Inorganic and organic geochemical data obtained from contact-metasomatic and skarn-like mineralisation and associated country rocks from the Zloty Stok Au-As deposit in Southwest Poland have been studied. Magnetite-rich calcite-dolomite marbles have the highest total organic carbon content of the rocks studied. Organic matter consists of solid bitumen, with a minor extractable fraction composed mainly of low molecular weight aromatics. There are positive correlations between organic matter and Fe 2 O 3 and MgO content, suggesting remobilisation of organic matter by the hydrothermal fluids during serpentinisation processes. Results of the organic geochemical and isotope studies suggest that the hydrocarbons were formed by thermal and later hydrothermal alteration of indigenous organic matter. The ranges of d 34 S values of sulphides show that in Au-rich arsenopyrite and pyrrhotite, most of the sulphur may have originated from a magmatic source. However, some of results indicate a contribution from isotopically heavier sulphur, most probably associated with fluids derived from the metamorphic sedimentary environment. Rare earth element patterns of the mineralised samples point to a granitic source of the studied orebodies.
The Kraków-Lubliniec tectonic zone (KLFZ) in southern Poland, which divides the Małopolska Block (MB) from the Upper Silesia Block (USB), is a portion of the SW margin of the Trans-European Suture Zone. Zircon U-Pb dating of a variety of igneous rocks (granodiorites, dacites, lamprophyre and diabase) from the subsurface Kraków-Lubliniec igneous belt along the KLFZ shows that magmatism spanned within a narrow time period (ca. 10 Ma) between 303.8 ± 2.2 and 292.7 ± 4.9 Ma. The earlier magmatism (303.8 ± 2.2-294.7 ± 2.3 Ma) was felsic calc-alkaline, and the contemporaneous or/and slightly later alkaline volcanism (294.4 ± 4.9-292.7 ± 4.9 Ma) was of mafic-intermediate composition. The felsic rocks (granitoids and dacitoids) are weakly peraluminous, medium to high K, moderate Mg# (0.39-0.46), weakly evolved and I-type rocks. Due to the intensive development of hydrothermal alteration, these rocks are commonly strongly altered and locally mineralized by porphyry and other types of Mo-Cu (W) ores that are closely related to the felsic magmatism in space and time. The zircon U-Pb dating yielded ages which are similar to the previously measured Re-Os ages of molybdenites from the KLFZ. Felsic magmatism at the Myszków Mo-Cu-W deposit yielded ages in the range 301.0 ± 2.1-295.9 ± 2.9 Ma. The youngest rocks dated are from the Mysłów area in the USB-volcanic alkaline rocks (lamprophyre and diabase) of shoshonitic character, with low Mg# (0.49 and 0.69, respectively) and Ni contents (< 62 ppm), indicative of a relatively juvenile magma composition. Inherited zircon cores, remnant detrital zircon from a sediment component in the source rocks, were dated to be ranging from ca. 2775 to 575 Ma. Inheritance of ca. 600 Ma (Cadomian basement) and ca. 1.40 Ga (Mesoproterozoic) is common in the rocks from both blocks, but those from the MB contain additional inheritance with dates of 2.78-2.67 and 2.05-1.92 Ga, both ages characteristic of zircon from the Svecofennian of northern Europe (Baltica). The inherited zircon from the youngest alkaline rocks provided evidence for Mesoproterozoic (ca. 1.55-1.44 and 1.09 Ga) and Palaeoproterozoic (1.96 Ga) thermal events in the USB, and its possible affinity to Avalonian cratonic crust as a source for its igneous protolith. U-Pb isotopic studies of zircons from KL igneous belt indicate its inherited signatures from the crustal sources and magma emplacements during the KLFZ wrenching which allowed channels and room for magma emplacement along the MB and USB in upper Carboniferous-lower Permian on SW margin of the East-European Craton. Mo-Cu (W) ore mineralization, associated with the ~ 300 Ma felsic magmatism, represents rather the product of decompression melting induced in the areas of decreased pressure, undergone in the regional wrench fault zones than the classic Mo-Cu porphyry-style mineralization.
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