Electrical properties of natural clay permafrost

Abstract

The resistivity, dielectric constant, and loss tangent of natural clay permafrost samples that have never been thawed have been measured as functions of temperature, applied uniaxial confining load, and applied electric field strength. DC resistivities are on the order of 105 ohm-m at −10 °C, with the complex resistivity becoming strongly frequency dependent within and above the range of 10 to 103 Hz (resistivity decreasing with increasing frequency). Below 103 Hz, the electrical properties are slightly dependent upon applied electric held, and below 105 Hz, the electrical properties are very strongly dependent upon applied uniaxial confining load. Several different mechanisms are responsible for the observed properties, including ionic conduction, a colloidal response that is similar to a Maxwell-Wagner type of effect, the relaxation of Bjerrum defects in ice, the relaxation of the unfrozen water molecules, and a possible relaxation of organic molecules in the unfrozen water sheath surrounding clay particles.