Calculated Phase Relations in the System Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O with Applications to UHP Eclogites and Whiteschists

Abstract

Pressure–temperature grids in the system Na2O–CaO–K2O–FeO–MgO– Al2O3–SiO2–H2O and its subsystems have been calculated in the range 15–45 kbar and 550–900°C, using an internally consistent thermodynamic dataset and new thermodynamic models for amphibole, white mica, and clinopyroxene, with the software THERMOCALC. Minerals considered for the grids include garnet, omphacite, diopside, jadeite, hornblende, actinolite, glaucophane, zoisite, lawsonite, kyanite, coesite, quartz, talc, muscovite, paragonite, biotite, chlorite, and plagioclase. Compatibility diagrams are used to illustrate the phase relationships in the grids. Coesite-bearing eclogites and a whiteschist from China are used to demons..