NSF-SNSF: Thermodynamic framework for modeling hydrothermal fluid-rock interaction and the mobility of critical elements in the Earth's crust

Critical elements such as lithium (Li), copper (Cu), nickel (Ni), cobalt (Co), and the rare earth elements (REE) are important to society. Magnets, computers, cell phones, and batteries all use critical elements. In geological systems, critical elements are transported and enriched by interactions between rocks and fluids. Enrichment can occur at a wide range of pressures and temperatures. These conditions occur in environments such as surface geothermal systems and deep ore deposits. This project will use experiments and geochemical data to model the behavior of critical elements. Broader impacts include student and postdoctoral researcher training. The project also includes workshops and student internships. This collaborative NSF-SNSF funded research project aims at improving geochemical modeling of hydrothermal systems. The focus of the work will be on major rock-forming and critical elements including Li, Cu, Ni, Co, and the rare earth elements (REE). These are important components in the high-tech and energy industry (i.e., permanent magnets, computers, cell phones, etc.). Thermodynamic modeling of fluid-rock interaction has many geoscience applications from near-surface geothermal to deep magmatic-hydrothermal ore deposits. Hydrothermal fluids can transport and enrich critical minerals in the Earth’s crust via the formation of aqueous complexes. However, the accuracy of thermodynamic models strongly depends on two main challenges: (1) the quality and completeness of thermodynamic datasets for aqueous species, minerals, and gases; (2) the equations of state for calculating the necessary thermodynamic properties over a wide range of pressure and temperature. This project involves three thrusts. Thrust 1 aims at developing a novel framework to integrate multiple equations of state for different pressure-temperature regimes. The framework is built on a strong foundation of open-source tools (ThermoEcos) for data fitting, modeling, and visualization. Thrust 2 aims to determine the thermodynamic properties of Li, Cu, Ni, Co, and REE aqueous complexes in hydrothermal solutions. Thrust 3 aims to test and apply the thermodynamic model to natural geothermal systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.