166 / 2022-02-27 22:14:12

大焦石坝地区差异构造变形

大焦石坝地区；差异构造变形；前展式结构；褶皱带

摘  要：大焦石坝地区位于四川盆地东南缘褶皱构造带，针对其东西向差异构造变形特征及成因机制，对构造区的地质资料、地震资料、钻井资料进行精细解释，结果表明了大焦石坝地区冲断-断滑（断展）-滑脱变形前展式结构，前展式结构横向上为由隔槽式褶皱向隔档式褶皱过渡的箱状褶皱过渡带，垂向上为前寒武系区域滑脱层向寒武系区域滑脱层传递的逆冲前锋带；以乌江断层为界南北分区，乌江断层以北变形方式为冲断-隐冲、断滑-滑脱，乌江断层以南为冲断-断展-滑脱；东西向以石门2号断层与吊水岩—梓里场断层分带，大焦石坝地区燕山期以来受到南东-北西向、近东西向和北东-南西向3期挤压应力作用，东西向发生前展式递进变形，导致石门2号断层以东表现冲断作用、石门2号断层与吊水岩—梓里场断层之间北部表现断滑、南部表现断展，吊水岩-梓里场断层以西表现滑脱作用。

关键词: 大焦石坝地区；差异构造变形；前展式结构；褶皱带

 



Abstract: The Dajiaoshiba area is located in the fold belt in the south-eastern margin of Sichuan Basin. The geological information, seismic data and drilling data of the structural area are carefully explained to research the differential structural deformation and the mechanism for the formation from east to west in the Dajiaoshiba area and the results show the piggy-back structure of thrust—fault-detaching (fault-propagation)—decollement. Laterally, there is a box fold transition zone from trough-like folds to ejective folds in lateral direction and a front belt of the thrust structure from the pre-Cambrian detachment to the Cambrian detachment in vertical direction. Taking Wujiang fault as the boundary, the deformation pattern of the north to Wujiang fault is thrust—hidden-thrust-fault-detaching—detaching, and the south is thrust—fault-propagation—decollement. ShimenⅡ fault and Diaoshuiyan-Zilichang fault are zonated from east to west. Studied area has undergone SE-NW-trending, nearly WE-trending and NE-SW-trending compressive stress since the Yanshan Movement and gone through the piggy-back progressive deformation from east to west. As a result, there is thrusting in the east of ShimenⅡ fault, detaching in the west of Dangshuiyan-Zilichang fault, fault-detaching to the north between ShimenⅡ fault and Diaoshuiyan-Zilichang fault presents and fault-propagation to the south.

Key words:  Dajiaoshiba area, differential structural deformation, piggy-back deformation, fold belt