HR: 0800h
AN: T31A-1274    [Abstracts]
TI: Kinematic Deformation of the Interior Western U.S. Extensional Regime with Mantle Flow
AU: * Puskas, C M
EM: cmpuskas@mines.utah.edu
AF: Univ. of Utah, Dept Geology and Geophysics, Salt Lake City, UT 84112 United States
AU: Smith, R B
EM: rbsmith@mines.utah.edu
AF: Univ. of Utah, Dept Geology and Geophysics, Salt Lake City, UT 84112 United States
AU: Waite, G
EM: gwaite@usgs.gov
AF: USGS, 345 Middlefield Rd MS 910, Menlo Park, CA 94025 United States
AU: Flesch, L
EM: flesch@dtm.ciw.edu
AF: Carnegie Inst of Washington, Dept of Terrestrial Magnetism, Washington, DC 20015 United States
AB: GPS campaign and continuous data were recorded and compiled for over 1600 stations in order to study the Yellowstone-Snake River Plain volcanic system within the larger tectonic framework of the western U.S. The Yellowstone-Snake River Plain volcanic system lies at the eastern and northern margins of the Basin-Range Province and is associated with the Yellowstone hotspot. Campaign GPS surveys from 1995-2003 have revealed up to 4 mm/yr SW extension across the Yellowstone caldera with respect to stable North America, while the SRP is extending at 2 mm/yr SW and the eastern Basin-Range at 2 mm/yr E-W. The high rates at the caldera are part of the local, time-varying deformation observed there and imply compression between the caldera and SRP. GPS data for the YSRP are combined with GPS data for the Wasatch front, Basin-Range, and the continental margin to determine the velocity and strain field of the western U.S. The resulting deformation field shows the SW motion for the YSRP rotating into E-W motion in the Basin-Range and westward motion rotating to the northwest and northeast at rates of 10-20 mm/yr in California and the Pacific Northwest, respectively. The deformation field was additionally constrained by fault slip data from USGS fault database, which provided slip rates and directions. Once the strain field has been determined from the velocity data, it remains to relate the strain to the distribution of stress. The stress field is consequently calculated from geoid and topography data. The resulting models describe the stress and strain fields of the lithosphere for the YSRP and the Basin-Range. These results are then compared with SKS split directions, which are indicators of flow in the upper mantle. Splitting directions recorded for the Basin-Range, Yellowstone caldera, and Snake River Plain are used. The comparison of the kinematic field with shear wave split alignments will enable us to estimate consistency of motion between the lithosphere and upper mantle, and to observe effects of the Yellowstone Hotspot in the upper mantle.
DE: 7218 Lithosphere and upper mantle
DE: 8110 Continental tectonics--general (0905)
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8122 Dynamics, gravity and tectonics
DE: 8164 Stresses--crust and lithosphere
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting