HR: 1330h
AN: V12B-0591    [PDF]
TI: Anisotropic Surface Wave Tomography of the Yellowstone Hotspot
AU: * Schutt, D L
EM: schutt@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006 University of Wyoming, Laramie, WY 82071 United States
AU: Dueker, K G
EM: dueker@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006 University of Wyoming, Laramie, WY 82071 United States
AB: Yellowstone is the most prominent continental hotspot. Over the last 17Ma, it has tracked from the Oregon-Nevada-Idaho region (also the source of flood basalts and the beginning of the Newberry hotspot), to its current location within the Wyoming Craton. Whether it is a mantle plume or caused by some sort of upper mantle convection is a matter of debate; however, the upper mantle has certainly been dramatically altered by the hotspot, and significant amounts of melt have been released. Despite this, regional SKS splitting measurements are mostly aligned in the direction of absolute plate motion, and do not show any Yellowstone signature. That SKS splitting is unaffected by the profound mantle disturbance causing Yellowstone is perplexing, especially as earlier tomography suggests small-scale convection is occurring. It may be that SKS splitting is averaging out the effects of depth-varying anisotropic fabrics caused by Yellowstone flow; that Yellowstone mantle is unexpectedly flowing more or less uniformly in the direction of plate motion; or that the anisotropy seen by the SKS lies deeper than the mantle perturbed by the Yellowstone system. We will present the results of anisotropic surface wave tomography. using array processing techniques to extract inter-station phase and amplitude variations. This will provide relatively high resolution results. Preliminary inversions show that ray coverage is excellent, and should provide reasonable constraints on the depth-dependence of radial anisotropy to 200 km depth. Results will be used to constrain Yellowstone mantle flow fields, temperature, melting, and composition, which will be compared to existing plume and non-plume models for Yellowstone.
DE: 7255 Surface waves and free oscillations
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 9350 North America
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting