Holocene glacial history of Renland Ice Cap, East Greenland, reconstructed from lake sediments

QUATERNARY SCIENCE REVIEWS

卷:258

Article

Medford, Aaron K.^1,2  Hall, Brenda L.^1,2  Lowell, Thomas V.³  Kelly, Meredith A.⁴  Levy, Laura B.⁵  Wilcox, Paul S.⁶  Axford, Yarrow⁷ 

[1] Univ Maine, Sch Earth & Climate Sci, 5790 Bryand Global Sci Ctr, Orono, ME 04469 USA

[2] Univ Maine, Climate Change Inst, 5790 Bryand Global Sci Ctr, Orono, ME 04469 USA

[3] Univ Cincinnati, Dept Geol, 500 Geophys Bldg, Cincinnati, OH 45221 USA

[4] Dartmouth Coll, Dept Earth Sci, HB 6105 Fairchild Hall, Hanover, NH 03755 USA

[5] Humboldt State Univ, 1 Harpst St, Arcata, CA 95521 USA

[6] Univ Innsbruck, Inst Geol, 52 Innrain, A-6020 Innsbruck, Austria

[7] Northwestern Univ, Dept Earth & Planetary Sci, 2145 Sheridan Rd, Evanston, IL 60208 USA

关键词: Greenland;    Renland ice cap;    Holocene;    Glacier variations;    Lake sediments;   

DOI  :  10.1016/j.quascirev.2021.106883

来源: Elsevier

【 摘 要 】

Shrinking glaciers, melting permafrost, and reduced sea ice all indicate rapid contraction of the Arctic cryosphere in response to present-day climate warming, a trajectory that is expected to continue, if not accelerate. The reaction of the Arctic cryosphere to past periods of climate variation can afford insight into its present and future behavior. Here, we examine a-12,000 year record of glacier fluctuations and meltwater variation associated with the Renland Ice Cap, East Greenland, that extends from the early Holocene thermal optimum through the cooling of the Little Ice Age to present. Sediment records from glacially fed lakes indicate rapid early Holocene deglaciation, with ice extent likely slightly smaller than at present by-9500 yr BP. Glacial activity resulted in occasional deposition of rock flour in the studied lakes in the early Holocene until at least-7500 yr BP. Rock flour is absent for much of the period -7000-4000 yr BP, suggesting ice extent generally was smaller than at present. However, thin layers of blue-gray clay throughout this period may indicate millennial-scale ice expansions, with Renland Ice Cap briefly reaching extents during cold phases that may have been similar to today. Glacial sediment deposition occurred again in the late Holocene at-3200e340 0 yr BP and was followed by a brief glacial episode at-1340 yr BP and then a major event beginning shortly after-1050 yr BP. We infer that rock flour deposition in the lakes in the last millennium corresponds with advance of Renland glaciers to their Little Ice Age positions, marked by a fresh, gray drift limit. Radiocarbon dates of in situ plant remains adjacent to the present ice cap indicate a short relatively warm period-500 yr ago, when ice was within its AD 2011 limit, followed by glacier readvance. The general pattern of ice fluctuations in Renland is similar to that at other ice caps in the region, but also has important differences, including the preservation of a possible mid-Holocene record at times when lower-elevation ice caps in the Scoresby Sund region may have been absent. This finding reinforces the concept that examination of multiple geographic and geomorphologic settings is necessary for a full understanding of ice variations in a region. (c) 2021 Elsevier Ltd. All rights reserved.

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