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地球与行星物理

ISSN  2096-3955

CN  10-1502/P

Citation: Yang, B., Wang, Y. B., Zhao, L., Yang, L. M. and Sha, C. N. (2021). Depth variation of the Conrad discontinuity in the Qaidam Basin, northwestern China, and its crustal dynamic implications. Earth Planet. Phys., 5(3), 296–304. http://doi.org/10.26464/epp2021030

2021, 5(3): 296-304. doi: 10.26464/epp2021030

SOLID EARTH: SEISMOLOGY

Depth variation of the Conrad discontinuity in the Qaidam Basin, northwestern China, and its crustal dynamic implications

1. 

Department of Geophysics, School of Earth and Space Sciences, Peking University, Beijing 100871, China

2. 

Earthquake Administration of Qinghai Province, Xining 810001, China

Corresponding author: YanBin Wang, ybwang@pku.edu.cn

Received Date: 2020-12-31
Web Publishing Date: 2021-04-14

We use broadband records from a dense seismic network deployed in and around the Qaidam Basin in northwestern China to analyze the crustal phases and investigate the depth of the Conrad and Moho discontinuities as well as the P-wave velocity. Waveform cross-correlation is used to assist in the identification of the crustal phases and in determining their arrival times. Depth of the Conrad discontinuity is determined by fitting the travel times of Conrad-diffracted P-waves using a two-layer model. The depth of the Conrad discontinuity under the eastern part of the basin is shallower than the western part, which can be attributed to different crustal shortening mechanisms. The upper crust shortening in the western part of the basin leads to thickening of the upper crust, while multiple thrust faults result in the rise of the Conrad discontinuity in the east. These two different mechanisms determine the depth change of the Conrad discontinuity in the basin from the west to the east, which is supported by the results in this study.

Key words: Conrad discontinuity, regional seismic data, crustal structure, Qaidam Basin, Tibetan Plateau

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Depth variation of the Conrad discontinuity in the Qaidam Basin, northwestern China, and its crustal dynamic implications

Biao Yang, YanBin Wang, Li Zhao, LiMing Yang, ChengNing Sha