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Exploring controls of the early and stepped deglaciation on the western margin of the British Irish Ice Sheet

Benetti, Sara and Chiverrell, Richard C. and Cofaigh, Colm Ó and Burke, Matt and Medialdea, Alicia and Small, David and Ballantyne, Colin and Bateman, Mark D. and Callard, S. Louise and Wilson, Peter and Fabel, Derek and Clark, Chris D. and Arosio, Riccardo and Bradley, Sarah and Dunlop, Paul and Ely, Jeremy C. and Gales, Jenny and Livingstone, Stephen J. and Moreton, Steven G. and Purcell, Catriona and Saher, Margot and Schiele, Kevin and Van Landeghem, Katrien and Weilbach, Kasper (2021) 'Exploring controls of the early and stepped deglaciation on the western margin of the British Irish Ice Sheet.', Journal of Quaternary Science, 36 (5). 833 - 870.

Abstract

New optically stimulated luminescence dating and Bayesian models integrating all legacy and BRITICE-CHRONO geochronology facilitated exploration of the controls on the deglaciation of two former sectors of the British–Irish Ice Sheet, the Donegal Bay (DBIS) and Malin Sea ice-streams (MSIS). Shelf-edge glaciation occurred ~27 ka, before the global Last Glacial Maximum, and shelf-wide retreat began 26–26.5 ka at a rate of ~18.7–20.7 m a–1. MSIS grounding zone wedges and DBIS recessional moraines show episodic retreat punctuated by prolonged still-stands. By ~23–22 ka the outer shelf (~25 000 km2) was free of grounded ice. After this time, MSIS retreat was faster (~20 m a–1 vs. ~2–6 m a–1 of DBIS). Separation of Irish and Scottish ice sources occurred ~20–19.5 ka, leaving an autonomous Donegal ice dome. Inner Malin shelf deglaciation followed the submarine troughs reaching the Hebridean coast ~19 ka. DBIS retreat formed the extensive complex of moraines in outer Donegal Bay at 20.5–19 ka. DBIS retreated on land by ~17–16 ka. Isolated ice caps in Scotland and Ireland persisted until ~14.5 ka. Early retreat of this marine-terminating margin is best explained by local ice loading increasing water depths and promoting calving ice losses rather than by changes in global temperatures. Topographical controls governed the differences between the ice-stream retreat from mid-shelf to the coast.

Item Type:Article
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1002/jqs.3315
Publisher statement:This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Date accepted:18 March 2021
Date deposited:30 July 2021
Date of first online publication:02 June 2021
Date first made open access:30 July 2021

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