Experimental Studies of Petrologic and Geochemical Kinetics

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

This project involves experimental investigations of chemical phenomena occurring at high pressures and temperatures in the Earth's crust and upper mantle. Specifically, the experiments are designed to shed light on the mechanisms and pathways by which low-abundance chemical elements and their isotopes move around in the Earth. Three specific sub-topics are being examined: 1) the effect of isotopic mass on the migration rates of atoms or molecules in molten rock (emphasizing the gas-forming elements S, C, H, O, and Cl); 2) the solubilities and migration rates of noble gases (He, Ne, Xe) in key minerals of the Earth's crust and upper mantle; and 3) the migration rates and storage of rare metallic elements (Pt, Au, Pd, W) in the boundaries between mineral grains of the Earth's mantle. The intellectual merit of these studies resides mainly in their addressing fundamental properties of Earth materials that serve as a basis for understanding the chemical evolution of our planet and its subsystems (core, mantle, crust and atmosphere). The mass effect on volatile-element mobility, for example, may lead to heretofore-unanticipated isotopic differences between volcanic emanations and their "parent" magmas. The behavior of noble gases in deep-seated minerals has a direct bearing on gas storage in the Earth and the evolution of the atmosphere. The presence and mobility of rare-metal atoms in grain boundaries could influence models of core-mantle separation and continued chemical "communication" between core and mantle over geologic time. Beyond the purely scientific merits, the broader impacts of this project lie in the education and training of graduate students in the design, execution and interpretation of experiments in high pressure-temperature materials science. The diverse skills gained in this endeavor are equally relevant to man-made materials as to those of the Earth, and the techniques developed are transferable to any field or application where the technology of high pressures and temperatures is important for materials synthesis or processing.