Experimental investigation of silicate systems containing two volatile components; part I, Geometrical considerations

A discussion of the geometric representation of a system which contains two volatiles and albite at constant pressure. The possible phase relations of the general case albite-H_2O-C (or any other volatile) is depicted on ternary isobaric (TX) prisms, following a detailed description of the PTX model of the system albite-H_2O. Isothermal, isobaric sections are also illustrated for the general case. The petrologic significance of these diagrams is illustrated by considering the intrusion of magma into limestone where the experimentally determined system albite-H_2O-CO_2 could be utilized to indicate a crystallization sequence.