Ice marginal dynamics of the last British-Irish Ice Sheet in the southern North Sea: ice limits, timing and the influence of the Dogger Bank

• Published in: Quaternary Science Reviews
• Main Authors: Roberts, David H., Evans, David J.A., Callard, S. Louise, Clark, Chris D., Bateman, Mark D., Medialdea, Alicia, Dove, Dayton, Cotterill, Carol J., Saher, Margot, Cofaigh, Colm Ó, Chiverrell, Richard C., Moreton, Steven G., Fabel, Derek, Bradwell, Tom
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2018
• Subjects: Dogger Bank; Ice Sheet; Sea ice
• Online Access: http://nora.nerc.ac.uk/id/eprint/521836/; https://nora.nerc.ac.uk/id/eprint/521836/1/1-s2.0-S0277379117310612-main.pdf; https://doi.org/10.1016/j.quascirev.2018.08.010

The southern North Sea is a particularly important area for understanding the behaviour of the British-Irish Ice Sheet (BIIS) during the last glacial cycle. It preserves a record of the maximum extent of the eastern sector of the BIIS as well as evidence for multiple different ice flow phases and the dynamic re-organisation of the BIIS. However, to date, the known ice sheet history and geochronology of this region is predominantly derived from onshore geological evidence, and the offshore imprint and dynamic history of the last ice sheet remain largely unknown. Using new data collected by the BRITICE-CHRONO project this paper explores the origin and age of the Dogger Bank; re-assesses the extent and age of the glaciogenic deposits across the shallow areas of the North Sea between the Dogger Bank and the north Norfolk coast and; re-examines the dynamic behaviour of the BIIS in the southern North Sea between 31.6 and 21.5 ka. This paper shows the core of the Dogger Bank to be composed glaciolacustrine sediment deposited between 31.6 and 25.8 ka. Following its formation the western end of the Dogger lake was overridden with ice reaching ∼54°N where the ice margin is co-incident with the southerly extent of subglacial tills previously mapped as Bolders Bank Fm. This initial ice override and retreat northwards back across the Dogger lake was complete by 23.1 ka, but resulted in widespread compressive glaciotectonism of the lake sediments and the formation of thrust moraine complexes. Along the northern edge of the bank moraines are on-lapped by later phase glaciolacustrine and marine sediments but do not show evidence of subsequent ice override. The shallow seafloor to the west and southwest of the Dogger Bank records several later phases of ice advance and retreat as the North Sea Lobe flowed between the Dogger Bank and the Yorkshire/Lincolnshire coasts and reached North Norfolk. New optically stimulated luminescence (OSL) ages from Garrett Hill on outwash limit the arrival of the BIIS on the Norfolk coast to ...