双帚状断层的成因和生长发育

Mechanism and growth of broom-like faults

通过几何学、运动学和成因分析及物理模拟试验,对渤海湾盆地临南洼陷双帚状断层的成因及演化进行研究。结果表明:夏口断层为东端收敛、西端撒开的张剪帚状断层,早白垩世受伸展与右行走滑作用产生,新生代受伸展叠加走滑作用继续发育成为一条走滑—正断层,临邑"帚状断层"西敛东撒,为新生代正向以及斜向伸展叠加走滑的产物,其撒开端与收敛端级别相同而非次级断层;双帚状断层出现在古新世—早始新世,活动强度由收敛端向撒开端迁移,即夏口断层由西向东迁移,临邑断层由东向西变强,并在渐新世后超过了夏口断层直到上新世;早白垩世以来区域构造应力场的变化、兰聊断层的走滑作用及鲁西隆起新生代的抬升是控制双帚状断层形成和发育的根本因素。

The formation and evolution of the double broom-like faults in Lin'nan sag of Bohai Bay Basin were studied by u-sing geometrical,kinematic and genetic analyses and analogue modeling.The results are as follows:Xiakou fault is a ten-sional-shear broom-like fault mainly formed by the extension and dextral strike slip faulting in the early Cretaceous,in whichthe fault plan converged at the eastern end and opened at the western end.The fault continued to develop in the Cenozoic byextension and dextral strike slipping to form a strike slip-normal fault.Linyi fault is a normal fault with a"broom-shaped"west end bunching and an eastern end opening,which was formed by the Cenozoic orthodox and oblique extension.The open-ing end and the converging ends of the fault are at the same fault level.The double-broom-like fault appeared in the Paleo-cene/Early Eocene,and the faulting activity intensifies from the convergent end to the opening end,resulting in a strongwestern end of Linyi fault and a strong eastern end of Xiakou fault.The intensity of fault activity of Linyi fault is greater thanthat of Xiakou fault in the Oligocene until the Pliocene.The strike-slip faulting of Langliao fault,the regional tectonic stress field since the Early Cretaceous,and the Cenozoic uplifting of Luxi uplift were the fundamental controlling factors of the for-field since the Early Cretaceous,and the Cenozoic uplifting of Luxi uplift were the fundamental controlling factors of the double-broom fault.