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Sedimentological signatures of the sub-Amery Ice Shelf circulation

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Hemer, M and Post, AL and O'Brien, PE and Craven, M and Truswell, EM and Roberts, D and Harris, PT (2007) Sedimentological signatures of the sub-Amery Ice Shelf circulation. Antarctic Science, 19. pp. 497-506. ISSN 0954-1020

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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. 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.

Item Type: Article
Journal or Publication Title: Antarctic Science
Publisher: Cambridge University Press
Page Range: pp. 497-506
ISSN: 0954-1020
Identification Number - DOI: 10.1017/S0954102007000697
Additional Information:

Copyright © 2007 Cambridge University Press

Date Deposited: 07 Apr 2008 14:15
Last Modified: 18 Nov 2014 03:33
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