Silicate diffusion in alkali-carbonatite and hydrous melts at 16.5 and 24GPa: Implication for the melt transport by dissolution–precipitation in the transition zone and uppermost lower mantle.

Highlights: [•] Mg2SiO4 diffusivity in K–Mg carbonatite melt is 2×10−9 m2/s at 16.5GPa and 1700°C. [•] MgSiO3 diffusivity in hydrous K–Mg carbonatite melt is 4×10−9 m2/s at 24GPa, 1500°C. [•] MgSiO3 diffusivity in hydrous-silicate melt is 5×10−8 m2/s at 24GPa and 1500°C. [•] Stress-driven transcrystalline migration rate of TZ and LM melts is 10−1–102 m/year. [ABSTRACT FROM AUTHOR]