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Exploring controls of the early and stepped deglaciation on the western margin of the British Irish Ice Sheet
Author(s) -
Benetti Sara,
Chiverrell Richard C.,
Cofaigh Colm Ó,
Burke Matt,
Medialdea Alicia,
Small David,
Ballantyne Colin,
Bateman Mark D.,
Callard S. Louise,
Wilson Peter,
Fabel Derek,
Clark Chris D.,
Arosio Riccardo,
Bradley Sarah,
Dunlop Paul,
Ely Jeremy C.,
Gales Jenny,
Livingstone Stephen J.,
Moreton Steven G.,
Purcell Catriona,
Saher Margot,
Schiele Kevin,
Van Landeghem Katrien,
Weilbach Kasper
Publication year - 2021
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.3315
Subject(s) - deglaciation , geology , ice sheet , moraine , ice shelf , oceanography , ice stream , wisconsin glaciation , glacial period , physical geography , paleontology , geomorphology , sea ice , cryosphere , holocene , geography
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 km 2 ) 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.