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Seaward growth of Antarctic continental shelves since establishment of a continent-wide ice sheet: Patterns and mechanisms

Author:
Hochmuth, Katharina, Gohl, Karsten
Source:
Palaeogeography, palaeoclimatology, palaeoecology 2019 v.520 pp. 44-54
ISSN:
0031-0182
Subject:
continental shelf, geophysics, hinterland, ice, paleoceanography, stream flow, tectonics, Antarctic region, Antarctica
Abstract:
The location and setting of the continental shelf break along the Antarctic continental shelves influences the paleoceanographic circulation patterns as well as sedimentation and ice sheet dynamics. By evaluating the available multichannel seismic reflection data and drill core information, we mapped the base of progradational features associated with the first advances of grounded ice sheet to the outer shelf. The distance between the modern shelf edge and the pre-glacial shelf edge varies from >200 km (e.g. Ross Sea) to <6 km (e.g. Thurston Island, West Antarctica). We identified multiple processes and mechanisms which influence the amount of shelf progradation during the establishment of a grounded ice sheet on the outer Antarctic shelves. The tectonic structure of the shelves proves to be a key factor by establishing the width of the shelf as well as local tectonics such as horst/graben and fault systems, which guide the ice stream flow and therefore the resulting sedimentation. Unlike expected, the erosional potential of the hinterland seems to play a minor role in building progradational sequences, whereas fewer long-term grounding events on the shelf edge result in more continental shelf progradation than presumed from a more dynamic ice sheet. By using these observed relationships to extrapolate the former shelf edge to unmapped regions around the Antarctic continent, we estimate an overall seaward growth of the continental shelves by 7% in area and 1.28 ∗ 106 km3 of approximated sedimentary volume deposited along the shelf edge and upper slope.
Agid:
6281353