海安凹陷上白垩统—新生界断裂形成及演化

The fracture formation and its evolution from Upper Cretaceous to Cenozoic in Haian Depression

根据近年来在海安凹陷获得的地震资料,对上白垩统—新生界内部断裂特征进行了研究。海安凹陷断层展布为北东向、北东东向和北西西或近东西向。主断层不同段走向不同,深浅层结构不同,控制凹陷结构;次级断层多受主断层控制,其形成和走向受主断层影响。断层活动表现出旋回性特点,控制着盆地结构的旋回性演化。断层展布反映泰州组—阜宁组沉积期间断层为北西—南东向的伸展作用,同时又表现出受右旋扭动的影响;三垛组沉积早期为伸展性断层发育时期,伸展方向为北西—南东向;三垛组沉积晚期,受近东西向挤压,一些断层表现出走滑特点;新近纪早期,断裂继承性活动,晚期主要沿主断裂活动。这种构造应力场的变化与板块运动的改变有关。

Base on the seismic data acquired in recent years in Haian Depression,the internal fracture characteristics from the Upper Cretaceous to Cenozoic have been studied. The facture extending direction of the Haian Depression is NE,NEE and NWW or approximately EW. The main fault has different strike in different segments,the structures are different in the deep and the shallow,and the main fault controls the depression structure,the secondary faults are generally controlled by main fault,and their formation and strike are affected by main fault as well. The fault activities show cycle feature,they control cycle evolution of the basin structure. The fault distribution reflects its NW-SE extension during Taizhou-Funing formation Sedimentation and meanwhile the distribution is shown affected by dextral twist,the early sediment period for the Sanduo formation was extending fault development period,its extending direction is NW-SE,in Sanduo sediment late period,due to compression from approximately EW some faults show strike-slip feature. In early Cenozoic the faults acted succeedingly,in late Cenozoic the faults acted along the main fault. The change in tectonic stress field is related to the change of plate movement.