Accomplishment-Based Renewal: Experimental Determination of the PVTX and Phase Equilibrium Properties of Aqueous Chloride Fluids at Magmatic-hydrothermal Conditions

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Increasing world population, combined with an overall increase in global standard of living, requires an ever-increasing amount of resources to meet human demands. The Earth is the source of all the minerals, metals and other natural resources required to manufacture the products needed to sustain a modern technological society. Exploration models designed to discover new occurrences of minerals and metals are based on an understanding of the various physical, chemical and biological processes that lead to the accumulation of metals and other resources into economic concentrations. Most mineral and metal deposits are formed when heated fluids in the Earth's crust dissolve, transport and deposit metals to form ore deposits, and most of the ore-forming fluids are highly-saline brines containing various salts. The goal of this project is to develop a better understanding of the fundamental properties of saline fluids at temperature and pressure conditions appropriate for ore-forming systems. This information, in turn, will lead to development of better mineral exploration models and contribute to economic stability and prosperity and promote a more secure future by reducing dependence on external sources to provide the raw materials needed for technological and defense applications. The project will also provide training in state-of-the-art experimental and analytical techniques for several students and young researchers from diverse backgrounds. Most natural saline fluids in the Earth's crust are approximated by the H2O-NaCl-KCl-CaCl2-FeCl2 system. Previous work has shown that the physical and chemical behavior of saline fluids at elevated temperatures and pressures is highly dependent on the total salinity of the fluid as well as the ratios of the various major salt components in the fluid. In this project experiments will be conducted to determine the Pressure-Volume-Temperature-Composition (PVTX) and phase equilibrium properties of aqueous chloride fluids at magmatic-hydrothermal PTX conditions. Synthetic fluid inclusions containing fluids with various binary, ternary, quaternary and quinary compositions within this five-component system will be trapped at magmatic-hydrothermal PTX conditions. Phase boundaries (liquid-vapor curves and liquidi), critical points, and isochores (lines of constant density) will be determined using the synthetic fluid inclusion technique that has proven to be successful in numerous earlier studies. Empirical numerical recipes to estimate compositions of fluids in the various sub-systems based on microthermometric and microanalysis of natural fluid inclusions will be developed from the experimental data. These data provide the basis for interpretations of microthermometric data from natural fluid inclusions and provide feedstock for future studies to develop empirical numerical models describing the PVTX properties of hydrothermal fluids over the range of PTX conditions appropriate for crustal hydrothermal systems. The results of this project will lead to a better understanding of the phase equilibrium and PVTX behavior of ?real? magmatic-hydrothermal fluids, and provide a solid basis for developing more robust mineral exploration models based on data obtained from studies of fluid inclusions in natural systems.