Sedimentological signatures of the sub-Amery Ice Shelf circulation
Two sediment cores collected from beneath the Amery Ice Shelf, East Antarctica describe the physical sedimentation patterns beneath an existing major embayed ice shelf. Core AM01b was collected from a site of basal freezing, contrasting with core AM02, collected from a site of basal melting. Both co...
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British Antarctic Survey
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ftanucanberra:oai:digitalcollections.anu.edu.au:1885/53180 2023-05-15T13:21:59+02:00 Sedimentological signatures of the sub-Amery Ice Shelf circulation Hemer, M.A. Post, A O'Brien, Philip Edward Craven, M. Truswell, Elizabeth Roberts, Donna Harris, P.T. 2015-12-10T22:24:16Z http://hdl.handle.net/1885/53180 unknown British Antarctic Survey 0954-1020 http://hdl.handle.net/1885/53180 Antarctic Science Keywords: diatom freezing ice shelf lithology organic matter sediment core sediment transport sedimentation sedimentology topography Amery Ice Shelf Antarctica East Antarctica Bacillariophyta Antarctica Baroclinic circulation Sediment Sub-ice shelf circulation Journal article 2015 ftanucanberra 2015-12-28T23:28:12Z Two sediment cores collected from beneath the Amery Ice Shelf, East Antarctica describe the physical sedimentation patterns beneath an existing major embayed ice shelf. Core AM01b was collected from a site of basal freezing, contrasting with core AM02, collected from a site of basal melting. Both cores comprise Holocene siliceous muddy ooze (SMO), however, AM01b also 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 AM01b 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. Localized topographic (ice draft and bed elevation) variations are likely to play a dominant role in the resulting sub-ice shelf melt and sediment distribution. Article in Journal/Newspaper Amery Ice Shelf Antarc* Antarctic Science Antarctica East Antarctica Ice Shelf Prydz Bay Australian National University: ANU Digital Collections East Antarctica Prydz Bay Amery ENVELOPE(-94.063,-94.063,56.565,56.565) Amery Ice Shelf ENVELOPE(71.000,71.000,-69.750,-69.750) |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: diatom freezing ice shelf lithology organic matter sediment core sediment transport sedimentation sedimentology topography Amery Ice Shelf Antarctica East Antarctica Bacillariophyta Antarctica Baroclinic circulation Sediment Sub-ice shelf circulation |
spellingShingle |
Keywords: diatom freezing ice shelf lithology organic matter sediment core sediment transport sedimentation sedimentology topography Amery Ice Shelf Antarctica East Antarctica Bacillariophyta Antarctica Baroclinic circulation Sediment Sub-ice shelf circulation Hemer, M.A. Post, A O'Brien, Philip Edward Craven, M. Truswell, Elizabeth Roberts, Donna Harris, P.T. Sedimentological signatures of the sub-Amery Ice Shelf circulation |
topic_facet |
Keywords: diatom freezing ice shelf lithology organic matter sediment core sediment transport sedimentation sedimentology topography Amery Ice Shelf Antarctica East Antarctica Bacillariophyta Antarctica Baroclinic circulation Sediment Sub-ice shelf circulation |
description |
Two sediment cores collected from beneath the Amery Ice Shelf, East Antarctica describe the physical sedimentation patterns beneath an existing major embayed ice shelf. Core AM01b was collected from a site of basal freezing, contrasting with core AM02, collected from a site of basal melting. Both cores comprise Holocene siliceous muddy ooze (SMO), however, AM01b also 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 AM01b 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. Localized topographic (ice draft and bed elevation) variations are likely to play a dominant role in the resulting sub-ice shelf melt and sediment distribution. |
format |
Article in Journal/Newspaper |
author |
Hemer, M.A. Post, A O'Brien, Philip Edward Craven, M. Truswell, Elizabeth Roberts, Donna Harris, P.T. |
author_facet |
Hemer, M.A. Post, A O'Brien, Philip Edward Craven, M. Truswell, Elizabeth Roberts, Donna Harris, P.T. |
author_sort |
Hemer, M.A. |
title |
Sedimentological signatures of the sub-Amery Ice Shelf circulation |
title_short |
Sedimentological signatures of the sub-Amery Ice Shelf circulation |
title_full |
Sedimentological signatures of the sub-Amery Ice Shelf circulation |
title_fullStr |
Sedimentological signatures of the sub-Amery Ice Shelf circulation |
title_full_unstemmed |
Sedimentological signatures of the sub-Amery Ice Shelf circulation |
title_sort |
sedimentological signatures of the sub-amery ice shelf circulation |
publisher |
British Antarctic Survey |
publishDate |
2015 |
url |
http://hdl.handle.net/1885/53180 |
long_lat |
ENVELOPE(-94.063,-94.063,56.565,56.565) ENVELOPE(71.000,71.000,-69.750,-69.750) |
geographic |
East Antarctica Prydz Bay Amery Amery Ice Shelf |
geographic_facet |
East Antarctica Prydz Bay Amery Amery Ice Shelf |
genre |
Amery Ice Shelf Antarc* Antarctic Science Antarctica East Antarctica Ice Shelf Prydz Bay |
genre_facet |
Amery Ice Shelf Antarc* Antarctic Science Antarctica East Antarctica Ice Shelf Prydz Bay |
op_source |
Antarctic Science |
op_relation |
0954-1020 http://hdl.handle.net/1885/53180 |
_version_ |
1766362605716242432 |