The characteristics of spatial distribution of silver minerals and Agin ore minerals within the Lower Zechstein formations at the contact zone between reduced rocks and the Rote Fäule oxidized rocks are shown. All presented outcomes are on based on rock material taken from mining profiles and some archival boreholes in the Radwanice-Gaworzyce deposit area. These studies were used microscopic observations in reflected light and by microprobe analyses using the CAMECASX-100. In all analyzed profiles, oxidized rocks (enriched in hematite) were found, which occur at various levels of the Kupferschiefer series beneath the reduced zone enriched in ore minerals. Silver in the reduced zone occurs in the form of its own minerals, such as: native silver, stromeyerite, mckinstryite, jalpaite, naumannite, silver amalgams. Futhermore, silver is present as Cu and Fe isomorphic substitutions in the crystal lattice of copper sulfides of the Cu-S and Cu-Fe-S groups and in As and Sb sulfosalt. In the oxidized zone, silver occurs as electrum, silver amalgams and substitutions in remnant copper sulfides. A decrease in the concentration of silverin ore minerals and in the content of silver minerals towards the top of the mineralized interval is characteristic. The concentration of silver (both in the form of its own minerals and as isomorphic substitutions in ores) is impoverished in the zone where the oxidation front crosses the Kupferschiefer shale than in the case when the stabilization of the redox front is at the border boundary of the Weissliegend sandstone with and the Kupferschiefer shale. The spatial distribution of silverin the Lower Zechstein formations at the contact zone between the reduced and oxidized rocks is the result of the evolution of ore mineralization, caused by the flows of mineralizing solutions, as evidenced by the depletion of the oxidized zone in silver, and its enrichment in the adjacent reduced rocks.
The characteristic of ore mineralization in the immediate vicinity of fault zones in the Lower Zechstein deposits is shown. All presented outcomes are on the basis of rock material taken from mining profiles in the Radwanice-Gaworzyce deposit area. During conducted studies ore minerals and oxide minerals were identified under optical microscope in reflected light and photographic documentation of the examined samples was undertaken. In addition, microprobe examination was carried out for selected samples from the studied profiles along with calculations of the chemical composition of individual ore minerals. In all analyzed profiles, Rote Fäule oxidized zone (enriched with hematite) was found, which occurs at various levels of the Kupferschiefer series and the reduced zone (enriched with ore minerals) over the oxidized series. The redox front cuts across the boundaries oflithostratigraphic units, moving from the Weis- liegend to the higher parts of the Zechstein Limestone. The primary ore mineralization in the examined profiles is the chalcocite-digenite association with subordinate bornite and covelitte recorded in the reduced series. Furthermore, the secondary sulphide mineralization in the direct vicinity of tectonic deformation and faults superimposed on primary ore mineralization and hematite enrichments is observed and it is represented by chalcopyrite, bornite, tennantite, tetrahedrite and pyrite, both within reduced and oxidized zones.
Discovered by J. Wyżykowski in 1957, the Lubin-Sieroszowice deposit is a classic representative of the giant Kupferschiefer-type Cu-Ag stratabound deposit. Its disclosure and documentation was provided by the research work of many geologists of the Polish Geological Institute and many other institutions. During the period of 60 years, the mining and metallurgical industry has been developed to such extent that Poland is now among the world’s major producers of copper and silver. This discovery marked the beginning of the recognition of the S Oszczepalski A Chmielewski deposit and gave rise to further exploration for prospective areas elsewhere in SW Poland. Detailed studies of Rote Fäule alteration have shown that redox boundary is the principal guide to exploration. Later studies of numerous boreholes allowed the researchers to distinguish 38 prospective areas on the reductive side of the redox border and Au-Pt-Pd enrichments in oxidized rocks. The Kupferschiefer-type deposits were long considered classic examples of syngenetic mineralization. However, the close relationship between the occurrence of Cu-Ag orebodies and oxidized altered areas, and ore zones progressively transgressive to bedding relative to the Rote Fäule front indicates that these deposits were formed as a result of fluid-rock interaction caused by ascending migration of moderately low-temperature basinal chloride brinesfrom the underlying red beds within reasonable periods of diagenesis of the reduced hosts. The hematitization was the result of an influx of oxidizing solutions across the centers of oxidized areas that acted as the innermost parts of the telescoped Rote Fäule/ore systems. The early-to-late diagenetic timing of mineralization is constrained by paleomagnetic age of hematite, K-Ar dating of authigenic illite and Re-Os dating of Cu sulfides. The fluid circulation was due to paleogeothermal activity, compactive expulsion, recirculation and (or) seismic movements, corresponding to intracontinental Permian-Triassic rifting. Due to the depletion of shallow resources, extensive deep exploration drilling is required to verify the resource potential in concession prospects existing around the documented deposits. The long-term challenges related to the substantial copper and silver scarcity problems in the future demand for overcoming geological barriers (considerable depths, high overburden pressure, elevated temperature, gas hazard) require the use of innovative technology, creation of favorable investment conditions and preparation of a long-term raw materials strategy.
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