TY - JOUR
T1 - Teleseismic P-wave tomography and mantle dynamics beneath Eastern Tibet
AU - Lei, Jianshe
AU - Zhao, Dapeng
N1 - Funding Information:
We thank X. Zha for his help at the data-processing stage, G. Zhang and Y. Li for their participating in our portable seismic observations, the CEA Geophysical Exploration Center, and Earthquake Administration of Yunnan Province for supporting our field work, and the Data Management Centre of China National Seismic Network, waveform data of China National Seismic Network, Institute of Geophysics, China Earthquake Administration, 2007, doi:10.11998/SeisDmc/SN, http://www.seisdmc.ac.cn. We are grateful to S. Grand, F. Niu, and L. Liu for thoughtful discussions. This work was partially supported by a key project of the National Natural Science Foundation of China (NSFC) (41503212), NSFC (41274059, 40974021, and 40774044), a special project (ZDJ2009-01) and the 10,000 Talents Award from the Chinese government to J. Lei. The GMT software package distributed by Wessel and Smith [] was used for making the figures. We thank Thorsten Becker (the Editor), Sergei Lebedev (the Associated Editor), Bernhard Steinberger and an anonymous reviewer for their constructive comments and suggestions, which have improved the manuscript significantly. The data recorded by the portable seismic stations and the Chinese provincial seismic networks are available from the corresponding author and Zheng et al. [2010], respectively.
Publisher Copyright:
© 2016. The Authors.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - We determined a new 3-D P-wave velocity model of the upper mantle beneath eastern Tibet using 112,613 high-quality arrival-time data collected from teleseismic seismograms recorded by a new portable seismic array in Yunnan and permanent networks in southwestern China. Our results provide new insights into the mantle structure and dynamics of eastern Tibet. High-velocity (high-V) anomalies are revealed down to 200 km depth under the Sichuan basin and the Ordos and Alashan blocks. Low-velocity (low-V) anomalies are imaged in the upper mantle under the Kunlun-Qilian and Qinling fold zones, and the Songpan-Ganzi, Qiangtang, Lhasa and Chuan-Dian diamond blocks, suggesting that eastward moving low-V materials are extruded to eastern China after the obstruction by the Sichuan basin, and the Ordos and Alashan blocks. Furthermore, the extent and thickness of these low-V anomalies are correlated with the surface topography, suggesting that the uplift of eastern Tibet could be partially related to these low-V materials having a higher temperature and strong positive buoyancy. In the mantle transition zone (MTZ), broad high-V anomalies are visible from the Burma arc northward to the Kunlun fault and eastward to the Xiaojiang fault, and they are connected upward with the Wadati-Benioff seismic zone. These results suggest that the subducted Indian slab has traveled horizontally for a long distance after it descended into the MTZ, and return corner flow and deep slab dehydration have contributed to forming the low-V anomalies in the big mantle wedge. Our results shed new light on the dynamics of the eastern Tibetan plateau.
AB - We determined a new 3-D P-wave velocity model of the upper mantle beneath eastern Tibet using 112,613 high-quality arrival-time data collected from teleseismic seismograms recorded by a new portable seismic array in Yunnan and permanent networks in southwestern China. Our results provide new insights into the mantle structure and dynamics of eastern Tibet. High-velocity (high-V) anomalies are revealed down to 200 km depth under the Sichuan basin and the Ordos and Alashan blocks. Low-velocity (low-V) anomalies are imaged in the upper mantle under the Kunlun-Qilian and Qinling fold zones, and the Songpan-Ganzi, Qiangtang, Lhasa and Chuan-Dian diamond blocks, suggesting that eastward moving low-V materials are extruded to eastern China after the obstruction by the Sichuan basin, and the Ordos and Alashan blocks. Furthermore, the extent and thickness of these low-V anomalies are correlated with the surface topography, suggesting that the uplift of eastern Tibet could be partially related to these low-V materials having a higher temperature and strong positive buoyancy. In the mantle transition zone (MTZ), broad high-V anomalies are visible from the Burma arc northward to the Kunlun fault and eastward to the Xiaojiang fault, and they are connected upward with the Wadati-Benioff seismic zone. These results suggest that the subducted Indian slab has traveled horizontally for a long distance after it descended into the MTZ, and return corner flow and deep slab dehydration have contributed to forming the low-V anomalies in the big mantle wedge. Our results shed new light on the dynamics of the eastern Tibetan plateau.
KW - Chinese provincial networks
KW - Eastern Tibetan plateau
KW - mantle dynamics
KW - portable seismic array
KW - teleseismic tomography
UR - http://www.scopus.com/inward/record.url?scp=84971421955&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84971421955&partnerID=8YFLogxK
U2 - 10.1002/2016GC006262
DO - 10.1002/2016GC006262
M3 - Article
AN - SCOPUS:84971421955
VL - 17
SP - 1861
EP - 1884
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
SN - 1525-2027
IS - 5
ER -