This grant supports acquisition of equipment for research on microscale heterogeneity in trace element, radiogenic, and stable isotopic compositions of natural materials. The Department of Geology at Northern Arizona University will acquire a Nd-YAG UV laser and desolvation nebulizer sample introduction systems to be interfaced to an existing multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS), a microdrill, and a continuous flow system to be mated to an existing stable isotope ratio mass spectrometer (SIRMS). These peripherals will allow for micron-scale sampling of microgram sized samples that can be directly introduced into the mass spectrometers. The UV laser ablation system and desolvation nebulizer will support research on the residence time and chemical evolution of crustal magma chambers that requires radiogenic isotope geochronologic (e.g., U-series disequilibria) and trace element analysis of microscale, concentric growth rims of accessory phases (e.g., zircon and allanite). The microdrill and continuous flow system will support research on pathways and geochemical evolution of crustal fluids driven by tectonic forces at active margins. Additional research that would be supported include: themobarometric investigations of the Proterozoic crustal assembly of the North American Continent; stratigraphic correlation and evaluation of the distal extent of Quaternary tephras in the Western U.S.; and "forensic" studies of the transport and fate of radioactive fallout.
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