珠江口盆地形成机制浅析

THE FORMING MECHANISM OF ZHUJIANGKOU BASIN

金庆焕

Jin Qinghuan

地质部南海地质调查指挥部

Headquarter or Geological Survey of South China Sea

南海北临我国华南大陆,西接印支半岛和马来半岛,东邻菲律宾的吕宋岛和巴拉望岛,南界婆罗洲和勿里洞岛,总面积约350万平方公里。在南海辽阔的陆架及部分陆坡上发育有珠江口、北部湾、琼南及台湾浅滩等含油气盆地,堆积了巨厚的新生代沉积,并已钻获了工业油气流。其中尤以珠江口盆地以它的面积大、沉积厚、时代新、堆积速度快、生油层组多、油质好而引起了国内外的普遍关注和重视,具备了良好的含油气远景。

Zhoujiangkou basin was developed at the passive continental margin of South China.After the Middle and Late Eocene tectonic event, the basin underwent three evolution stages, i.e. fault down (rifting), warp down (subsidence) and depression. The basin has a tectonic pattern of south-north zonation(NEE trend) and east-west zonation (NE trend).The NE trending structure is formed under the tectonic regime of the early stage.While the NEE trending structure can be related to the north-south extention of South China Sea basin taking place about 32-17 million years ago. The intereaction of the two tectonic regimes created the inharmony between the NE trending structure on the land and the NEE trending structure of the sea area. The Zhujiangkou basin shows that the NEE newly formed structure superimposed on the NE trending inherited structure. The compression occurring in the lower part of the crust caused the extension of the upper part, and made the Zhoujiangkou a great basin. The Moho raised obviously, and a "converted image" is formed with convex at the bottom and hollow at the top. The characteristics of the local structures within the basin depended on the intensity of the movements and their time spans. Zhoujiangkou basin not only possesses some favourable conditions such as large area,thick sediments,and well developed local structure, but also has a rather high geothermal gradient and a rather low intensity in tectonic movement,favouring oil generation and accumulation. Therefore, Zhonjiangkou basin has a bright prospect in oil finding.

https://doi.org/10.11781/sysydz198104257