雪峰山区韧性剪切构造带

THE DUCTILE SHEAR,TECTONIC ZONES IN XUEFENGSHAN REGION

雪峰山区存在着三条与山脉步向一致的北东向弧形韧性剪切带(Fl、F_2、F_3),F_1以左旋剪切为主,F_2、F_3以右旋剪切为主,但均系同一次构造剪切力所致。由变形岩石中的旅转应变体估算出剪切中心地带的剪切应力值大约是7-8,有限应变沿X最大拉伸量195％,沿Z方向最大缩短量为62％。其深部韧性剪切发生于加里东构造期,这之后又遭受浅部脆性应变叠加而构成断裂构造综合实体。

There exist three northeast-trending arc-shaped ductile shear zones in Xuefengshan region, parallel to the direction of the mountain range. F1 shows mainly sinistral shear, while F2, F3 show dextral shear dominantly, Allof them resulted from the same tectonic shear action, It is estimated from the rotational strain system of the deformed rocks that the shear stress value in the central shear zone is about 7-8, the maximum stretch of finite strain along X direction is 195%, and the maximum shortening along Z direction is 62%. The ductile shearing in deep part took place in the period of Caledonian orogeny, thereafter, shallow brittle strain superimposed to form a synthetical fault-fracture structural body.