基于磁力资料的珠江口盆地构造单元分布特征

珠江口盆地是南海北部陆坡最大的前新生代沉积盆地,油气资源丰富,由于新的地球物理资料未得以充分应用等问题导致盆地内部构造单元分布特征存在诸多不同看法,这些问题制约了盆地的进一步勘探和开发。本文以最新实测1∶10万高精度航磁数据为基础,采用切线法对研究区航磁异常深度进行反演计算,结合钻井、地震及南海北部陆域物性资料研究珠江口盆地磁性基底分布特征。在充分调研珠江口盆地已有构造单元划分的基础上,以盆地磁性基底展布特征为基础,结合断裂、区域构造等对珠江口盆地内部构造单元进行研究。研究表明:珠江口盆地磁性基底深度在0～9 km之间,磁性基底呈"三隆两坳"构造格局,整个坳陷区具有"南北分带,东西分块"的特征; NE向深大断裂为控盆断裂,常为盆地二级构造单元的边界,NW向断裂常控制次一级构造单元并影响其展布形态。

Distribution characteristics of tectonic units in Pearl River Mouth basin based on magnetic data

The Pearl River Mouth basin is the largest pre-Cenozoic sedimentary basin on the continental slope of the South China Sea. It is rich in oil and gas resources. Due to the lack of new geophysical data, the distribution characteristics of the internal tectonic units in the Pearl River Mouth basin have many different views. This problem has constrained further exploration and development of the basin. This study aims to throw light on the magnetic basement structure of Pearl River Mouth basin based on the latest high resolution aeromagnetic data, combined with drilling data, seismic profiles and basic geological data. Tangent method was used in the inversion. On the basis of fully investigating the existing structural unit division in the Pearl River Mouth basin and in combination with the faults and regional structures, the internal tectonic units were studied. The result shows that the magnetic basement depth of the basin is between 0 and 9 km, and the magnetic basement is characterized by "three uplift and two depressions". The whole depression area has the characteristics of "north-south zoning, east-west sub-block". The NE trending fault is the main fault that controls sedimentary depression, while the NW-trending faults are secondary faults which control depressions.