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Crustal seismic anisotropy in central Tibet: Implications for deformational style and flow in the crust
Author(s) -
Ozacar A. Arda,
Zandt George
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021096
Subject(s) - geology , crust , anisotropy , azimuth , seismology , seismic anisotropy , inversion (geology) , fibrous joint , petrology , slip (aerodynamics) , geophysics , tectonics , mantle (geology) , geometry , medicine , physics , mathematics , anatomy , quantum mechanics , thermodynamics
Receiver functions obtained at INDEPTH III stations located near the Bangong‐Nujiang suture in central Tibet display a weak Moho signal and strong P to S conversions within the first 5 s that vary systematically with back‐azimuth. A single station with representative azimuthal variations located at the sharp onset of strong SKS splitting, is modeled for both dipping layers and seismic anisotropy by using a global minimization technique. Inversion results indicate strong anisotropy (>10%) near the surface and in the middle crust separated by a south‐dipping (∼25°) layer, possibly related to the earlier phase of crustal shortening. Near‐surface anisotropy has a fabric dipping steeply southward and trending WNW‐ESE that correlates with the suture and younger strike‐slip faults. In contrast, mid‐crustal anisotropy occurs in a low‐velocity zone and has a fabric dipping gently (∼18°) northward that might be related to a well‐developed near‐horizontal rock fabric induced by crustal flow.