10Be chronology of the last deglaciation of County Donegal, northwestern Ireland |
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| Authors: | JORIE CLARK A MARSHALL McCABE CHRISTOPH SCHNABEL PETER U CLARK STEWART FREEMAN COLIN MADEN SHENG XU |
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| Institution: | School of Environmental Science, University of Ulster, Coleraine, County Londonderry BT52 1SA, UK;;NERC Cosmogenic Isotope Analysis Facility, Scottish Enterprise Technology Park, East Kilbride, UK G75 0QF NERC;;Department of Geosciences, Oregon State University, Corvallis, Oregon 97331, USA;;Scottish Universities Environmental Research Centre (SUERC), Scottish Enterprise Technology Park, East Kilbride, UK G75 0QF |
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| Abstract: | A well-preserved moraine on the northern coast of County Donegal, Ireland, has played a critical role in our understanding of the glacial history of this sector of the Irish Ice Sheet (IIS). Because of a lack of numerical dating of the moraine, however, previous interpretations of its age and significance to the glacial history of this region have varied widely. Here we report eight in situ cosmogenic 10Be ages on boulders sampled from the moraine. Two of these ages are outliers, with the remaining six ranging from 18.8±1.0 10Be kyr to 20.9±1.3 10Be kyr, with an uncertainty-weighted mean age of 19.4±0.3 10Be kyr (19.4±1.2 kyr accounting for production rate uncertainty). Our results confirm one previous 10Be age obtained from the moraine, with the combined data ( n =7) constraining the age of initial deglaciation of the IIS from its LGM position on the continental shelf to be 19.3±0.3 10Be kyr (19.3±1.2 kyr accounting for production rate uncertainty). These ages are in excellent agreement with calibrated 14C ages that constrain retreat of the IIS margin from the continental shelf elsewhere in northwestern and western Ireland and the Irish Sea Basin associated with the start of the Cooley Point Interstadial (≥20–≤18.2 cal. kyr BP), suggesting widespread deglaciation of the IIS ～19.5–20 kyr ago. |
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