HR: 08:45h
AN: C41C-04    [Abstracts]
TI: Crustal and Lithospheric Structural Controls on Thwaites Glacier, West Antarctica
AU: * Diehl, T M
EM: theresa@ig.utexas.edu
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road, Austin, TX 78758, United States
AU: Blankenship, D D
EM: blank@ig.utexas.edu
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road, Austin, TX 78758, United States
AU: Jordan, T A
EM: tomj@bas.ac.uk
AF: British Antarctic Survey, Earth Sciences Division, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AU: Young, D A
EM: duncan@ig.utexas.edu
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road, Austin, TX 78758, United States
AB: Thwaites Glacier in the Amundsen Sea Embayment of West Antarctica is changing rapidly. Satellite observations show that the glacier is accelerating, its grounding line is retreating, and its floating portion is thinning. These changes are dynamic and could be related to the nature of the sub-ice geology, though the geology is not well- understood. We know from the Ross Sea Embayment ice streams of West Antarctica that the locations of subglacial water (and sediment) are critical to initiating fast flow. Subglacial water can be created in areas where the base of the ice is at the pressure melting point, particularly in areas that may have elevated geothermal heat flux. To fully understanding the thermal state of the base of the ice, we must determine the deeper geology of the continent below. We hypothesize that the crustal and lithospheric structure of the Thwaites Glacier catchment (TGC) impacts the behavior of Thwaites Glacier through spatially heterogeneous geothermal heat flux. Here we use airborne gravity results collected primarily by the University of Texas at Austin in 2004-2005 to test this hypothesis. The airborne gravity free-air and Bouguer anomalies can be used in two ways to estimate sub-ice earth structure. First, the long-wavelength Bouguer gravity anomalies reflect changes in Moho depth. Based on spectral estimates of the gravity anomalies for gross crustal structure, there are two crustal provinces in the TGC: the West Antarctic Rift System in the eastern side of the catchment with a Moho at approx. 27 km b.s.l., and the Marie Byrd Land crustal block in the western side of the catchment with a Moho at approx. 20 km b.s.l. To determine the spatial variability of crustal thickness across these crustal provinces, we invert the long-wavelength Bouguer anomalies for Moho depth. This method will also more precisely locate the boundary between the two provinces. Second, we use admittance/coherence techniques on the gravity and topography to estimate the elastic thickness (Te) of the lithosphere containing the crustal blocks. The elastic thickness of the lithosphere is related to the lithosphere's actual thickness and thus the temperature at the base of the lithosphere. Based on our crustal and lithospheric structure results, we will comment on both the potential heterogeneity of subglacial heat flux and the creation of deep sedimentary basins.
DE: 0758 Remote sensing
DE: 0774 Dynamics
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 8122 Dynamics: gravity and tectonics
DE: 8138 Lithospheric flexure
SC: Cryosphere [C]
MN: 2007 Fall Meeting