9709783 Dilles This grant provides $20,000 as partial support of the costs of acquiring a heating/freezing stage coupled with a microscope and video system for use in studies of the physical and chemical properties of fluid inclusions. A recently funded research proposal (EAR-9614683) will rely on data produced using this instrument to constrain fluid inclusion trapping pressures to augment isotopic and petrologic data in the interpretation of the temporal evolution of hydrothermal fluid compositions and subsequent wall rock alteration that led to the formation of the porphyry ore deposit at Butte, Montana. In addition, this system will be used in combination with isotopic analyses of primordial helium contained in fluid inclusions trapped in mafic phenocrysts and xenoliths to yield insight into the petrogenesis of mid-ocean ridge and oceanic hot spot basalts. Other projects that will benefit from this system include, studies of fluid inclusions in metasomatized evaporite deposits and studies of fluid inclusions trapped in diagenetic quartz overgrowths in clastic sedimentary rocks. ***
