从航空重力看郯庐断裂系(渤海)及其围区构造几何学特征

本文以我国首次试验的渤海西、南部海陆结合带航空重力测量资料为依据, 探讨了郯庐断裂在渤海西、南部海域的空间展布及其围区的构造几何学特征。研究表明, (1)渤海南部和西部两个明显的NNE向 重力异常梯级带属于区域不同重力场的分界线, 分别是郯庐断裂带东支断裂(主干断裂)和西支断裂的反映; (2)郯庐主断裂东侧主要发育NE-NNE向重力异常梯级带, 西侧呈现NW向、NE-NNE向、近EW向重力异常梯级带相互交错的面貌, 反映了东、西两侧不同的断裂构造格局; (3)重力异常小区与异常梯级带的不同组合, 反映了拉张、压缩、扭动三类构造样式; (4)不同的重力异常区、亚区、小区, 反映了不同的沉积构造特征, 分别对应不同的构造单元。

Tectonic Geometry of Tan-lu Faults in the Bohai Sea and Its Adjacent Areas Viewed from Airborne Gravity

Based on the airborne gravimetric data obtained from the first test in China, the authors studied the tectonic geometry of the Tanlu faults in the onshore-offshore transitional area of the western and southern part of the Bohai Sea and its adjacent areas. As a result, some conclusions have been reached: (1)the two obvious NNE-trending gravity anomaly gradient belts in the southern and western parts of the Bohai Sea are the dividing lines of different regional gravity fields, which respectively correspond to the east Tanlu fault(dominant fault)and the west Tanlu fault; (2)there are mainly the NE-NNE striking gravity anomaly gradient belts on the east side of the Tanlu fault, and the intercrossed NW, NE-NNE and near EW-striking gravity anomaly gradient belts on the west side of the Tanlu fault, which show different structural frameworks on the east side and the west side; (3)different assemblages of gravity anomaly blocks and gradient belts reflect three types of structural styles, namely, stretching, compression and torsion; (4)different gravity anomaly areas, subareas and blocks reflect different sedimentary-structural characteristics, which correspond to different structural units.