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Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland

Callard, S. Louise; Ó Cofaigh, Colm; Benetti, Sara; Chiverrell, Richard C.; Van Landeghem, Katrien J.J.; Saher, Margot H.; Livingstone, Stephen J.; Clark, Chris D.; Small, David; Fabel, Derek; Moreton, Steven G.

Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland Thumbnail


Authors

S. Louise Callard

Sara Benetti

Richard C. Chiverrell

Katrien J.J. Van Landeghem

Margot H. Saher

Stephen J. Livingstone

Chris D. Clark

Derek Fabel

Steven G. Moreton



Abstract

During the Last Glacial Maximum, the British-Irish Ice Sheet extended across the continental shelf offshore of Galway Bay, western Ireland, and reached a maximum westward extent on the Porcupine Bank. New marine geophysical data, sediment cores and radiocarbon dates are used to constrain the style and timing of ice-sheet retreat across the mid to inner-shelf. Radiocarbon dated shell fragments in subglacial till on the mid-shelf constrains ice advance to after 26.4 ka BP. Initial retreat was underway before 24.4 ka BP, significantly earlier than previous reconstructions. Grounding-line retreat was accompanied by stillstands and/or localised readvances of the grounding-line. A large composite Mid-Shelf Grounding Zone Complex marks a major grounding-line position, with the ice grounded and the margin oscillating at this position by, and probably after, 23 ka BP. The continental shelf was ice-free by 17.1 cal. ka BP, but the ice sheet may have retained a marine margin until c. 15.3 ka BP. Retreat occurred in a glacimarine setting and the ice sheet was fringed by a floating ice-shelf. Collectively, this evidence indicates a dynamic and oscillatory marine-terminating ice sheet offshore of western Ireland during the last deglaciation.

Citation

Callard, S. L., Ó Cofaigh, C., Benetti, S., Chiverrell, R. C., Van Landeghem, K. J., Saher, M. H., …Moreton, S. G. (2020). Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland. Marine Geology, 420, Article 106087. https://doi.org/10.1016/j.margeo.2019.106087

Journal Article Type Article
Acceptance Date Nov 21, 2019
Online Publication Date Nov 26, 2019
Publication Date Feb 28, 2020
Deposit Date Nov 26, 2019
Publicly Available Date Mar 29, 2024
Journal Marine Geology
Print ISSN 0025-3227
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 420
Article Number 106087
DOI https://doi.org/10.1016/j.margeo.2019.106087

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