To quantify the effect of H upon the kinetics of Fe–Mg interdiffusion in olivine, diffusion couples composed of crystals with Mg/(Mg + Fe) ratios of 0.91 and 0.83 were annealed under water-saturated conditions at 1373K and 300MPa. With fO2 buffered at the Ni/NiO phase boundary, fH2O of about 300MPa. The resulting interdiffusivity of about 10–16m2/s was approximately one order of magnitude larger than that measured under anhydrous conditions. The enhancement in diffusivity in the presence of water resulted from an increase in the concentration of cation vacancies associated with the introduction of high concentrations of protons as point defects into the olivine structure.

Effect of H+ on Fe–Mg Interdiffusion in Olivine, (Fe,Mg)2SiO4. Z.Wang, T.Hiraga, D.L.Kohlstedt: Applied Physics Letters, 2004, 85[2], 209-11