The Zagros orogenic belt of Iran is part of the Alpine–Himalayan belt and stretches from the Turkish–Iranian border in the northwest to the Makran zone in the southeast. It is characterized by three parallel tectono-magmatic zones, i.e., the Zagros fold and thrust belt, the Sanandaj-Sirjan Zone, and the Urumieh-Dokhtar magmatic arc (UDMA). From a tectonic point of view, orogenic magmatism refers to igneous activity associated with subduction of oceanic plate or collision between two continents. The UDMA is composed of voluminous mafic to felsic volcanic successions with minor intrusive rocks. The volcanic successions largely comprise basaltic and andesitic lava flows, pyroclastic tuffs and ignimbrites. Moreover, the plutonic rocks including gabbro, diorite, granodiorite, and granite bodies of different sizes. The important key factors in ore-forming processes for generating porphyry Cu systems are still being challenge and, the mineral-chemical compositions of fertile porphyry Cu systems and barren intrusions at the regional scale in the UDMA have not yet been compared. In this research, amphibole, biotite, and plagioclase chemical data from the barren and fertile intrusions along the UDMA are integrated, to examined magmatic physicochemical conditions as important signatures to evaluate the Cu (Au) potential of UDMA intrusive rocks. Comparisons between fertile intrusions with barren intrusions in the UDMA suggests that all these intrusions formed under relatively similar physicochemical conditions, although the more fertile magmas in the UDMA were crystallized at relatively higher temperatures, ƒO2, H2O, and F contents than the barren intrusions. In the fertile intrusions, a large volume of basic magma interacts with acidic magma until those magmas became homogenized. These fertile intrusions are associated with mid-late Miocene Pliocene post collisional stages with a transition from overall compression to extension that can be favorable to generating fertile magmas. To form mineralized porphyry systems, large volumes of fluid must be channeled through host rocks, which are controlled by large strike slip faults and pre-existing fractures to facilitate magma emplacement and for focusing buoyant fluid flow. Moreover, absence of coeval volcanism prevented the direct escape of volatiles to the atmosphere from crystallizing metalliferous sulfur-rich subvolcanic magmas, facilitating the formation of porphyry Cu deposits. In the barren intrusions, a small amount of basic magma interacts with a large proportion of acidic magma and mingling is generated along with MMEs. They are related to the pre-collisional subduction processes, which probably did not activate pre-existing structural features in the upper crust that would have enabled magma and (or) fluid transport upwards towards the near-surface. In addition, coeval volcanic activity during emplacement of barren intrusions may cause significant outgassing of volatiles.
