库车冲断带秋里塔格构造带东段构造样式与构造演化

秋里塔格构造带位于库车褶皱冲断前缘,其东段包括东秋里塔格背斜和库车塔吾背斜。野外调查和地震剖面解释表明:秋里塔格构造带东段盐下发育断层转折褶皱; 盐上东秋里塔格背斜为滑脱箱状背斜,库车塔吾背斜核部为南倾逆冲断层所破坏。演化剖面显示秋里塔格构造带东段在侏罗纪断陷期发育了正断裂,其后为平静期,直到库车晚期后逆冲断层和褶皱快速发育,背斜最终形成。膏盐岩及古构造对构造变形具有重要影响,一方面作为滑脱层,分割了盐下层与盐上层,导致二者形成不同的构造样式; 另一方面塑性流动充填于背斜核部。由于膏盐岩的厚度差异,东秋里塔格背斜盐上发育褶皱,而库车塔吾背斜核部被逆冲断层破坏,膏盐层厚度还影响了膏盐层上下构造高点的相对位置。盐下构造的发育受侏罗纪古构造控制,进而影响了盐上构造的发育。

The structural styles and evolution of eastern Qiulitage structure belt in Kuqa fold and thrust belt,northwest China

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.