Depth variation of the Conrad discontinuity in the Qaidam Basin, northwestern China, and its crustal dynamic implications. Issue 3 (7th June 2021)

• Record Type: Journal Article
• Authors: Yang, Biao; Wang, YanBin; Zhao, Li; Yang, LiMing; Sha, ChengNing
• Is Part Of: Earth and planetary physics. Volume 5:Issue 3(2021)
• Page Start: 296
• Page End: 304
• Publication Date: 2021-06-07
• Subjects: Conrad discontinuity -- regional seismic data -- crustal structure -- Qaidam Basin -- Tibetan Plateau; Geophysics -- Periodicals; Earth sciences -- Periodicals; Planets -- Geology -- Periodicals; 550.5
• DOI: 10.26464/epp2021030
• Languages: English
• ISSNs: 2096-3955

Abstract

Abstract: 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 Points: Broadband records from a dense seismic network were used to analyze the crustal phases and investigate the depth of the Conrad and Moho discontinuities in the Qaidam Basin. 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 depth of the Moho discontinuity under the Qilian orogenic belt and Bayan Har block is deeper than under the Qaidam Basin, which is consistent with the previous results.