Exploring controls of the early and stepped deglaciation on the western margin of the British Irish Ice Sheet
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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.
Benetti , S , Chiverrell , R C , Cofaigh , C Ó , Burke , M , Medialdea , A , Small , D , Ballantyne , C , Bateman , M D , Callard , S L , Wilson , P , Fabel , D , Clark , C D , Arosio , R , Bradley , S , Dunlop , P , Ely , J C , Gales , J , Livingstone , S J , Moreton , S G , Purcell , C , Saher , M , Schiele , K , Van Landeghem , K & Weilbach , K 2021 , ' Exploring controls of the early and stepped deglaciation on the western margin of the British Irish Ice Sheet ' , Journal of Quaternary Science , vol. Early View . https://doi.org/10.1002/jqs.3315
Journal of Quaternary Science
Copyright © 2021 The Authors. Journal of Quaternary Science Published by Wiley Periodicals LLC. 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.
DescriptionThis research was funded by the UK Natural Environment Research Council consortium grant NE/J007196/1 BRITICE-CHRONO. The work was supported by the NERC Radiocarbon Facility and NERC Cosmogenic Isotope Facility Analysis.
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