【摘要】 针对基底先存构造对裂陷盆地断层控制作用研究中存在的问题,应用脆性断裂新理论——"不协调性准则"来阐述、分析裂陷盆地基底先存构造控制断层形成和演化的力学机理,确定基底先存构造活动性的变化规律,探讨并初步确定基底先存构造对裂陷盆地断层形成和演化的控制作用具有如下规律:(1)先存构造(特别是先存断裂)优先活动,这是基底先存构造能控制沉积盆地断层形成和演化的根本原因。(2)先存构造对盆地断层控制作用的强度决定于其活动性,它由先存构造的产状、力学性质和应力状态决定,可以用先存构造活动性系数(fAS)来定量描述。(3)受基底先存断裂控制的断层发育的位置和延伸方向(走向)、形成次序、继承性特征,以及分布规模等都表现出显著的规律性。(4)与伸展方向垂直,且与σ1夹角为45°-(/2)的基底先存断裂对断层的控制作用最强;随着走向与伸展方向的夹角α逐渐变小,以及倾角偏离45°+(/2),对断层的控制作用就逐渐减小。(5)基底先存断裂的规模越大,对断层的控制作用就越强;受大规模基底先存断裂控制的断层往往构成裂陷盆地的构造格架。(6)随着薄弱带抗剪强度的减小,基底先存薄弱带发生破裂的可能性不断增大,对断层的控制作用不断增强;而相对基底先存断裂而言,其影响程度则相对偏弱。上述认识可以为裂陷盆地地震资料的构造解释提供理论模型,为裂陷盆地断裂系统的形成和演化的深入研究提供理论指导。更多还原

【Abstract】 In this paper we use the new brittle faulting theory,the "non-coordination criteria",to expound and analyze the mechanical mechanism of basement pre-existing fabric controlling fault formation and evolution,to determine the law of change in pre-existing basement fabric activity,and to investigate the controlling role of basement pre-existing fabric on fault formation and evolution.Through the study we came to the following conclusions.(1)The basement pre-existing fabric(particularly the pre-existing fault)has priority in activity,which is the root cause of its control over fault formation and evolution in sedimentary basin.(2)The controlling power of pre-existing fabric on basin faulting is determined by its activity that is controlled by the attitude and mechanical property of the pre-existing fabric,as well as its stress state,and its activity can be quantitatively described using the activity coefficient(fAS)of pre-existing fabric.(3)The faults controlled by basement pre-existing fault exhibit remarkable regularity in their locations and trends(strikes),formation orders,inherited features,and the size distributions.(4)The controlling power of basement pre-existing fault is the strongest when the fault is perpendicular to the extension direction of the controlled fault and the angle between the pre-existing fault and the σ1 of the controlled fault is 45°-(/2);when the angle(α)between the strike of the pre-existing fault and the extension direction of the controlled fault becomes smaller gradually,and the dip-angle deviated from 45°+(/2),the controlling power will be reduced progressively.(5)The larger the size of the pre-existing fault is,the more intensive the controlling power of the pre-existing fault on fault formation and evolution will be.The faults controlled by large-scale pre-existing basement faults tend to constitute the structural framework in rift basin.(6)When the shear strength becoming smaller,the possibility of the occurrence of the rupture in the pre-existing weak-zone will be increasing,and its controlling power will steadily be enhanced,but its affection is relatively weak comparing to the basement pre-existing fault.Using the above-mentioned conclusions,a theoretical model for the structural interpretation of seismic data may be constructed.These conclusions may also be used as a theoretical guidance for in-depth study of fault system formation and evolution in rift basin.更多还原