南海西南部万安盆地构造样式特征、成因及找油意义

万安盆地的地震构造样式主要表现为基底卷入式的潜山构造、张性断块构造,盖层内的挤压背斜构造、骨牌式断裂构造、反转构造、捩断层及勺形构造,其中潜山构造、挤压背斜构造和骨牌式断裂构造是最为有利的油气聚集部位,而张性断块构造、反转构造、捩断层及勺形构造亦是有利的油气富集部位。万安盆地形成演化过程中早期的礼乐运动(TG)造就了现今盆地构造格局的最初雏型；稍后发生的西卫运动(T₅)使早期的陆缘张裂断陷范围进一步扩大,转化为渐新－中中新统的断坳沉积；而最终万安运动(T₃)则导致盆内地层强烈挤压、隆升剥蚀,产生构造反转、断块及褶皱,这是盆内圈闭构造最发育的时期。伴随万安盆地主要的构造运动的发生,盆内形成了基底构造层(Tg或T₅以下)、主体构造层(T₃－T₅)和表层构造层(T₃以上)等3个构造层,各构造层内均发育有不同的构造样式,其中主体构造层内构造圈闭最发育,构造样式最丰富。综合分析认为礼乐运动和西卫运动奠定了盆地沉积格架,而万安运动则对盆内圈闭构造的形成贡献最大。 

THE CHARACTERISTICS OF STRUCTURAL STYLES AND THEIR INFLUENCES ON OIL AND GAS ACCUMULATION OF THE WAN'AN BASIN IN THE SOUTHWESTERN SOUTH CHINA SEA

The paper described the characteristics of main tectonic movements and structural styles in each structural layer in the Wan'an basin in detail.Three tectonic movements including the Cretaceous Lile movement,the Middle Late Eocene Xiwei movement and the Late Miocene Wan'an movement occurred in the basin.The earlier Lile movement resulted in the basin's embryonic tectonics,the later Xiwei movement caused expansion of the continental margin fault depression,and the latest Wan'an movement lead to the former strata folded,block faulting,denuding and structural inversion.Most structural traps were formed in the latest movement.With occurring of main tectonic movement,there are three suites of tectonic layer in the basin,i.e.basement layer(under T₅ or Tg),principal layer(between T₃ and T₅)and superficial layer in which various characteristics structural styles have been developed.In terms of hydrocarbon accumulation,the principal layer is the habitat due to its wide development of structural traps.