Carrara大理岩在轴向压缩实验过程中的显微构造特征及变形机制研究  

Microstructural Characteristics and Deformation Mechanism of Carrara Marble in Axial Compression Experiments

作　　者：张桂男 宋茂双[1] 李建峰[1] 邵同宾 嵇少丞 王浩 ZHANG Guinan;SONG Maoshuang;LI Jianfeng;SHAO Tongbin;JI Shaocheng;WANG Hao(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;;Départment des Génies Civil,Geologique et des Mines,Ecole Polytechnique de Montréal,Monetréal,H3C3A7,Canada)

机构地区：[1]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]加拿大蒙特利尔综合工学院民用、地质与采矿工程系,蒙特利尔H3C3A7

出　　处：《大地构造与成矿学》2018年第5期786-797,共12页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(41574079和41174072);中国科学院战略性先导专项(B类)(XDB18000000);中国博士后基金项目(2016M602550)联合资助。

摘　　要：为了研究大理岩在变形过程中显微构造特征的演化及其主导变形机制,本文以利用Paterson气体介质高温高压流变仪轴向压缩模块在一定温度(600～900℃)、围压(～300 MPa)和应变速率(5.92×10^(-3)~1.04×10^(-5) s^(-1))条件下施加不同应变量(2%～25.8%)的Carrara大理岩实验变形样品为研究对象,利用光学显微镜对变形前后Carrara大理岩的显微构造特征进行系统的观察和对比分析。观察发现本研究实验条件下样品发育机械双晶、波状消光、颗粒细化等显微构造特征,表明变形过程中激活的塑性变形机制包括双晶滑移、位错蠕变和动态重结晶等。通过统计动态重结晶方解石颗粒的粒度,结合前人的实验研究结果,厘定了方解石颗粒边界迁移动态重结晶古应力计和亚颗粒旋转动态重结晶古应力计。对比不同应变量和温度条件下变形样品的显微构造特征,发现方解石的显微构造特征随着应变量的增加和温度的升高不断发生变化,暗示着主导Carrara大理岩塑性变形的微观变形机制也发生了相应的改变,为力学数据拟合时应力指数n的变化提供了合理的解释。此外, Carrara大理岩在高温条件下也会发生双晶滑移,在应变量和应力相同的情况下,双晶厚度随温度的升高而增加。In order to investigate the microstructural evolution and corresponding plastic strain mechanism during deformation,we observed and analyzed the deformed Carrara marble samples that have been axial compressed using a Paterson gas-medium apparatus at the pressure of^300 MPa,temperatures of 600℃to 900℃,strain rates of 5.92×10?3 to 1.04×10?5 s?1,and strains of 2%to 25.8%,using transmitted-light microscope with camera and polarizer.Mechanical twins,undulating extinction and grain size reduction were observed in the samples that were recovered after deformation experiments,indicating twinning,dislocation glide and recrystallization occurred during the deformation.Based on the measured grain sizes of recrystallized samples after experiments and combined with related previous studies,we quantified paleopiezometer parameters of calcite for grain boundary migration dynamic recrystallization and subgrain rotation dynamic recrystallization,respectively.Furthermore,the microstructural characteristics varied with increasing strain and temperature,suggesting the dominant deformation mechanism changed accordingly.It reasonably explained the variation of stress exponent n when we did the best fitting of the collected mechanical data.Specially,increasing temperature and strain can reinforce driving energy for deformation,and help activate the deformation mechanism,which need relative high driving energy to be activated.In addition,we can find mechanical twin even at high temperature;and the thickness of the twin increases with temperature while keeping strain and stress fixed.

关 键 词：Carrara大理岩 轴向压缩 高温高压 显微构造特征 变形机制 

分 类 号：P542[天文地球—构造地质学]