Abstract: On the basis of observations of the mineral assemblages and microstructures in the tectonic rocks from the ductile shear zones in the southern part of the Tancheng Lujiang fault,the feldspar was analyzed by means of EPMA,XRD and infrared spectrometry. It has been found that there are close correlations between the intensity of the rock deformation and the composition and structural state of the feldspars in the rocks. The relations are as follows: the positive correlation between the intensity of shearing deformation and the parameters of the feldspar structural state,the deformed index of feldspar(I_ss) and An values of plagioclase,and the negative correlation between intensity of shearing deformation and the unit cell volume of the feldspars and Si/Al value of the plagioclase. These results provide simple and effective methods for studies of the deformation metamorphism in structural strain field.

Key words: Tancheng Lujiang fault zone, shear zone, Mylonite, Microstructure, Tectonic stress field, feldspar

摘要： 在对郯庐断裂带南段3条韧性剪切带中糜棱岩及围岩进行矿物组合、结构构造观察研究的基础上,对长石矿物进行了多项分析测试,发现长石成分及其结构状态参数的变化与构造应力场的构造作用存在明显的对应关系:随剪切变形作用的加强,长石矿物的结构状态参数呈增大趋势,矿物单位晶胞的体积和斜长石中Si/Al比值随之减小;长石的变形指数(I_ss)和斜长石中的钙长石分子(An)与岩石的变形强度呈明显的正相关关系。这些研究结果为探讨构造变形场中矿物岩石的变形 变质作用提供了一种简捷有效的手段。

关键词: 郯(城)-庐(江)断裂带, 剪切带, 糜棱岩, 显微构造, 构造应力场, 长石