AGE AND GENESIS OF W-MO-CU MINERALIZATION, GOLD HILL, UTAH

Increases in demand for tungsten and copper combined with a lack of domestic production of the former has led to an increase in exploration for these key commodities. Primarily thought to be skarn deposits, Utah's Gold Hill and Clifton mining districts host a Jurassic felsic pluton emplaced into a Mississippian to Pennsylvanian carbonate-dominated sedimentary sequence that is spatially associated with numerous polymetallic mineral deposits. This study focuses on W-Mo-Cu mineralization and aims to determine the relationships between geological setting, magma compositions, paleo-fluid evolution, and the resulting deposit characteristics of these skarn-like systems. The deposits in this region have not been extensively studied beyond observation and rough quantification of resource potential. Here, we present the preliminary results of research examining a number of different aspects of this type of mineralization. This includes in-depth petrographic analyses of samples from several mines in the district to outline deposit paragenesis, key mineral assemblages, and cross-cutting mineral relationships to determine the relative timing of mineralization. Multiple distinct phases of skarn formation and metal mineralization have been identified to date. Further research to be undertaken includes determining hydrothermal fluid compositions, the nature of the mineralization and associated alteration, and the timing of mineralization using field observations, fluid inclusion, whole-rock geochemical, and geochronological (molybdenite Re-Os) analyses. The timing of the mineralization in the Gold Hill region is uncertain, however, new Re-Os geochronological data combined with existing dates for the spatially associated Jurassic pluton will allow us to constrain the timing of mineralization. This data will provide information on the genesis of the W-Mo-Cu mineralization as well as insights for future exploration targeting within these understudied districts.