用动态重结晶石英颗粒的分形确定变形温度及应变速率

Determination of the Deformation Temperature and Strain Rate by the Fractal Shape of Dynamically Recrystallized Quartz Grains

韧性变形岩石中动态重结晶石英颗粒边界形态具有自相似性 ,表现出分形特征。动态重结晶石英颗粒边界的分形维数随温度的升高而减小 ,随应变速率的增加而增大 ,可作为韧性变形温度及应变速率的标度计。适合重结晶石英边界分维值的计算方法有封闭折线法和面积周长法。鲁西青邑韧性剪切带中糜棱岩动态重结晶石英颗粒边界具有自相似性 ,分维值为 1.2 2 8～ 1.32 6 ,初步估算出古应变速率为 10 - 7.6～ 10 - 8.7s- 1,属绿片岩相。

Grain shapes of dynamically recrystallized quartz in ductile deformed rocks, characterized by fractal dimension, are statistically self_similar. The fractal dimensions of dynamically recrystallized quartz grains, decreasing with deformation temperature and rising with strain rate, can be an indictor for the deformation condition. Two methods of polygon and area_perimeter are applicable to calculate the fractal dimension of dynamically recrystallized quartz grains. Grain shapes of dynamically recrystallized quartz in mylonites within Qingyi ductile shear zone show statistical self_similarity, in which numbers of fractal dimension are from 1.228 to 1.326 and paleo_strain rates vary from 10 -7.6 to 10 -8.7 s -1 . Qingyi ductile shear zone experienced deformation under the conditions of green_schist facies and medium strain_rate.