Study of Hypogen Alteration and Copper Mineralization in Sonajil Area (East of Herris, East Azarbaidjan)

The Sonajil area is located in ~17 km east of Heris, East-Azarbaidjan. The major lithological units in the area include bodies of volcanic and volcanoclastic rocks (lower to middle Eocene), Sonajil porphyry stock (upper Eocene-lower Oligocene), Incheh granitoid stock (diorite, syeno-diorite, gabbro) (middle-upper Oligocene), and Okuzdaghi volcanic rocks (Plio-Quaternary). The Sonajil porphyry stock hosts a porphyry copper-type mineralization and varies in composition from micro-syenodiorite through micro-gabbro-diorite to micro-gabbro and micro-granodiorite, featuring principally porphyritic to microlithic porphyry textures. The parental magma of these igneous bodies had shoshonitic character (to high-K calc-alkaline), and tectonically belongs to post-collisional volcanic arc. Various generations of banded quartz, quartz-sulfides, quartz-oxides, and sulfides veinlets and micro-veinlets were developed within the porphyry body featuring typical stockwork texture. Veins of sulfide mineralization are also present in peripheral parts of the porphyry body. Alteration and mineralization occurred principally within the Sonaljil porphyry stock. Three types of pervasive hypogene alterations are developed in Sonajil stock: (1) potassic; (2) phyllic; and (3) propylitic. The principal hypogene opaque minerals include pyrite, chalcopyrite, bornite, tetrahedrite, enargite, molybdenite, hematite and magnetite occurring as dissemination and stockwork (veinlets and micro-veinlets). The chief supergene minerals in this body are hematite, goethite, malachite, azurite, chalcocite, covellite, and clay minerals.