徐家围子断陷深层挤压构造样式及成因分析

以J D Lowell的构造样式分类方案为基础,对研究区三维地震资料进行了精细解释,指出该区主要发育5种挤压构造样式：断弯褶皱构造、断展褶皱构造、挤压背斜构造、断背斜构造、正反转构造。研究认为,沙河子组末期的西太平洋板块斜向俯冲导致郯庐断裂带大规模左旋走滑及营城组时期西太平洋正向俯冲与地幔上涌,是徐家围子断陷挤压构造样式形成的主要原因。同时,营城组沉积时期的火山活动,也是形成局部挤压的应力场的另一个重要原因。

Deep compressional structure styles and genesis analysis in Xujiaweizi fault depression

Based on J D Lowell′s classification scheme about structure style,the precise interpretation of three-dimensional seismic data is conducted in this study area.Five kinds of compressional structures are developed in Xujiaweizi fault depression,including fault-bend fold,fault-propagation fold,compression anticline,faulted anticline and positive inversion structure.The study shows that the extensive sinistral strike-slip of Tanlu fault zone and the forward direction underthrust and mantle upwelling of western Pacific plate at Yingcheng Formation period,caused by the declinate underthrust of western Pacific plate at the last stage of Shahezi Formation,are main forming reasons of compressional structure style in Xujiaweizi fault depression.Meanwhile,the volcanic activity during the sedimentation of Yingcheng Formation is also an important reason of stress field formation of regional compressional structure in this area.