Density Calculation for NaCl-H2O Solutions in the Liquid-Solid Two-Phase Field in NaCl-H2O Three-Phase Inclusions.

Three-phase NaCl-H2O fluid inclusions featuring halite dissolution temperature ( Tm) higher than vapor bubble disappearance temperature ( Th) are commonly observed in porphyry copper/molybdenum deposits, skarn-type deposits and other magmatic - hydrothermal ore deposits. Based on | ΔV1| (the absolute value of volume variation of NaCl-H2O solution in a heating or cooling process of inclusions)= | ΔVs| (the absolute value of volume variation of the halite crystal in a heating or cooling process of inclusions) and on the principle of conservation of the mass of NaCl and H2O, we systematically calculated the densities of NaCl-H2O solutions in the solid-liquid two-phase field for temperatures ( Th) from 0.1°C to 800°C and salinities from 26.3 wt% to 99.2wt%. Consequently for the first time we obtained the upper limit of the density of NaCl-H2O solutions in the solid-liquid two-phase field for Th< Tm inclusions with variant salinities. The results indicate that for inclusions of the Th< Tm type with the same Th, the higher the Tm or salinity is, the higher the density of the NaCl-saturated solution will be. If a group of fluid inclusions were homogeneously trapped, they must have the same Th value and the same Tm or salinity value. This may be used to distinguish homogeneous, inhomogeneous, and multiple entrapments of fluid inclusions. [ABSTRACT FROM AUTHOR]