THE INFLUENCE AND CONTROL OF THE BASEMENT AND PERIPHERY OF FAULT BASIN TO THE STRUCTURE AND DEPOSITION OF BASIN MARGIN:A case study of Yitong graben

The basement of Yitong graben is composed of granite and stratified sedimentary series.The boundary faults in the southeastern margin of the graben are obviously affected by the basement lithology.In the granite area,high angle extensional faults are developed.While in the sedimentary rock area,listric faults are developed.The style of boundary faults in the northwestern margin is rarely affected by the basement lithology.The assemblage,size and distribution of sedimentary facies in the basin margin are mostly influenced and controlled by different basement lithology.In the area with granite basement,the depositional system of northwestern margin consists of deep lake facies and a special subaqueous fan—waterfall fan—facies.While the depositional system of southeastern margin is mainly small fan-delta and shore-shallow lacustrine facies.In the area with stratified rock basement,the sedimentary system is mainly composed of braided delta and shore-shallow lacustrine facies.