HR: 1340h
AN: T23A-1206    [Abstracts]
TI: Seismic Imaging Beneath the Region of the Wallowa Mountains in Northeast Oregon
AU: * Gao, H
EM: hgao@uoregon.edu
AF: Haiying Gao, Dep. of Geological Sciences 1272 U. of Oregon, Eugene, OR 97403,
AU: Humphreys, G
EM: genehumphreys@gmail.com
AB: I use seismic imaging to resolve and constrain the geometry and physical properties of the Columbia River Basalt (CRB) magma chamber, as well as the velocity structure in the crust and the upper mantle beneath the Wallowa batholith in Northeast Oregon. Northeast Oregon is composed of accreted oceanic terranes and is both tectonically and magmatically unusual. This is where Earth's most recent flood basalt erupted, the ~16 Ma old CRB. The source of the CRB is around the Wallowa batholith, ~ 500 km north of the Yellowstone hotspot track, which indicates the existence of a magma chamber beneath this area. The current elevation of the Wallowa batholith is up to ~2 km, standing in the center of a circular region of post-eruption uplift, indicating major changes in isostatic forces related to major modifications in lithospheric structure associated with these eruptions. The Wallowa region is a good place to study the process of CRB flood basalt and the related lithospheric effects. However, the tectonic activity, deep structure and magmatic processes in this area are not well understood. Twenty broadband three-component seismometers were borrowed from PASSCAL in Fall 2006. All seismometers have already been installed around the Wallowa Mountains. The array, oriented NW-SE, crosses the major structures of interest, covering SE Washington, NE Oregon and part of western Idaho. Currently we collect teleseismic data for 9 months. I also use data from Gene Humphrey's former project, US Array and the Pacific Northwest Seismograph Network (PNSN). In the next several months, by analyzing those data I will do receiver function imaging and SKS splitting to image variations in the crust and upper mantle structure with high resolution.
DE: 1236 Rheology of the lithosphere and mantle (7218, 8160)
DE: 7218 Lithosphere (1236)
DE: 8031 Rheology: crust and lithosphere (8159)
DE: 8138 Lithospheric flexure
DE: 8159 Rheology: crust and lithosphere (8031)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting