Complex kame belt morphology,stratigraphy and architecture |
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| Authors: | Harold Lovell Stephen J Livingstone Clare M Boston Adam D Booth Robert D Storrar Iestyn D Barr |
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| Institution: | 1. Department of Geography, University of Portsmouth, Portsmouth, PO1 3HE;2. Department of Geography, University of Sheffield, Sheffield, S10 2TN;3. School of Earth and Environment, University of Leeds, Leeds, LS2 9JT;4. Department of the Natural and Built Environment, Sheffield Hallam University, Sheffield, S1 1WB;5. School of Science and the Environment, Manchester Metropolitan University, Manchester, M15 6BH |
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| Abstract: | The development of glacier karst at the margins of melting ice sheets produces complex glaciofluvial sediment-landform assemblages that provide information on ice sheet downwasting processes. We present the first combined geomorphological, sedimentological and geophysical investigation of the Brampton Kame Belt, an important glaciofluvial depositional zone at the centre of the last British-Irish Ice Sheet. Ground-penetrating radar (GPR) data allow the broad scale internal architecture of ridges (eskers) and flat-topped hills (ice-walled lake plains) to be determined at four sites. In combination with sediment exposures, these provide information on lateral and vertical variations in accretion styles, depositional boundaries, and grain size changes. Building on existing work on the subject, we propose a refined model for the formation of ice-walled lake plains resulting from the evolution and collapse of major drainage axes into lakes as stable glacier karst develops during deglaciation. The internal structure of esker ridges demonstrates variations in sedimentation that can be linked to differences in ridge morphologies across the kame belt. This includes low energy flow conditions and multiple accretion phases identified within large S-N oriented esker ridges; and fluctuating water pressures, hyperconcentrated flows, and significant deformation within a fragmented SW–NE oriented esker ridge. In combination with updated geomorphological mapping, this work allows us to identify two main styles of drainage within the kame belt: (1) major drainage axes aligned broadly S-N that extend through the entire kame belt and collapsed into a chain of ice-walled lakes; and (2) a series of smaller, fragmented SW–NE aligned esker ridges that represent ice-marginal drainage as the ice sheet receded south-eastwards up the Vale of Eden. Our study demonstrates the importance of integrated geomorphological, sedimentological and geophysical investigations in order to understand complex and polyphase glaciofluvial sediment-landform assemblages. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd. |
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| Keywords: | kame glaciofluvial geomorphology sedimentology ground-penetrating radar (GPR) British-Irish Ice Sheet |
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