Abstract

High-quality, short-period Rayleigh-wave group velocity tomography is conducted through ambient noise cross-correlation among 54 stations in the newly upgraded Xinjiang Provincial Digital Seismic Network in northwest China. The velocity maps obtained in this study give more details in most parts of Xinjiang than previous surface wave studies that mostly focused on large scale patterns in Eurasia, Asia, or the whole of China. The tomography results have a high correlation with the major tectonic and geological features in the study area. In general, low velocities are associated with the two basins, and high velocities are associated with the two mountain belts in the Xinjiang area. The southernmost part of the Tianshan mountains has the same velocity structure as that of the neighboring part of the Tarim Basin, implying that they may have the same crustal composition. The velocity in the Tarim Basin is spatially inhomogeneous, due to the fact that it comprises several sub-blocks that have different thickness of sediments and crustal layers. In the Dzungaria Basin, as the period becomes longer, the low-velocity zone shrinks toward the south, reflecting the fact that the sediments and the upper crust in the southern part of the Dzungaria Basin are thicker than in the northern part.

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