| 高温高压下天然玄武岩样品电导率的实验研究 |
| 蒋建军
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| 导师 | 代立东
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| 2013
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| 学位授予单位 | 中国科学院研究生院
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| 学位授予地点 | 北京
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| 学位名称 | 硕士
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| 学位专业 | 矿物学、岩石学、矿床学
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| 关键词 | 高温高压
电导率
玄武岩
阻抗谱
导电机制
电导率-深度剖面
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| 摘要 | 高温高压下，矿物岩石的电导率对自身的物理化学性质 (缺陷、微量杂质、各向异性等)、所处热力学条件 (温度、压力等) 与地球化学环境 (氧逸度等) 具有高敏感性，因此，电导率作为探究地球内部物质组成、状态和性质的重要物理参数之一，常常与大地电磁测深 (Magnetotelluric, MT) 和磁测深 (Geomagnetic Deep Sounding, GDS)结合，为反演地球内部的矿物组成、化学成分、热学结构、热力学状态、水的分布、部分熔融以及内部物质的运动过程提供约束。 玄武岩是一种基性喷出岩，是组成地壳的重要岩石。对天然玄武岩样品的电导率进行实验研究，可以更有效地约束地球物理大地电磁测深数据反演，建立更可靠的地壳内部电学分布模型。 本次实验利用YJ-3000t六面顶高压设备和Solartron-1260阻抗/增益相位分析仪，在0.5-2.0 GPa、823-1173 K和10-1-106 Hz下，采用交流阻抗谱方法，对三个不同地区的天然玄武岩样品进行了电导率原位测量。研究了温度、压力和成分对矿物电导率的影响，探讨了样品的导电机制，并取得了以下结论： 1. 实验样品的电导率对频率有很强的依赖性，实验中可获得表征样品导电性能的阻抗弧；电导率随温度的升高而增大，两者符合Arrhenius关系；随着压力升高，样品的电导率降低。 2. 不同的玄武岩样品电导率存在较大差别，通过对比其化学成分的差别，认为其电导率的不同是由铁含量的差异引起，随着样品中铁含量的升高，玄武岩的电导率增大。 3. 通过拟合计算，获得了表征样品电学性质的指前因子、活化焓、活化体积等物性参数。结合前人研究结果，认为样品的主要导电机制进为小极化子导电。 4. 利用不同温度和压力下测得的天然玄武岩电导率数据，结合各地的地温和地压梯度模型，粗略估算了样品采区的电导率-深度剖面。 |
| 其他摘要 | Electrical conductivity of Earth’s interior materials at high temperature and high pressure has a high sensitivity to its own physical and chemical properties (defects, trace impurities, anisotropic, etc.), thermodynamic conditions (temperature, pressure, etc.) and geochemical environment (oxygen fugacity, etc.). As an indispensable physical parameter to exploring the composition, status, and nature of Earth’s interior materials, the electrical conductivity data is often combined with results of magnetotelluric (MT) and geomagnetic deep sounding (GDS) to constrain the interpretion of the mineral components, chemical composition, thermal structure, thermodynamic state, distribution of water, and the partial melting and movement of materials in Earth’s interior. Basalt is an important mafic extrusive rock in the crust. Therefore, the study on the electrical conductivities of natural basalt samples has great significance for constraint of geophysical inversion and calculating a more accurate electrical distribution model in the crust. In this experiment, we adopt the AC impedance spectroscopy method to measured the in situ electrical conductivities of three natural basalt samples under the condition of 873-1173 K and 0.5-2.0 GPa by using the YJ-3000t cubic-anvil high-pressure apparatus and Impedance/Gain-Phase analyzer (Solartron-1260). We then discussed the influence of temperature, pressure, and composition on the electrical conductivity and mechanism of the conductivity of the sample. Our conclusion included: 1. Experimental results showed that the electrical conductivity of the samples demonstrated a strong dependence on frequency and gained an impedance arc which characterize the electrical properties of sample; The electrical conductivity increased with the rising temperature and fitted with the Arrhenius relation, decreasing slightly with the increase of pressure. 2. Electrical conductivities of natural basalt samples collected from three different regions were measured under high temperature and high pressure and compared with their chemical composition. Variations in electrical conductivity were believed to be contributed by differences in iron content. The electrical conductivity increased significantly with the increasing iron content in samples. 3. Appropriate calculations were made in order to obtain the physical parameters of the sample, such as pre-exponential constant, activation energy, and activation volume. The electrical conduction mechanism was supposed to be small polaron conduction after the comparison with previous research results. 4. Using the experimental data obtained from the electrical conductivity measurement of natural basalt samples and the particular geothermal and geopressure curves, we were able to estimate the conductivity-depth profiles located there. |
| 学科领域 | 地球深部物质与流体作用地球化学
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| 语种 | 中文
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| 文献类型 | 学位论文
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| 条目标识符 | http://ir.gyig.ac.cn/handle/352002/5829
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| 专题 | 研究生_研究生_学位论文
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推荐引用方式
GB/T 7714 |
蒋建军. 高温高压下天然玄武岩样品电导率的实验研究[D]. 北京. 中国科学院研究生院,2013.
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