济阳坳陷滩海地区基底断裂特征及其演化规律

Structural characteristics and evolution of basement faults in the beach area of Jiyang Depression

胜利油田滩海地区是济阳坳陷东部重要的油气聚集带,前古近系基底断裂对新生代含油气盆地构造演化及油气成藏具有十分重要的影响。通过对滩海地区及济阳坳陷前新生代地层的分布、残留厚度与构造特征的分析,结合区域构造演化规律,揭示了该地区前新生代基底断裂空间展布与发育规律,总结了基底断裂成因、演化过程。研究结果表明,滩海地区前新生代主要发育北西向、北北东向与北东向3组基底断裂,其分布格局与构造样式在空间上具有明显的差异。其中北西向基底断裂起源于印支期大别—苏鲁造山带碰撞造山期形成的前陆褶皱与逆冲断层系统,北北东基底断裂属于晚侏罗世郯庐断裂带第二次大规模左行走滑活动中伴生的左行平移断层系统,北东向基底断裂一部分形成于印支期北西向褶皱作用中的横向调节正断层或逆冲作用中的撕裂断层,另一部分可能形成于早白垩世期间北西—南东向区域拉张背景之下。3组基底断裂在多期构造活动中相互叠加、改造,并发生了多次的构造反转活动,新生代期间逐渐消失并被新生的东西向断裂所取代。

The beach area of Shengli oil field is an important oil-gas accumulation zone in the eastern Jiyang Depression.The pre-Tertiary basement faults have significant influence on the geology evolution and the oil-gas reservoir formation of the Cenozoic petroleum basin.Combined with the regularity of regional tectonic evolution,the paper revealed the structural evolution pattern and spatial distribution of the basement faults,and their origin and evolution were also summarized,based on analysing the distribution and residual thickness of the pre-Cenozoic stratum and structural characteristics in the beach of Jiyang Depression.The results showed that the NW,NNE and NE trending faults are mainly developed in pre-Cenozoic stages in this area,which distribution patterns and structural styles are obviously different.The NW-trending faults originated from foreland thrusts which generated by Dabie-Sulu collision zone,formed during Indosinian.The NNE-trending faults belong to sinistral strike-slip,associated with the second strong sinistral strike-slip faulting of the Tan-Lu fault zone occurred in late Jurassic.Parts of the NE-trending faults belong to the transverse accommodation normal faults or the tear-faults generated by the NW-folding during Indosinian.The other parts probably formed under the NW-SE regional stretching environment during early Cretaceous.The three groups of basement faults superimposed and transformed with each other in the multi-stage tectonic movements,and also had undergone multiple structural inversion activities.Moreover,they are replaced by large numbers of EW faults during Cenozoic.