桐柏杂岩北界剪切带的构造变形特征研究

发布时间：2018-02-06 02:22

本文关键词： 桐柏杂岩北界剪切带位移量分维度差异应力应变速率　出处：《地质论评》2017年03期 　论文类型：期刊论文

【摘要】：桐柏杂岩北界剪切带是桐柏—大别造山带发育的一条大型的左行走滑韧性剪切带,发育糜棱岩、超糜棱岩以及强直片麻岩等强变形岩石。通过对剪切带内岩石的矿物共生组合、剪切带的位移量计算、石英的分维数计算、石英颗粒的差异应力以及应变速率的估算等多种方法分析结果显示:桐柏杂岩北界剪切带的位移量为38.3~41.1km;动态重结晶石英颗粒边界统计数据的相关系数R均大于0.96,动态重结晶颗粒边界具有统计意义上的自相似性;分维数为1.207~1.302之间,从剪切带的核部向边部,颗粒粒径和分维值的变化是逐渐变大的。石英的分维值反映出石英的动态重结晶与剪切带密切相关,变质变形由剪切带核部向边部逐渐减弱。桐柏杂岩北界剪切带的差异应力值为23.583~46.983 MPa之间,应变速率为1.70×10~(-11)~9.74×10~(-11)s~(-1)。通过对比剪切带内动态重结晶石英颗粒的粒径、差异应力和应变速率可以发现,差异应力与应变速率表现出一定的正相关性,都随着从剪切带的核部到边部慢慢变小;而石英的粒径则与差异应力和应变速率表现出负相关性,从剪切带核部到边部,随着石英粒径的变大,差异应力和应变速率变小。差异应力越大,导致石英颗粒的受力强度越大,变形越强,表现出来的就是应变速率越强。从显微构造变形角度来研究认识该剪切带,对揭示桐柏—大别造山带的构造演化以及构造模型的建立有着重要的构造意义。
[Abstract]:The north boundary shear zone of Tongbai complex is a large left strike-slip ductile shear zone developed in Tongbai-Dabie orogenic belt and developed mylonite. Ultramylonite and strong gneiss are strongly deformed rocks. Through the mineral symbiotic assemblage of rocks in the shear zone, the displacement of shear zone and the fractal dimension of quartz are calculated. The analysis results of different stress and strain rate of quartz grain show that the displacement of the shear zone in the north boundary of Tongbai complex is 38.3 km; The correlation coefficient R of the dynamic recrystallized quartz grain boundary statistical data is greater than 0.96, and the dynamic recrystallization grain boundary has statistical self-similarity. The fractal dimension is between 1.207 and 1.302, from the core to the edge of the shear band. The change of particle size and fractal dimension is gradually increasing. The fractal dimension of quartz reflects that the dynamic recrystallization of quartz is closely related to the shear zone. Metamorphic deformation gradually weakened from the core to the edge of the shear zone. The differential stress of the northern boundary shear zone of the Tongbai complex is between 23.583 and 46.983 MPa. The strain rate is 1.70 脳 10 ~ (10) ~ (-11) ~ 9.74 脳 10 ~ (10) ~ (-1) ~ (-1). The particle size of dynamic recrystallized quartz in the shear zone is compared. Differential stress and strain rate can be found that the differential stress and strain rate show a certain positive correlation with the shear band from the core to the edge gradually become smaller; The particle size of quartz is negatively correlated with the differential stress and strain rate. From the core to the edge of the shear band, the differential stress and strain rate become smaller with the increase of the quartz particle size. The greater the differential stress is, the greater the differential stress is. As a result, the greater the stress strength of quartz particles, the stronger the deformation, and the stronger the strain rate. The shear zone is studied and recognized from the angle of microstructure deformation. It is of great tectonic significance to reveal the tectonic evolution of Tongbai-Dabie orogenic belt and the establishment of tectonic model.
【作者单位】：合肥工业大学资源与环境工程学院;青海省地质调查局;
【基金】：国家自然科学基金资助项目(编号:41272222;41502193)的成果~~
【分类号】：P542

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