基底断层在断陷盆地断层系统发育中的作用——以苏北盆地南部高邮凹陷为例  

Role of Basement Faults in Faulting System Development of A Rift Basin: An Example from the Gaoyou Sag in Southern Subei Basin

作　　者：朱光[1] 姜芹芹[1] 朴学峰[1] 谢成龙[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《地质学报》2013年第4期441-452,共12页Acta Geologica Sinica

基　　金：国家自然科学基金重大研究计划(编号91214301);江苏油田项目共同资助的成果

摘　　要：苏北盆地南部的高邮凹陷,是一古近纪半地堑式断陷盆地。其中发育了近东西向、北东东向与北北东向3套断层系统。高邮凹陷基底存在着中三叠世末前陆变形所形成的北东东向逆冲断层与晚侏罗世北北东向左行平移断层。古近纪期间该凹陷处于近南北向拉伸的区域伸展应力状态,近东西向断层就是在此应力作用下新生的正断层。高邮凹陷边界上总体北东东向的真①断层、吴①断层与柳菱断层皆是追踪北东东与北北东向两组基底断层而发育的,并以前者为主。它们呈现为右行平移正断层活动,因而真①断层派生了3条左阶雁列状的真②断层。凹陷中、西部大量出现的北东东向断层,一方面是由于南、北边界上北东东向断层影响了局部应力状态,另一方面也有部分是复活的基底断层。凹陷内部北北东向断层皆为复活的基底断层,以活动早、规模小为特征。高邮凹陷各类基底断层的复活方式包括形成直接复活断层、派生雁列状断层、断续分布断层与连接断层。高邮凹陷断层系统的形成机制表明,区域应力状态与基底断层是决定断陷盆地内断层系统方位与活动方式的两个关键因素,基底断层的作用与影响是不容忽视的。The Gaoyou Sag in the south of the Subei Basin is a Paleogene, half-graben basin. Nearly E-W, ENE-and NNE-striking fault systems occur in the sag. Basement faults in the sag include ENE-striking thrusts formed by the latest Middle Triassic foreland deformation and NNE-striking sinistral faults developed during the Late Jurassic. The Paleogene sag was under a regional extensional stress field with N-S extension, leading to formation of the E-W normal faults. Its boundary faults include the generally ENE-striking Zhen-① Fault, Wu-① Fault and Liuling Fault. They formed by following the ENE-and NNE-striking basement faults, mostly along the ENE-striking basement faults. They are dextral normal faults, and three left-step, en echelon Zhen-② faults were therefore produced by the dextral normal faulting along the Zhen-① Fault. Many ENE-striking faults in the middle and west of the sag were developed due to influence of the ENE-striking, southern and northern border faults on local stress states and reactivity of some ENE-striking basement faults. NNE-striking faults in the sag are all derived from reactivity of the basement faults. They are characterized by earlier activity and smaller faults. The reactivated ways of all basement faults in the Gaoyou Sag include formation of directly reactivated faults , derived echelon faults, discontinuous faults and connection fault. Formation mechanism of the fault systems in the Gaoyou Sag suggests that the regional stress state and basement faults are two key factors in controlling fault system orientation and active methods, and role and effect of the basement faults should be ignored.

关 键 词：高邮凹陷 基底断层 应力场 断层系统 斜向拉伸 

分 类 号：P548[天文地球—构造地质学]