The solubility of corundum in H2O at high pressure and temperature and its implications for Al mobility in the deep crust and upper mantle

The solubility of corundum in H2O was measured at 700–1100 °C and 0.5–2.0 GPa using a piston–cylinder apparatus and weight-loss methods. At 700 °C, 0.5 GPa, Al concentration is 0.41 ± 0.15 millimolal (1σ analytical error). Corundum solubility increases strongly with pressure (P) and temperature (T), reaching 2.57 ± 0.15 millimolal at 700 °C, 2.0 GPa, and 27.3 ± 1.5 millimolal at 1100 °C, 2.0 GPa. The results were fitted with the equation log mAl = 1.131 + 3827 / T − (2.277 − 7336 / T)logρH2O, where mAl is molality of Al, ρH2O is the density of H2O in g/cm3, and T is in Kelvin. The data indicate that Al can have significant solubility in H2O during metamorphic and metasomatic processes in the deep crustal and upper mantle.