皖东黄栗树—破凉亭断裂带北段构造岩显微—超显微变形特征及地质意义

本文就郯庐断裂带南段东部的黄栗树—破凉亭断裂带内构造岩,特别是中深层次的韧性剪切带中的糜棱岩进行了细致的野外考察、采样,在室内显微构造研究的基础上,选择有代表性的样品和视域进行透射电镜制样观察,在对各超显微构造特征分析归纳的基础上,讨论了构造岩的塑性变形特征,并对构造岩的应变参数(最大差异应力和应变速率)进行了计算,从显微—超显微构造角度仔细研究该断裂带内典型的构造岩的变形特征,初步判明断裂带的性质和运动发展历史,证实了该断裂带是形成在较深构造层次的一条以韧性变形为主的脆—韧性剪切带,应变形式为简单剪切。应变参数的计算结果表明,自东向西从前陆褶皱冲断带根部到后缘带,构造岩中石英的位错密度逐渐减小,最大差异应力逐渐降低。

Micro-Ultra-Micro Structural Characteristics of the Tectonites from the Northern Huanglishu-Poliangting Fault Belt, Eastern Anhui Province, China

This paper focuses on the mylonites from the brittle-ductile shear zones in the northern part of the Huanglishu-Poliangting fault belt, eastern Anhui Province. On the basis of field surveys, several of the typical brittle-ductile shear zones were chosen and altogether 10 typical samples were collected for a detailed study. Using TEM analysis on the deformed minerals in the tec-tonites from the fault belt, the characteristics of the dislocation in quartz has been studied and the plastic deformation of the mylonites discussed. The parameters of the differential paleo-stress and the strain rate in the mylonites have been calculated and the history of geological movements in the fault belt discussed. It has been proved that this fault is formed in a brittle-ductile shear zone at depth, representing simple shearing. The calculated results show that the differential stress in quartz of the tectonites become smaller from east to west.