晓天—磨子潭断裂带构造变形分析及其对大别山构造变形的启示

Analysis on Structural Deformation of Xiaotian—Mozitan Shear Zone and It's Implication on Dabie Orogen

晓天—磨子潭断裂带是大别造山带非常重要的韧性剪切带之一,叠加在北大别灰色片麻岩之上。通过其构造几何学、运动学的研究表明:晓天—磨子潭韧性剪切带具有管壁状弯曲的几何学特征,运动学方式为沿NWW—SEE向近水平左旋剪切。地质温压计和变形矿物动态重结晶型式揭示了剪切带变形温度约618.2℃,地质压力约0.7GPa,相当于中下地壳环境。据此推测大别造山带曾上覆一管状背形韧性剪切层(大部分现已被剥蚀),晓天—磨子潭剪切带为其北界部分;造山带中下地壳物质曾发生近平行造山带走向的侧向流动。。

Xiaotian—Mozitan ductile shear zone is one of the most important shear zone in Dabie Orogen,which overprints upon grey gneiss of northern Dabieshan. Through the research about structural geometry,kinematics,the author get the conclusion that： Xiaotian—Mozitan ductile shear zone shows characteristics of a pipe on geometry,and has a subhorizontal sinistral shear style on kinematics. Geothermobarometer and the type of recrystallization of the deformed mineral reveal that its deforming temperature is about 618. 2℃,and the geological pressure about 0. 7GPa which indicates a mid—lower crust settings. Above research lead to a implication that： a pipe-like ductile layer with a northern boundary of Xiaotian—Mozitan shear zone covered upon Dabieshan and the materials among the mid—lower crust flowed laterally along the orogen during orogenic period.