The metal inventory and formation of hydrothermal ore deposits

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A variety of elements, mostly metals, are important to support the technology that is a foundation to our modern society. This includes green technologies such as wind turbines and hybrid cars. It is important that we are able to efficiently find concentrations of these metals, which requires an understanding of how they are transported and concentrated in the crust of the Earth. My research is concerned with understanding the processes that lead to such concentrations of metals and the nature of the mineral deposits that contain them. Of particular interest are rare or critical elements such as lanthanum, neodymium, zirconium, tungsten and indium. Some of these are very important to green technologies; the average hybrid car contains 30 kg of rare earth elements. These elements are concentrated by a variety of processes that involve metal transport by magmas and fluids. It is the chemistry of these magmas and fluids that I study to gain insights into the concentration processes on a variety of scales. Natural systems such as these are chemically and physically complex on a microscopic scale, requiring us to develop and use techniques for the chemical characterization of earth materials on the micron scale. This includes using the abundances of various isotopes in minerals to trace the origins of the magmas and fluids from which they precipitated. In addition, the fluids that have carried the metals in many cases are trapped as microscopic "fluid inclusions" within minerals. Analysis of these allows us examine and characterize the actual fluids that were responsible for metal transport and concentration, even if this happened billions of years ago. These fluid inclusions are very small (typically <30 microns) and so we also develop and use micro-analytical techniques to chemically characterize them. The abundances of the commodities (metals and other elements) that are concentrated in ore deposits can vary significantly from one apparently similar environment to another, as can the size of otherwise similar deposits. This research is designed to understand the fundamental parameters and processes that influence the metal inventories of deposits and their size.