EGU22-7104
https://doi.org/10.5194/egusphere-egu22-7104
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Formation of deep hydrothermal vein-type Mo greisen and base metal mineralization at the Sweet Home mine, Colorado (USA)

Malte Stoltnow1,2, Volker Lüders2, Stefan de Graaf3, and Samuel Niedermann2
Malte Stoltnow et al.
  • 1University of Potsdam, Geosciences, Germany (mstolt@gfz-potsdam.de)
  • 2GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 3Max Planck Institute for Chemistry, Mainz, Germany

Deep hydrothermal Mo, W, and base metal mineralization at the Sweet Home mine (Detroit City portal) formed in response to magmatic activity during the Oligocene. Fluid inclusions in early-stage greisen quartz and fluorite precipitated from low- to medium-saline (1.5-11.5 wt.% equiv. NaCl), CO2-bearing fluids at temperatures between 360 and 415°C and at depths of at least 3.5 km. Stable isotope data indicate that greisen formation and base metal mineralization at the Sweet Home mine was related to fluids of different origins. Early magmatic fluids were the principal source for mantle-derived volatiles (CO2, H2S/SO2, noble gases), which subsequently mixed with significant amounts of heated meteoric water. Mixing of magmatic fluids with meteoric water is constrained by δ2Hw18Ow relationships of fluid inclusions. The deep hydrothermal mineralization at the Sweet Home mine shows features similar to deep hydrothermal vein mineralization at Climax-type Mo deposits or on their periphery. This suggests that fluid migration and the deposition of ore and gangue minerals in the Sweet Home mine was triggered by a deep-seated magmatic intrusion. The findings of this study are in good agreement with the results of previous fluid inclusion studies of the mineralization of the Sweet Home mine and from Climax-type Mo porphyry deposits in the Colorado Mineral Belt.

How to cite: Stoltnow, M., Lüders, V., de Graaf, S., and Niedermann, S.: Formation of deep hydrothermal vein-type Mo greisen and base metal mineralization at the Sweet Home mine, Colorado (USA), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7104, https://doi.org/10.5194/egusphere-egu22-7104, 2022.

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