Metal (re)distribution in and around the Kupferschiefer-type mineralization, Röhrigschacht Wettelrode (Saxony-Anhalt)

The Kupferschiefer-type mineralisation of the Southern Permian basin in Poland and Germany represents the largest base metal mineralisation and resource in Europe. Outstanding scientific questions still to be solved include the spatial zoning of metals within some of the deposits and the mineralogical host phases of specific trace elements (e.g. Co, Se, Mo, V) that had been extracted in the past and still contribute to the economic potential of the mineralisation. This study investigates samples associated with the Kupferschiefer-type mineralisation of the Rotliegend sandstone, the basal black shale (T1) of the Zechstein, and Zechstein carbonates. The three lithotypes were continuously sampled along vertical profiles from underground exposures in the Röhrigschacht of the Sangerhausen mining district. Thin sections of the samples were examined by µXRF to obtain element distribution maps. Mineral assemblages and ore textures were determined by reflected light microscopy, BSE-imaging and EDS. The investigations confirm the classical base metal zoning from bottom to top: copper-lead-zinc, typical for the Sangerhausen district, but also reveal anomalous elemental distributions that deviate from expected patterns. In addition to common sulfide minerals (e.g., pyrite, chalcopyrite, bornite, galena, sphalerite), Pb- and Cu-chloride minerals of presently unclear origin were identified as carriers of value trace metals. Moreover, mineralised faults and the brittle-ductile deformation of ore minerals indicate the post-ore tectonic influence of the Upper Cretaceous Harz mountains uplift affecting the Wettelrode deposit. These findings provide new insights into the mineralogical complexity and the metallogenic processes of the Kupferschiefer-type mineralisation.