城口–房县断裂带位于上扬子板块北缘，以其为界可进一步将大巴山构造带划分为南大巴山弧形构造带(南大巴山)和北大巴山逆冲推覆构造带(北大巴山)。城口–房县断裂带不仅控制着该地区的岩浆活动和沉积作用，同时对大巴山的构造演化起到了重要的主导作用。综合大量的野外调查、构造解析和显微构造观察，对城口–房县断裂带进行了分段性的构造解析，厘定出城口–房县断裂带发育两条不同走滑性质的走滑断裂带，并追踪其展布范围。右行走滑断裂带自西向东贯穿城口–房县断裂带，与扬子板块相对华北板块的斜向俯冲碰撞有关；左行走滑断裂带发育于城口–房县断裂带东段，形成于陆内造山阶段，并改造了东段早期的右行走滑构造。在板块碰撞造山之前，早期的城口–房县断裂带处于伸展环境中呈线状分布。在陆内逆冲推覆过程中，由于东西两侧砥柱的阻碍作用，城口–房县断裂带发生弧形弯曲呈现SW向弧形展布。%The Chengkou-Fangxian fault zone is located in the northern margin of the Yangtze Block. The fault zone divided the Dabashan orogenic belt into two units:the South Dabashan orocline (i.e. the South Dabashan) and the North Dabashan thrust belt (i.e. the North Dabashan). The Chengkou-Fangxian fault zone played a key role in regional magmatism and sedimentation, and the tectonic evolution of the Dabashan area as well. Based on detailed field investigations, structural analyses and microscopic observation, two strike-slip fault zones, which are characterized by its dextral and sinistral strike-slipping, respectively, were recognized along the Chengkou-Fangxian fault zone. The dextral strike-slip faulting affected the whole fault zone was resulted from the oblique collision between the Yangtze Block and the North China Block, and the sinistral strike-slip faulting, which involved only the eastern part of the fault zone, was related to intra-continental orogeny. In addition, the former was superposed and transformed by the latter. Before the collisional orogeny, the Chengkou-Fangxian fault zone was a linear fault, however, due to the thrusting of the intra-continental orogeny, the Chengkou–Fangxian fault zone was deformed into a SW-convex arcuate fault zone, which is likely resulted from the pinning of both of its ends.
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