Authors / CoAuthors
O'Brien, P.E. | Post, A. | Hemer, M. | Craven, M.
Abstract
Processes across the grounding zone are important in understanding the retreat behaviour of ice streams but are poorly understood because of the difficulty of accessing the region. The Antarctic Shelf preserves geomorphic features and sedimentary structures left by ice retreat which can provide insights into processes in and close to the grounding zone. Sidescan sonar records from Prydz Bay image a range of features that reflect changes in processes across the Amery Ice Shelf grounding zone during retreat after the Last Glacial Maximum. The presence of fluted and mega-scale glacial lineations indicates that the ice moved over an unfrozen, deforming bed in the zone up stream of the grounding zone. For most of the Amery Ice Shelf, the inter-flute dunes reflect strong thermohaline circulation in the ice shelf cavity. Sand and gravel recovered in cores from beneath the Amery Ice Shelf indicate significant current speeds, possibly enhanced by tidal pumping. The sea floor in the Lambert Deep on the western edge of the Amery Ice Shelf lacks inter-flute dunes and has a sea floor covered in subglacial features. Transverse steps cutting across flutes indicate the presence of subglacial cavities at the bed between patches of grounded ice as the ice approached the grounding zone. The presence of an esker indicates water flowing in a subglacial tunnel. The polygonal ridges are similar to those formed where surging glaciers have stagnated. This at least implies periods of stagnation before the ice flowing into the Lambert Deep retreated from successive grounding line positions.
Product Type
nonGeographicDataset
eCat Id
70264
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Custodian
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
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2601
Australia
Keywords
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- External PublicationAbstract
- ( Theme )
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- Antarctic data
- ( Theme )
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- geomorphology
- ( Theme )
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- seabed
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- AQ
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2010-01-01T00:00:00
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geoscientificInformation
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