塔中隆起NNE向走滑断裂特征及形成机制

摘要

In this study, the correlation method of structural factors and structural analysis were used to determine the formation mechanism of NNE-trending strike-slip faults in the Tazhong Uplift. The interpretation of 2D and 3D seismic data revealed deformation characteristics of the NNE-striking faults and determined their formation mechanism. NNE-trending strike-slip faults exhibit vertical superposition of compresso-shear faults and tenso-shear faults in seismic profiles. They have experienced two stages of activities:the late Ordovician compresso-shear faulting and the late Silurian-middle Devonian tenso-shear faulting. The formation of the NNE-trending strike-slip faults was controlled by the pre-existing basement weak zone and the evolution of the orogenic belts around Tarim plate. At the end of Middle Ordovician, a NS-trending compressive stress was generated by the subduction and closure of the ocean basin on the south margin of Tarim plate, and it acted on the NE-trending basement weak zone, resulting in the formation of NNE-trending strike-slip faults. Meanwhile, the compressive stress from the northwest margin of Tarim plate vertically acted on the NNE-striking strike-slip fault, leading to the compresso-shear deformation. In late Silurian-middle Devonian period, the NS-trending compressive stress continually acted on the strike-slip faults, resulting in continued strike-slip deformation. Moreover, the extensional stress from the northwest margin of Tarim plate vertically acted on the NNE-striking strike-slip fault, leading to the tenso-shar deformation.%为了确定塔中隆起NNE向走滑断裂特征及形成机制，利用构造要素相关性分析及构造解析方法，通过对二维和三维资料的解释，揭示了走滑断裂的构造变形特征，确定了走滑断裂的形成机制。NNE向走滑断裂在地震剖面上表现为压扭和张扭在垂向上叠加的特点，其形成演化主要经历了中奥陶世末压扭和晚志留世—中泥盆世张扭两个阶段。先存基底软弱带和塔里木板块周缘造山带的演化共同控制了这套走滑断裂的形成。中奥陶世末，塔里木板块南缘洋盆俯冲闭合产生的近南北向挤压应力斜向作用于NNE向的基底软弱带之上，导致断裂上部地层被撕裂产生走滑分量，从而形成了北东向的左旋走滑断裂系统，同时，来自塔里木板块西北缘的挤压应力垂向作用于走滑断裂上，导致NNE向走滑断裂发生压扭变形。晚志留世—中泥盆世，塔里木板块南缘的挤压应力继续斜向作用于NNE向走滑断裂之上导致其继续发生走滑变形，同时，来自塔里木盆地西北缘的NW向伸展应力垂向作用于走滑断裂上，导致NNE向走滑断裂发生张扭变形。