南海构造格局及其演化

On tectonic framework and evolution of the South China Sea

依据重磁资料在南海及其邻区识别出17条深大断裂和10个重磁异常区.据此并结合其他地质资料,在南海及其邻区划分出7个地质结构不同的构造单元.早白垩世南海地区曾形成过统一的基底,新生代时统一的南海基底发生肢解,这一个肢解过程经历了两个在时空上接踵发生、交叠作用的构造事件.第一个构造事件为巽他地块与华夏古陆之间古南海的萎缩、闭合和地块碰撞;第二个构造事件为南沙地块裂离华夏古陆并向巽他地块增生,且伴随新南海的持续扩张,直至中中新世.区域构造演化控制了南海沉积盆地呈"北三南三、东西两竖"格局分布,进而控制了油气富集区的分布.

Based on gravity-magnetic data,17 deep major faults as well as 10 gravity-magnetic anomaly area have been identified in the South China Sea(SCS)and its adjacent area.Combined these results with other geological material,7 tectonic units which have different geological structures can be divided in the SCS and its adjacent area.A uniform basement once formed in the Early Cretaceous in the SCS,and broke up during the Cenozoic.This breakup process experienced two tectonic events which happened one after another in spatial and overlapped.The first one was the shrinking,closing of the pro-SCS as well as collisions of blocks which located between the Sunda block and the Cathaysia archicontinent.The other one was the Nansha block broken up from the Cathaysia archicontinent,accreted to the Sunda block and associated with the continous expansion of the new SCS until to the Middle Miocene.Regional tectonic evolution had controlled the distribution of sedimentary basins in the SCS,forming“three basin belts in North continential margin,three basin belts in South continential margin,and one basin belt in East continential margin and one basin belt in West continential margin”,which further controlled distributions of oil and gas enrichment area.