伸展断层传播褶皱研究现状

Research Status of Extensional Fault-Propagation Folding

伸展断层传播褶皱是伸展环境中重要的一种褶皱类型,是由于隐伏基底正断层活化向上传播而引起上覆地层发生的弯曲。多年的研究认为这是一种向上变宽的三角形分布式剪切调节过程,断层的上端点限定了三角剪切区的顶点。运用三角剪切的速度模型很好地拟合和描述变形区内物质的运动,三角剪切区的顶角和断层向上传播/断层向下滑移比值(p/s)是控制伸展断层传播褶皱变形过程和几何形态的重要的运动学参数。伸展断层传播褶皱的发育过程可以根据断层是否切穿上覆盖层而划分为两个阶段。在沉积过程中,伸展断层传播褶皱作用对生长地层的几何形态和叠置样式有较强的控制作用。通过对保留的生长地层几何形态的分析,可以确定隐伏基底断层的初始破裂点和断层传播量,并最终重建伸展断层传播褶皱的变形过程。

Extensional fault-propagation fold,an important kind of folds in extensional environment,is formed by propagation of the basement blind normal fault into sedimentary cover which was bent and thinned.The deformation is accommodated by trianglelike upward widening distributional shearing,and the up tip of blind fault controls the position of the apical angle of the shear zone.The tri-shear modeling matched well with the material movement in deforming zone.The apical angle of tri-shear zone and the fault propagation to slip ratio（p/s ratio）are both important parameters controlling the geometry and deformation of the extensional faultpropagation fold.The process of extensional fault-propagation folding can be divided into two stages by whether the blind fault propagates through cover strata.During deposition,extensional fault-propagation folding controls the geometry and superimposed pattern of grow strata strongly.The blind fault nucleation point and propagation amount can be determined exactly by analysis of the geometry of reserved growth strata and the development of extensional fault-propagation fold can be finally restored.