The phase diagram of the CaO-Al2O3-SiO2 system at pressures of up to 40 kbar

On the basis of known experimental data, analysis of the topology of the ph ase diagram of the CaO-Al2O3-SiO2 system at pressures of up to 40 kbar has been carried out. The main phase relationships are experimentally verified and refined, and stability regions for such phases as wollastonite, larnite , rankinite, anorthite, helenite, grossular, Ca-tschermakitic clinopyroxene , calcium aluminates, etc. are characterized. The paper considers the locat ion of lines for monovariant equilibria and of points for nonvariant equili bria in the temperature-pressure coordinates. Also, a phase diagram for the CaO-Al2O3-SiO2 system is constructed, which includes all main phase relati onships at pressures of up to 40 kbar. From the topologic regularities of t he phase diagram of this system, the character of monovariant and nonvarian t equilibria for the stability regions of grossular, Ca-tschermakitic clino pyroxene, anorthite, etc. is refined. It is known that stable associations of Ca-tschermakitic clinopyroxene with quartz cannot exist. The constructed phase diagram is based only on the experimental data and is a noncontradictory model of the phase diagram of the CaO-Al2O3-SiO2 system at pressures of up to 40 kbar. It may be a basis for further refining phas e relationships in this system and for practical use in petrology and mater ials technology and on thermodynamic modeling.