Preprints
https://doi.org/10.5194/se-2019-119
https://doi.org/10.5194/se-2019-119

  10 Jul 2019

10 Jul 2019

Review status: this preprint was under review for the journal SE but the revision was not accepted.

The formation of North-South Seismic Zone and Emeishan large igneous province in Western China: Insight from teleseismic tomography

Chuansong He1,2 Chuansong He
  • 1Institute of Geophysics, CEA, Beijing 100081, China
  • 2Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China

Abstract. Several models have been suggested to explain the earthquake mechanism of the North-South Seismic Zone (NSSZ) and the formation of the Emeishan Large Igneous Province (ELIP). In this study, I extended the study region and carried out detailed teleseismic tomography in the NSSZ and near-by regions. Results identified by this study reveal large plate-like high-velocity anomalies beneath the Songpan-Ganzi Block and the South China Block, which may be associated with large-scale lithospheric delamination, and low-velocity structures at 50–200 km depths in the western and southern parts of this study region, which imply upwelling asthenosphere induced by delamination and the absence of the rigid lithosphere there. Two high-velocity structures beneath the Sichuan Basin and the Alashan Block are revealed, which might be the lithospheric roots of these structures. These rigid lithospheric roots obstructed the eastward extrusion of the Tibetan Plateau and led to stress accumulations and releases (earthquakes) in the Longmenshan Orogenic Belt and the northern part of the NSSZ. Due to obstruction by the Sichuan Basin’s lithosphere, eastward extrusion was redirected southeastward to Yunnan in the southern part of the NSSZ, which led to stress accumulations and releases (earthquakes) along the Honghe and Xiaojiang Faults. This study provide velocity images reveal a slab-like high-velocity structure, which might be associated with the lithospheric vestige of the Paleo-Tethys Ocean that subducted beneath the ELIP, which resulted in large-scale return mantle flow or mantle upwelling and contribute to the LIP formation in early Mesozoic.

Chuansong He

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Chuansong He

Data sets

SEISDMC Waveform data for this study were provided by the Data Management Center of the China National Seismic Network at the Institute of Geophysics https://doi.org/10.11998/SeisDmc/SN

Chuansong He

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Short summary
This study reveal large plate-like high-velocity anomalies beneath the Songpan-Ganzi Block and the South China Block and low-velocity structures at 50–200 km depths in the western and southern parts of this study region, which are important for understanding the formation of the North-South Seismic Zone and Emeishan large igneous province.