Formation of carbonate-hosted Kızılüzüm Pb–Zn–Ag deposit within the Bornova Flysch Zone, İzmir, Western Türkiye

The Kızılüzüm Pb–Zn–Ag deposit is hosted within carbonate rocks belonging to the Bornova Flysch Zone (BFZ) in Western Anatolia. The base of the BFZ in the study area comprises Upper Cretaceous recrystallized dolomitic limestones with rudist fossils, overlain by Late Cretaceous–Paleocene flysch-type sequences consisting predominantly of fossil-free sandstone and shale alternations, along with occasional limestone lenses. Cataclastic granitic dike, possibly of Miocene (?) age, intrude these units. The BFZ exhibits an imbricated internal structure, and the Kızılüzüm Pb–Zn–Ag mineralization has developed within the recrystallized dolomitic limestones particularly at the intersections of low-angle thrust zones and faults. The ore zone is oxidized and contains 0.4–44% Zn, 0.2–12.5% Pb, 65–3305 ppm As, and 1.5–347 ppm Ag. The moderately strong correlation of Ag with Pb and sulfur (r = 0.7) suggests its association with galena. Fluid inclusions yield an average 238°C the homogenization temperature (Th) and 5.4 wt.% NaCl equivalent salinity, indicating a dominantly magmatic-hydrothermal origin for the ore-forming fluids. δ34S for sulfide minerals average –6.89‰ (range: –11.95‰ to 4.46‰; n = 27), while barite shows 8.75‰ (range: 0.67‰ to 14.05‰; n = 5). These data suggest that sulphur may have been derived from dominantely magmatic sulphate sources with partly sedimentary sulphate contribution, reduced and fractionated through thermochemical sulfate reduction (TSR) processes. Considering its geological setting, mineral paragenesis, fluid inclusion data, sulfur isotope compositions, and ore geochemistry, the Kızılüzüm Pb–Zn–Agmineralization may have been formed through the mixing of magmatic-hydrothermal fluids derived from Oligocene–Miocene magmatic rocks intruded into the Bornova Flysch Zone (BFZ), and shows similarities to Carbonate Replacement Deposit (CRD)-type Pb–Zn deposits worldwide.