PETROLOGIC AND PETROGENETIC STUDY OF KIGHAL PORPHYRY STOCK (NORTH OF VARZEGHAN, EAST AZARBAIDJAN PROVINCE, NW IRAN)

Quartz-monzonite porphyry stock at Kighal is located in ~12 km north of Varzeghan, East Azarbaidjan Province, NW Iran. It has intruded older volcanic units during magmatic activities of Pyrenean orogenic phase and produced Cu-Mo mineralization and hydrothermal alteration zones (potassic, phyllic, argillic, advanced argillic, propylitic and later supergene leached zones) in the region. After its emplacement, numerous cross-cutting dikes, ranging in composition from diorite through quartz diorite, granodiorite, microdiorite and monzodiorite have intruded into porphyry stock. In oxide-oxide (Harker) diagrams, all of the samples analyzed from dykes and porphyry stock show single trends, suggesting a common source for their parental magma and occurrence of mineralogical variations in these dyke suits, proportional to their temporal order of intrusion, in a manner that the first generation dykes (Dk1a) are more felsic and toward to Dk1b and Dk1c, MID and MZD dyke suits, the composition gradually becomes more basic and the silica content decreases. The REE patterns of cross-cutting dykes and porphyry stock in spider diagrams are also similar, which confirm the existence of a common source for their parental magma and occurrence of differentiation in the magma chamber. Additionally, based on chemical analyzes, it has been distinguished that different rock types of this complex have high-K calc-alkaline to shoshonitic nature, and have emplaced in a post-collisional volcanic arc and active continental margin setting. The investigation of geochemical characteristics of these rocks indicates the interference and influence of fluids derived from subducting slab in the evolution of parental magma.