南海南部海域新生代万安运动的构造意义及其油气资源效应

TECTONIC SIGNIFICANCE AND ITS PETROLEUM EFFECT OF THE WAN'AN TECTONIC MOVEMENT IN THE SOUTH OF THE SOUTH CHINA SEA

南海南部海域在中中新世末发生了一次区域构造运动,被命名为万安构造运动。这次构造运动在新生代沉积中的表现是断裂、块断、挤压背斜和向斜,部分地区发育逆冲构造等。根据南海区域构造分析,产生这次构造运动的起因可能与菲律宾海板块和欧亚板块于13MaBP在民都洛岛处发生碰撞,以及澳大利亚板块和欧亚板块在苏拉威西岛处发生碰撞(10MaBP)有关。这两次碰撞事件均对南海南部海域产生挤压,尤其是第一次碰撞挤压(向西方向)很强烈,是这次构造事件的主导因素。万安构造运动在南海南部海域沉积盆地中产生了许多挤压构造;而该海域沉积盆地中生烃的关键时刻是6MaBP,构造形成时间在生烃关键时间之前,因此,该海域形成了极其丰富的油气资源。

There was a regional tectonic movement in the end of middle Miocene in the south of the South China Sea,which was named the Wan'an movement. The Wan'an movement showed faulting, block faulting, compressional anticline and syncline as well as thrusting structures in some areas.The movement resulted from collision between the Philippine Sea plate and Eurasian plate in the Mindoro Island during 13 MaBP, and from collision between the Australian plate and the Eurasian plate in the Sulawesi Island during 10 MaBP. These two collision events compressed the southern area of the South China Sea, especially the first event that gave an intensive westward compression that was the main cause of the Wan'an movement. The Wan'an movement produced a lot of compressional structures in Cenozoic sedimentary basins in the south of the South China Sea. The key period for the hydrocarbon generation in these sedimentary basins was 6 MaBP. The period to form the structures(13~10 MaBP) in these sedimentary basins was earlier than the hydrocarbon generation period and, therefore, there are very rich petroleum resources in the south of the South China Sea.