HR: 17:45h
AN: T14A-08    [Abstracts]
TI: Comprehensive geophysical study of the Transantarctic Mountains
AU: * Lawrence, J F
EM: jfisher@levee.wustl.edu
AF: Scripps Institute of Oceanography, Institute of Geophysics and Planetary Physics Scripps Institute of Oceanogaphy Univiersity of California, San Diego 9500 Gilman Drive, La Jolla, CA 92093-0225 United States
AU: Wiens, D A
EM: doug@kermadec.wustl.edu
AF: Washington University, Earth And Planetary Sciences Washington University Campus Box 1169 One Brookings Drive, St Louis, MO 63130 United States
AU: Nyblade, A A
EM: andy@geosc.psu.edu
AF: Penn State University, Dept of Geosciences Penn State University Deike Bldg, University Park, PA 16802 United States
AU: Anandakrishan, S
EM: sak@essc.psu.edu
AF: Penn State University, Dept of Geosciences Penn State University Deike Bldg, University Park, PA 16802 United States
AU: Shore, P J
EM: patrick@seismo.wustl.edu
AF: Washington University, Earth And Planetary Sciences Washington University Campus Box 1169 One Brookings Drive, St Louis, MO 63130 United States
AU: Voigt, D
EM: voigt@geosc.psu.edu
AF: Penn State University, Dept of Geosciences Penn State University Deike Bldg, University Park, PA 16802 United States
AB: We use teleseismic receiver function and surface wave phase velocities to model the seismic velocity structure of the crust and upper mantle between the Ross Sea and Vostok Subglacial Highlands. The West Antarctic Rift System (WARS) has a thinner crust (~20 km) and slower seismic mantle velocities than East Antarctica (EA). Attenuation of shear body waves is also higher in the WARS, which suggests the presence of a thermal anomaly. The transition between EA and the WARS occurs beneath the Transantarctic Mountains (TAMs), ~100 km from the coast. Within EA the crust is remarkably uniform in thickness (~35 km) for a lateral distance greater than 1400 km. We calculated theoretical gravity from density models that are based on the seismic results. The observed gravity is consistent with ~1 percent denser mantle material under EA than in the WARS. This density increase is consistent with temperature variations that would cause a 2.5-5 percent velocity increase. The flexural model of ten Brink et al., [1997] adequately accounts for the otherwise uncompensated topography. The buoyant thermal and erosional loads are sufficient to cause the observed uplift. As predicted by Strudinger et al., [2003], a crustal root is present, causing some isostatic support.
DE: 7255 Surface waves and free oscillations
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1242)
DE: 7218 Lithosphere and upper mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting