HR: 17:15h
AN: T34B-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: vi_mo@yahoo.com
AF: Dept of Geology & Geophysics, University of Bucharest, 6 Traian Vuia Street, 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, Blanco Encalada 2002, Santiago, 1, Chile
AU: Murdie, R E
EM: ruth.murdie@ctbto.org
AF: CTBTO, Vienna International Centre, Vienna, 1, Australia
AU: VanDecar, J C
EM: jvandecar@hotmail.com
AF: DTM-Carnegie, 5241 Broad Branch Rd. NW, Washington, DC 20015, United States
AU: van der Lee, S
EM: suzan@earth.northwestern.edu
AF: Dept. of Geological Sciences, Northwestern University, 1850 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 extends 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 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 provides an excellent snapshot of upper mantle flow in the region: Shear wave splitting in the study area, which may be caused by mineral alignment during upper mantle flow or possibly by aligned pockets of partial melt, is strong (delay times up to 3 s) and highly variable, with a marked change from trench-parallel in the northern network to trench normal in the western Taitao Peninsula, near the most recently subducted Chile ridge segment.
UR: http://seismology.geology.ufl.edu/chile
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7245 Mid-ocean ridges
DE: 8104 Continental margins: convergent
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting