Abstract
To investigate continental dynamics underneath the south-central Tibetan plateau, which composes the Himalayan, Lhasa, and Qiangtang blocks, we have conducted comprehensive examinations of seismic azimuthal anisotropy in the crust using receiver functions (RFs) and crustal and mantle anisotropy using teleseismic shear wave splitting (SWS) analysis. In the Qiangtang block, the observed predominantly E-W fast orientations from RF and SWS analyses with similar magnitude are interpreted as resulting from eastward crustal flow with minor contributions from the mantle. In the Lhasa block, the crustal anisotropy is approximately N-S oriented, which is parallel to the strike of rift basins and southward crustal flow. Anisotropy revealed by SWS demonstrates a rotation from E-W in the north to NE-SW in the south, which can be interpreted as reflecting mantle flow field induced by the northward movement of the subducting Indian plate. The addition of PKS and SKKS measurements and extension of epicentral distance range to 171.8° for SWS analysis revealed dominantly strong E-W oriented anisotropy in most parts of the Himalayan block, where most previous studies reported pervasively null measurements. The absence of azimuthal anisotropy is observed in two regions in the Himalayan block which is attributable to mantle upwelling through a previously identified slab window. A two-layered anisotropy structure with different fast orientations for the upper and lower layers can be constrained in the southern Qiangtang and the vicinity of the Main Boundary Thrust.
Recommended Citation
C. Shen et al., "Tectonic Implications of Seismic Anisotropy Layering Beneath the Southern Tibetan Plateau Revealed by Integrated Shear Wave Splitting and Receiver Function Analyses," Journal of Geophysical Research: Solid Earth, vol. 129, no. 8, article no. e2024JB029268, American Geophysical Union; Wiley, Aug 2024.
The definitive version is available at https://doi.org/10.1029/2024JB029268
Department(s)
Geosciences and Geological and Petroleum Engineering
Publication Status
Full Access
Keywords and Phrases
receiver functions; seismic anisotropy; shear wave splitting; Tibetan plateau
International Standard Serial Number (ISSN)
2169-9356; 2169-9313
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2024 American Geophysical Union; Wiley, All rights reserved.
Publication Date
01 Aug 2024
Comments
National Science Foundation, Grant 1830644