HR: 0800h
AN: C51A-0078    [Abstracts]
TI: Crustal thinning and low Lithospheric Rigidity Revealed Beneath the Catchment of Pine Island Glacier: Implications for the West Antarctic Ice Sheet
AU: Jordan, T A
EM: tomj@bas.ac.uk
AF: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AU: * Ferraccioli, F
EM: ffe@bas.ac.uk
AF: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AU: Holt, J W
EM: jack@ig.utexas.edu
AF: The University of Texas at Austin, Institute of Geophysics, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road, Austin, TX 78758-4, United States
AU: Diehl, T M
EM: theresa@ig.utexas.edu
AF: The University of Texas at Austin, Institute of Geophysics, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road, Austin, TX 78758-4, United States
AU: Corr, H F
EM: hfjc@bas.ac.uk
AF: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AU: Blankenship, D D
EM: blank@ig.utexas.edu
AF: The University of Texas at Austin, Institute of Geophysics, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road, Austin, TX 78758-4, United States
AU: Vaughan, D G
AF: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AB: Within the West Antarctic Ice Sheet (WAIS) glaciers flowing into the Amundsen Sea Embayment (ASE) are known to be presently thinning and retreating fast, leading to accelerated global sea level rise. Crustal structures may provide critical, but largely unconstrained, geological boundary conditions for enhanced ice flow over this highly dynamic "collapse prone" sector of the WAIS. During the 2004-05 field season an integrated aerogeophysical survey was conducted over the catchment of Pine Island Glacier, as part of a joint US-UK exploration effort over the ASE. Here we examine 30,000- line km of airborne gravity data, which provide new insights on crustal properties and tectonic structure of a segment of the underlying West Antarctic Rift System (WARS). Modern continental rifts are often associated with thinned crust, high heat flow, and low lithospheric rigidity. Knowledge of the lithospheric rigidity is important when estimating the amount of long-term sea-level rise associated with deglaciation processes. Comparison between the observed gravity data and isostatic compensation models suggests that the lithospheric rigidity is regionally low beneath the catchment of Pine Island Glacier. Our estimated value of equivalent elastic thickness (T_e) 0-10 km is significantly lower compared to previous estimates beneath the better studied Ross Sea segment of the WARS (~30km). Modelling of the Bouguer and terrain de-correlated gravity anomalies reveals several segments of highly thinned continental crust beneath Pine Island Glacier, the Byrd Subglacial Basin and the Bentley Subglacial Trench. Crustal thinning may increase regional heat-flow, and hence increase the availability of water at the base of the ice sheet, which has implications for the long-term stability of the WAIS. Additionally we image thick subglacial sedimentary basins, which may further enhance fast glacial flow in the ASE region.
DE: 0726 Ice sheets
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 1621 Cryospheric change (0776)
DE: 8109 Continental tectonics: extensional (0905)
DE: 8138 Lithospheric flexure
SC: Cryosphere [C]
MN: 2007 Fall Meeting