渝东大焦石坝地区差异构造变形

在地震资料的基础上，结合区域地质资料，对大焦石坝地区进行分层、分带和分期差异构造变形特征研究，总结了南、北段的差异变形规律，并探讨了南北向乌江断裂构造变形带和大耳山断裂构造变形带的成因机制。结果表明，大焦石坝地区纵向上发育4套构造形变层，平面上由东到西分为冲断褶皱带、逆冲-滑脱褶皱带和滑脱褶皱带，燕山期以来先后遭受南东-北西向、近东西向和北东-南西向3期挤压应力作用。大焦石坝地区为逆冲推覆构造的前锋带，主滑脱层由前寒武系向寒武系转变，自东向西发生前展式递进变形，同时由于齐岳山断层分段性及前寒武系基底滑脱断层的结构差异，导致了近南北向大耳山和乌江断裂构造变形带的形成，使北段、中段和南段自东向西分别表现出冲断作用-压扭作用-断滑作用-滑脱作用、冲断作用-压扭作用-断展作用-滑脱作用和冲断作用-断弯作用-断展作用-滑脱作用的变形规律。

Differential structural deformation of the Dajiaoshiba area,East Chongqing

The structural deformation characteristics of different layers,zones and stages at the Dajiaoshiba area were analyzed based on seismic and regional geological data.Thereafter,we summarized the differential deformation patterns of the north and south sections,and discussed the mechanism for the formation of the S-N oriented Wujiang and Daershan structural fault deformation zones.The results show that four sets of structural deformation layers occur vertically in the Dajiaoshiba area,while horizontally it can be divided into thrust-fold belt,thrust-decollement fold belt and decollement-fold belt from east to west,which have undergone SE-NW-trending,nearly WE-trending and NE-SW-trending compressive stress since the Yanshan Movement.The studied area represents the front belt of the thrust nappe structure,and the major decollement formation shifts from the Precambrian to the Cambrian,which has gone through the piggy-back progressive deformation from east to west.Due to the segmentation of the Qiyueshan fault and the structural difference of the Precambrian basement decollement fault,the composition of east to west deformation zones changes along the trend of the nearly SN-trending Daershan and Wujiang structures,with a deformation pattern of thrusting-compresso-shearing-fault-detaching-decollement in the northern section,thrusting-compresso-shearing-fault-propagation-decollement in the middle section and thrusting-fault-bending-fault-propagation-decollement in the southern section,respectively.