中文摘要：

南部断阶带为苏北盆地高邮凹陷边界构造带，由吴堡断阶带和真武断阶带两个部分组成，具有复杂的构造作用过程和构造样式。在南部断阶带几何学特征研究基础上，以应力-应变分析理论为指导，利用平衡剖面法反演所得的伸展率进行横向对比，明确高邮凹陷各时期的优势伸展方位，从而分析南部断阶带的构造作用及其对构造样式的控制。结果表明，高邮凹陷优势伸展方位经历了NW向（K2t^2-E2d），NS向（E2^s）和NW向（Ny-Qd）的变化过程，首次从定量角度深入认识了高邮凹陷晚白垩世以来的构造应力场方向。由于不同时期优势伸展方位与断阶带呈不同角度斜交，吴堡断阶带经历了纯伸展、右行走滑-伸展与纯伸展3期构造作用，形成了平面斜交式和剖面马尾状的简单断层组合样式；真武断阶带经历了左行走滑-伸展、右行走滑-伸展和左行走滑-伸展3期构造作用，形成了平面网格式与剖面复式马尾状的复杂断层组合样式。伸展速率与走滑速率研究表明，断阶带伸展与走滑作用主要发生在阜宁组、戴南组和三垛组，多期次的走滑-伸展作用是南部断阶带构造样式的主要控制因素。

英文摘要：

As the tectonic boundary belt,the south fault terrace,which consists of Wubao fault terrace and Zhenwu fault terrace,has complicated tectonic history and style.Based on the geometrical characteristics of the south fault terrace,guided by the stress-strain theory and extensional rate from the balanced section,we figured out the dominate extensional direction in different periods and analyzed the amount of extension and strike-slip of the south fault terrace,and their control on structural style.The evolution of the dominate extension direction of the Gaoyou sag can be divided into three stages since the late Cretaceous,including NW（K2t^2-E2d）,NS（E2^s）,and NW（Ny-Qd）.Detailed understanding of the direction of stress field in the Gaoyou sag was obtained since the late Cretaceous in a quantitative way for the first time.Because the dominate extensional direction is not always parallel with the axis of fault terrace,Wubao fault terrace experie-nced 3 periods of tectonism,extension,right-lateral slip-extension,and extension.This resulted in the simple faults style with skew traces in plane view and horse tail-like in profiles.Similarly,Zhenwu fault terrace also experienced 3 periods of tectonism,left-lateral slip-extension,right-lateral slip-extension and left-lateral slip-extension,which resulted in the complicated faults style of grid fault trace in plane view and duplex horse tail-like in profiles.The study on the history of extension rate and strike-slip shows that E1f,E2d and E2s were the main periods of extension and strike-slip,which played a key role in the formation of structural style.