济阳坳陷青东凹陷构造格局及构造演化

Structural framework and evolution of Qingdong sag,Bohai Bay Basin

青东凹陷构造特征复杂,构造格局及构造演化过程不清,严重制约了该区石油地质条件研究的深入。综合钻井、地震资料对青东凹陷的边界类型及构造格局进行了分析,利用平衡剖面技术对其构造演化特征进行了研究。明确了青东凹陷是在郯庐断裂带控制下形成的新生代走滑拉分断陷盆地,具有"三断一超"的边界特征;凹陷内部断裂构造具有强烈的走滑特征,雁列式、花状构造发育;构造格局表现为南北向垒堑相间、东西向东断西超的箕状特征;凹陷新生代的构造演化经历初始裂陷、强烈断陷、继承发展、抬升剥蚀和整体拗陷5个阶段,其中强烈断陷阶段是青东凹陷的构造定型期,控制了凹陷的构造格局。

Qingdong sag,a sub-structural unit of Bohai Bay Basin,which is located adjacent to the west of Tan-Lu Fault,has highly complex structural characteristics due to its unique structural location.Without sufficient understanding of its structural characteristics and tectonic evolution,the analysis about its petroleum geological conditions can not meet the requirements of pe-troleum exploration.Applying all the wells and seismic data to analyze the boundary type and the structural framework and bal-anced section method for the study of tectonic evolution of Qingdong sag,thereafter,several new conclusions are proposed as fol-lows.Qingdong sag is a Cenozoic strike-slip and extensional rhombochasm with three fault boundary and one overlapped slop con-trolled by the Tan-Lu Fault＇s strike-slip motion;Qingdong sag has the internal structural frame of horst-graben interval change pattern in the SN direction and dustpan pattern in EW direction with Tan-Lu Fault boundary in east and slope boundary in west;it has lots of strike-slip structures,such as echelon and flower-like structures;the tectonic evolution of the Qingdong Cenozoic sag can be divided into five stages：the original rift phase,the graben fault basin stage,the inheritance and development stage,the up-lifting and denudation stage,and the Neogene-Quaternary depression basin stage.The framework of the sag is formed and main-tained during the graben fault basin stage.