ECO: A new reference model of dry olivine electrical conductivity

Abstract

Electrically Conductive Olivine, ECO, is presented as a new reference model for the electrical conductivity of dry olivine. The model takes into account the prevailing redox state, temperature and pressure in the upper mantle, as well as their effects on the conductivity, and is based on conductivity analyses of dry single crystal olivine at high pressures. The model demonstrates higher conductivity of olivine than those previously proposed standard olivine models, which rely on the conductivity of olivine measured at room pressure. Accepting that the bulk electrical structure is in general dominated by olivine, the upper mantle is more conductive than the estimates of the previous models. The olivine conductivity is in fact high at the oxidizing conditions of the shallow mantle, but drops at greater depths where the mantle portion is reducing. The model provides a new reference basis for understanding the electrical structure of the upper mantle, and is important for invoking any other conductive candidates to explain enhanced mantle conductivity.