石英C轴组构指示北大别造山后伸展期中-下地壳流变形式

发布时间：2018-04-09 04:39

本文选题：中-下地壳流动　切入点：造山后伸展　出处：《大地构造与成矿学》2017年05期

【摘要】：造山带中-下地壳韧性流变形式反映深部岩石圈构造活动形式,是造山带深部岩石圈运动学及动力学研究的重要内容。前人对板块俯冲阶段造山带中-下地壳流动开展了较为深入的研究,但对造山后伸展期中-下地壳流变形式及其深部动力学认识不足。本次工作对北大别造山后伸展期中-下地壳岩石开展了详尽的构造观察和石英C轴组构分析,研究造山后伸展期中-下地壳流变形式。本次研究表明,中-下地壳流变带内岩石变形从边界区域的简单剪切变形为主导逐渐转变为在核部区域以纯剪切变形为主。流变带内部岩石变形特征表明北大别中-下地壳流变带的流变形式是介于活动边界条件下的透入性剪切流动和固定边界条件下韧性垮塌流动的过渡形式。这一流变形式可能是深俯冲太平洋板块的绕屈回撤和加厚造山带地壳活化韧性垮塌叠加的结果。
[Abstract]:The ductile rheology of the middle and lower crust of the orogenic belt reflects the tectonic activity of the deep lithosphere and is an important part of the kinematics and dynamics of the deep lithosphere in the orogenic belt.Previous researches on the middle-lower crustal flow of the orogenic belt in plate subduction stage have been carried out, but there is a lack of understanding of the rheological form of the lower crust and its deep dynamics during the post-orogenic extensional period.In this work, detailed tectonic observation and quartz C-axis fabric analysis were carried out on the post-extensional and lower crustal rocks of Beidabie orogeny, and the rheological patterns of the post-orogenic extension-lower crust were studied.The results show that the deformation of rocks in the middle and lower crustal rheological zone is gradually changed from simple shear deformation in the boundary region to pure shear deformation in the core region.The characteristics of rock deformation in the rheological zone indicate that the rheological form of the middle-lower crust rheological zone in Beidabie is a transitional form of permeable shear flow under active boundary condition and ductile collapse flow under fixed boundary condition.This rheological form may be the result of the deep subduction of the Pacific plate and the collapse of the crust activation ductile in the thickening orogenic belt.
【作者单位】：安徽大学资源与环境工程学院;合肥工业大学资源与环境工程学院;安徽省地质调查院;
【基金】：国家自然科学基金项目(41472194,41002069,40902064)资助
【分类号】：P542

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