Compositions of aqueous fluids in equilibrium with pyroxenes and olivines at mantle pressures and temperatures

Interaction of jadeite with water at 20-30 kbar and 650°C

“…In contrast to jadeite and omphacitic pyroxenes, all the phases with low densities stable at lower pressures including quartz, albite, sanidine, and phlogopite exhibit solubilities increasing with rising pressure, fig. 3 (Kennedy, 1950;Clark, 1966;Ryabchikov and Boettcher, 1980). In comparison with the results of the present work for jadeite, it implies that for the isochemical phase assemblage a maximum should exist on the sodium concentration in the fluid-pressure curve in the pressure range where the plagioclase-clinopyroxene reaction takes place.…”

The composition of liquids coexisting with dense hydrous magnesium silicates at 11–13.5GPa and the endpoints of the solidi in the MgO–SiO2–H2O system

“…Nakamura and Kushiro (1974) showed that a fluid in equilibrium with forsterite and enstatite at 1.5 GPa, 1310°C dissolves more silica than magnesia on a molar basis. Ryabchikov et al (1982) indicated that at 3 GPa, 1100°C the molar Mg/Si ratio becomes 1.0 and fluids coexisting with forsterite and enstatite dissolve more than 30 wt% of silicate components. Kawamoto et al (2004), based on their experiments and previous investigations, presume that the Mg/Si ratio of aqueous fluid coexisting with enstatite and forsterite changes rapidly from silica-rich to magnesia-rich at around 3 GPa, 1000°C due to an inferred structural change of liquid water.…”

Composition of aqueous fluid from serpentinite in the subducted lithosphere.

“…Experimental studies on synthetic systems have shown that SiO2 and K2O can be dissolved to a certain extent in the aqueous fluid under mantle pressures (Nakamura and Kushiro, 1974;Ryabchikov and Boettcher, 1980;Ryabchikov et al, 1982).…”