“不协调伸展”作用下裂陷盆地断层的形成演化模式

Fault formation and evolution model under uncoordinated extension in rift basin

应用"不协调伸展"的目标砂箱模拟实验成果和新的脆性断裂力学模型——"不协调性准则",分析了裂陷盆地断层形成和演化的控制影响因素,建立了裂陷盆地断裂系统形成和演化的新模式——"不协调伸展"模式。该模式显示:"不协调伸展"的递进变形过程是导致裂陷盆地断裂系统的复杂性的根本原因,实质是不同方向、性质和规模的基底先存构造(主要是先存断裂)的活动性方面存在差异,导致所控制形成的断层在走向、形成的先后次序、规模等方面存在差异,从而形成复杂的断层组合;"不协调伸展"模式是裂陷盆地断裂系统形成和演化的基本型式,复杂的断裂系统可以在方向不变的区域伸展构造作用下在递进变形过程中逐渐形成;裂陷盆地断裂系统虽然比较复杂,但断层的形成和演化是有序的,分布是有规律的,可以通过"不协调性准则"加以分析和预测。

In this paper,applying target sandbox modeling results of ＂uncoordinated extension＂ and the new mechanical model of brittle faulting-＂non-coordination criterion＂,the controlling factors of fault formation and evolution are analyzed,and a new model of fault formation and evolution,which is called the ＂uncoordinated extension＂ model,is proposed.According to the model,the progressive deformation process of ＂uncoordinated extension＂ is the root cause which leads to the complexity of fault system in rift basins.Because the activity of each pre-existing fabric （mainly pre-existing fault） of different trend,property and size in the basement is different,it will lead to different,controlled faults in the strike,formation order and size and the complicated fault assemblage forms.＂uncoordinated extension＂ is the basic patterns of fault formation and evolution,the complicated fault system can be formed progressively in progressive extension process under ＂uncoordinated extension＂ with unchanged extension direction.It is pointed out that the fault system in the rift basin is relatively complex,but the fault formation and evolution is orderly,and there is a law in the fault distribution,which can be analyzed and predicted with ＂non-coordination criterion＂.