Deciphering 6 My of the Greenland Ice Sheet History using in situ 10-Be from marine sediment cores

This research will explore a new method of deciphering the history of the Greenland Ice Sheet over the Pliocene and Pleistocene by measuring the cosmogenic isotope beryllium-10 in sediment cores previously collected off southern and eastern Greenland by the Ocean Drilling program. Beryllium-10 is produced by cosmic rays in exposed rock. The premise of this investigation is that Be-10 accumulates in surface rock during times of ice-sheet retreat and is eroded and deposited in marine sediment during times of ice-sheet growth. The isotopic time series will include Pleistocene and Pliocene sediment stretching back 4 to 6 million years, possibly beyond the onset of continental-scale glaciation in Greenland. The investigators hope to 1) constrain the time at which continental glaciation on Greenland began, 2) estimate the relative areal extent of the ice sheet through time, 3) determine the erosivity and sediment transport efficiency of the ice sheet, and 4) constrain the erosion rate of Greenland prior to the onset of glaciation. Understanding Greenland Ice Sheet dynamics in the past (particularly the extent of deglaciation and the timescale of regrowth) is key to understanding how the ice sheet might behave in the future. A central part of the project is the training of a young postdoctoral research associate, and two undergraduate students will work on the project as well.

本研究拟通过测定海洋钻探计划（Ocean Drilling Program）此前在格陵兰岛南部与东部海域获取的沉积物岩芯中的宇宙成因同位素铍-10（beryllium-10），解析上新世（Pliocene）与更新世（Pleistocene）时期格陵兰冰盖（Greenland Ice Sheet）的演化历史，提出一种全新的研究方法。铍-10由宇宙射线在裸露岩石中生成。本研究的核心前提为：冰盖退缩阶段，铍-10会在地表岩石中富集；而当冰盖扩张时，铍-10会被侵蚀并搬运沉积至海洋沉积物中。本次研究的同位素时间序列将涵盖可追溯至400万至600万年前的上新世与更新世沉积物，甚至可能覆盖格陵兰大陆规模冰川作用启动之前的时段。研究团队期望达成四项核心目标：1）限定格陵兰大陆规模冰川作用的起始时间；2）估算不同地质时期冰盖的相对面积范围；3）明确冰盖的侵蚀能力与沉积物搬运效率；4）限定冰川作用启动前格陵兰地区的侵蚀速率。解析格陵兰冰盖的古动态变化（尤其是冰盖消退的范围与重新生长的时间尺度），是理解该冰盖未来演化趋势的关键所在。本项目的核心内容之一是培养一名青年博士后研究人员，同时还将有两名本科生参与项目研究。