Mineralogy and fluid characteristics of the Waschleithe Zn skarn-a distal part of the Schwarzenberg mineral system, Erzgebirge, Germany

The Waschleithe skarn is situated in the northern sector of the Schwarzenberg district in the western Erzgebirge (Germany), a district which hosts several large polymetallic skarn deposits. The Waschleithe is a Zn-dominant skarn comprising abundant dark Mn-rich hedenbergite, minor grandite garnet and magnetite related to the prograde stage as well as epidote, quartz, fluorite, amphibole, chlorite, ilvaite and Mn-rich pyroxenoids related to the retrograde stage of skarn formation. Ore minerals are related to the early retrograde stage and include sphalerite, galena, chalcopyrite, pyrite as well as minor amounts of scheelite and cassiterite. Fluid inclusion homogenization temperatures range from -385 to 360 ?C and from -320 to 285 ?C for the prograde and retrograde skarn stage, respectively. Thus, late-stage cooling is proposed as the major controlling factor for sulfide mineral precipitation. Fluid salinities for both stages are very low ( 3% eq. w[NaCl]) and all observed fluid inclusion assemblages show homogeneous liquid?vapor ratios. Formation pressures 25 MPa suggest a minimum depth of formation of approximately 3 km. Oxygen fugacity during prograde skarn formation was initially low and increased towards the late prograde stage. The late-Variscan Eibenstock granite is identified as the most likely source of the skarn-forming fluids. The recognition of the Waschleithe skarn as a distal Zn skarn has major implications for the understanding of the Schwarzenberg district mineral system and provides valuable information for exploration targeting.

Automated summary

The Waschleithe skarn in the Erzgebirge district of Germany is a Zn-dominant skarn with minerals like hedenbergite, garnet, and magnetite, formed during both prograde and retrograde stages. Mineral temperatures and pressures suggest a depth of formation around 3 km, with the Eibenstock granite identified as the likely fluid source.