地震地质 ›› 2015, Vol. 37 ›› Issue (1): 81-93.DOI: 10.3969/j.issn.0253-4967.2015.07

• 研究论文 • 上一篇    下一篇

高温高压条件下角闪岩脆-塑性转化实验研究

宋娟1, 周永胜2, 钟柯3, 刘贵4, 刘照星2   

  1. 1 中国石油大学(华东), 青岛 266580;
    2 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029;
    3 中国地质大学(北京), 北京 100083;
    4 中国科学院大学地球科学学院, 中国科学院计算动力学重点实验室, 北京 100049
  • 收稿日期:2013-10-07 修回日期:2014-12-26 发布日期:2015-05-15
  • 通讯作者: 周永胜,男,研究员,E-mail:zhouysh@ies.ac.cn
  • 作者简介:宋娟,女,1975年生,2004年在中国地震局地质研究所获得固体地球物理专业硕士学位,讲师,主要从事高温高压岩石力学与流变学及与地震学相关的教学和研究工作,电话:18669880408,E-mail:songjuan95@126.com。
  • 基金资助:

    国家自然科学基金(41374184)和地震动力学国家重点实验室自主研究课题(LED2010B03,LED2013A05)共同资助

THE BRITTLE-PLASTIC TRANSITION IN EXPERIMENTALLY DEFORMED HORNBLENDE UNDER HIGH TEMPERATURE AND HIGH PRESSURE

SONG Juan1, ZHOU Yong-sheng2, ZHONG Ke3, LIU Gui4, LIU Zhao-xing2   

  1. 1 China University of Petroleum, Qingdao 266580, China;
    2 State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
    3 China University of Geosciences(Beijing), Beijing 100083, China;
    4 Key Laboratory of Computational Geodynamics, CAS, University of Chinese Academy of Sciences, Beijing 100049
  • Received:2013-10-07 Revised:2014-12-26 Published:2015-05-15

摘要:

在高温高压条件下开展了天然角闪岩样品的变形实验研究, 并且利用偏光显微镜和扫描电镜对实验样品进行微观结构观察, 研究了在不同的温压和应变速率条件下角闪石的变形机制。实验结果表明, 随着温度升高, 样品的应力-应变曲线由强化逐渐转化为屈服, 并且出现弱化, 样品强度显著降低, 随着围压增加, 样品强度增大, 随着应变速率降低, 样品强度降低, 压缩方向与样品面理斜交的实验样品强度显著降低。实验变形样品在500℃时, 角闪石表现为晶内破裂和碎裂变形, 其变形以脆性为主导;在600℃时, 样品中发育由角闪石残斑和碎裂基质构成的碎裂组构, 部分角闪石晶体出现了波状消光, 角闪石以碎裂变形为主, 局部具有塑性变形的特征;在700℃时, 样品以晶体扭折变形为主, 局部出现脱水和细粒微晶, 并且含有微破裂, 显示了样品以晶体扭折变形为主, 含有微破裂, 样品变形处于脆-塑性转换域;在800℃时, 样品中基本没有发现明显的脆性变形, 样品以动态重结晶作用为主, 角闪石出现脱水。因此, 在实验温压范围内, 在500℃→600℃→700℃→800℃条件下, 角闪石变形机制表现为脆性破裂→碎裂流动→晶体扭折→动态重结晶和脱水作用, 显示了角闪石经历了脆性—脆-塑转化—塑性变形的变形机制。

关键词: 角闪石, 高温高压, 脆-塑性转化, 微观结构, 变形机制

Abstract:

In this paper, rheological experiments are carried out on natural hornblende under high temperature and high pressure. We used polarizing microscope and scanning electron microscope to analyze the experimental samples' microstructure, investigating the mechanisms of hornblende under the condition of different temperature, pressure and strain rate. The experimental results reveal the following features of the stress-strain curves of deformed samples: As the temperature increases, the stress-strain curve of the samples changes gradually from strengthening to yielding and weakening, sample strength reduces significantly; with the increase of confining pressure, the sample strength increases; and with the decrease of strain rate, the sample strength reduces, and it significantly reduces in the samples with the compression direction heterotropic to foliation. Plenty of transgranular fractures as well as a small amount of cataclastic deformation occur in hornblendite at temperature of 500℃, and the deformed sample is dominated by brittle deformation. At temperature of 600℃, porphyroclast system consisting of residual plaques and cataclastic series grows in the samples, wavy extinction appears in part of hornblende crystals, the deformation is characterized mainly by cataclastic deformation with ductile deformation, locally. At temperature of 700℃, the deformation is mainly dominated by intragranular kink, and dehydration and fine-grained microcrystalline appear locally, containing microcracks. The deformation of the sample is in the brittle-plastic transition phase; At temperature of 800℃, almost no obvious brittle deformation is observed in the deformed samples, the samples are dominated by dynamic recrystallization, and dehydration appears. Therefore, at the temperature conditions of 500℃, 600℃, 700℃ and 800℃, the deformation of hornblende is characterized by brittle fracture, cataclastic flow, crystal kink, dynamic recrystallization and dehydration, which shows the deformation mechanism varying from brittle to brittle-ductile, and to ductile deformation.

Key words: hornblende, high pressure and high temperature, brittle-ductile transition, microstructure, deformation mechanism

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