四川盆地的磁场特征及地质意义

Magnetic field characteristics and geological significance of Sichuan basin

根据航磁测量资料,对四川盆地的磁场特征进行了分析,确定了盆地的边界及范围,并在编制四川盆地变质基底深度图、构造区划图的基础上,对盆地的基底结构、性质及其深度变化特点以及构造格局、盖层厚度等方面进行了研究。研究表明四川盆地基底由前震旦系变质岩系组成,埋深可达5~12 km,盖层为震旦纪一古生代和中新生代地层;盆地的发生和发展主要受NE向和近EW向构造制约,呈"四坳三隆"的构造格局。这些认识和结论,为今后在该盆地进行油气勘探提供了参考依据。

According to aeromagnetic and gravitational data,the boundary and scope of Sichuan basin were determined based on the analyses of the characteristics of gravity and magnetic fields.And on the basis of compiling depth map of the metamorphic basement and structuring zoning map,the research has been conducted on the basin＇s basement structure,characteristics and features of depth change,structure framework,and caprock thickness.The research indicates that the metamorphic basement is composed of Proterozoic metamorphic series,and the buried depth of crystalline basement can reach to 5 000 to 20 000 meters.The caprock is the layers of Ediacaran,Paleozoic,and Mesozoic.The occurrence and development of the basin are restricted by near-northeast and northwest-west construction,which has a pattern of four depression and three uplifts.All these new cognitions and conclusions provide a reference for further oil and gas exploration in the basin.