HR: 16:15h
AN: T14A-02 INVITED     [Abstracts]
TI: Thermal structure of the upper mantle beneath Antarctica with implications for heat flux and visco-elastic rebound
AU: * Ritzwoller, M H
EM: ritzwoller@ciei.colorado.edu
AF: University of Colorad at Boulder, Department of Physics, Boulder, CO 80309 United States
AU: Shapiro, N M
EM: nshapiro@ciei.colorado.edu
AF: University of Colorad at Boulder, Department of Physics, Boulder, CO 80309 United States
AU: Zhong, S
EM: szhong@ciei.colorado.edu
AF: University of Colorad at Boulder, Department of Physics, Boulder, CO 80309 United States
AU: Wahr, J M
EM: wahr@ciei.colorado.edu
AF: University of Colorad at Boulder, Department of Physics, Boulder, CO 80309 United States
AB: Although substantial international efforts have and will continue to improve the number and distribution of broad-band seismic stations from both permanent and temporary deployments across Antarctica, the horizontal and vertical resolution of upper mantle structures remains poor beneath most of Antarctica relative to other continents. Short of a revolutionary deployment of seismometers across the continent, resolution is likely to remain less than ideal into the foreseeable future. To produce higher quality lithospheric models, therefore, requires introducing better a priori constraints into the inversion largely from what has been learned from other, better instrumented continents. We present the results of an iterative inversion of surface wave dispersion data for upper mantle temperature structure in which heat flow is applied as an explicit constraint. The heat flow values are extrapolated from other continents based upon similarities in lithospheric structure revealed in the first iteration of the inversion. The result yields estimates of the probabilistic distribution of surface heat flux across Antarctica, as well as bounds on the mantle component of heat flux and lithospheric thickness across the continent. The inferred variations in surface heat flux may have a profound effect on ice stream and ice sheet dynamics. We also present results from numerical simulations that illustrate how the estimated upper mantle temperature variations (and associated changes in lithospheric thickness) are likely to affect the nature and magnitude of visco-elastic rebound. These 3-D visco-elastic effects may prove to be important to understand the growth and decay of ice sheets over long time scales.
DE: 8180 Tomography
DE: 7255 Surface waves and free oscillations
DE: 8130 Heat generation and transport
DE: 7218 Lithosphere and upper mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting