摘要:郯庐断裂带肥东段烟头山及桃源地区，发育多条左行韧性剪切带，岩性以糜棱岩和糜棱岩化片麻岩为主，岩石变形强烈。通过详细的野外观测及室内分析发现：肥东北部烟头山及桃园地区几何学形态呈一背形构造，其枢纽走向NE-SW，轴面倾向SE，自核部向两翼岩性出露具有一定的规律性和对称性。古应力方向及运动学涡度研究表明：研究区内构造体主要受到近南北方向的挤压，涡度值Wk在0.73～0.90之间，指示区域内的韧性剪切活动以简单剪切为主。对区内变形岩石展开精细化的构造变形分析，包括石英的分形特征、变质变形温度估计、差应力和应变速率的计算等，结果显示：区内动态重结晶石英颗粒边界具有统计学上的自相似性，分维值D在1.111～1.187之间，变质变形温度集中在520 ℃～610 ℃之间，为高绿片岩相到低角闪岩相变质；韧性剪切带的差异应力Δσ介于18.493～95.266 MPa之间，应变速率ε范围在5.418×10-15 s-1～4.748×10-11 s-1之间。对比以上参数发现：韧性剪切带核部和背形转折端附近，岩石变形强烈，变质变形温度高，动态重结晶石英颗粒粒径较小，分维值较大，差异应力和应变速率也较大，远离剪切带核部和背形两翼则相反。本文从几何学、运动学特征以及显微构造变形分析等方面展开精细化研究，对进一步认识郯庐断裂带乃至大型韧性剪切带的构造样式和演化过程有着重要的意义。
关键词: 郯庐断裂带/
韧性剪切带/
几何学/
运动学/
构造变形分析
Abstract:A number of sinistral ductile shear belts are exposed in Yantou Mountain and Taoyuan areas from the Feidong segment of the Tanlu fault zone. The lithology is mainly mylonite and mylonitic gneiss, and the rocks are strongly deformed. Through detailed field observation and indoor analysis, it is found that the geometric shape of Yantou Mountain and Taoyuan area in the north of Feidong to be an antiform, and its hinge strikes NE?SW, the axial plane trends to SE. And following the shape of the antiform, the lithology shows certain regularity and symmetry. The paleo?stress direction and kinematic vorticity study show that the structure in the study area is mainly squeezed from the north?south direction, and the vorticity value Wk is between 0.73 and 0.90, indicating that the ductile shearing activity in the region is dominated by simple shear. The detailed structural deformation analysis of the deformed rocks in the area, including the fractal characteristics of quartz, the estimation of metamorphic deformation temperature, the calculation of differential stress and strain rate. The results show that the boundary of dynamically recrystallized quartz particles in the study area has a statistical self-similarity, the fractal dimension D is between 1.111 and 1.187, and the metamorphic deformation temperature is concentrated between 520℃ and 610℃, which is the metamorphism of the high greenschist facies to the low amphibolite facies. The differential stress Δσ of the ductile shear zone is between 18.493 MPa and 95.266 MPa, and the strain rate ε ranges from 5.418×10-15 s-1 to 4.748×10-11 s-1. Comparing the above parameters, it is found that the rock is strongly deformed and the metamorphic deformation temperature is high near the core of the ductile shear zone and the hinge zone of the antiform. By comparing the above parameters, it can be found that the rock is strongly deformed and the metamorphic deformation temperature is high near the core of the ductile shear zone and the hinge zone of the antiform. The dynamic recrystallized quartz particles size is small, the fractal dimension is large, and the differential stress and strain rates are large, away from the core of the ductile shear zone and the hinge zone of the antiform are opposite. In this paper, the detailed research on geometry, kinematics and microstructural deformation analysis is of great significance for further understanding of the tectonic style and evolution process of the Tanlu fault zone and even the large ductile shear zone.
Key words:The Tanlu fault zone/
Ductile shear zone/
Geometry/
Kinematics/
Structural deformation analysis
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