Electrical Conductivity Models of the Crust

Abstract

Compositional crustal models (continental, subcontinental, oceanic) are used as a basis for a construction of the electrical conductivity distribution within the crust. In addition, the procedure incorporates other parameters, such as pressure, porosity, pore fluid salinity, and resistivity. Calculation is made in three steps. First, 'dry' models based on mineral conduction alone are constructed. Second, electrolytic conduction through the pore fluids is estimated from the Archie's Law. Both results are then combined to produce the final, 'wet' models. These appear to agree with generalized conductivity profiles for the stable continental areas, as well as with the published values for the oceanic crust. Magnetotelluric response curves calculated for the final models give, for each crustal type, a band of possible responses which agree well with theoretical and in situ results.