南海边缘海构造旋回控制深水区烃源岩有序分布

Tectonic cycle of marginal sea controls the ordered distribution of source rocks of deep water areas in South China Sea

南海演化经历了古南海形成与发育、新南海扩张与古南海消减、新南海快速沉降与萎缩等3个阶段,其主要地质事件是古南海与新南海边缘海构造旋回,控制了深水区烃源岩有序分布,使不同盆地类型具有不同的烃源岩特征。研究表明,边缘海构造旋回控制了南海深水区主力烃源岩发育时期和类型。南海北部被动大陆边缘盆地深水区发育3套烃源岩,在古南海消亡构造旋回影响下发育始新世断陷期的湖相烃源岩和早渐新世断拗期的海陆过渡相烃源岩,在新南海构造旋回影响下发育晚渐新世拗陷期的海相烃源岩;南沙地块漂移裂谷盆地受古南海构造旋回控制,发育始新世和渐新世断拗期陆源海相2套烃源岩;南海南部活动大陆边缘挤压盆地主要受新南海扩张影响,发育渐新统和中新统海陆过渡相和陆源海相3套烃源岩。

The evolution of South China Sea（SCS） includes three phases, formation and development of Proto-SCS,expansion of Neo-SCS and subduction of Proto-SCS, subsidence and shrink of Neo-SCS. The tectonic cycle of the marginal sea of Proto-SCS and Neo-SCS are the major geological events,which controls the ordered distribution of source rocks in deep water areas, different basin types have different characteris- tics of source rocks. Studies show that the tectonic cycle of marginal sea controls the forming time and type of major source rocks in deep water areas. There are three sets of source rocks developed in deep water are- as of the northern continental margin in SCS, the tectonic cycle of Proto-SCS influences lacustrine source rocks formed in the rift period of the Eocene and transitional source rocks formed in the rift-subsiding peri- od of the early Oligocene,the tectonic cycle of Neo-SCS influences marine facies source rocks formed in the depression period of the late Oligocene. Drifting rift basin of Nansha block, controlled by tectonic cycle of Proto-SCS, develops terrestrial marine source rocks in the Eocene and Oligocene. The southern compressional basin on active continental margin, controlled by tectonic cycle of Neo-SCS, develops transitional source rocks and terrestrial marine source rocks in Oligoeene and Miocene.