Abstract: The electrical conductivity of Beijing dolomite and limestone has been studied by means of a high pressure apparatus of solid medium piston cylinder type. It is found that on each lgγ=f(1/T) curve there was a discontinuity interval followed by a straight line segment with a steep slope,and the electrical resistivity was very low (several Ω-m) at higher temperatures.Post-run X-ray powder diffraction revealed that graphite was deposited on the surfaces of samples. It was the newly deposited graphite layer that resulted in high conductivity of the sample.The physicochemical environments of the decarbonation and the onset temperature of graphite deposition were investigated and it is reasonable that a graphitic high conductivity layer might be formed in certain geolgical period, provided that there exists carbonate along with proper geological conditions in the crust.

Key words: High temperature and pressure, Carbanate, Electrical conductivity, Graphite, Oxygen Fugacity, Low resitivity layer

摘要： 利用固体介质活塞圆筒式高压容器测量白云岩与石灰岩的电导率。实验表明每种岩石的电导率变化都有一个不连续区间,实验后样品的x-射线粉晶分析结果证明样品表层的黑色物质为石墨,初步研究了石墨在高压容器中生成的条件。据此,本文认为,处于适当地质环境中的碳酸岩有可能形成石墨质的低阻层。

关键词: 高温高压, 碳酸岩, 电导率, 石墨, 氧逸度, 低阻层