Abstract

Field magnetotelluric (MT) observation data confirmed the widespread existence of electrical anisotropy in the mid-lower crust and upper-mantle regions. Several potential electric transport mechanisms, such as the mineralogical fabric, the lithologic layering, the preferential alignment of fluid or melt, etc., have been put forward to reasonably explain the anisotropic electrical conductivity. However, the detailed contributions of each mechanism to rock-scale electrical anisotropy are difficult to quantify using laboratory-based electrical conductivity measurements. Herein, we develop GeoAnisoLab, an absolutely new numerical modeling program to characterize the anisotropic electrical conductivity of rocks at high temperature and high pressure. It integrates crystallographic preferred orientations, mineral conductivity data, and resistor-network modeling by constructing five typical petrological models (i.e., a randomly distributed rock model, two lithologically layered models, a fluid-bearing layered model, and a melt-bearing layered model). In comprehensive considerations of previously available high-pressure experimental and filed MT results, the GeoAnisoLab numerical modeling method can systematically assess the anisotropic conductivity anomalies in the deep Earth.

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