A geochemical study of the Sweet Home mine, Colorado Mineral Belt, USA: formation of deep hydrothermal vein–type molybdenum greisen and base metal mineralization

Abstract Deep hydrothermal Mo, W, and base metal mineralization at the Sweet Home mine (Detroit City portal) formed in response to magmatic activity during Oligocene. Microthermometric data of fluid inclusions trapped greisen quartz fluorite suggest that early-stage precipitated from low- medium-salinity (1.5–11.5 wt% equiv. NaCl), CO 2 -bearing fluids temperatures between 360 415 °C depths least 3.5 km. Stable isotope noble gas indicate formation was related different origins. Early were principal source for mantle-derived volatiles (CO , H S/SO gases), which subsequently mixed with significant amounts heated meteoric water. Mixing water is constrained by δ w –δ 18 O relationships inclusions. The deep shows features similar vein Climax-type Mo deposits or on their periphery. This suggests migration deposition ore gangue minerals triggered a deep-seated intrusion. findings this study are good agreement results previous inclusion studies porphyry Colorado Mineral Belt.