Diffusion in wadsleyite and ringwoodite and implications for the rheology of the mantle transition zone

Abstract

Si and O diffusion rates on polycrystalline (Mg,Fe)2SiO4 wadsleyite and ringwoodite have been determined at pressures between 16 to 22 GPa and temperatures between 1673 to 1873 K. The results show that Si diffusion rates is slower than O diffusion rates and previously reported Mg-Fe interdiffusion rates in both (Mg,Fe)2SiO4 wadsleyite and ringwoodite. Consequently, Si is likely to be rate-controlling species in high-temperature creep.