Tectonics of the Amundsen Sea Embayment, West Antarctica: Constraining factor for ice-sheet expansion?


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Karsten.Gohl [ at ] awi.de

Abstract

An understanding of the glacial history of the Amundsen Sea Embayment and Pine Island Bay (PIB) is essential for proposing models on the future development of the West Antarctic Ice Sheet (WAIS). It requires both an understanding of the tectonic history, because basement morphology and inherited erosional features may control the flow direction of ice-sheets and the influx of Circum-Polar Deep Water at later times. We attempt to reconstruct the tectonic history with the aim to search for basement features and crustal boundaries which may be correlated to the flow and dynamics of ice-sheet advances. The Amundsen Sea Embayment of West Antarctica is in a prominent location for a series of tectonic and magmatic events from Paleozoic to Cenozoic times. It played a central role in the rifting and break-up of greater New Zealand from West Antarctica as it is the location where the junction of Chatham Rise and Campbell Plateau (New Zealand) lies conjugate to the West Antarctic margin. New seismic, magnetic and gravity data from the Amundsen Sea Embayment and Pine Island Bay reveal the crustal thickness and tectonic lineations. The Moho is 24-22 km deep on the shelf. NE-SW trending magnetic and gravity anomalies and the thin crust indicate a former rift zone that was active during or in the run-up to breakup between Chatham Rise and West Antarctica before or at 90 Ma. NW-SE trending gravity and magnetic anomalies, following a prolongation of Peacock Sound between Thurston Island and Ellsworth Land, indicate the extensional southern boundary to the Bellingshausen Plate which was active between 79 and 61 Ma. However, both lineation trends, NE-SW and NW-SE, seem to be observed over broad regions. This infers stepwise and multiple rift and extension phases over a wide period of time before, during and after the break-up between New Zealand and West Antarctica. We propose that these tectonically inherited erosional trends on the continental shelf of the Amundsen Sea Embayment have controlled the main directions of ice streams during times of an advancing West Antarctic ice-sheet.



Item Type
Conference (Talk)
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
23. Internationale Polartagung, 10.-14. March 2008, Münster..
Eprint ID
18109
Cite as
Gohl, K. , Weigelt, E. , Teterin, D. , Eagles, G. , Uenzelmann-Neben, G. and Larter, R. (2008): Tectonics of the Amundsen Sea Embayment, West Antarctica: Constraining factor for ice-sheet expansion? , 23. Internationale Polartagung, 10.-14. March 2008, Münster. .


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