Seismic structure in the southeastern China using teleseismic receiver functions

• Published in: Tectonophysics 2013-10, Vol.606, p.24-35
• Main Authors: Li, Qiusheng, Gao, Rui, Wu, Francis T., Guan, Ye, Ye, Zhuo, Liu, Qimin, Kuo-Chen, Hao, He, Rizheng, Li, Wenhui, Shen, Xuzhang
• Format: Article
• Language: English
• Subjects: Arrays; China; Constraints; Crusts; Discontinuity; LAB; Mantle; Mantle transition zone; Mathematical models; Moho; Plates (structural members); Receiver functions; Receivers; SE China; Stacking; Stations
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2013.06.033

The southeastern margin of China is an ideal area to study the modern plate interactions. The previous models, however, are poorly constrained with respect to the geometry due to the sparse coverage. Here we present new observations from a temporary array with 20 stations in southeastern China. We isolated converted seismic phases in the P and S wave coda to generate receiver function from the structure of the crust and upper mantle. By using H–K stacking and common conversion point stacking, the geometry of discontinuities above was imaged along the southeastern Chinese coastline. The CCP section shows Moho dips gently northeastward with a mean depth of 30km. The 410 and 660km discontinuities are at the depth close to IASP91 model. This means that we have not seen any significant anomaly from Moho and mantle transition zone that corresponded with the geodynamics of plate subducting, instead, we found that the crust was ruptured by Min River fault to depth of the Moho. We provide a 2D map of Moho topography by combining our crustal thickness to that from permanent stations, active seismic and OBS offshore profiles. The map is consistent with previous studies and shows a crust that thins coastward and southwestward in the rate of ~1.5km per 100km. We image the lithosphere–asthenosphere boundary at a depth of 60 to 70km by using S-wave to combine with the P-wave. Our crustal structure suggests that Min River fault certainly plays an important role in adjusting regional stress field induced by plate interactions in the study area. Our lithospheric thickness is more consistent with a very strongly attenuated continental lithosphere. Given the close proximity to the coast this might suggest that the lithospheric mantle transitions to oceanic before the crust does. Alternatively, we may infer that the continental lithosphere has been thermally eroded in this region. •Provide new constraints of lateral extension of coastal crust, SE China•Provide observation evidences of LAB using P and S receiver function•A representative extension rate of the crust coastward beneath SE China is estimated.