Grant: Discovery Grants Program - Individual

) The goal of my research program is to understand how rare elements, such as tantalum, niobium and lanthanides, exist as dissolved constituents in fluids and melts within the crust of the Earth, and to use this knowledge to more accurately model geochemical processes such as rare element ore formation. The method proposed consists of two parts: [1] detailed analyses of fluid and melt inclusions (i.e., tiny samples of fluid or melt trapped within minerals), and [2] direct studies of relatively simple experimental fluid and melt systems at geologically relevant temperatures and pressures. The chemical composition of fluid and melt inclusions collected from major ore deposits will be determined using complementary micro-analytical techniques. These data will then be used to prepare experimental melt and fluid systems that will be directly analyzed at elevated pressures and temperatures in a diamond window cell, using high brilliance x-rays from a synchrotron light source. The x-ray emission and absorption spectroscopic data obtained will provide new and important insights into the structure and composition of aqueous fluids coexisting with melts or solid phases. These data are needed to understand the chemical controls of rare element transport and deposition by hot fluids within the Earth. The results of this research will enhance our ability to predict where rare elements may concentrate to form ore deposits and improve our ability to interpret chemical fingerprints in rocks that were influenced by hydrothermal (i.e., hot water) processes. Furthermore, the new methods employed and the data obtained have wider application to solving problems such as industrial boiler corrosion, degradation of toxic wastes, and the confinement of radioactive wastes.