HR: 0800h
AN: T51D-1388    [Abstracts]
TI: The Yellowstone Hotspot and Related Plume: Volcano-Tectonics, Tomography, Kinematics, Dynamics and Mantle Flow
AU: * Jordan, M
EM: mjordan@mines.utah.edu
AF: University of Utah, 135 So. 1460 East, Salt Lake City, UT 84112 United States
AU: Smith, R B
EM: R.Smith@earth.utah.edu
AF: University of Utah, 135 So. 1460 East, Salt Lake City, UT 84112 United States
AU: Puskas, C
EM: cmpuskas@mines.utah.edu
AF: University of Utah, 135 So. 1460 East, Salt Lake City, UT 84112 United States
AU: Farrell, J
EM: jfarrell@mines.utah.edu
AF: University of Utah, 135 So. 1460 East, Salt Lake City, UT 84112 United States
AU: Waite, G
EM: gwaite@usgs.gov
AF: USGS, 345 Middlefield Road, Menlo Park, CA 94025 United States
AB: Earth's violent forces have produced the renowned scenery and the world's largest display of geysers at Yellowstone National Park. The energy responsible for these features is related to the Yellowstone hotspot, a coupled crust-mantle magmatic system that has had a profound influence on a much larger area of the western US: the Yellowstone-Snake River Plain-Newberry volcanic field (YSRPN). The volcanic system has produced a 16 Ma track of NE-trending, time progressive, silicic-basaltic volcanism from the Snake River Plain (SNR) to Yellowstone with a mirror image of NW-trending magmatism across the high lava plains to the Newberry caldera, OR. The origin of this magmatic-tectono system has been variously ascribed to plume-plate interaction, lithosphere extension, return mantle flow, decompression melting, etc. We interpret and integrate results from modeling of data from a prototype EarthScope experiment in 1999-2002. These include crust-mantle tomography, geoid and gravity modeling, kinematics from GPS, and geodynamic models. We present a comprehensive model for the mechanism behind YSRPN that is in accordance with our observations and models, e.g. from GPS and seismology. Geodetic data show high rates of deformation at the Yellowstone Plateau, with periods of pronounced uplift and subsidence as well as significant EW extension. Seismic tomography reveals a pronounced mid-crustal P- and S-wave low velocity body of > 8% melt extending from ~6 km to 15 km beneath the caldera. This system is fed by an upper-mantle low velocity plume-like body of up to 1.5% melt in the upper 200 km. The body further extends down to the the base of the transition zone at 650 km depth, notably tilting WNW. At this depth, we estimate the excess temperature between 85 K and 120 K, depending on the water content. Using the inclined plume-geometry and the 650-km source depth we extrapolate the mantle source southwestward as a plume-head in oceanic-type lithosphere beneath the Columbia Plateau basalt field at 16 Ma. Ascent of mantle magma from this source was truncated by SW motion of the thicker continental lithosphere at ~12 Ma, resulting in a less energetic plume-tail along the YSRP. West of the original plume head, continuing mantle return flow above the subducting Juan de Fuca plate could have fueled magmatism of the High Lava Plains and Newberry system.
DE: 8121 Dynamics: convection currents, and mantle plumes
DE: 8123 Dynamics: seismotectonics
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
SC: Tectonophysics [T]
MN: Fall Meeting 2005