No effect of water on oxygen self‐diffusion rate in forsterite

We systematically measured oxygen self‐diffusion coefficients (DO) in forsterite along b crystallographic axis at a pressure of 8 GPa and temperatures of 1600–1800 K, over a wide range of water content (CH2O) from <1 up to ~800 weight ppm. The experimental results suggest that DO ∝ (CH2O)0.05±0.06 ≈ (CH2O)0. Thus, water has no significant effect on oxygen self‐diffusion rate in forsterite. Since the CH2O dependence of silicon self‐diffusion rate is also very small, the effect of water on olivine rheology is not significant by assuming the diffusion controlled creep mechanism.