长春东南劝农山地区早二叠世范家屯组岩石变形组构及流变学特征

发布时间：2018-03-30 10:50

本文选题：构造变形　切入点：EBSD　出处：《地球科学》2017年12期

【摘要】：劝农山地区位于长春市东南部,处于佳-伊断裂和西拉木伦河缝合带交汇处.详细野外调查发现,该区曾遭受强烈韧性剪切变形,剪切带内岩石普遍糜棱岩化,主要由下二叠统范家屯组(P1f)钙质糜棱岩与侵入其中的燕山期花岗质糜棱岩组成,变形程度处于初糜棱岩至糜棱岩之间,多具有糜棱结构.岩石应变类型主要为压扁型应变,偏一般压缩,为L=S型构造岩,指示其形成于挤压型剪切带的构造环境.多种宏微观韧性剪切变形标志,指示明显的左行剪切运动.电子探针方解石-白云石地质温度计、方解石和石英EBSD组构特征、方解石e双晶形态以及石英长石变形行为等均显示岩石具有低温塑性流变特点,变形环境不超过绿片岩相.剪切带内应变速率偏高,应变集中带应变速率最大,在10-6.95~10-8.89之间,远离强变形带应变速率在10-9.25~10-12.17之间,糜棱岩化作用过程中差异应力下限应大致为51.27~65.46MPa,代表剪切带糜棱岩化作用为低温中等强度应变,在稍快的应变速率条件下形成.压溶扩散和双晶滑移为劝农山韧性剪切带变形初期的主要变形机制,随着递进变形,逐渐以双晶滑移和晶内滑移为主,递进变形晚期,局部强变形域内发生了粒间滑移.劝农山韧性剪切带形成与早白垩世中晚期伊泽纳崎板块NNW向高斜度斜向俯冲于欧亚大陆之下有关,是佳-伊断裂带左旋走滑事件的局部表现.
[Abstract]:Quannong mountain area is located in the southeast of the city in Changchun, Jiamusi and Silas Iran fault of Mulun River suture zone interchange. Found with field investigation, the district had suffered strong ductile shear deformation in the shear zone rocks generally mylonization, mainly by Jia Tun two Permian fan group (P1f) and calcareous mylonite invasion of Yanshan the composition of the granitic mylonite and protomylonite mylonite deformation degree is to, with mylonitic structure. The main rock type strain flattened strain, partial general compression, L=S type tectonic rocks formed in the tectonic environment, indicating the compressional shear zone. The ductile shear deformation of a variety of macro micro mark, indicating the left for the shearing motion obviously. Electron probe calcite dolomite geothermometry, calcite and quartz EBSD fabric characteristics, calcite and quartz feldspar morphology e twinning deformation behavior all showed that the rock has low temperature plasticity. Rheological characteristics, deformation environment does not exceed the greenschist facies. The shear band strain rate, strain rate and strain concentration zone, between 10-6.95~10-8.89, far away from the strong deformation zone of strain rate between 10-9.25~10-12.17, difference of mylonitization process should lower stress resulted from 51.27~65.46MPa, on behalf of shear band mylonitization for low temperature middle strain, at a slightly faster rate should be formed under the conditions. The main deformation mechanism of pressure solution diffusion and crystal slippage Quannong in ductile shear zone in early deformation, with progressive deformation, gradually to twin slip and intracrystal slip, progressive deformation stage, local strong deformation occurred intergranular slip domain. Quannong in ductile shear zone formation and early Cretaceous Iran zehner Zaki plate NNW to high slope in oblique subduction beneath the Eurasian continent, is good - Iran fault sinistral Affair Bureau The performance of the Department.

【作者单位】：吉林大学地球科学学院;吉林大学东北亚矿产资源评价国土资源部重点实验室;北京大学地球与空间科学学院;中国地质调查局沈阳地质调查中心;
【基金】：国家自然科学基金项目(Nos.41230206,41602211)
【分类号】：P534.46;P584

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