【作者】 吴敬武；

【导师】 陈汉林； 吕福亮；

【作者基本信息】 浙江大学 ， 构造地质学， 2008， 硕士

【摘要】 南海是西太平洋最大的边缘海之一,因其特殊的构造位置及丰富的油气资源而成为世界各国学者研究的热点。琼东南盆地处在南海北部陆缘的西北部,西部以1号断裂与莺歌海盆地相隔,东北连接珠江口盆地。其大地构造位置特殊,构造形成演化同时受到了太平洋构造域和特提斯构造域的影响,形成机制十分复杂。琼东南盆地南部凹陷受资料限制至今研究较少,是勘探和研究的薄弱区。研究该地区的构造特征和形成演化机制对认识整个南海北部的形成机制有着十分重要的意义,同时可以给我国对南海的油气勘探提供参考,加快我国在南海深水区油气勘探。本文在整理、吸收前人的研究成果基础上,综合分析解释中石油在琼东南盆地南部凹陷新采集的二维地震资料,运用地震地层学等原理划分了南部凹陷的主要构造层序,认为凹陷以T60为界划分为上下两个构造层序。在精细解释的基础上,对南部凹陷的断裂特征进行了系统的研究,发现凹陷构造走向被北北东向的控凹断裂所控制,并可以把凹陷进一步划分为西部高垒带和中部断阶带两个次级构造单元。通过对断裂的期次分析认为凹陷的断裂系统是由始新世断裂发育期、早渐新世末断裂发育期和中中新世末断裂发育期发育的断裂先后叠加而成,并对前两期的断裂平面特征进行了总结和分析,发现始新世发育断裂以北北东、北东向为主要走向,而早渐新世末发育断裂则以近东西向占优。通过对凹陷内发育的主要构造样式分析,认为凹陷在主要断裂发育时期处在区域拉张的应力环境之下。通过制作D—D′和E—E′剖面的构造演化史图,结合区域构造运动,分析了凹陷的构造演化史。对比南海北部主要新生代断陷盆地的构造特征和红河断裂的活动特征,讨论了琼东南盆地的构造形成机制,认为琼东南盆地南部凹陷的构造形成和南海北部有共同的成因机制。更多还原

【Abstract】 South China Sea (SCS), which is one of the largest marginal sea of west Pacific Ocean, is a hot research point in the world for its special location of structure and abundant hydrocarbon resources. Qiongdongnan Basin (QDNB) locates in the northwest part of north SCS, with Yinggehai Basin on the west separated by Fault No.1, and Zhujiangkou Basin on the northeast. Because of its special structural location, structural evolution of Qiongdongnan Basin is both affected by Pacific Structure Domain and Tethys Structure Domain, and formative mechanism of the basin is very complex. The South Depression of QDNB is a weak study and exploration area because of the lack of data in the past. The study of structural characteristics and formative mechanism of the area has a significant meaning for analyzing the formative mechanism of northern SCS, and also can give us some suggestions in petroleum exploration of SCS.On the basis of predecessors’ research, this dissertation interpreted 2D seismic data acquired by CNPC in recent years, and divided the main structure sequences of South Depression based on the sequence stratigraphy. The author realized that T60 is the breakup unconformity and it separates the strata into the upper structural sequence and the lower structural sequence. On the basis of studying the fault characteristics systematically based on the fine sequence interpretation, the author found that the structural direction of the depression was controlled by the NNE trend faults, and the depression could be divided into west uplift area and mid break-step area. By subdividing of fault period the author found that the faults in the area developed in three different periods: Eocene, early Oligocene and mid-Miocene. Then the plan characteristics of faults in Eocene and early Oligocene were summarized ,and realized that faults developed in Eocene have a main trend of NNE and NE, faults developed in early Oligocene have a main trend of EW. By analyzing the main structural styles, concluded that the depression was under the regional extensional environment when major faults developed. Through a sequential restoration of two structural sections (D—D’ and E—E’), combined with the regional structural movements, the structural evolution history of this depression were analyzed. By comparing with the main Cenozoic rift basins, the author analyzed the structural Characteristics and formative mechanism of QDNB and realized that the structural Characteristics of South Depression and northern SCS were both affected by the Red River Strike Fault.更多还原