TY - JOUR
T1 - Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland
AU - Callard, Louise
AU - Ó Cofaigh, Colm
AU - Benetti, S.
AU - Chiverrell, Richard
AU - Van Landeghem, Katrien J J
AU - Saher, Margot
AU - Livingstone, Stephen J
AU - Clark, Chris D
AU - Small, David
AU - Fabel, Derek
AU - Moreton, Steven G
PY - 2020/2/1
Y1 - 2020/2/1
N2 - 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.
AB - 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.
KW - British-Irish Ice Sheet
KW - Continental shelf
KW - Glacimarine
KW - Grounding zone wedges
KW - Ice shelf
KW - Ice-sheet retreat
KW - Last Glacial Maximum
UR - http://www.scopus.com/inward/record.url?scp=85076174477&partnerID=8YFLogxK
U2 - 10.1016/j.margeo.2019.106087
DO - 10.1016/j.margeo.2019.106087
M3 - Article
VL - 420
JO - Marine Geology
JF - Marine Geology
SN - 0025-3227
M1 - 106087
ER -