摘要
中生代末期以来,中国南海区域经历古南海裂开—萎缩、新南海裂开—萎缩两大边缘海旋回,形成了南海北部大陆边缘、新南海洋盆、南沙地块、古南海残余洋盆、古南海南部大陆边缘、南海西部大陆边缘和南海东部大陆边缘等构造单元。由于古、新南海洋盆位置的不同,古南海裂开形成的构造格局在后期受到不同的截切、改造,并且形成新的构造格局。两大旋回构造叠加控制了不同单元的性质及其上叠盆地的类型与油气地质条件。南海北部大陆边缘在两大旋回中均表现为被动大陆边缘特征,但早期旋回的大陆边缘规模大(包括新南海旋回被裂离出去的南沙地块),现今残余的早期旋回仅是其陆内陆相裂谷部分,与晚期旋回陆缘海陆过渡—海相裂谷区叠加,形成拉张盆地。早期烃源岩以中—深湖相地层为主,晚期烃源岩为海陆过渡相三角洲和海相泥岩;早期旋回烃源岩近岸分布,晚期旋回烃源岩远岸分布;早期主要呈陆生陆储或陆生海储,晚期则呈海生海储。南沙地块早期为古南海北部边缘裂陷盆地,发育海相烃源岩;中期向南飘移数千公里,夹持于古、新洋盆之间,沉积欠补偿;晚期被挤压改造,盆地沉积以早期旋回为主,呈现海生海储。古南海南部大陆边缘在早期为被动大陆边缘,晚期被改造成活动大陆边缘;早期的伸展盆地上叠挤压盆地,早期旋回地层被深埋处于变质状态,晚期旋回地层以大型三角洲群和海相泥岩为主,油气兼生,海生海储。南海西部大陆边缘早期为陆内环境,晚期被改造成转换型大陆边缘,张扭盆地发育,早期发育局限的陆相地层,晚期以海陆过渡三角洲相地层为主,该区域热流值高,以生气为主,发育底辟、潜山、生物礁等油气藏。南海东部大陆边缘正在俯冲,发育增生楔盆地。两期旋回不同的叠加关系,导致不同区域油气潜力差异巨大。古南海南�
Since Late Mesozoic, the united South China Sea region has experienced at least two tectonic cycles of marginal seas, i.e. the cleav- age to convergence of the paleao-south China Sea, and the cleavage to convergence of the neo-south China Sea, which formed a couple of structural units, such as the northern continental margin of the South China Sea, the oceanic basin of the neo-South China Sea, the Nansha block, the residual oceanic basin of the palaeo-South China Sea, the northern continental margin of Borneo, and the western and eastern con- tinental margins of the South China Sea. The tectoic framework developed in the cleavage of the palaeo-South China Sea was afterwards trun- cated and reworked to form a new tectoic framework because of the difference in locations of the palaeo-South China Sea and the neo-South China Sea. The superimposition of these two cycles controls properties of these different units, types of overlying basins and geological condi- tions of hydrocarbons. The northern continental margin of the South China Sea was of a passive continental margin in both the cycles though its scale （including the Nansha block parting away during the second cycle） was larger in the first cycle than the present residual part of the first cycle, which, only as an intracontinental rift part, was superimposed by the transitional marine rift developed in the late cycle to form tensional basins. Source rocks of the early cycle dominated by semi-deep lake strata, are distributed offshore and mainly generate oil that ac- cumulate in nonmarine or marine facies, while those of the late cycle, composed of mainly transitional deltaic deposits and marine mudstones, are distributed infralittorally and generate oil that are reservoired in marine facies. The Nansha block used to be a rift basin that developed marine source rocks and was located at the northern continental margin of the South China Sea in the early cycle, afterwards it drifted south-ward for thousand kiometers and lay between the palaeo- and neo-oceanic
出处
《石油学报》
EI
CAS
CSCD
北大核心
2013年第4期611-627,共17页
Acta Petrolei Sinica
基金
国家重点基础研究发展计划(973)项目"南海深水盆地油气资源形成与分布"(2009CB219400)
国家重大科技专项"海洋深水区油气勘探关键技术"(2008ZX05025
2011ZX05025)
国土资源部全国油气资源战略选区调查与评价项目(XQ-2004-05
XQ-2007-05)资助
关键词
大陆边缘
盆地类型
地质条件
构造格局
边缘海旋回
烃源岩
南海
continental margin
basin type
geological condition
tectoic framework
cycle of marginal sea
hydrocarbon resource
South China Sea
