This grant supports the development of a rapid-quench, cold-seal hydrothermal laboratory, capable of operating to ~2 kbar and ~950 deg C and with the capability of automated, long-duration decompression and/or pressure increase/decrease cycling. The device will enable experimental simulation of static and/or dynamic processes in a pressure range that is appropriate for shallow magmatic, volcanic conduit, or ore-forming environments. Specific studies envisioned include: using pressure cycling to simulate repeated venting and resealing of volcanic conduits or hydrothermal ore forming systems and evaluating its impact on the formation of complexly zoned phenocrysts or quartz vein systems; using controlled decompression to study the development of vesicularity and permeability in volcanic systems, and; using long duration static experiments to determine stable isotope fractionations between coexisting melts and to study volatile solubilities in melts at volcanologically relevant pressures. The lab will facilitate collaborative research between the PI, colleagues in volcanology (K Cashman, P Wallace), ore deposits research (MH Reed) and stable isotope geochemistry (I Bindeman), and their students in the Department of Geological Sciences, University of Oregon. ***