HR: 17:35h
AN: S44A-06    [Abstracts]
TI: Shear Wave Splitting and Seismic Anisotropy in the Chile Ridge Subduction Region
AU: * Russo, R M
EM: rrusso@ufl.edu
AF: Dept. of Geological Sciences University of Florida, P.O. Box 112120, 241 Williamson Hall, Gainesville, FL 32611, United States
AU: Mocanu, V I
EM: mocanu@gg.unibuc.ro
AF: Dept. of Geophysics, University of Bucharest 6 Traian Vuia Str., Bucharest, RO-70139, Romania
AU: Gallego, A
EM: agallego75@gmail.com
AF: Dept. of Geological Sciences University of Florida, P.O. Box 112120, 241 Williamson Hall, Gainesville, FL 32611, United States
AU: Comte, D
EM: dcomte@dgf.uchile.cl
AF: Departamento de Geofisica, Universidad de Chile 2002 Blanco Encalada, Santiago, 837-0449, Chile
AU: Murdie, R E
EM: ruth.murdie@ctbto.org
AF: CTBTO, P.O. BOx 1200 Vienna International Centre , Vienna, A-1400, Austria
AU: VanDecar, J C
EM: jvandecar@hotmail.com
AF: DTM, Carnegie Inst. of Washington, 5241 Broad Branch Road NW, Washington, DC 20015, United States
AU: van der Lee, S
EM: suzan@earth.northwestern.edu
AF: Dept. of Geological Sciences Northwestern University, Campus Drive, Evanston, IL 60201, United States
AB: We present new shear wave splitting measurements of SK(K)S and PKS phases recorded at 39 broadband seismic stations in the Chile triple junction region. The network, deployed December 2004-February 2005 and operated jointly by the University of Florida and the Universidad de Chile (Santiago), spans the region where the Chile Ridge subducts beneath South America, from the Pacific coast of the Taitao Peninsula to the Argentine border, and extending 250 km north and south of the actual triple junction. Given increasing temperature with depth, it has long been hypothesized that ridge subduction should result in creation of slab windows asthenosphere-filled gaps between continually separating edges of oceanic lithosphere formed at the Earth's surface. The Chile Ridge Subduction Project (seismology.geology.ufl.edu/chile) was formulated in part to test this notion. The network was demobilized during January-February 2007. In conjunction with teleseismic travel time inversions and studies of seismic attenuation in the Chile Ridge subduction region, shear wave splitting as recorded at the Project network will likely provide an excellent snapshot of upper mantle flow in the region: The tomography and attenuation studies will allow us to define the distribution of lithosphere and asthenosphere to determine if slab windows exist in the area. The shear wave splitting, which may be caused by mineral alignment during upper mantle flow or possibly by aligned pockets of partial melt, will then define the upper mantle flow pattern and/or partial melt distribution in the region of ridge subduction, and possibly also mineral alignments in the subducted Nazca and Antarctic plates. We will present preliminary results at the meeting.
UR: http:seismology.geology.ufl.edu/chile
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7218 Lithosphere (1236)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Seismology [S]
MN: 2007 Joint Assembly