Complex conductivity of graphitic schists and sandstones

Spectral Induced Polarization spectra were carried out on 3 graphitic schists and 2 graphitic sandstones. The microstructural arrangement of graphite of two graphitic schists was studied with thin sections using transmitted and reflected light optical and electron microscopic methods. Chemical maps of selected areas confirm the presence of carbon. The complex conductivity spectra were measured in the frequency range 10 mHz to 45 kHz and in the temperature range +20°C down to -15°C. The measured spectra are fitted with a double Cole Cole complex conductivity model with one component associated with the polarization of graphite and the second component associated with the Maxwell Wagner polarization. The Cole Cole exponent and the chargeability are observed to be almost independent of temperature including in freezing conditions. The conductivity and relaxation time are dependent on the temperature in a predictable way. As long as the temperature decreases, the electrical conductivity dec...

本数据集针对3块石墨片岩与2块石墨砂岩开展了频谱激发极化（Spectral Induced Polarization, SIP）谱测试。研究人员借助薄片样品，结合透射光、反射光光学显微与电子显微技术，分析了其中2块石墨片岩内石墨的微观结构排布特征。选定区域的化学图谱证实了碳元素的存在。复电导率谱的测试频率范围为10毫赫兹（mHz）至45千赫兹（kHz），温度覆盖+20℃至-15℃区间。所测得的谱图采用双科尔-科尔（Cole-Cole）复电导率模型进行拟合，其中一个分量对应石墨的极化效应，另一分量对应麦克斯韦-瓦格纳（Maxwell Wagner）极化。研究发现，科尔-科尔指数与充电率几乎不受温度影响，即便在冻结条件下亦是如此；而电导率与弛豫时间则随温度呈现可预测的变化规律。随着温度降低，电导率随[原文未完整表述]