【摘要】 通过对盆地地震剖面构造-地层的详细解释,在莺歌海盆地和琼东南盆地(简称莺-琼盆地)古近纪同裂陷充填序列中识别出一条区域性的构造变革界而T70,该界面在地震剖面上表现为显著的下削上超的地震反射结构特征,发育的时代为32～30 Ma,与南海海底扩张起始和红河断裂带左旋走滑的时间一致;T70界面将莺-琼盆地的同裂陷期地层分隔为断陷层和断坳层(琼东南盆地)或坳陷层(莺歌海盆地)两个构造-地层单元,这些构造地层单元和构造变革界面是南海及其周缘区域板块构造重组事件在莺-琼盆地的响应.论文结合前人成果,论述了以红河—越东—Lupar线断层为界,可以将南海及其周缘地区划分为结构构造、演化特征和动力学背景有显著区别的两个构造变形区:挤出-逃逸构造区和古南海俯冲拖曳构造区.以此构造变形分区为基础,确定了莺-琼盆地的动力学机制,建立了其构造演化模式.本研究有助于从整体上理解南海周缘盆地的发育演化过程及主要控制机制,并对大陆边缘动力学研究和陆缘盆地区的油气勘探有重要意义.更多还原

【Abstract】 The Yinggehai and Qiongdongnan basins together form one of the largest Cenozoic sedimentary basins in SE Asia.Here we present a prominent regional tectonic revolution boundary T70 in the Paleogene filling sequence based on structure-stratigraphic analysis of regional seismic profiles in the basins.The T70 boundary,characterized by distinct truncation and onlap seismic reflections,were dated at 32～30 Ma consistent with the onset and spreading of South China Sea oceanic ridge.This boundary separated two tectonic-stratigraphic units in the Paleogene sediments,i.e.,the lower faulting-controlled subsidence layer in Yinggehai and Qiongdongnan basins,and the upper faulting-sag layer in Qiongdongnan basin and the sag layer in Yinggehai basin.The tectonic-stratigraphic units and tectonic revolution boundaries in Yinggehai and Qiongdongnan basins were originally responses to reorganization of plates in SE Asia.This study in Yinggehai and Qiongdongnan basins confirmed that South China Sea and its adjacent areas can be divided into collision-extrusion tectonic province and proto-SCS slab pull tectonic province,which was mostly suggested by works on southern South China Sea.In this paper we clarify distinct structure features,different evolution history and dynamic settings of the two tectonic provinces.They are bounded by a transform boundary of Red River fault extended south along the Vietnamese margin and joined with the trench along the Lupar Line.Considering the dynamic deformational division in this paper,the dynamic mechanisms and their evolution models for Yinggehai and Qiongdongnan basins have been clearly determined.Our research will improve our understanding on the development and evolution of South China Sea and its peripheral area,and has a great significance for geodynamics of the continental margins and petroleum exploration in the South China Sea.更多还原