The structural styles and evolution of eastern Qiulitage structure belt in Kuqa fold and thrust belt,northwest China
Zhao Xing1, Jia Chengzao1, Li Benliang1, Cheng Haiyan2
1. Key Laboratory of Basin Structure and Hydrocarbon Accumulation,Research Institute of Petroleum Exploration and Development,Beijing 100083;
2. Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081
Qiulitage structure belt is the thrust front of the Kuqa fold and thrust belt of the southern piedmont of Tianshan Mountain.Its eastern part includes Dongqiulitage anticline and Kuchetawu anticline.Field work and seismic interpretation imply that fault-bend folds were developed in the subsalt stratum.In the suprasalt stratum Dongqiulitage anticline developed detachment folds,but Kuchetawu anticline was faulted.According to the structural evolution section,the Jurassic normal fault was reversed in Kuche period.The salt structures were mainly formed in Kuche period to Quaternary.Salt and paleo-structure controlled the deformation of the eastern Qiulitage structure belt.Salt,as a detachment layer,decoupled its lower and upper stratum.As a result,the subsalt and supra-salt stratum developed different structures and shorting amout.At the same time,the salt flowed to fill in the core of the fold.Due to the diversity of salt thickness,Dongqiulitage anticline is a box-anticline,while Kuchetawu anticline was faulted.The paleo-structure played an important role on the deformation of the eastern Qiulitage structure belt.The reversion of the former structures formed subsalt fault bend folds and affected the supra-salt structure furthermore.