Publication Date:
2014-02-18
Description:
[1] We collected continuous seismic data recorded between 2007-2010 by 208 broadband stations from the Chinese Provincial Digital Seismic Networks, A Seismic Collaborative Experiment of Northern Tibet (ASCENT), and the NorthEastern Tibet Seismic experiment (NETS). Cross-correlations of vertical-component records are computed to extract Rayleigh wave empirical Green's functions. Group and phase velocities are then constructed from the empirical Green's functions in 8- to 50-s period. At periods ≤ 25 s, more than 10% lower velocities are imaged beneath the Qaidam basin, and high velocities are observed beneath the non-basin regions. At periods ≥ 30 s, up to 10% lower velocities are imaged in the Qiangtang and Songpan-Ganze terranes. From these group and phase velocity maps, a three-dimensional (3-D) Vsv model of the crust is derived. The model shows that the Qiangtang and Songpan-Ganze terranes have a very thick crust with a prominent low-velocity zone (LVZ) in the middle crust. The LVZ thins out in the vicinity of the eastern Kunlun Mountains, providing a new constraint on the mode of deformation across the Tibetan Plateau. The northwestern Qilian orogen, where receiver functions reveal a Moho deeper than the surrounding areas, also features a relatively weak mid-crustal LVZ, which we interpret as an intracrustal response associated with the shortening between the North China craton and Tibetan Plateau.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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