Quantitative mineralogical analysis for the development of new exploration vectors at the Spremberg-Graustein-Schleife Cu-Ag Kupferschiefer deposit, Lusatia, Germany

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.