Epithermal base metal Veins is located 30 km southwest of Qeydar, Znajan district, in northwestern part of Orumieh-Dokhtar volcano-plutonic zone, Iran. The oldest outcrops in the area are Upper-Cretaceous alternatives of grey argillaceous limestone and shale which are overlain by an Oligo-Miocene volcano-sedimentary sequence. Volcano-plutonic activity occurs in Pliocene as rhyodacitic subvolcanic domes and volcanic dacitic.
Two aspects of hydrothermal activity are present: hydrothermal alteration of the rocks and ore deposition. The epithermal event was characterized by hydrothermal brecciation when delicate to coarsely banded vein material was precipitated.
The metalliferous veins form parallel systems generally with constant northeast-southwest trend. The richest assemblages occur in the
upper mineralized levels and in the center of the ore deposits belt. Host rock of mineralization is rhyolite to rhyolitic tuff. The mineralization at this deposit consists consists of:
1- Silicic-Sulfidic veins, this vein includes quartz, pyrite, chalcopyrite, galena, sphalerite, bornite, digenite and covelite.
2- Silicic, sulfidic and carbonate veins comprise quartz, calcite, pyrite, galena and minor chalcopyrite.
Secondary minerals include malachite, azurite, chalcocite, covellite, cerussite, anglesite, smithsonite, hemimorphite, hydrozincite, siderite and Fe-Mn oxides The vein textures are described as open space filling,Crustiform, banded vein, brecciated and comb textures.
The varying extent of the hydrothermal process is reflected in various mineral assemblages that characterize successive alteration zones and different types of hydrothermal alteration. These types range from alteration, represented by silicic type argillic, sericitic, carbonate and propylitic. The most important characteristics of mineralization at this deposit such as tectonic setting, host rocks, mineralogy, mineral paragenesis and alteration suggest that Gomish-tappeh show similarities with epithermal Zn-Pb-Cu (Ag) deposits.