TY - JOUR
T1 - Complex deformation in western Tibet revealed by anisotropic tomography
AU - Zhang, Heng
AU - Zhao, Junmeng
AU - Zhao, Dapeng
AU - Yu, Chunquan
AU - Liu, Hongbing
AU - Hu, Zhaoguo
N1 - Funding Information:
This work was supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB03010702 ), National Science Foundation of China (Grant No. 41404079 ), the NSFC Innovation Research Group Fund (Grant No. 41321061 ), and the Japanese MEXT (Grant No. 26106005 ). Some of the instruments used were provided by the Institute of Geology and Geophysics, Chinese Academy of Science. We thank two anonymous reviewers for their constructive comments and suggestions that have improved the manuscript. The Seismic Handler and Crazyseismic software package were used for the arrival-time picking. All the figures were made using the Generic Mapping Tools package ( Wessel and Smith, 1998 ).
PY - 2016/10/1
Y1 - 2016/10/1
N2 - The mechanism and pattern of deformation beneath western Tibet are still an issue of debate. In this work we present 3-D P- and S-wave velocity tomography as well as P-wave radial and azimuthal anisotropy along the ANTILOPE-I profile and surrounding areas in western Tibet, which are determined by using a large number of P and S arrival-time data of local earthquakes and teleseismic events. Our results show that low-velocity (low-V) zones exist widely in the middle crust, whereas low-V zones are only visible in the lower crust beneath northwestern Tibet, indicating the existence of significant heterogeneities and complex flow there. In the upper mantle, a distinct low-V gap exists between the Indian and Asian plates. Considering the P- and S-wave tomography and P-wave azimuthal and radial anisotropy results, we interpret the gap to be caused mainly by shear heating. Depth-independent azimuthal anisotropy and high-velocity zones exist beneath the northern part of the study region, suggesting a vertically coherent deformation beneath the Tarim Basin. In contrast, tomographic and anisotropic features change with depth beneath the central and southern parts of the study region, which reflects depth-dependent (or decoupled) deformations there. At the northern edge of the Indian lithospheric mantle (ILM), P-wave azimuthal anisotropy shows a nearly east-west fast-velocity direction, suggesting that the ILM was re-built by mantle materials flowing to the north.
AB - The mechanism and pattern of deformation beneath western Tibet are still an issue of debate. In this work we present 3-D P- and S-wave velocity tomography as well as P-wave radial and azimuthal anisotropy along the ANTILOPE-I profile and surrounding areas in western Tibet, which are determined by using a large number of P and S arrival-time data of local earthquakes and teleseismic events. Our results show that low-velocity (low-V) zones exist widely in the middle crust, whereas low-V zones are only visible in the lower crust beneath northwestern Tibet, indicating the existence of significant heterogeneities and complex flow there. In the upper mantle, a distinct low-V gap exists between the Indian and Asian plates. Considering the P- and S-wave tomography and P-wave azimuthal and radial anisotropy results, we interpret the gap to be caused mainly by shear heating. Depth-independent azimuthal anisotropy and high-velocity zones exist beneath the northern part of the study region, suggesting a vertically coherent deformation beneath the Tarim Basin. In contrast, tomographic and anisotropic features change with depth beneath the central and southern parts of the study region, which reflects depth-dependent (or decoupled) deformations there. At the northern edge of the Indian lithospheric mantle (ILM), P-wave azimuthal anisotropy shows a nearly east-west fast-velocity direction, suggesting that the ILM was re-built by mantle materials flowing to the north.
KW - Tibetan plateau
KW - anisotropic tomography
KW - crustal and uppermantle structures
KW - diverse deformation patterns
KW - lateral heterogeneities
UR - http://www.scopus.com/inward/record.url?scp=84979536650&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84979536650&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2016.07.020
DO - 10.1016/j.epsl.2016.07.020
M3 - Article
AN - SCOPUS:84979536650
VL - 451
SP - 97
EP - 107
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
ER -