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Structure and Evolution of the Post-Collisional Fault Structures in the Three River Orogenic Belt, Exemplified by the Cenozoic Jianchuan-Lanping Basin

LIU Jun-lai1, WANG An-jian2, CAO Dian-hua2, XIU Qun-ye2   

  1. 1. College of Earth Sciences and Mineral Resources/Lithosphere Evolution and Mineral Resources Laboratory, China University of Geosciences, Beijing 100083, China; 2. Strategic Research Center of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
  • Received:2004-12-20 Revised:2004-12-20 Online:2004-12-20 Published:2004-12-20

Abstract: The Jianchuan-Imnping Cenozoic basin is located in the Three River orogenic belt,an important tectonic belt generated during collisional or post-collisional processes due to India-Asia interaction.There are several fault zones in the basin and adjacent areas,including the Lancangjiang fault zone,the Central axis fault zone and the Qiaohou fault zone.The N-S extending Lancangjiang fault zone is characterized by occurrence of mylonites and strongly foliated granitic rocks and meta-sedimentary rocks.Foliations dip steeply either to the east or to the west with stretching lineations in the direction along their strikes.Shear sense indicators in tectonites suggest a left-lateral shear during mylonitizartion along the fault zone,The Central axis fault zone is a zone of brittle fractures in N-S direction.The fracture surfaces mainly dip to the west with dip angles varying from 0。to 90。.The shallowly dipping surfaces often cut across those with high angles form thrusts and nappe structures at different scales.Qiaohou fault zone dipping to the NNE with dip angles mainly of 60。-70。to the east is the northern extension of the Ailaoshan-Red River fault zone.Evidences for both strike-slip faulting and thrusting are obvious along the fault zone.