Authors / CoAuthors
Hemer, M.A. | O'Brien, P.E. | Post, A.L. | Craven, M. | Truswell, E.M. | Roberts, D. | Harris, P.T.
Abstract
Two sediment cores collected from beneath the Amery Ice Shelf, East Antarctica describe the physical sedimentation patterns beneath an existing major embayed ice shelf. The latest core, AM01b, was collected from a site of basal freezing, contrasting with the previous core AM02, collected from a site of basal melting. Both cores comprise Holocene siliceous muddy ooze (SMO) however AM01b recovered interbedded siliciclastic mud, sand and gravel with inclined bedding in its lower 27 cm. This interval indicates an episode of variable but strong current activity before SMO sedimentation became dominant. 14C ages corrected for old surface ages are consistent with previous dating of marine sediments in Prydz Bay however the basal age of the AM01b core of 28250 +/- 230 14C yr BP probably results from greater contamination by recycled organic matter. Lithology, 14C surface ages, absolute diatom abundance, and the diatom assemblage are used as indicators of sediment transport pathways beneath the ice shelf. The transport pathways suggested from these indicators do not correspond to previous models of the basal melt/freeze pattern. This indicates that the overturning baroclinic circulation beneath the Amery Ice Shelf (near-bed inflow - surface outflow) is a more important influence on basal melt/freeze and sediment distributions than the barotropic circulation that produces inflow in the east and outflow in the west of the ice front. Localised topographic (ice draft and bed elevation) variations are likely to play a dominant role in the resulting sub-ice-shelf melt and sediment distribution. The inflow of marine sediments in the Holocene section of AM01b, as shown by the abundance of marine diatoms and other planktonic organisms, supports a diverse filter feeder community beneath the ice shelf through the supply of suspended organic matter and oxygen.
Product Type
nonGeographicDataset
eCat Id
64224
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- External PublicationScientific Journal Paper
- ( Theme )
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- Antarctic data
- ( Theme )
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- palaeoclimatology
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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
2006-01-01T00:00:00
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geoscientificInformation
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Unknown
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Extents
[-72.0, -68.0, 68.0, 76.0]
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