青东凹陷断裂特征及其对沉积的控制作用

通过对青东凹陷古近纪的断裂体系和主要同沉积断裂的活动和特征分析,表明区内主要发育NNE、EW、NW向三组断裂体系,NNE向的凹陷边界断裂青东1号断层和EW向的主要二级同沉积断层f1、f2控制了凹陷内次级构造单元的划分,凹陷由北向南依次划分为北部深洼、北部凸起、中部次洼、南部凸起、南部次洼、西南缘缓坡带以及东部陡坡带等7个次级构造单元。研究表明,凹陷内各洼陷的沉降中心在古近纪发生了明显的分异和迁移,这些变化受控于区内主要同沉积断裂的差异活动和演化,青东1号断裂和f3断裂在古近纪的持续活动共同控制了北部深洼的沉积充填,f1和f4断裂分别控制了中部次洼和南部次洼的发育;主要断裂的活动及其组合样式控制着湖底扇、扇三角洲、辫状河三角洲等粗碎屑沉积体系的发育。与生油洼陷相邻的主要同沉积断裂形成的断裂带具备形成砂岩油气藏的各种有利条件,其中东部盆缘断裂带是区内砂岩油气藏勘探最有利的区带。

Characteristics of Faults and Its Control on Sedimentation in Qingdong Depression

Through studying the distribution and characteristics of Paleogene fault systems and main syndepositional faults in Qingdong Depression,faults developed in Qingdong area can be divided into three different types according to their strikes: NNE,EW,and NW.Fault 1 of qingdong in NNE direction and fault f1,f2 in EW direction controlled the division of secondary tectonic units.Qingdong depression can be divided into northern sub-depression,northern bulge,middle sub-depression,southern bulge,southern sub-depression,south-western gentle slope and the eastern actic region from north to south.Studies indicates that subsidence centers of different depressions experienced obviously migration in Paleogene,which was controlled by the differential activity and evolution of main syndepositional faults.Continuing activity of f1 and f3 controlled the depositional filling of the northern deep depression,f1 and f4 controlled development of middle sub-depression and southern sub-depression respectively.Activity and assemble style of main faults controlled the development of coarse-clastic depositional systems,such as sublacustrine fan,fan delta and braided delta.Fault zone formed by syndepositional faults adjacent to oil generating depression have favorable conditions for formation of sandstone reservoirs,and the eastern basin marginal fault zone was the most favorable zone.