控制热力学下各向异性对含水的橄榄石及形变的橄榄岩电导率的实验研究

项目名称： 控制热力学下各向异性对含水的橄榄石及形变的橄榄岩电导率的实验研究

项目编号： No.41474078

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： 代立东

作者单位： 中国科学院地球化学研究所

项目金额： 100万元

中文摘要： 将交流阻抗谱技术与多面顶高温高压设备 (YJ-3000t和6-8型铰链式二级顶砧) 相结合，以美国San Carlos单晶和合成的多晶橄榄石为初始样品，通过热压合成不同水含量的样品，在高温高压条件下原位测量样品的电导率，通过样品电导率的Arrhenius 关系拟合出活化焓、指前因子、活化能、活化体积等物性参数，建立起单晶橄榄石随着温度、压力、氧逸度、水含量和晶轴各向异性函数关系模型；通过对不同铁分数的合成多晶橄榄石电导率的原位测量，建立起样品电导率随着成分和水含量变化的函数关系模型；建立样品电导率随着时间、剪切应力、不同熔融分布状态和晶轴方向变化的函数关系模型。该工作将为解释大地电磁测深观测的软流圈顶部的电导率高导异常、东太平洋南部隆起与中美洲尼加拉瓜海沟的板块构造活动带的成因及地球与行星内部的电导率-深度剖面的建立，提供重要的科学依据。

中文关键词： 电导率；晶轴各向异性；橄榄石；形变；水

英文摘要： In conjunction with the AC impedance spectroscopy technique of electrochemistry and multi-anvil high-pressure apparatus (e.g. YJ-3000t and 6-8 type of second class anvil), we selected San Carlos olivine single crystal and polycrystalline olivine aggregates as starting materials. The experimental samples were obtained by virtue of hydrothermal hot-press synthesis. The in-situ electrical conductivities were measured at corresponding high temperature and high pressure conditions. A series of bulk parameters that is expressed in the Arrhenius linear relation will be obtained such as the activation enthalpy, pre-exponential factor, activation energy, activation volume, etc. A novel functional relation model will be established based on the electrical conductivity of San Carlos single crystal along with temperature, pressure, oxygen fugacity, water content and different crystallographic axis. Through the electrical conductivity measurements of polycrystalline olivine aggregates with a different iron percentage, a functional relation model will be obtained from electrical conductivity of sample along with the variation of chemical composition and water content. A functional model for peridotite will be built on the base of the relationship between electrical conductivity and time, shear strain, distribution of partial melting state and different crystallographic axis. All of present results will provide an important constraint for the explanation of high electrical conductivity anomaly on the top of asthenosphere for geophysicist, the cause of southern East Pacific Rise and the tectonic band of Cocos plate in the Middle America trench offshore of Nicaragua, and as well as the establishment of conductivity-depth profile in the deep Earth and planetary interiors. The electrical conductivities of hydrous single crystals and polycrystalline aggregates will present a crucial basic database and scientific evidence.

英文关键词： Electrical conductivity;anisotropy;olivine;deformation;water