Intrusion of granodioritic and quartz-dioritic igneous bodies of the Oligocene age into andesitic rocks with the Eocene age resulted in occurrence of widespread argillic alteration zone in the Asbkhan area of Heris (East Azerbaijan Province, NW Iran). A significant portion of this system formed the argillic alteration zone. Based on mineralogical examinations, kaolinite, quartz, smectite, aluni...
