Rutile solubility in hydrous rhyolite melts at 750-900 °C and 2 kbar, with application to titanium-in-quartz (TitaniQ) thermobarometry

Application of this extended TiO2 solubility model to natural melt inclusions in quartz phenocrysts from five silicic volcanic systems returns TiO2 activities that are similar to those calculated with a previous experiment-based model and to those calculated from pairs of coexisting Fe-Ti-oxides, but are up to 2.9 times higher than those calculated with MELTS and rhyolite-MELTS. Pressures calculated from Ti concentrations in the host quartz using the most recent calibration of the TitaniQ thermobarometer are in good agreement with independent pressure estimates, suggesting that at upper crustal conditions this calibration is valid.