Contrib Mineral Petrol 145:119–129īenisek A, Kroll H, Cemič L (2004) New developments in two-feldspar thermometry. Geochim Cosmochim Acta 45:847–853īenisek A, Kroll H, Cemič L, Kohl V, Breit U, Heying B (2003) Enthalpies in (Na, Ca)- and (K, Ca)-feldspar binaries: a high temperature solution calorimetric study. Miner Mag 53:337–345Īndersen DJ, Lindsley DH (1981) A valid Margules formulation for an asymmetric ternary solution: revision of the olivine-ilmenite thermometer, with applications. The reasons for the problems associated with phase-equilibrium based mixing models are discussed.Īi Y, Green DH (1989) Phase relations in the system anorthite-potassium-feldspar at 10 kbar with emphasis on their solid solutions. It was found that the new model largely eliminates discrepancies between observed and predicted feldspar compositions that were present in earlier attempts. a teschenite sill in Scotland, the Klokken syenogabbro in Greenland, and a granulite-facies metapelite in Sri Lanka) were used to test the mixing models. Natural feldspar assemblages from well-studied magmatic and high-grade metamorphic rocks (i.e.
The incorporation of K into Ca-rich plagioclase and of Ca into K-rich alkali feldspar is more strongly limited by our calorimetry-based model, whereas the stability field of Na-rich feldspars is broadened. Comparisons with existing mixing models, which are based on phase-equilibrium experiments, reveal distinct differences. A mixing model for high structural state ternary feldspars in the NaAlSi 3O 8–KAlSi 3O 8–CaAl 2Si 2O 8 system is presented based exclusively on calorimetric and volumetric measurements.
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