The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation



Chiverrell, RC ORCID: 0000-0002-7307-2756, Thomas, GSP, Burke, M, Medialdea, A, Smedley, R ORCID: 0000-0001-7773-5193, Bateman, M, Clark, C, Duller, GAT, Fabel, D, Jenkins, G
et al (show 3 more authors) (2020) The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation. Journal of Quaternary Science.

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Abstract

ABSTRACT Here we reconstruct the last advance to maximum limits and retreat of the Irish Sea Glacier (ISG), the only land-terminating ice lobe of the western British Irish Ice Sheet. A series of reverse bedrock slopes rendered proglacial lakes endemic, forming time-transgressive moraine- and bedrock-dammed basins that evolved with ice marginal retreat. Combining, for the first time on glacial sediments, optically stimulated luminescence (OSL) bleaching profiles for cobbles with single grain and small aliquot OSL measurements on sands, has produced a coherent chronology from these heterogeneously bleached samples. This chronology constrains what is globally an early build-up of ice during late Marine Isotope Stage 3 and Greenland Stadial (GS) 5, with ice margins reaching south Lancashire by 30?±?1.2?ka, followed by a 120-km advance at 28.3?±?1.4?ka reaching its 26.5?±?1.1?ka maximum extent during GS-3. Early retreat during GS-3 reflects piracy of ice sources shared with the Irish-Sea Ice Stream (ISIS), starving the ISG. With ISG retreat, an opportunistic readvance of Welsh ice during GS-2 rode over the ISG moraines occupying the space vacated, with ice margins oscillating within a substantial glacial over-deepening. Our geomorphological chronosequence shows a glacial system forced by climate but mediated by piracy of ice sources shared with the ISIS, changing flow regimes and fronting environments.

Item Type: Article
Additional Information: doi: 10.1002/jqs.3229
Uncontrolled Keywords: British–Irish ice sheet, deglaciation, geomorphology, glacial lakes, luminescence dating
Depositing User: Symplectic Admin
Date Deposited: 07 Jul 2020 13:05
Last Modified: 01 Sep 2022 08:11
DOI: 10.1002/jqs.3229
Open Access URL: https://doi.org/10.1002/jqs.3229
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3093127