琼东南盆地古近纪海侵及沉积环境演化  

Marine transgression and evolution of depositional environment in the Paleogene strata of Qiongdongnan Basin,South China Sea

作　　者：蔡国富[1] 邵磊[1] 乔培军[1] 梁建设 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]中海油研究总院,北京100027

出　　处：《石油学报》2013年第S02期91-101,共11页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.91128207);国家重大科技专项(2011ZX05025-006);国家重点基础研究发展计划(973)项目(2009CB219400)资助

摘　　要：综合应用地震、测井、钻井岩心、古生物及地球化学资料,对琼东南盆地古近纪的海侵历史与沉积环境演化进行了分析。琼东南盆地古近纪经历了始新世陆相沉积向渐新世海相沉积的转变,盆地北部凹陷带自崖城组三段沉积晚期开始发生明显海侵,从而使得下渐新统崖城组与上渐新统陵水组形成截然不同的沉积格局。崖城组沉积环境为半封闭古海湾,与广海沟通有限,构造沉降控制了区域海平面的升降,持续而较缓慢的海侵使得沉积体系丰富多样,中央凹陷带两侧持续且广泛发育扇三角洲、潮坪和潟湖等海陆过渡相沉积体系;陵水组沉积环境为开阔海,以滨、浅海相为主,在陵水组二段全区海侵明显,全球海平面变化对区域海平面的上升具有较大影响。琼东南盆地是南海海盆西部及北部的大陆边缘盆地中最早发生海侵的盆地之一,南海的初始扩张是盆地发生初始海侵的主要原因。This study investigated records of marine transgression and evolution of depositional environment in the Paleogene strata of Qiongdongnan Basin （QDNB） by analyzing data of seismic reflections, geophysical loggings, drilling cores, fossils, and geochemis- try. Results show that the Paleogene strata of QDNB underwent change from the Eocene non-marine deposits to the Oligocene ma- rine deposits. Significant marine transgression occurred from the late depositional stage of the third member of Yacheng Formation in the northern depression belt of QDNB, leading to formation of completely different sedimentary frameworks of the Lower Oligocene Yacheng Formation and the Upper Oligocene Lingshui Formation. During deposition of Yacheng Formation, QDNB acted as a semi- enclosed palaeo-gulf with restrictive access to the open sea~ tectonic subsidence controlled the regional eustatic fluctuation; together with persistent and slow transgression resulted in the formation of a wide range of depositional systems~ additionally, transitional fa- cies such as fan delta, tidal flat, and lagoon were widely developed in the two flanks of the central depression belt. During the depo- sition of Lingshui Formation, open marine facies were developed in QDNB and the sedimentary environment was dominated by lit- toral and neritic facies; the second member of Lingshui Formation witnessed a significant transgression, and the global eustatic fluctuation imposed a strong influence on the regional sea-level rise. QDNB is among the earliest basins associated with marine transgression in the western marine basin and northern continental margin basin of South China Sea. The main cause of marine transgression in QDNB is the initial expansion of South China Sea.

关 键 词：琼东南盆地 南海 古近纪 海侵 沉积环境 

分 类 号：TE111.3[石油与天然气工程—油气勘探]