A meltwater origin for Antarctic shelf bedforms with special attention to megalineations |
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| Authors: | J Shaw A Pugin RR Young |
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| Institution: | aDepartment of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2W2;bGeological Survey of Canada, 601 Booth Street, Ottawa, Ontario, Canada K1A 0E8;cGeography and Earth and Environmental Sciences, University of British Columbia Okanagan, 3333 University Way, Kelowna, British Columbia, Canada V1V 1V7 |
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| Abstract: | The geomorphology of troughs crossing the Antarctic shelf is described and interpreted in terms of ice-stream hydrology. The scale of tunnel channels on the inner shelf and the absence of sediment at their mouths are taken to infer catastrophic drainage. Drumlins on the inner and outer shelves with pronounced crescentic and hairpin scours are also interpreted as products of catastrophic flow. Gullies and channels on the continental slope and turbidites on the rise and abyssal plain point to abundant meltwater discharge across the shelf. Attempts to explain this morphology and sedimentology in terms of release or discharge of meltwater by pressure melting, strain heating, Darcian flow, or advection in deforming till are shown to be unrealistic. We suggest that meltwater flow across the middle and outer shelves might have been in broad, turbulent floods, which raises the possibility that megascale glacial lineations (MSGL) on the shelf might originate by erosion in turbulent flow. This possibility is explored by use of analogs for MSGL from flood and eolian landscapes and marine environments. An extended discussion reflects on objections that stand in the way of the flood hypothesis. |
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| Keywords: | Drumlin Tunnel channel Megalineation Meltwater Ice stream Analogy |
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