Zangalou Manto‐type deposit in the Sabzevar zone, northeast Iran: Evidence of mineralogy, geochemistry, U–Pb dating, fluid inclusion, and stable isotopes

The Zangalou Cu deposit lies in the Sabzevar volcanic‐plutonic zone, northeastern Iran. The deposit is hosted by the middle Eocene volcanic‐sedimentary sequences and it has been affected by propylitic, carbonate, sericitic, and minor argillic alterations. The volcanics have features typical of calc‐alkaline and metaluminous magmas and are plotted in the continental volcanic arc region. Zircon U–Pb dating of the andesite porphyry yield ages of 41.2 and 38.4 Ma (Bartonian). Ore mineralization occurs as stratabound with open‐space filling, dissemination, veinlet, and replacement textures in mineralized conglomerate, andesite porphyry, and trachyandesite host rocks. Cu content in Zangalou deposit vary from 1,234 g/t to 6.24% which mostly occurred as chalcocite mineral. Fluid inclusion data of mineralization‐related calcites indicate medium salinities (12.8–16.6 wt.% NaCl equivalents) and a wide range of temperatures (154–295°C) and show evidence of fluid cooling trend during the ore formation. The δ13C (between 19.3 and −2.8‰) and δ18OSMOW (between 24.8 and 25.34‰) values of ore‐related calcites suggests a contribution of sedimentary organic matter and marine carbonates as the source of carbon in the ore‐forming fluid. High positive δ34S values (27.8–33.47‰) suggest that the source of sulphur is related to sedimentary country rocks. Mineralization is lithologically and structurally controlled and it is epigenetic. According to geological, petrological, alteration, mineralization textures and geometry of deposit, fluid inclusion, and isotopic studies, the Zangalou deposit is similar to manto‐type deposits. Properties of Zangalou deposit is very similar to manto‐type deposits. There are two reasons why assuming volcanic host rocks as the Cu source for manto‐type deposits is questionable: (1) High Fe content of volcanic host rocks (2) lack of vast argillic alteration and acidic (pH