The Deformational Characteristics of the Tekilik Thrust-nappe Structures in Southwest Tarim Basin

The Tekilik thrust-nappe structures in southwest Tarim Basin were developed in the piedmont of the Kunlun Mountain.The zonation of the structures was clearly displayed with regard to the structural components,its deformational characteristics and intensity,it could be divided into frontal zone,middle zone,and root zone,as well as the frontal boundary and back boundary zones.The frontal zone was deformationally characterized by the imbricate structures composed of a series of splay thrust faults,along with the duplexes and klippes locally;and in the middle zone the penetrative slaty cleavages,the inclined and overturned folds were grown locally with the slip cleavages,the rootless folds and boutin structures.In the root zone a ductile shear zone was developed with 1km wide,the mylonitic foliations,the associated Afolds and sheath folds were developed within the zone.The investigations show that the studied thrust-nappe structures began to form during the Devonian-Carboniferous periods,as a result of the southward Type A subduction zone is caused by collision of the Middle Kunlun Islands and the southern boundary of Tarim Block.