Solubility of enstatite forsterite in H2O at deep crust/upper mantle conditions: 4 to 15 kbar and 700 to 900°C
نویسندگان
چکیده
Ten reversed brackets of aqueous silica concentration in equilibrium with enstatite (Mg2Si2O6) and forsterite (Mg2SiO4) were determined at 700 to 900°C and 4.35 to 14 kbar. Silica solubilities were measured by a weight loss-weight gain method and by approaching equilibrium from higher and lower silica concentrations. Both single-crystal and fine-grained synthetic enstatite and forsterite starting material were used, as well as low-Fe natural minerals. Results for all three kinds of starting material were concordant. Silica concentrations buffered by enstatite forsterite at 10 kbar increase from 0.16 moles/kg H2O (m) at 700°C to 0.50 m at 900°C, but show only small variation with pressure in the range 7 to 14 kbar. The ratio XS /XS , where XS Q is the mole fraction of aqueous SiO2 (S) in equilibrium with quartz (Q) from Manning (1994), and XS FE is the corresponding mole fraction in equilibrium with forsterite (F) and enstatite (E) at the same P and T, from 1 to 15 kbar and 700 to 900°C is described by
منابع مشابه
Quartz solubility in H2O-NaCl and H2O-CO2 solutions at deep crust-upper mantle pressures and temperatures: 2–15 kbar and 500–900°C
The solubility of quartz in H2O-NaCl solutions was measured at 2, 4.35, 10 and 15 kbar and 500–900°C, and at NaCl concentrations up to halite saturation, usually greater than 75 wt.%. Quartz solubility was also measured in CO2-H2O solutions at 10 kbar and 800°C. Solubilities were determined by weight loss of ground and polished quartz crystal fragments which were equilibrated with solutions in ...
متن کاملExperimental determination of calcite solubility in H2O-NaCl solutions at deep crust/ upper mantle pressures and temperatures: Implications for metasomatic processes in shear zones
The solubility of calcite in NaCl-H2O solutions was measured at 600–900 ∞C, 10 kbar, at NaCl concentrations ranging from dilute to near halite saturation, and at 6–14 kbar, 700 ∞C, in 30 mol% NaCl solutions. Solubility was determined from the weight loss of cleavage rhombs of a pure natural calcite after experiments of 1/2 to 6 days in a piston-cylinder apparatus with NaCl-graphite furnaces. Ca...
متن کاملThe 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. Th...
متن کاملThe reaction talc 1 forsterite 5 enstatite 1 H 2 O : New experimental results and petrological implications
The reaction talc 1 forsterite 5 enstatite 1 H2O has been investigated between 6 and 20 kbar. Previous high-pressure experimental studies suggested various reaction positions, mostly with positive P-T slopes. The new results show that the reaction has a negative slope in the pressure range studied. It was bracketed between 640 and 680 8C at 10 kbar, between 620 and 640 8C at 15 kbar, and betwee...
متن کاملMobilizing aluminum in crustal and mantle fluids
Aluminum is a major rock-forming element, but its low solubility in H2O at upper crustal conditions has led to the assumption that it is effectively immobile during fluid–rock interaction in the deep crust and upper mantle. However, new experimental results on Al solubility in H2O–SiO2–NaCl fluids at high pressure and temperature challenge this view. The combined effects of temperature, pressur...
متن کامل