南海南部北康盆地构造样式及构造演化

Structural Styles and Evolution of Beikang Basin,Southern South China Sea

南海南部是我国油气资源调查的前沿,开展南海南部北康盆地构造样式及其形成演化研究对于明确盆地油气远景区带及南部诸盆地构造演化历史具有重要的借鉴意义。利用2D地震资料,在精细构造‒地层解释基础上,厘定了北康盆地主要的构造样式;采用平衡剖面技术,对北康盆地的伸展率和伸展量进行定量恢复,重建盆地的构造演化史。结果表明,北康盆地共发育5类主要的构造样式,分别为伸展、反转、挤压、走滑‒伸展和底辟构造样式,其中走滑‒伸展构造、挤压构造和反转构造为油气最有利富集部位。盆地的形成演化总体上经历了三期六幕,即裂陷期(初始裂陷幕、裂陷鼎盛幕)、断坳转换期(断坳转换1幕、断坳转换2幕)和拗陷期(拗陷1幕、拗陷2幕)。

The southern South China Sea(SCS)is the forefront of petroleum investigation in China,and therefore,it is of great significance to define the tectonic evolution history of the basins and reveal petroleum prospect zones in this area.Based on the 2D seismic data and regional geological research results,we analyzed the main structural styles,quantitatively estimated the extensional rate and extensional quantity,and thus,reconstructs the structural evolution history of the Beikang Basin in the southern SCS.The results show that there are 5 main structural styles developed in the Beikang Basin,which are extensional structure,reverse structure,compressional structure,strike slip structure,igneous structure,mud diaper,and drape structure.The local structures are greatly affected by the fault activity,which resulted in the regional and genetic differences.The compressional structure and reverse structure are favorable settings for oil and gas accumulation.The formation and evolution of the Beikang Basin experienced three periods,which can be further divided into six episodes,i.e.,syn-rift period(initial rifting episode,peak rifting episode),rifting-depression transition period(episode 1,episode 2)and depression period(episode 1,episode 2).