Deep MT Sounding Across the Yellowstone-Snake River Hotspot Track

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EAR-0229814DeGroot-HedlinThe investigators propose to use magnetotelluric (MT) sounding to constrain the temperature and melt fraction of plume material in the Yellowstone-Snake River region, and provide constraints on models of the dynamics of the Yellowstone plume flow and its interaction with a continent. Several previous studies have indicated the presence of a narrow, low P-wave velocity beneath the eastern Snake River Plain in Idaho, aligned in the direction of motion of the Yellowstone hotspot. The lower seismic velocities can be attributed to the combined effects of temperature differences, partial melt, and compositional differences resulting from melt segregation. The investigators propose to deploy long period MT sounding instruments along two perpendicular lines: the first a northwest to southeast transect for which a P-wave velocity model was previously obtained from tomographic inversion, the second centered along the Snake River Plain. Given that the conductivity of olivine-rich rocks is strongly dependent upon both melt fraction and temperature, interpretation of MT sounding data can be used to determine mantle temperatures and melt fraction, hence yielding an estimate of plume viscosity.