Magmatic-hydrothermal evolution of the Gorouh porphyry Cu-(Mo) deposit in the Kerman copper belt, southeastern Iran

The temporal-geochemical evolution and fluid history of the Gorouh porphyry Cu-(Mo) deposit have remained poorly constrained relative to well–studied analogues in the Kerman copper belt of southeastern Iran. The Gorouh deposit is hosted by Oligocene-Miocene andesitic volcanics and quartz diorite-granodiorite intrusions. Multi–phase magmatic-hydrothermal activity at the deposit, dated to 23.8–15.9 Ma, generated potassic-phyllic alteration and Cu-Mo mineralization, recorded by high–T low–salinity fluids that later boiled to produce super–saline ore fluids. The four pioneer drill holes yielded limited mineralized intervals—approximately 67 m, averaging 0.29 wt.% Cu (>0.2%) and 96 m averaging 121 ppm Mo (>50 ppm). However, such preliminary results are not sufficient to constrain the tonnage or geometry of the system. Here, we integrate field observations, petrography, whole-rock geochemistry, fluid inclusions, and O-H-S isotopes to introduce a genetic model for the Gorouh deposit. Intrusive rocks are calc-alkaline, metaluminous I-type (magnetite-series) with island-arc to continental-margin signatures. Fluid inclusion microthermometry reveals three main fluid stages (Th ≈103–650 °C; salinity ∼0.7–60 wt.% NaCl). Measured δ 34 S (+5.5 to +7.9‰) and δ 18 O (-7.0 to -11.0‰; corresponding to fluid δ 18 O +3.0 to +6.6‰) indicate a magmatic fluid source. These data support a three-stage magmatic-hydrothermal evolution model for Gorouh.