Solubility of water and carbon dioxide in an icelandite at 1400 degrees C and 10 kilobars

The concentrations of water and carbon dissolved in an icelandite glass quenched from 1400 degrees C and 10 kbar were measured using Fourier transform infrared spectroscopy and elemental analyses of carbon and hydrogen. Only carbon dioxide and water were observed in the fluid phase as analysed after quenching with a qudrupole mass analyser. The mole fraction of carbon dioxide in the fluid phase ranged from 0.36 to 0.95. Carbon is dissolved as carbonate except at the highest CO2 fluid fugacity, where a small amount of molecular CO2 is observed. Dissolved carbon in the glasses, calculated as CO2, remained constant at approximately 1 wt%, in spite of the different CO2 fluid fugacities. Water was dissolved as molecular water and as hydroxyl groups, the hydroxyl concentration in the quenched glasses remaining almost constant over the whole interval, whereas the molecular water dissolves in accordance with Henry's law. Molecular water peaks at 5200 cm(-1) and 1630 cm(-1), the hydroxyl peak at 4500 cm(-1), and the carbonate peaks at 1400 cm(-1)-1550 cm(-1) have been calibrated using elemental analyses of C and H in the quenched glasses. As molecular water decreases in the melt the higher wavenumber carbonate peak is observed to move towards the molecular water peak at 1630 cm(-1) causing a split of the carbonate peaks, ranging from 45 cm(-1) to 100 cm(-1).