南海盆地演化对生物礁的控制及礁油气藏勘探潜力分析  

Constraints on biogenetic reef formation during evolution of the South China Sea and exploration potential analysis

作　　者：魏喜[1] 邓晋福[1] 谢文彦[2] 祝永军[2] 赵国春[1] 李玉喜[3] 陈亦寒[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国石油天然气集团公司辽河油田分公司,辽宁盘锦124010 [3]国土资源部油气资源战略研究中心,北京100034

出　　处：《地学前缘》2005年第3期245-252,共8页Earth Science Frontiers

基　　金：国家自然科学基金资助项目(40234048);科学技术部资助项目(2001cb711002)

摘　　要：南海盆地经历了断陷、坳陷和区域热沉降等演化过程。古新世—早渐新世,包括南沙地块在内的古南海北部陆缘的岩石圈伸展作用导致断陷湖盆的形成,局部遭受海侵。该期仅在古南海北部陆架和陆坡地区具备形成生物礁的条件。晚渐新世—中中新世,由于洋壳扩张南海盆地形成,南沙地块漂移到现今位置。随着海水大面积入侵,早期形成的断阶高部位成为水下隆起,岩石圈伸展引起的地幔岩浆喷发,形成水下火山高地,为生物礁的形成创造了地形地貌条件。在物源供给不足的地区,出现适于生物礁发育的温暖、透光、洁净、具有正常盐度的浅水环境,生物礁繁盛。从南海盆地演化和生储盖等地层层系形成时间上看,生物礁具有有利的生储盖配置关系和油气运聚条件。晚中新世-全新世区域热沉降形成全区统一的区域盖层,南海生物礁油气藏得以保存。上述情况决定了南海盆地生物礁具有很大的油气勘探潜力。The evolution of the South China Sea includes three stages which control the formation and distribution of biogenetic reefs. First, from the Paleocene to the early-Oligocene, lithosphere extension at the northern margin （including Nansha block） of Proto-South China Sea induced the formation of continental rift basins and local transgression. Biogenetic reefs were mainly distributed along the north continental shelf and slope of the Proto-South China Sea. Second, from late-Oligocene to mid-Miocene, oceanic spreading of the South China Sea caused the Nansha block to move to its present location. Along with seawater flooding in, the higher fault blocks formed early turned into shallows; mantle related magmatism caused by lithosphere extension formed submarine volcanic highlands, which created landform environments for biogenetic reef formation. In the areas distant from sediment provenance, the shallow, warm seawater environment, with its characteristics of sediment-free, light transparent, and having normal salinity, caused biogenetic reef blooming. Third, the unified South China Sea Basin formed after late-Miocene due to regional thermal cooling and subsidence. Biogenetic reefs shrink from lower parts to higher parts of shallows and regional cap rocks formed. The evolution of the South China Sea and the times of source rock, reservoir rock, and cap rock formation show that biogenetic reef reservoirs have good matching relationships to source and cap rocks, and are advantageous for oil and gas migration and reservoir storage. Biogenetic reef oil and gas reservoirs have been preserved in the South China Sea because little faulting followed after regional cap rocks formation during regional heat subsidence from the lateMiocene to the Holocene. This situation provides a great oil and gas exploration potential of the biogenetic reefs in the South China Sea.

关 键 词：构造演化 生物礁 形成条件 勘探潜力 南海盆地 

分 类 号：P618.130.2[天文地球—矿床学] P737.2[天文地球—地质学]