The Bashibos Zn-Pb-Cu deposit, southeastern Macedonia, occurs within a lithologically diverse sequence of metamorphosed carbonate sandstone intercalated by chlorite-muscovite slate and in the lowest section of the deposit by metamorphosed basaltic slate. Carbonate sandstone contains variable proportions of chlorite, volcanic quartz and plagioclase, suggesting its deposition synchronous to volcanic activity. Rock sequence is often severely limonitized and altered, especially near highly fragmented zones along fractures. Fractured rock enabled infiltration of oxygen-rich rain water, causing oxidation of primary sulfides. Detailed core mapping and optical microscopy revealed a gradual transition from dominantly mafic basaltic to the felsic rhyolitic composition of pelitic volcanoclastic rock in the sequence. Careful macroscopic observation and microscopy showed precipitation of ore minerals by three metallogenetic mechanisms: 1) synsedimentary, 2) metasomatic and 3) vein hydrothermal. In synsedimentary stage, fine-grained pyrite and sphalerite precipitated along primary lamination and bedding planes of carbonate sandstone and pelitic rocks. The metasomatic stage is manifested as intensive carbonate sandstone and subordinately chlorite-muscovite slate dissolution by high-temperature hydrothermal fluids and precipitation of pyrite, sphalerite, chalcopyrite and tennantite and gangue quartz and calcite. In vein hydrothermal phase fractures and cleavage enabled vertical and horizontal fluid mobility. In early stages of vein hydrothermal phase was dominant pyrite and high-temperature sphalerite precipitation, while in later stages precipitated pyrite, low-temperature sphalerite, galena, chalcopyrite, and tennantite. Minute chalcopyrite exsolutions characterize High-temperature sphalerite. Veins were in later phases regenerated and filled with calcite and quartz. Most significant mineralization type is, from the aspect of economic geology, metasomatic carbonate replacement.
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