Thermodynamic analyses of equilibria involving olivine, orthopyroxene and garnet
1983; Elsevier BV; Volume: 47; Issue: 10 Linguagem: Inglês
10.1016/0016-7037(83)90017-0
ISSN1872-9533
AutoresToshisuke Kawasaki, Yoshito Matsui,
Tópico(s)Nuclear materials and radiation effects
ResumoExperiments were made on the orthopyroxene-garnet relationships in the system FeSiO3-MgSiO3-Al2O3 at 50 kbar and 1100–1500°C. Combining new and previously published data, thermodynamic analysis was carried out on the following equilibria: (1) Mg2Si2O6 + MgAl2SiO6 = Mg3Al2Si3O12 opx solid solution garnet (2) Fe2Si2O6 + FeAl2SiO6 = Fe3Al2Si3O12 opx solid solution garnet (3) 12Fe2Si2O6 + 13Mg3Al2Si3O12 = 12Mg2Si2O6 + 13Fe3Al2Si3O12 opx garnet opx garnet (4) 12Fe2SiO4 + 13Mg3Al2Si3O12 = 12Mg2SiO4 + 13Fe3Al2Si3O12. olivine garnet olivine garnet A multisite regular solution for orthopyroxene and regular solutions for both olivine and garnet are sufficient to describe equilibria between these phases. The microscopic model shows that the ferrosilite-enstatite solid solution system is macroscopically an asymmetric mixture with an excess free energy that is practically temperature-independent above 1100°C.
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