太仓-奉贤断裂基于遥感、重磁数据的构造特征研究

利用遥感影像数据研究太仓-奉贤断裂地貌特征,通过小波多尺度方法对布格重力数据进行分解,并应用重力、航磁数据分析其深部结构,结合前人人工地震及沉积演化历史资料进一步探讨该断裂与古海岸线的关系.布格重力异常显示,该断裂形成NW向的重力梯度带,由北向南依次控制白茆断凹、甪直断凹和松江断凹的东部边界;重力小波细节图表明,该断裂切穿中上地壳到达下地壳,在下地壳太仓-奉贤断裂仍与太仓-陈家镇断裂、昆山-嘉定断裂、青浦-龙华断裂、松江-嘉善断裂和南汇-平湖断裂相交;航磁场揭示该断裂两侧的地质体存在明显的磁性差异.综合重力、航磁及前人资料可知,太仓-奉贤断裂是江苏地区一条重要的隐伏构造断裂,切穿底部基岩至下地壳,构成全新世中期古海岸线.

The structural characteristics research of Taicang-Fengxian Fracture based on remote sensing, gravity and magnetic data

In this paper, remote sensing image data were used to study the geomorphic feature of Taicang-Fengxian fracture. Meanwhile, wavelet multi-scale analytical method was applied to decomposing Bouguer gravity data, and the deep structure of Taicang-Fengxian fracture was analyzed based on the gravity, aeromagnetic data. And then the relationship between Taicang-Fengxian fracture and the ancient coastline was further explored on the basis of the previous artificial earthquake and sedimentary evolution history data. The Bouguer gravity anomalies figure shows that Taicang-Fengxian fracture forms NW-trending gravity anomalies gradient zone and controls respectively the eastern boundary of Baimao fault depression, Luzhi fault depression and the Songjiang fault depression from north to south. These gravity wavelet detail figures show that the fracture cuts through the upper and middle crust to the lower crust and still intersects Taicang-Fengxian fault, Taicang-Chenjiazhen fracture, Kunshan-Jiading fault, Qingpu-Longhua fault, Songjiang-Jiashan fault and Nanhui-Pinghu fault at the lower crust. The aeromagnetic field reveals the magnetic differences of geological bodies in both sides of the fracture. According to gravity, aeromagnetic and previous data, Taicang-Fengxian fracture is an important buried structure fracture in Jiangsu area, cuts through the bottom of bedrock to the lower crust and formed the mid-Holocene coast line.