琼东南盆地深水区构造格局和幕式演化过程  

Tectonic Framework and Multiple Episode Tectonic Evolution in Deepwater Area of Qiongdongnan Basin,Northern Continental Margin of South China Sea

作　　者：雷超[1,2] 任建业[1,2] 裴健翔 林海涛[1] 尹新义[1] 佟殿君[1] 

机构地区：[1]中国地质大学资源学院,湖北武汉430074 [2]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [3]中海石油有限公司湛江分公司,广东湛江524057

出　　处：《地球科学（中国地质大学学报）》2011年第1期151-162,共12页Earth Science-Journal of China University of Geosciences

基　　金：国家重点基础研究发展规划"973"项目(No.2007CB41170502);国家自然科学基金(No.40672089);博士点基金(No.20070491004);2009年美国石油地质学家学会研究生科研基金(AAPG-In-Grant)

摘　　要：基于大量琼东南盆地深水区高精度的地质-地球物理和钻井资料解释,确立了该盆地"南北分带,东西分块"的基本构造格局;通过构造-地层、沉降史和沉降中心厘定等方面的综合研究,在琼东南深水盆地中深入描述和分析了T70重要的构造变革界面特征,该界面之下发育了一系列分散的、NE向展布的小型断陷盆地群,该界面之上一直到T60界面发育时期,盆地的沉降中心逐渐迁移到位于琼东南盆地中央坳陷区的、呈NE-WE-NWW弧形展布的大型断坳式盆地内,该断坳盆地与下伏小型断陷盆地群构成显著的叠加关系;以控盆边界断层的性质和几何学分布,确定下伏的NE向展布的小型断陷盆地群受控于NW-SE向拉伸应力场,而上覆的断坳盆地由近SN向拉伸应力作用所形成;区域对比表明该界面广泛分布于南海北部大陆边缘盆地中,具有区域性分布的特征;生物地层和区域对比表明该界面年龄为32Ma,与南海初始扩张的年龄一致.因此,该界面是一个发育于南海北部的、代表了南海扩张开始的一个区域性构造变革界面.该界面的发育导致了琼东南盆地深水区盆地结构和构造演化的复杂性,以该界面为基础,结合盆地充填序列中的其他重要界面和盆地的沉降史分析,将盆地的构造演化划分为断陷、断坳、裂后热沉降和加速沉降4个构造演化幕,从而确定了该盆地具有典型的幕式演化特征;详细讨论了盆地周缘板块运动学重组事件和岩石圈深部活动对琼东南盆地幕式发育过程的控制机制.Based on geological structural interpretation of a number of available high-resolution geological-geophysical and drilling data etc.,a tectonic framework with zonal array in N-S direction and block division in W-E direction was established in deepwater area of Qiongdongnan basin （QDNB）. A key tectonic revolutionary boundary,T70,was identified in QDNB by integrated analysis of tectono-stratigraphy,subsidence history and subsided depocentre migration. A series of small distributed NE-trending faulted basins developed widely below this boundary,while basin depocentre of QDNB above T70 boundary is located in center depression area trending NE-WE-NWW,forming a great fault-sag type basin,which is superimposed clearly over underlying faulted basin group above. Analyses of genetic type and geometry of basin-boundary fault indicate that NW-SE extensional tectonic stress field strongly controlled development of small distributed NE-trending faulted basin group underlying T70 boundary,and nearly SN extensional tectonic stress field resulted in formation of fault-sag basin over this boundary. The T70 boundary can be found and traced in northern continental margin basins of South China Sea. The evidence of regional and biostratigraphical correlation shows that the age of this boundary is 32 Ma,which is consistent with the time of initial spreading of South China Sea. Thus T70 boundary is a regional tectonic revolutionary boundary. The development of this boundary leads to complexity of tectonic framework and structure evolution. According to the T70 boundary,combining with other important boundaries identified in previous literatures in the basin filling sequence and subsidence analysis,four tectonic evolution episodes of QDNB,which are syn-rifted episode,fault-sag episode,post-rifted thermal subsidence episode and post-rifted accelerating subsiding episode,are proposed in this paper. Finally,Cenozoic lithospheric dynamic,kinematical reorganization of plates circum-South China Sea controlling on these tectonic episodes ar

关 键 词：南海 琼东南盆地 构造格局 幕式演化 动力学机制 沉积学 

分 类 号：P618[天文地球—矿床学]