The electrical conductivity structure of geodynamic processes

Abstract

Geodynamic processes involving heating and especially melting should have distinctive electrical conductivity structures, as the electrical conductivity of rock is strongly dependent on temperature and may change by an order of magnitude upon incipient melting, electrical conductivity can also change with the fabric modification of a rock, as in the formation of serpentine. Regional electrical conductivity can be studied by exploiting the common phenomenon of natural electromagnetic induction in the earth. Much of the physics of this process is still being analyzed and described, so that the method is not at the stage of being part of "orthodoxy". Both model and field examples show that rifts and trenches, the basic elements of geodynamics, should and do exhibit conductivity anomalies. While the anomaly of a particular model can be computed quite accurately, quantitative models for particular field data usually have poor resolution and are useful mainly to demonstrate the nature of any qualitative conductivity contrast present. A number of major conductivity structures have so far been found in Australia, a continent free of active first-order rifts and trenches. The causes of these structures are undetermined at present and are a subject for research in the future. Show more