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Implications for the Late Wisconsin-holocene Extent of the West Antarctic Ice Sheet from Regional Free-air Gravity Anomalies in the Ross Embayment (Abstract only)

Published online by Cambridge University Press:  20 January 2017

Larry L. Greischar  and
Charles R. Bentley
Larry L. Greischar
Affiliation:
Geophysical And Polar Research Center, University Of Wisconsin, Madison, Wisconsin 53706, U.S.A.
Charles R. Bentley
Affiliation:
Geophysical And Polar Research Center, University Of Wisconsin, Madison, Wisconsin 53706, U.S.A.
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Abstract

Gravity data from cruises 32, 51, and 52 of the USNS Eltanin (Hayes and Davey 1975), approximately adjusted to the new gravity datura (IGSN 71) and reference system (GRS 67), have been used to extend the Ross Ice Shelf gravity map to the edge of the Ross Sea continental shelf. Various regional gravity anomaly fields obtained by applying low-pass filters to these data are strongly negative over the entire Ross embayment; values increase gradually from approximately -300 gu (-30 mgal) near the Siple Coast to -150 gu (-15 mgal) near the edge of the Ross Sea continental shelf.

Type
Research Article
Information
Annals of Glaciology , Volume 3 , 1982 , pp. 340
Copyright
Copyright © International Glaciological Society 1982

Comparison of the regional gravity-anomaly fields measured at the surface with the low-order terms of the Goddard Earth Model (GEM) series of satellite-derived gravity fields shows close agreement near the edge of the Ross Sea continental shelf, and a departure of the surface gravity field from the regional satellite-determined field that becomes increasingly negative in a grid-northerly direction. We assume the deviation to be the result of crustal depression remaining from former ice loading, and calculate that a crustal depression of 0 to 190 m remains along a grid-south-east to north-west transect through the Ross embayment.

An estimated 50 to 170 m of crustal uplift remains unadjusted in the grid-western part of the present Ross Ice Shelf, assuming a particular initialice load at 18 ka BP (CLIMAP) and a simple exponent ial model of crustaluplift. The approximate agreement between the two methods has encouraged us to use the crustal up - lift estimated from the gravity field and a simple exponential model of crustal rebound to test models of past ice loading and retreat models. Preliminary results show agreement with the CLIMAP reconstruction of the 18 ka BP West Antarctic ice sheet and a retreat model similar to that of Reference Thomas and BentleyThomas and Bentley (1978).

References

Hayes, D E, Davey, F J 1975 A geophysical study of the Ross Sea, Antarctica. Initial Reports of the Veep Sea Drilling Project 28: 887–907 Google Scholar
Thomas, R H, Bentley, C R 1978 A model for Holocene retreat of the West Antarctic ice sheet. Quaternary Research 10 (2): 150–170 Google Scholar