The Kupferschiefer districts in Central Europe contain some of the world’s largest sediment-hosted stratiform Cu deposits. The fine-grained sulfides are hosted by the Rotliegend sandstone (S1), organic matter-rich Kupferschiefer (T1) mudstones and Zechstein Limestone (Ca1). In this study, standard and high-resolution microscopy techniques (reflected-transmitted light, SEM, FIB-TEM) are combined with quantitative mineralogical data (X-ray diffraction, QXRD) to characterize the key mineral assemblages and styles of sulfide mineralization in drill core samples from different localities (Sangerhausen, Allstedt, Wallendorf) of the Saale subbasin, Eastern Germany. Our QXRD data show a progressive decrease in calcite abundance from the underlying S1 into the T1 in the Sangerhausen and Allstedt drill cores and an upward increase in calcite in the Wallendorf drill core. Petrographic data show extensive in situ alteration of rock fragments and detrital feldspar in the S1. Diagenetic calcite has formed intergranular pore-filling cement that occludes primary porosity in the S1 and T1. The ore-stage sulfides (bornite, sphalerite, galena, ± pyrite) in the S1 and T1 are mostly formed as a replacement of calcite cement and, to a lesser extent, feldspar. High-resolution TEM data has helped to identify hematite and magnetite within particular calcite growth zones in the S1, which likely corresponds with the “Rote Fäule” alteration associated with the Cu sulfide mineralization. Nanoscale Cu-chloride complexes have also been identified, intergrown with pore-filling illite in the T1. In summary, the distribution and dissolution of calcite cement were critical to the secondary porosity development and migration of the mineralizing fluids in the Saale subbasin.

The Spremberg-Graustein-Schleife deposit is part of the Kupferschiefer district in the southern Permian Basin and comprises copper and silver mineralized rocks hosted by pre-Zechstein sandstones, Kupferschiefer, and Zechstein carbonates. As there is still significant exploration potential across the southern Permian basin, the goal of the present study is to identify mineralogical signatures, which may be usable as exploration vectors. The specific focus in this study is on the gangue mineralogy, since it is more likely to provide a larger detectable footprint in the mineralizing system.

Multiple analytical methods were combined to investigate samples from three mineralized and non-mineralized drill-cores. Scanning Electron Microscope (SEM) based image analysis (MLA) was carried out to obtain quantitative data on mineralogy as well as major-element carbonate chemistry of each stratigraphic unit. Quantitative bulk-powder XRD was performed as an external validation. In addition, the SEM-MLA data are being integrated with hyperspectral core-scans for upscaling observations.

Zechstein carbonate rocks in the well-mineralized drill-hole are dominantly composed of dolomite, in contrast to the weakly-mineralized drill-hole that contains more calcite. In the mineralized sandstones, three successive generations of carbonate cement have been identified from backscatter electron imaging and semi-quantitative EDX measurements, comprising i) dolomite to ii) Mn-Fe dolomite, and finally the deposition of iii) ankerite rims. Kaolinite, one of the main cement minerals in the sandstones, appears more abundantly in the mineralized than in the barren sandstones. The occurrence of ankerite and kaolinite may indicate overprinting by the mineralizing fluids and may thus be useable vectors towards mineralization.

The sediment-hosted Spremberg-Graustein-Schleife deposit is located in Lusatia, eastern Germany. Mineralization occurs in the lower Zechstein units, extending from the Grauliegend conglomerates and sandstones into the overlying organic-rich Kupferschiefer black shales and Zechstein carbonates. Around 100 Mt of Cu-Ag ore is present within the deposit. The ore is also enriched in Pb, Zn, Co, Ni, Au, Bi, Se, Re, and Ge (in addition to Cu and Ag). Despite the metal endowment, detailed quantitative metal deportment studies have not been carried out for this deposit, or indeed any other Kupferschiefer deposit. This study aims to bridge the gap. Core samples representing the complete mineralization interval (31 m in total) at three different sites within the deposit were mineralogically and geochemically analyzed. To ensure a comprehensive, high-quality and internally consistent dataset, various analytical methods including X-ray fluorescence (XRF), ICP-OES, ICP-MS, X-ray diffraction (XRD), Mineral Liberation Analysis (MLA), electron probe micro-analysis (EPMA) and laser ablation ICP-MS (LA-ICP-MS) were performed. The results reveal that the concentration and main hosts of copper and potential by-products vary vertically between the stratigraphical units, and spatially at different locations of the deposit. Such information will eventually help to predict deportments across the deposit, track each element within the minerals processing plants and also to get an idea of expected recoveries and thus optimizing the procedure.

Sphalerite (ZnS) is the main ore mineral in clastic-dominant (CD-type) massive sulfide deposits. However, the precise physicochemical conditions of ore formation are often poorly constrained. This study uses sphalerite mineral chemistry and fluid inclusion microthermometry to constrain conditions of Zn mineralization at the Boundary Zone prospect of Macmillan Pass district, Canada.

The sulfide mineralization comprises pyrite, sphalerite, galena, and minor chalcopyrite. Sphalerite with contrasting trace element compositions is hosted in Late Ordovician-Early Silurian (Duo Lake Formation) and Late Devonian (Portrait Lake Formation) black mudstones. Different paragenetic stages of sphalerite formation preserve distinct trace element patterns within and between host rock intervals, and overall, Ge, Ga, Cu, and Cd, are relatively enriched compared to In. Trace element incorporation mechanisms vary, with both direct and coupled substitution (e.g., 3Zn²⁺ ↔ (Ge)⁴⁺ + 2Cu⁺) pathways suggestive of compositional and fluid temperature differences during sphalerite precipitation.

Homogenization temperatures (T_h) of CO₂-N₂-bearing, 2-phase primary aqueous fluid inclusions in Portrait Lake sphalerite range between 154 – 249°C (median= 179°C). The T_h values of quartz-hosted CO₂-N₂-H₂S-CH₄-bearing aqueous inclusions from late veins are in the range of 207 – 236°C (median= 223°C). These temperatures are consistent with sphalerite trace element geothermometry (GGIMFis; 163 – 279°C) and are comparable to nearby Tom and Jason CD-type deposits in the Macmillan Pass district.

The Zinnwald/Cinovec Sn-W-Li greisen deposit on the border between Germany and Czech Republic in the eastern part of Krušné Hory/Erzgebirge represents a fluorine-rich hydrothermal alteration of a granite-rhyolite association. We investigated the effects of fluid-rock interaction on distal rhyolites of the deposit, using petrological and mineralogical data to constrain the process of greisenization in detail. The samples were selected from the contact between granite and rhyolite. Three distinct zones of high- and low-degree topaz-greisenization and albitization developed with different textures, mineral assemblages and mineral compositions. Beyond the albitization zone, a continuous transition to the least altered rhyolite was observed. In the greisen part, the predominant minerals are quartz (~80 vol%) and topaz (~10 vol%) with minor mica (~5 vol%). We employed a reactive transport model based on mass conservation and local equilibrium to unravel the detailed process of greisenization. We integrated solution models and endmember thermodynamic data for topaz in recent thermodynamic datasets. The model accounts for fluid flow, porosity and density evolution. The model is used to emulated the sequence of observed petrological zones as obtained with automated mineralogy to constrain the original fluid chemistry and reconstruct elements redistribution during greisenization. By comparing fluid-rock interaction models producing topaz greisen and topaz-free mica greisen, we quantify the F-content necessary to form the greisen at Zinnwald/Cínovec. The comparison implies that F content has a great influence on the greisenization types, which may be related to different metallogenic processes and give insights into W-Sn ore deposits.