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

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

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16 Citations (Scopus)
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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.
Original languageEnglish
Article number106087
JournalMarine Geology
Volume420
Early online date26 Nov 2019
DOIs
Publication statusPublished (in print/issue) - 1 Feb 2020

Bibliographical note

Funding Information:
This research was funded by the UK Natural Environment Research Council grant; BRITICE-CHRONO NE/J007196/1. The work was supported by the NERC Radiocarbon Facility (allocation numbers 1722.0613 and 1878.1014). Thanks are due to the staff at the NERC AMS Laboratory, East Kilbride for carbon isotope measurements. We thank the officers and crew of the RRS James Cook for their help with acquisition and the British Geological Survey and National Oceanography Centre for vibrocore and piston core collection during the cruise JC106. We also thank Kasper Weilbach, Riccardo Arosio, Catriona Purcell, Zoe Roseby, Kevin Schiele and Elke Hanenkamp for their scientific support on the JC106 leg 2 cruise. Finally, thanks to Hans Petter Sejrup and two anonymous reviewers who provided detailed comments and suggestions to improve the manuscript.

Funding Information:
This research was funded by the UK Natural Environment Research Council grant; BRITICE-CHRONO NE/J007196/1 . The work was supported by the NERC Radiocarbon Facility (allocation numbers 1722.0613 and 1878.1014 ). Thanks are due to the staff at the NERC AMS Laboratory, East Kilbride for carbon isotope measurements. We thank the officers and crew of the RRS James Cook for their help with acquisition and the British Geological Survey and National Oceanography Centre for vibrocore and piston core collection during the cruise JC106. We also thank Kasper Weilbach, Riccardo Arosio, Catriona Purcell, Zoe Roseby, Kevin Schiele and Elke Hanenkamp for their scientific support on the JC106 leg 2 cruise. Finally, thanks to Hans Petter Sejrup and two anonymous reviewers who provided detailed comments and suggestions to improve the manuscript. Appendix A

Publisher Copyright:
© 2019 Elsevier B.V.

Keywords

  • British-Irish Ice Sheet
  • Continental shelf
  • Glacimarine
  • Grounding zone wedges
  • Ice shelf
  • Ice-sheet retreat
  • Last Glacial Maximum

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