Glacier expansion on Baffin Island during early Holocene cold reversals

QUATERNARY SCIENCE REVIEWS

卷:241

Article

Crump, Sarah E.^1,2  Young, Nicolas E.³  Miller, Gifford H.^1,2  Pendleton, Simon L.^1,2,4  Tulenko, Joseph P.⁵  Anderson, Robert S.^1,2  Briner, Jason P.⁵ 

[1] Univ Colorado, INSTAAR, 4001 Discovery Dr, Boulder, CO 80309 USA

[2] Univ Colorado, Geol Sci, 4001 Discovery Dr, Boulder, CO 80309 USA

[3] Columbia Univ, Lamont Doherty Earth Observ, 61 Rte 9W, Palisades, NY USA

[4] Woods Hole Oceanog Inst, 86 Water St, Woods Hole, MA 02543 USA

[5] Univ Buffalo, Dept Geol, 126 Cooke Hall, Buffalo, NY USA

关键词: Holocene;    Paleoclimatology;    Glaciology;    Arctic;    Cosmogenic isotopes;    Glacial geomorphology;    Abrupt climate change;   

DOI  :  10.1016/j.quascirev.2020.106419

来源: Elsevier

【 摘 要 】

The North Atlantic was a key locus for circulation-driven abrupt climate change in the past and could play a similar role in the future. Abrupt cold reversals, including the 8.2 ka event, punctuated the otherwise warm early Holocene in the North Atlantic region and serve as useful paleo examples of rapid climate change. In this work, we assess the cryospheric response to early Holocene climate history on Baffin Island, Arctic Canada, using cosmogenic radionuclide dating of moraines. We present 39 new Be-10 ages from four sets of multi-crested early Holocene moraines deposited by cirque glaciers and ice cap outlet glaciers, as well as erratic boulders along adjacent fiords to constrain the timing of regional deglaciation. The age of one moraine is additionally constrained by in situ C-14 measurements, which confirm Be-10 inheritance in some samples. All four moraines were deposited between similar to 9.2 and 8.0 ka, and their average ages coincide with abrupt coolings at 9.3 and 8.2 ka that are recorded in Greenland ice cores. Freshwater delivery to the North Atlantic that reduced the flux of warm Atlantic water into Baffin Bay may explain brief intervals of glacier advance, although moraine formation cannot be definitively tied to centennial-scale cold reversals. We thus explore other possible contributing factors, including ice dynamics related to retreat of Laurentide Ice Sheet outlet glaciers. Using a numerical glacier model, we show that the debuttressing effect of trunk valley deglaciation may have contributed to these moraine-building events. These new age constraints and process insights highlight the complex behavior of the cryosphere during regional deglaciation and suggest that multiple abrupt cold reversals-as well as deglacial ice dynamics-likely played a role in early Holocene moraine formation on Baffin Island. (C) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

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