Interaction between Aqueous Fluid and Silicate Melt in the Pressure and Temperatures Regime of the Earth's Crust and Upper Mantle
Mysen, Bjorn O.
published: May 1, 1998
ArtNo. ESP154017202006, Price: 29.00 €
The solubility and solubility mechanisms of H2O have been determined for melts in the system K2O-SiO2-H2O from 0.8 to 2.0 GPa in the 700-1100 °C temperature range. Solubility and solubility mechanisms of the silicate in coexisting aqueous fluids were also determined. Solubility mechanisms of water and silicate in coexisting melts and aqueous fluids were determined by in-situ, high-temperature/high-pressure Raman spectroscopy. Solubility of silicate and H2O was determined chemographically. The water solubility in the melts displays a weak negative correlation with K/Si, whereas the silicate solubility in the coexisting fluid is a strong positive function of K/Si so that for the most potassic composition studied, K2Si2O5, nearly complete miscibility between hydrous melt and silicate saturated aqueous fluids were observed at 2.0 GPa. The H2O solubility shows a small linear and negative correlation with temperature. The silicate solubility in aqueous fluid increases with increasing temperature. Both solubilities are strong non-linear and positive functions of pressure. The temperature-dependence becomes more pronounced with increasing pressure and with increasing K/Si. From high-pressure/high-temperature in-situ Raman spectroscopy the silicate speciation in both melts and coexisting aqueous fluids resemble one another with Q3 and Q2 species associated with adjacent K + in the structure, and with H2O bonded as K-OH and H4SiO4 type complexes.