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DOI	10.1016/j.epsl.2020.116673
	Measuring multiple cosmogenic nuclides in glacial cobbles sheds light on Greenland Ice Sheet processes
	Corbett L.B.; Bierman P.R.; Neumann T.A.; Graly J.A.; Shakun J.D.; Goehring B.M.; Hidy A.J.; Caffee M.W.
发表日期	2021
ISSN	0012821X
卷号	554
英文摘要	The behavior of the Greenland Ice Sheet during the Pleistocene remains uncertain due to the paucity of evidence predating the Last Glacial Maximum. Here, we employ a novel approach, cosmogenic nuclide analysis of individual subglacially-derived cobbles, which allows us to make inferences about ice sheet processes and subglacial erosion. From three locations in western Greenland, we collected 86 cobbles from the current ice sheet margin and nine cobbles exposed on the modern proglacial land surface. We measured the concentration of in situ 10Be in all cobbles (n = 95) and 26Al and 14C in a subset (n = 14). Cobbles deposited during Holocene retreat have 10Be exposure ages generally consistent with the timing of ice retreat determined by other methods. Conversely, most of the 86 subglacial cobbles contain very low concentrations of 10Be (median 1.0×103 atoms g−1), although several have ∼104 and one has ∼105 atoms g−1. The low concentrations of 10Be in most subglacial cobbles imply that their source areas under the Greenland Ice Sheet are deeply eroded, preserving minimal evidence of surface or near-surface exposure. The presence of measurable 14C in ten of the cobbles requires that they experienced cosmogenic nuclide production within the past ∼30 ka; however, 14C/10Be ratios of ∼6 suggest that nuclide production occurred during shielding by overlying material. Only two of the 86 subglacial cobbles definitively have cosmogenic nuclide concentrations consistent with prior surface exposure. Overall, isotopic analysis of subglacial cobbles indicates that much of western Greenland's subglacial landscape is characterized by deep erosion and minimal subaerial exposure. © 2020 Elsevier B.V.
关键词	cosmogenic nuclides geochemistry Greenland isotopes Pleistocene Pliocene
英文关键词	Erosion; Glacial geology; Glaciers; Isotopes; Cosmogenic nuclide analysis; Cosmogenic nuclides; Greenland Ice Sheet; Isotopic analysis; Last Glacial Maximum; Low concentrations; Nuclide production; Surface exposure; Ice; cosmogenic radionuclide; geochemistry; glacial deposit; glacial erosion; ice sheet; isotopic composition; Pliocene-Pleistocene boundary; subglacial environment; Arctic; Greenland; Greenland Ice Sheet
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203062
作者单位	Department of Geology, University of Vermont, Burlington, VT, United States; Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, United States; Department of Geography and Environmental Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom; Department of Earth and Environmental Sciences, Boston College, Boston, MA, United States; Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, United States; Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA, United States; Department of Physics and Astronomy, Purdue University, West Lafayette, IN, United States; Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, United States
推荐引用方式 GB/T 7714	Corbett L.B.,Bierman P.R.,Neumann T.A.,et al. Measuring multiple cosmogenic nuclides in glacial cobbles sheds light on Greenland Ice Sheet processes[J],2021,554.
APA	Corbett L.B..,Bierman P.R..,Neumann T.A..,Graly J.A..,Shakun J.D..,...&Caffee M.W..(2021).Measuring multiple cosmogenic nuclides in glacial cobbles sheds light on Greenland Ice Sheet processes.Earth and Planetary Science Letters,554.
MLA	Corbett L.B.,et al."Measuring multiple cosmogenic nuclides in glacial cobbles sheds light on Greenland Ice Sheet processes".Earth and Planetary Science Letters 554(2021).