globalchange  > 气候变化与战略
DOI: 10.1016/j.epsl.2020.116673
论文题名:
Measuring multiple cosmogenic nuclides in glacial cobbles sheds light on Greenland Ice Sheet processes
作者: Corbett L.B.; Bierman P.R.; Neumann T.A.; Graly J.A.; Shakun J.D.; Goehring B.M.; Hidy A.J.; Caffee M.W.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 554
语种: 英语
中文关键词: 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
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.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165440
Appears in Collections:气候变化与战略

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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

Recommended Citation:
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]. Earth and Planetary Science Letters,2021-01-01,554
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