Laboratory-based electrical conductivity in the Earth's mantle

Recent laboratory measurements of electrical conductivity of mantle mineral s are used in forward calculations for mantle conditions of temperature and pressure. The electrical conductivity of the Earth's mantle is influenced by many factors, which include temperature, pressure, the coexistence of mu ltiple mineral phases, and oxygen fugacity. Ln order to treat these factors and to estimate the resulting uncertainties, we have used a variety of spa tial averaging schemes for mixtures of the mantle minerals and have incorpo rated effects of oxygen fugacity. In addition, to better calculate lower ma ntle conductivities, we report new measurements for electrical conductivity of magnesiowustite (Mg0.89Fe0.11)O. Because the effective medium theory av erages lie between the Hashin-Shtrikman bounds for the whole mantle, a labo ratory-based conductivity-depth profile was constructed using this averagin g scheme. Comparison of apparent resistivities calculated from the laborato ry-based conductivity profile with those from field geophysical models show s that the two approaches agree well.