商南-商城断裂带中段大型韧性走滑剪切带研究

商南－商城断裂带中段的韧性剪切带是由多条糜棱岩带及其所夹的变质岩块体组成的大型韧性剪切带。它是以简单剪切为主要变形机制的、于绿片岩相温压条件下形成的韧性剪切带。剪切带内糜棱岩的塑性变形和恢复重结晶作用强烈。糜棱叶理产状多较陡倾，ａ线理近水平，表明为走滑断裂。大量不对称旋转构造指示该剪切带早期为左行剪切，后期在不同地段又叠加上程度不同的右行剪切

STUDY ON A LARGE DUCTILE STRIKE SLIP SHEAR ZONE IN THE MIDDLE OF THE SHANGNAN SHANGCHENG FAULT ZONE

The ductile shear zone in the middle of the Shangnan Shangcheng fault zone is a large ductile shear zone which consists of a series of mylonite zones and metamorphic rock blocks among them. The shear zone seems to be formed under green schist facies and to have undergone simple shear strain. The deformation and recrystallization in the shear zone are very strong. The foliations of mylonites mostly dip steeply and a lineations are nearly horizontal, and therefore, it is a strike slip fault. Many unsymmetrical rotation fabrics in the shear zone indicate an early sinistral slip, and then, the shear zone was overprinted by different extents of dextral slip in different areas.