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Analytical Methodologies - documents detailed analytical methodologies including analyzing processes, raw data processing, and analytical precision.

The Kahang Cu-Mo porphyry deposit is located in the middle part of the Urumieh-Dokhtar Magmatic Arc, Central Iran, and is hosted by middle to late Miocene (~14 Ma) porphyritic quartz-diorite and granodiorite stocks intruded into the Eocene tuff, basaltic andesite, and andesitic flow sequences. The Miocene intrusions are calc-alkaline in composition and reflect arc-type to collisional environments (Nb/Y ~ 0.6) based on Nb-Y, Sr/Y-Y, and La/Yb-Yb discrimination diagrams. Copper mineralization occurs within the quartz diorite and granodiorite porphyries and volcanic rock sequences, which have been extensively altered to a central potassic zone (biotite-rich-K-metasomatism), a medial quartz-sericite-pyrite (phyllic) zone, an outer argillic alteration zone, and a peripheral propylitic alteration zone. Hypogene mineralization predominantly occurs within the central potassic zone within veins and breccias. The grade of the mineralization (avgs. 0.6% Cu with 120 million metric tons (Mt) ore reserve and decreases outward from the potassic zone, through a transitional potassic-phyllic zone, to the phyllic zone. Supergene mineralization (5 Mt at 0.3% Cu) that is partially developed in upper parts of the system forms Three stages of mineralization are recognized based on vein geometry, mineral assemblages, and ore textures. Early-stage mineralization is characterized by the occurrence of quartz-magnetite-chalcopyrite ± molybdenite-pyrite assemblages in veins, veinlets, and breccias with biotite-K-feldspar envelopes. Main-stage Cu- (Mo) mineralization is represented by quartz-chalcopyrite ± molybdenite ± pyrite-gold assemblages in disseminations within biotite-K-feldspar-sericite-altered rocks, and is responsible for the bulk of economic Cu-(Mo) mineralization. Late-stage mineralization, characterized by quartz-pyrite-sphalerite-galena assemblages in veinlets, voids, and fractures with kaolinite-illite envelopes occurs in upper parts of the deposit, and overprints previous alteration and mineralization. Four main types of fluid inclusion are distinguished in quartz from quartz-sulfide veins and veinlets: type I vapor-rich (V) two-phase inclusions with vapor/liquid ratios of 60 to 90; type II liquid-rich (L-V) inclusions with vapor/liquid ratios of The calculated δ18Ofluid and δDfluid values for quartz-biotite veins associated with potassic alteration range between 9.7 and 3.1‰ and − 52 to − 49.8‰, respectively, consistent with precipitation from a high-temperature primary magmatic fluid, which gradually mixed with meteoric fluids in later stages. The δ34Ssulfide isotope compositions of stages II and III-chalcopyrite and pyrite range from 3.6 to 8.6‰ consistent with deposition from an oxidized, sulfate-dominant, high-temperature magmatic-hydrothermal fluid. The 40Ar/39Ar ages on hydrothermal biotite from porphyry stocks and potassic alteration zones indicate that the hydrothermal activity and subsequent porphyry Cu- (Mo) mineralization occurred between 14.73 ± 0.05 and 14.87 ± 0.06 Ma.

Cathodoluminescence imaging, combined with SHRIMP U–Pb dating, demonstrates that zircons from ore-bearing porphyries of the Gangdese porphyry copper belt on the southern Tibetan Plateau are composed of inherited, metamorphic and magmatic zircon with ages of 41.5 to 62.5 Ma, 17.69 to 26.0 Ma and 11.39 to 17.20 Ma, respectively. LA ICP-MS analysis also shows that the inherited zircons are characterized by high concentrations of Y (1121 ppm), HREE (641 ppm) and MREE (182 ppm), and low concentrations of U (208 ppm), Th (171 ppm) and Hf (0.96%). Compared with the inherited and magmatic zircons, the metamorphic zircons have markedly lower Th/U ratios (average = 0.54). Although the three types of zircons all have negative Eu anomalies and positive Ce anomalies, the magmatic zircons display much larger variations in Ce anomalies. Importantly, these zircon types correspond to three events during the evolution of the Gangdese collisional orogen that allow us to propose a tectonic model. During the India–Asia collision (50–60 Ma), mantle-derived mafic magmas were underplated, forming a dense crustally-contaminated mafic to ultramafic layer at the base of the crust. At about 21 Ma, asthenospheric upwelling resulted in partial melting of the underplated mafic rocks under granulite facies conditions and rapid uplifting of the southern Plateau. Concomitantly with the extensional crustal collapse after the uplift at about 15 Ma, the ore-bearing magmas were emplaced, forming porphyry copper deposits.