Geochemical, Fluid Inclusions and Stable Isotopes Constraint on the Genesis of the Hendouabad Cu–Au Mineralization, Central Urumieh–Dokhtar Magmatic Arc, Iran

ABSTRACT The Hendouabad Cu–Au deposit, located in the central Urumieh–Dokhtar Magmatic Arc, represents a newly explored example of an epithermal deposit hosted by Late Eocene volcanic rocks of basaltic andesite to andesite composition. Mineralization occurs in two zones: A Cu–Au zone in the east and a Cu‐only zone in the west hosted by andesite, basalt and associated dikes. Ore minerals include pyrite, chalcopyrite, chalcocite, galena and bornite, and enargite with supergene assemblages of malachite, haematite and chrysocolla. Hydrothermal alteration is dominated by propylitic and silicic assemblages. Fluid inclusions yielded homogenization temperatures of 109–280°C and low‐to‐moderate salinities (1.6–9.0 wt% NaCl equiv.), with petrographic evidence of boiling. Stable isotope analyses indicate mixed magmatic–meteoric signatures, with quartz‐ and epidote‐derived δ 18 O fluid values ranging from +2.2‰ to +14.2‰ and sulphide δ 34 S values from (−12.0‰ to −5.3‰, CDT). These results suggest that ore‐forming fluids were derived from a magmatic source but were strongly modified by meteoric water infiltration and evolving redox conditions. The combined geological, petrographic, geochemical, fluid inclusion and isotopic evidence supports classification of the Hendouabad deposit as a structurally controlled low‐to‐intermediate sulphidation epithermal Cu–Au system formed through boiling, mixing and cooling of magmatic–meteoric hydrothermal fluids.