一次冰川消融期间的消退日期，并测试冰川消退的时间和速度、向北冰洋排放融水和气候突变之间的关系。这项研究还将记录与北极西北部LIS退缩相关的融水可能是如何导致退冰期海平面上升的。研究人员将从东西长1000公里的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一个农贸市场，以及通过一年一度的耶洛奈夫地球科学论坛向北部社区和当地地球科学家进行公众宣传。该项目将对北极冰盖退缩、大西洋经向翻转环流和气候变化之间的关系提供新的理解。北极西北劳伦蒂德冰盖(LIS)的退缩将使用铍-10表面暴露年龄来确定，这些冰盖位于北纬65度，垂直于LIS退缩的1000公里长的横断面上的11个地点的80多块巨石。采样密度为100公里，可通过冰盖模型解决。研究人员将回答两个主要问题：1)北极西北部冰川消退的时空模式是什么，退缩是单调的还是加速退缩的时期？2)北极西北部的退缩速率变化是否与北半球突然气候变化的消冰期相对应，例如年轻的仙女木？第一个问题将用铍年龄来回答，取样方法能够解决冰缘退缩的百年尺度变化。第二个问题将通过将11个采样点北极西北部LIS退缩的时间与上次冰川消融的突然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，研究人员将使用年表过滤贝叶斯去冰川LIS模型模拟，这将迫使海平面/地球模型并与去冰川气候模拟进行比较。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。