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Solubility and solution mechanisms of chlorine and fluorine in aluminosilicate melts at high pressure and high temperature.
- Source :
-
American Mineralogist . Oct2015, Vol. 100 Issue 10, p2272-2283. 12p. - Publication Year :
- 2015
-
Abstract
- The solubility and solution behavior of F and Cl in peralkaline aluminosilicate compositions in the systems Na2O-Al2O3-SiO2 and K2O-Al2O3-SiO2 have been determined for glasses quenched from melts equilibrated at 1400 and 1600 °C in the 1.0-2.5 GPa pressure range. With Al/(Al+Si) increasing from 0 to 0.33 in sodium aluminosilicate melts, F solubility (saturation concentration) increases from 3.3 to 7.4 mol%, whereas Cl solubility decreases from 5.7 to 2.5 mol%. There is no difference in F solubility in sodium or potassium aluminosilicate melts. However, the Cl solubility in potassic aluminosilicate melts is 40-60% lower than in sodic melts with the same Al/(Al+Si) and Na or K mole fraction. Fluorine depolymerizes the silicate melt structure and forms Si-F, Al-F, and Na-F complexes, the proportion of which depends on the melt Al/(Al+Si) ratio. Dissolution of Cl results in a small degree of depolymerization of Al-free silicate melt, whereas Cl has a polymerizing effect in aluminosilicate melts. In both cases, formation of Na-Cl complexes appears to be the driving solution mechanism. The differences in F and Cl solution mechanisms result in contrasting depolymerizing effects that become more pronounced with increasing degree of magmatic differentiation. Through such modifications of melt structure, F and Cl have significant effects on magma properties such as viscosity, compressibility, and element partitioning. [ABSTRACT FROM AUTHOR]
- Subjects :
- *FLUORINE
*DISSOLUTION (Chemistry)
*ALUMINUM silicates
*SILICATES
*OXYGEN compounds
Subjects
Details
- Language :
- English
- ISSN :
- 0003004X
- Volume :
- 100
- Issue :
- 10
- Database :
- Academic Search Index
- Journal :
- American Mineralogist
- Publication Type :
- Academic Journal
- Accession number :
- 110122758
- Full Text :
- https://doi.org/10.2138/am-2015-5201