Method of synthetic fluid inclusions in quartz in experimental study of the water-sodium sulfate system

The aim of this study is to estimate the capability of the method of synthetic fluid inclusions in experimental investigation of the properties of aqueous salt solutions, whose phase diagram is attributed to the second (P-Q) type (in such solutions, critical phenomena are observable in both undersaturated and saturated states). The water-sodium sulfate system has been selected from the systems of the second type as the best studied with another experimental technique. Fluid inclusions in quartz have been synthesized in the field of examined temperatures and pressures in the presence of sodium sulfate solutions of a given concentration. Microthermometry of these inclusions shows a partial correspondence to properties of sodium sulfate solutions, which were previously studied by recording temperature-pressure and volume curves at the moment of phase transition. Discrepancies are probably caused by the active behavior of silica with respect to the fluid and the effect of the third component upon equilibrium in the fluid.