项目名称： 杂质(Na,Al,K,Ca)和相变对石英电导率影响的实验研究及其地学应用启示

项目编号： No.41472048

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 单双明

作者单位： 中国科学院地球化学研究所

项目金额： 95万元

中文摘要： 石英是地壳中最主要的造岩矿物之一，并广泛存在于多种岩石、脉体和矿石中，且随着温度压力的变化，其在地球内部存在多种同质多像体；其电导率的测定结果对研究地球内部的物理化学性质变化起着至关重要的作用。本项目拟首先利用LA-ICP-MS微区微量元素分析技术获得石英样品的杂质浓度剖面；然后在高温(500-1900 K)高压(1.0-12.0 GPa)条件下原位测量石英及其高压同质多像体的阻抗谱；继而，结合样品杂质浓度剖面合理选择表征样品导电与极化过程的等效电路，获得不同温度和压力下的电导率以及各种杂质缺陷的特征参数；最终，研究高温高压下杂质和相变对石英电导率的影响。该成果为深入研究含石英岩石各矿物间在高温高压下的互扩散过程、利用大地电磁测深数据反演地球内部物质组成与结构、解释地球内部局部区域电导率异常等提供基本参数，同时为石英材料的科学利用与改性研究提供重要的科学依据。

中文关键词： 高温高压；杂质；相变；石英；电导率

英文摘要： Quartz is one of the most important rock-forming minerals, which widely occurs in many kinds of rocks, veins and ores, and it has many kinds of polymorphism as increasing pressure and temperature in the Earth's interior. Result of electrical conductivity of quartz is one of the most important information to study the variety of certain physical and chemical properties in the Earth's interior. In this project, we will first, measure the content of several impurities(Na,Al,K,Ca) by LA-ICP-MS method, and then measure the impedance spectroscopy of quartz and its high pressure polymorphisms at different temperature(500-1900 K) and pressure(1.0-12.0 GPa) conditions in situ; secnd, try to obtain the equivalent circuit diagram of the conduct and activate progress based on the isomorphism model of substitution compensation of Al-Si and the impurities content; third, calculate electrical conductivity by using least square method with the equivalent circuit diagram based on the impedance spectroscopy results, and then calculate the crystal point defect's thermodynamics parameters; finally, study the effects of impurities and phase transition on the electrical conductivity of quartz and its high pressure polymorphisms. We believe this result can be used to research the inter-diffusion progress of quartz with other minerals at high pressure and high temperature, and supply basic parameters for the tomography of the structure and composition in the Earth's interior, and also be used as a basis for scientific usage and properties modification of quartz materials.

英文关键词： High pressure and high temperature;impurity;phase transition;quartz;electrical conductivity