Crustal anisotropy from Moho converted Ps wave splitting analysis and geodynamic implications beneath the eastern margin of Tibet and surrounding regions

被引:206
作者
Chen, Yun [1 ]
Zhang, Zhongjie [1 ]
Sun, Changqing [2 ]
Badal, Jose [3 ]
机构
[1] Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
[2] China Earthquake Adm, Inst Crustal Dynam, Seismol Lab, Beijing 100085, Peoples R China
[3] Univ Zaragoza, E-50009 Zaragoza, Spain
基金
中国国家自然科学基金;
关键词
Receiver functions; Pms converted phases; Shear wave splitting; Seismic anisotropy; Crust/mantle deformation; East Tibet; UPPER-MANTLE BENEATH; SEISMIC ANISOTROPY; FLOW BENEATH; CENTRAL-ASIA; DEFORMATION; PLATEAU; EVOLUTION; SICHUAN; RANGE; LITHOSPHERE;
D O I
10.1016/j.gr.2012.04.003
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
In addition to crustal thickening, distinctly different mechanisms have been suggested to accommodate the huge convergences caused by the continental collision between India and Eurasia. As the transition zone between the two grand tectonic domains of Asia, the Tethys and the Pacific, east Tibet and its surrounding regions are the ideal places to study continental deformation. Pervasive rock deformation may produce anisotropy on the scale of seismic wavelengths; thus, seismic anisotropy provides insight into the deformation of the crust and mantle beneath tectonically active domains. In this study, we calculated receiver function pairs of radial- and transverse-components at 98 stations located in Sichuan and Yunnan provinces, China. We selected 7423 pairs with high signal-to-noise ratio (SNR) and unambiguous Moho converted Ps phases (Pms) to measure the Pms splitting owing to the crustal anisotropy. Both the crustal thickness and the average crustal Vp/Vs ratio were calculated simultaneously by the H-k stacking method. The geodynamic implications were also investigated in relation to surface geological features, GPS velocities, absolute plate motion (APM), SKS/SKKS splitting, and other seismological observations. In addition to the fast polarization directions (FPDs) of the crustal anisotropy, we observed a conspicuous sharper clockwise rotation around the eastern Himalayan syntaxis than was revealed by GPS velocities. The distributed FPDs within and near the main active fault zones also favored the directions parallel to the faults. This implied that the deformation of a continuous medium revealed by GPS motions is a proxy for the deformation of the brittle shallow crust only, while the main active faults and the deep crustal interiors both play important roles in the deep deformation. Our results suggest that the deformation between the crust and upper mantle within the northernmost section of the Indochina block is decoupled due to the large difference in the directions between the observations related to the crust (GPS and crustal anisotropy) and mantle (APM and mantle anisotropy). Focusing on the transition zone between the plateau and the South China and Indochina blocks, we suggest that the motion of the Central Yunnan sub-block is a southeastward extrusion by way of tectonic escape. There is less deformation in the deep crust and the motion is controlled by the active boundary faults of the Ailaoshan-Red River shear zone to the west and the Xianshuihe-Xiaojiang fault to the east; the lower crustal flow within the plateau southeastward reached the Lijiang-Xiaojinhe fault, but further south it was obstructed by the Central Yunnan sub-block. (C) 2012 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
引用
收藏
页码:946 / 957
页数:12
相关论文
共 68 条
[1]   STRUCTURE AND EVOLUTION OF THE HIMALAYA-TIBET OROGENIC BELT [J].
ALLEGRE, CJ ;
COURTILLOT, V ;
TAPPONNIER, P ;
HIRN, A ;
MATTAUER, M ;
COULON, C ;
JAEGER, JJ ;
ACHACHE, J ;
SCHARER, U ;
MARCOUX, J ;
BURG, JP ;
GIRARDEAU, J ;
ARMIJO, R ;
GARIEPY, C ;
GOPEL, C ;
LI, TD ;
XIAO, XC ;
CHANG, CF ;
LI, GQ ;
LIN, BY ;
TENG, JW ;
WANG, NW ;
CHEN, GM ;
HAN, TL ;
WANG, XB ;
DEN, WM ;
SHENG, HB ;
CAO, YG ;
ZHOU, J ;
QIU, HR ;
BAO, PS ;
WANG, SC ;
WANG, BX ;
ZHOU, YX ;
RONGHUA, X .
NATURE, 1984, 307 (5946) :17-22
[2]  
[Anonymous], 1998, EOS, DOI [10.1029/98EO00426, DOI 10.1029/98EO00426]
[3]   Upper mantle anisotropy beneath Indochina block and adjacent regions from shear-wave splitting analysis of Vietnam broadband seismograph array data [J].
Bai, Ling ;
Iidaka, Takashi ;
Kawakatsu, Hitoshi ;
Morita, Yuichi ;
Dzung, N. Q. .
PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 2009, 176 (1-2) :33-43
[4]   A QUANTITATIVE-EVALUATION OF THE CONTRIBUTION OF CRUSTAL ROCKS TO THE SHEAR-WAVE SPLITTING OF TELESEISMIC SKS WAVES [J].
BARRUOL, G ;
MAINPRICE, D .
PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 1993, 78 (3-4) :281-300
[5]   Reconciling lithospheric deformation and lower crustal flow beneath central Tibet [J].
Bendick, R. ;
Flesch, L. .
GEOLOGY, 2007, 35 (10) :895-898
[6]   SHEAR-WAVE SPLITTING IN THE UPPER-MANTLE WEDGE ABOVE THE TONGA SUBDUCTION ZONE [J].
BOWMAN, JR ;
ANDO, M .
GEOPHYSICAL JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY, 1987, 88 (01) :25-41
[7]   Seismic anisotropy of upper mantle in Sichuan and adjacent regions [J].
Chang LiJun ;
Wang ChunYong ;
Ding ZhiFeng .
SCIENCE IN CHINA SERIES D-EARTH SCIENCES, 2008, 51 (12) :1683-1693
[8]   Love and Rayleigh Wave Tomography of the Qinghai-Tibet Plateau and Surrounding Areas [J].
Chen, Yun ;
Badal, Jose ;
Hu, Jiafu .
PURE AND APPLIED GEOPHYSICS, 2010, 167 (10) :1171-1203
[9]   Radial anisotropy in the crust and upper mantle beneath the Qinghai-Tibet Plateau and surrounding regions [J].
Chen, Yun ;
Badal, Jose ;
Zhang, Zhongjie .
JOURNAL OF ASIAN EARTH SCIENCES, 2009, 36 (4-5) :289-302
[10]  
Clark MK, 2000, GEOLOGY, V28, P703, DOI 10.1130/0091-7613(2000)28<703:TOBTEM>2.0.CO