苏北盆地海安凹陷现今构造应力场特征及构造样式

通过对苏北盆地海安凹陷T₄0反射层现今构造应力场、次级凹陷边界二级断裂和次级凹陷内三、四级断裂力学性质及其构造活动样式等分析研究认为:海安凹陷现今最大主应力方向为NE 70°左右；现今最大主应力为50 MPa左右，现今最小主应力为30 MPa左右。海安凹陷内次级凹陷边界二级断裂现今主要表现为张性或张扭性活动特征，张扭性活动方式既有顺扭也有反扭，并且同一断裂不同部位活动性质存在差异；海安凹陷内次级凹陷三、四级断裂现今也主要表现为张性或张扭性活动特征，张扭性活动方式既有顺扭也有反扭，个别表现为压性和压扭性活动，并且同一断裂不同部位活动性质存在差异。 

FEATURES OF PRESENT STRUCTURAL STRESS FIELD AND STRUCTURAL PATTERN IN HAIAN DEPRESSION,JIANGSU OILFIELD

In this paper,the present structural stress field of T40 reflection layer,the mechanic characteristics and structural active patterns of the second-level fault at the boundary of sub-depression and the third-and forth-level faults within sub-depression in Haian depression were analyzed.The direction of the present maximum principal stress is about NE 70°.The present maximum principal stress is about 50 MPa and the present minimum principal stress is about 30 MPa.By the present structural stress field finite element numerical modeling,we found that the second-level faults at the boundary of sub-depression are characteristic of tensile activity or tensile-shear activity which is in both clockwise and counter-clockwise,and that the activity features vary along the different part of a fault.The third-and forth-level faults within sub-depression have the same activity features as the second-level faults.In addition,some third-and forth-level faults also have compressive or compressive-shearing activity features.