DOI: 10.1016/j.tecto.2020.228430
论文题名: Seismic anisotropy beneath the eastern margin of the Tibetan Plateau from SKS splitting observations
作者: Liu J. ; Wu J. ; Wang W. ; Fang L. ; Chang K.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2020
卷: 785 语种: 英语
中文关键词: Anisotropy
; Deformation
; Shear wave splitting
; Tibetan Plateau
英文关键词: Compressive stress
; Deformation
; Earthquakes
; Average delay time
; Central Sichuan Basin
; Complex deformation
; Deformation mechanism
; Polarization direction
; Seismic anisotropy
; Strong anisotropy
; West Qinling orogenic belt
; Anisotropy
; body wave
; deformation mechanism
; earthquake event
; polarization
; seismic anisotropy
; stress
; upwelling
; wave splitting
; China
; Qinghai-Xizang Plateau
; Sichuan Basin
英文摘要: The eastern margin of the Tibetan Plateau is one of the areas of the entire region with the most complex deformation. Seismic anisotropy reveals the imprints of past and present deformation in the lithosphere and asthenosphere, which could help elucidate the deformation mechanism. This study investigated the characteristics of seismic anisotropy beneath 512 seismic stations based on SKS phases from ~200 earthquake. The measured splitting delay time varied from 0.2–1.4 s (average: 0.7 s). In the central Sichuan basin (SCB), the average delay time is only ~0.35 s, consistent with the characteristics of the relatively thick and rigid lithosphere of the stable SCB. However, the northeastern SCB has relatively stronger anisotropy with a fast polarization direction (FPD) with NE-SW orientation, which is markedly different from the weak anisotropy with NW–SE orientation in the central SCB. We speculate that owing to E–W compressive stress caused by eastward escape of material from the Tibetan Plateau, the lithosphere in this area has undergone considerable deformation along the right-lateral maximum shear direction. In the Chuandian diamond block, the FPD of several adjacent stations was approximately E-W, i.e., almost perpendicular to the FPD in the northern and southern regions, which might be related to partial melting in the lithosphere and to compressive stress. The FPD in the west Qinling orogenic belt is approximately parallel to the strike of the surface faults and the average delay time is approximately 1.3 s. As the lithosphere is insufficient to produce such strong anisotropy in this region, we infer that the lithosphere and asthenosphere both contribute to the seismic anisotropy. Delay time in the southern Songpan-Ganzi block is much smaller than in the north, which might be attributable to low-velocity mantle upwelling and complex tectonic stress in this area. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170647
Appears in Collections: 气候变化与战略
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作者单位: Institute of Geophysics, China Earthquake Administration, Beijing, 100081, China; Laboratory of Seismology and Physics of Earth's Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China
Recommended Citation:
Liu J.,Wu J.,Wang W.,et al. Seismic anisotropy beneath the eastern margin of the Tibetan Plateau from SKS splitting observations[J]. Tectonophysics,2020-01-01,785