鲁西地区韧性剪切带显微构造研究及岩组分析

MICROSTRUCTURE STUDY AND PETROFABRIC ANALYSES OF THE DUCTILE SHEAR ZONES IN WESTREN SHANDONG

通过对鲁西地区韧性剪切带显微构造及岩组特征等的研究，认为该区韧性剪切带具有多期次、多方向、多性质的变形特点，韧性变形主体具有右行剪切性质，最大主压应力方位为ＮＥ－ＮＥＥ。从岩组分析结果可知，区内岩石韧性变形较强，并且复杂，变形以压剪性变形为主，石英变形机制主要为柱面滑移，韧性变形时温度较高。石英自由位错密度法应力估算结果说明，区内最大差应力为７５．４ＭＰａ，平均值６８．４５ＭＰａ，金矿体的赋存与构造应力的大小无直接关系，但与变形强度直接相关。

From microstructure study and petrofabric analysis of the ductile shear zones in western Shandong, we found that the deformation in the ductile shear zones is in polyphase and polydirection, but the major part of the deformation is right handed, and the direction of the maximum compressive stress is nearly NE￣NEE. The results of petrofabric analysis show that: (1) quartz in the rocks was deformed by prism slip, so the temperature was very high during the ductile shear deformation; (2) the deformation in the area is very complex, and the deformation of rocks is mainly compressive shear deformation. The differential stress values of free dislocation density of quartz in the area suggest that the maximum differential stress value is 74.5MPa, and the average differential stress value is 68.45MPa. Compared with the differential stress values in many brittle faults(such as Altun fault in China), the differential stress value in the area is a little lower, which is correspondent to the fact that the ductile shear zones formed in deep area and the differential stress decreases form the surface to the depth.