The effect of oxygen fugacity on ionic conductivity in olivine

The oxygen fugacity (f(o2)) may affect the ionic conductivity of olivine under upper mantle conditions because Mg vacancies can be produced in the crystal structure by the oxidization of iron from Fe2+ to Fe3+. Here we investigated olivine ionic conductivity at 4 GPa, as a function of temperature, crystallo-graphic orientation, and oxygen fugacity, corresponding to the topmost asthenospheric conditions. The results demonstrate that the ionic conductivity is insensitive to f(o2) under relatively reduced conditions (f(o2) below Re-ReO2 buffer), whereas it has a clear f(o2)-dependence under relatively oxidized conditions (f(o2) around the magnetite-hematite buffer). The ionic conduction in olivine may contribute significantly to the conductivity anomaly in the topmost asthenosphere especially at relatively oxidized conditions. (C) 2021 China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.

Automated summary

This study investigated the ionic conductivity of olivine at 4 GPa and found that it is insensitive to oxygen fugacity under relatively reduced conditions, but has a clear dependence on oxygen fugacity under relatively oxidized conditions. The ionic conduction in olivine may play an important role in the conductivity anomaly in the topmost asthenosphere.