@article{StoltnowLuedersGraafetal.2022,
  author    = {Stoltnow, Malte and L{\"u}ders, Volker and Graaf, Stefan de and Niedermann, Samuel},
  title     = {A geochemical study of the Sweet Home mine, Colorado Mineral Belt, USA},
  series = {Mineralium deposita : international journal for geology, mineralogy and geochemistry of mineral deposits},
  volume    = {57},
  journal   = {Mineralium deposita : international journal for geology, mineralogy and geochemistry of mineral deposits},
  number    = {5},
  publisher = {Springer},
  address   = {Berlin ; Heidelberg},
  issn      = {0026-4598},
  doi       = {10.1007/s00126-022-01102-6},
  pages     = {801 -- 825},
  year      = {2022},
  abstract  = {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. Microthermometric data of fluid inclusions trapped in greisen quartz and fluorite suggest that the early-stage mineralization at the Sweet Home mine precipitated from low- to medium-salinity (1.5-11.5 wt\% equiv. NaCl), CO2-bearing fluids at temperatures between 360 and 415 degrees C and at depths of at least 3.5 km. Stable isotope and noble gas 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 delta H-2(w)-delta O-18(w) 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.},
  language  = {en}
}
@article{DesanoisLuedersNiedermannetal.2018,
  author    = {Desanois, Louis and L{\"u}ders, Volker and Niedermann, Samuel and Trumbull, Robert B.},
  title     = {Formation of epithermal Sn-Ag-(Zn) vein-type mineralization at the Pirquitas deposit, NW Argentina},
  series = {Chemical geology : official journal of the European Association for Geochemistry},
  volume    = {508},
  journal   = {Chemical geology : official journal of the European Association for Geochemistry},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0009-2541},
  doi       = {10.1016/j.chemgeo.2018.04.024},
  pages     = {78 -- 91},
  year      = {2018},
  abstract  = {The Pirquitas Sn-Ag-(Zn) deposit in northwestern Argentina is thought to be an analogue to the Miocene polymetallic epithermal Sn-Ag deposits of the southern Bolivian Tin Belt, but little is known in detail about the origin and evolution of ore-forming fluids at Pirquitas. This paper reports on a microthermometric study of fluid inclusions in quartz, sphalerite, Ag-Sn sulfides, and Ag-rich sulfosalts using transmitted near infrared and visible light, combined with noble gas isotope analyses of fluids released from mineral separates. The study focused on the vein-hosted mineralization, which formed during two major mineralization events, whereby the first event I comprises two stages (I-1 and I-2). All studied minerals exclusively contain aqueous two-phase inclusions, indicating that the ore-forming fluids did not undergo two-phase phase separation (boiling). Salinity of fluid inclusions in I-1 quartz that precipitated along with pyrite and pyrrhotite ranges between 0 and 7.5 wt\% NaCl equiv. and homogenization temperatures (Th) are between 233 and 370 degrees C. Stage I-2 is characterized by abundant Sn-Ag-Pb-Zn-sulfides and a variety of Ag-rich sulfosalts. Fluid inclusions in stage I-2 Ag-Sn sulfides have salinities up to 10.6 wt\% NaCl equiv. and Th between 213 and 274 degrees C. The deposition of stage I-2 ore is likely related to a new pulse of saline magmatic fluids to the hydrothermal system. The mineralization event II deposited the richest Ag ores at Pirquitas. Colloform sphalerite and pyrargyrite deposited during event II contain two-phase aqueous fluid inclusions with homogenization temperatures between 190 and 252 degrees C and salinities between 0.9 and 4.3 wt\% NaCl equiv. Noble gas concentrations and isotopic compositions of ore-hosted fluid inclusions were determined from crushing hand-picked ore minerals from both mineralization events. With one exception, all samples yielded He-3/He-4 ratios between 1.9 and 4.1 Ra, which is within the range of published data from the volcanic arc and somewhat higher than typical values of meteoric water-derived hot-springs in the region. This demonstrates a significant contribution of magmatic fluids to the Pirquitas mineralization although no intrusive rocks are exposed in the mine region. Taking the noble gas evidence for a magmatic fluid source, we interpret the trends of decreasing Th and salinity values in fluid inclusions from events I and II to represent waning of the magmatic-hydrothermal system and/or increased admixing of meteoric water to the magmatic fluids.},
  language  = {en}
}