Electrical properties of some magmatic dike rocks at high temperatures

Abstract

The electrical properties of magmatic rocks (diabase and granite porphyry) from the complex dike located in the Main Caucasian (Akhtychaisk) fault zone are examined at temperatures of 100–1000°C. It is established that the increase in the electrical conductivity from granite porphyry to diabase is caused by the decreased quartz content, increased total content of iron oxides FeO and Fe2O3, as well as the fine-grained texture of diabases and their secondary alterations. The pattern of temperature dependence of specific electrical conductivity observed in granite porphyry and diabases reflects the polymorphic transformation of the monoclinic structure to the triclinic structure (the MT-transformation), which occurs in the feldspar component of the rock. Another factor responsible for the shape of the mentioned temperature dependence is that the formation of an extrinsic mechanism of conduction is dominated by the defects (associated into complexes) in the crystal lattices of the minerals. This allows determining the energy of formation and migration of lattice defects and the energy of association of the lattice defects into complexes, which play an important role in the natural metamorphic processes. The AC measurements for the granite porphyry revealed frequency dispersion of the electrical conductivity, which decreases with increasing temperature.