杨晓松,,
姚路,
陈进宇,
马胜利
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
基金项目: 自然科学基金（41672197，41372202）项目和科技部地震行业科研经费专项（201508018）共同资助
详细信息
作者简介: 韩明明, 男, 1988年生, 硕士研究生, 构造地质学专业, 主要从事矿物岩石电导率相关的实验研究.E-mail:hanmmbj@126.com
通讯作者: 杨晓松, 男, 1959年生, 主要从事实验岩石物理学研究.E-mail:xsyang@ies.ac.cn
中图分类号: P313收稿日期:2018-03-14
修回日期:2018-04-17
上线日期:2019-03-05
A research on the conductivity characteristics of carbon-rich fault zones based on the middle-to high-velocity frictional experiments
HAN MingMing,YANG XiaoSong,,
YAO Lu,
CHEN JinYu,
MA ShengLi
State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
More Information
Corresponding author: YANG XiaoSong,E-mail:xsyang@ies.ac.cn
MSC: P313--> Received Date: 14 March 2018
Revised Date: 17 April 2018
Available Online: 05 March 2019
摘要
摘要:野外地质调查结果显示，断层带常富集碳质.断层带中碳的分布结构是影响断层带电导率特征的一种重要参数.本文在室温、室内湿度和2 MPa正应力条件下，对不同石墨含量（3，5，6和7 wt%）的石英-石墨混合断层泥模拟样品开展了滑动速率介于500 μm·s-1~1 m·s-1的摩擦实验及相应的电导率测量，以期研究断层运动对碳分布结构的影响以及断层带电性特征对碳含量及分布的响应情况.结果显示，摩擦滑动能够显著地改变样品的电性特征（电导率大小及其各向异性）.在平行滑动面方向（径向），样品电导率随着滑动位移的增加快速增加，在滑动约数十厘米之后，其电导率基本达到稳定状态；在垂直滑动面方向（轴向），样品电导率基本不随摩擦滑动速率和滑动距离而变化.SEM显微结构观测显示，摩擦滑动所引起的电导率各向异性直接反映了石墨分布结构的变化.该研究结果深化了对地震断裂带浅部电性特征的认识，为野外断层带大地电磁测深资料的解释提供了约束，同时对于了解含碳断层的力学性质和弱矿物相在剪切变形中的分布特征及其演化过程等方面也具有重要意义.
关键词: 断层带电导率/
导电结构/
摩擦滑动/
碳质/
石墨
Abstract:Field geological surveys reveal that carbon is often enriched within natural fault zones. The distribution of carbon in fault zones is a crucial parameter influencing the electrical conductivity of fault zones. In this paper, we study the impact of fault motion on carbon distribution and the effects of carbon content and distribution on the electrical characteristics of faults through friction experiments incorporated with electrical conductivity measurements. The experiments were conducted on the mixtures of quartz-graphite with different graphite contents (3, 5, 6 and 7 wt%), at a normal stress of 2 MPa and slip rates ranging from 500 μm·s-1 to 1 m·s-1, under room temperature and humidity. Experimental results indicate that frictional sliding can significantly change the electrical conductivity of samples (magnitude and anisotropy of conductivity). In the direction parallel to the slip surface, the conductivity of the sample increases rapidly with shear displacements and then stabilizes after slipping about tens of centimeters, while the sample conductivity does not change with slip velocities and distances along the direction perpendicular to the slip surface. SEM microstructures analyses show that the anisotropy of electrical conductivity caused by frictional slip directly reflects the distribution structure of graphite. This study deepens our understanding on the electrical characteristics of shallow fault zones, and provides an important constraint on the interpretation of field magnetotelluric data. Furthermore, our results are significant in understanding the mechanical properties of carbon-rich fault zones, besides the distribution characteristics and the evolution processes of weak minerals during displacements in the shear deformation.
Key words:Electrical conductivity of fault zone/
Conductive structure/
Frictional sliding/
Carbon/
Graphite
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