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Glaciotectonically induced water-throughflow structures in a Late Pleistocene drumlin, Kanrawer, County Galway, western Ireland

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MCCABE, AM and DARDIS, GF (1994) Glaciotectonically induced water-throughflow structures in a Late Pleistocene drumlin, Kanrawer, County Galway, western Ireland. SEDIMENTARY GEOLOGY, 91 (1-4). pp. 173-190. [Journal article]

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DOI: 10.1016/0037-0738(94)90128-7

Abstract

During drumlinisation, brecciated bedrock was sheared over the proximal end of a Late Pleistocene drumlin at Kanrawer, western Ireland. High effective water pressures generated by shearing at the ice/substrate interface during this event created a marked proximal-to-distal hydrostatic gradient affecting about 60% of the diamict which forms most of the drumlin sediment pile. This resulted in large-scale sediment reorganisation by Darcian throughflow and closed-conduit flow of expelled pore waters and subglacial meltwater. Proximally, this is reflected in the development of integrated honeycomb gravel structures formed by glaciotectonic shunting and tortuous throughflow in the diamicts. Distally, the honeycomb structures give way to dish and pillar structures, which are connected to gravelly and laminated sandy channel fill facies, which cut obliquely across the long axis of the drumlin. This facies transition reflects throughflow of pore water rising through the sediment pile and expelled along Nye-type channels excavated on the distal drumlin surface. These proximal-to-distal sediment transformations suggest that current theoretical models of drumlin formation do not adequately represent the continuum of subglacial processes which accompany drumlinisation.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Environmental Sciences
Research Institutes and Groups:Environmental Sciences Research Institute
Environmental Sciences Research Institute > Quaternary Environmental Change
ID Code:23104
Deposited By:Mrs Linda Allen
Deposited On:04 Sep 2012 11:52
Last Modified:04 Sep 2012 11:52

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