HR: 17:45h
AN: V34A-08 [Abstracts]
TI: Characteristics of mantle fabrics beneath the southern-central United States: Constraints from shear-wave splitting measurements
AU: * Gao, S S
EM: sgao@umr.edu
AF: Missouri University of Science and Technology, Dept. of Geological Sciences and
Engineering, Rolla, MO 65409,
AU: Liu, K H
EM: liukh@umr.edu
AF: Missouri University of Science and Technology, Dept. of Geological Sciences and
Engineering, Rolla, MO 65409,
AU: Stern, R J
EM: rjstern@utdallas
AF: University of Texas at Dallas, Dept. of Geosciences, Richardson, TX 75080,
AU: Keller, G R
EM: grkeller@gcn.ou.edu
AF: University of Oklahoma, School of Geology and Geophysics, Norman, OK 73019,
AU: Hogan, J P
EM: jhogan@umr.edu
AF: Missouri University of Science and Technology, Dept. of Geological Sciences and
Engineering, Rolla, MO 65409,
AU: Pulliam, J
EM: jay@utig.ig.utexas.edu
AF: University of Texas at Austin, Inst. for Geophysics, Austin, TX 78712,
AU: Anthony, E
EM: eanthony@geo.utep.edu
AF: University of Texas at El Paso, Dept. of Geological Sciences, El Paso, TX 79968,
AB:
New shear-wave splitting measurements at permanent broadband seismic
stations in the southern-central United States reveal the direction
and strength of mantle fabrics, and provide constraints on models of
the formation of these fabrics. For stations on the stable North
American craton, correspondence between observed fast directions and
the trend of Proterozoic and Paleozoic structures associated with
rifts and orogenic belts implies a lithospheric origin of the
observed anisotropy. The largest splitting times (up to 1.7 s) are
observed at stations located in the ocean-continent transitional
zone, in which the fast directions are parallel to the Gulf of Mexico
continental margin. The parallelism and the geometry of the keel of
the craton beneath the study area suggest that either asthenospheric
flow around the keel of the North American craton, lithospheric
fabrics developed during Mesozoic rifting, or a combination of the
two are responsible for the observed anisotropy above the
transitional crust.
DE: 1212 Earth's interior: composition and state (7207, 7208, 8105, 8124)
DE: 7203 Body waves
DE: 8159 Rheology: crust and lithosphere (8031)
DE: 8162 Rheology: mantle (8033)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting