Package fluids. Part 5: The NaCl-H2O system in fluid inclusion research and applications of the software AqSo_NaCl (Bakker, 2018)

The software AqSo_NaCl (Bakker, 2018) can be used to characterize the properties of phases that may exist in the binary H2O-NaCl system up to 1000 degrees C and 500 MPa. The model replaces all available correlation equations and other equation of state that are restricted to narrow temperature, pressure, and composition intervals. Liquid-vapour, liquid-solid, and vapour-solid immiscibility fields emerge with increasing salinity at relative high temperatures, and already occur at mass fractions of a few mu g per gram. The liquid-vapour immiscibility is split in two fractions in solutions between x(NaCl)=2.10(-5) and 0.00025, at salinities that cannot be detected by microthermometry. Properties such as density, molar volume, composition, and volume fraction of liquid, vapour, and solid phases in fluid inclusions can be calculated in heating and freezing experiments. Isochores can be calculated within the homogeneous fluid field, within immiscibility fields, and along the SLV (solid-liquid-vapour) curve. Iso-Th lines are obtained by modifying the total volume of fluid inclusion with the volumetric properties of quartz. Bulk properties of fluid inclusions can be directly calculated from microthermometric data.