Earth Science Frontiers ›› 2010, Vol. 17 ›› Issue (5): 106-116.

• Article • Previous Articles     Next Articles

Multilayer detachment crustal structure in the Longmen Mountains: Evidences from neotectonic deformation and geophysical data.

  

  1. 1State Key Laboratory of Geological Processes and Mineral Resources; Key Laboratory of Lithospheric Tectonics and Lithoprobing Technology of Ministry of Education,  Beijing 100083, China
    2School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
    3Exploration and Development Institute, Southwest Oil and Gas Branch, China Petroleum ＆ Chemical Corporation, Chengdu 610081, China
    4Chinese Academy of Land and Resource Economics, Beijing 101149, China
  • Received:2010-07-06 Revised:2010-08-03 Online:2010-09-15 Published:2010-10-22

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Abstract:

 The crustal structure and its affinity with the occurrence of 5.12 Wenchuan earthquake in the Longmen Mountains have become the focus of attention in the field of structural geology since 2008. However, present tectonic models for interpreting crustal structure in the Longmen Mountains only focus on surface structure, or only pay attention to deep structure; and thus, they could not furnish a comprehensive understanding. This paper reports a comprehensive structural section across the Pengguan complex and Xuelongbao pluton, which are the major tectonopetrological units generating the 5.12 Wenchuan earthquake, and reinterprets the geophysical data published by previous studies. We conclude that a detachment fault at a depth of ~10 km separated the insequence duplex imbricated thrust in the shallow tectonic level, while the rigid basement of the Yangtze Block northwestward wedged into the middle to lower crustal ductile channel, which produced multilayer detachment crustal structure. The upper layer of the ductile channel flow pushed and ruptured the Pengguan complex and Xuelongbao pluton, which resulted in the occurrence of 5.12 Wenchuan earthquake.

Key words: Longmen Mountains, multilayer crustal structure, crustal ductile channel flow, imbricated thrust

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