Mineralogy, alteration, and sulfur isotope geochemistry of the Zehabad intermediatesulfidation epithermal deposit, NW Iran

Authors : Somaye SHAHBAZI, Majid GHADERI, Pura ALFONSO

Pages : 882-901

View : 12 | Download : 4

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The Zehabad Pb-Zn-Au-Ag insert ignore into journalissuearticles values(Cu); deposit lies in the Alborz magmatic arc of northwestern Iran. Ore-bearing breccia veins hosted by Eocene tuffs emplaced along the 80?130° trending fault and fracture zone. Mineralization occurs in the contact of the late Eocene igneous bodies and the Eocene volcanic and volcanosedimentary Karaj Formation. Mineralization formed in five stages: 1); disseminated framboidal pyrite and minor chalcopyrite and sphalerite; 2); quartz veins containing chalcopyrite, bornite, pyrite, and sphalerite; 3); deposition of specularite and gold grains hosted in quartz veins that crosscut chalcopyrite; 4); the main stage of mineralization that contains galena, sphalerite, tennantite-tetrahedrite, pyrite, sulfosalts, and gold; 5); barren quartz-calcite veins with sulfide mineral fragments of earlier stages. The hydrothermal alteration from closest to the veins outwards includes: a); silicification; b); phyllic with quartz, pyrite, sericite, and calcite; c); argillic with illite, kaolinite, and montmorillonite; d); propylitic containing epidote, calcite, chlorite, and sericite and; e); carbonatization that crosscuts all previous alteration types. Quartz and calcite are the most important gangue minerals at the deposit and show a close relationship with mineralization. Sulfur isotope compositions insert ignore into journalissuearticles values(0.8‰ to -10.1‰); suggest that the ore-forming fluids derived from magmatic sources with a temperature range of 276-288 °C. According to the field insert ignore into journalissuearticles values(macroscopic);, microscopic, alteration, and sulfur isotope studies, the Zehabad base and precious metal mineralization is considered an intermediate-sulfidation epithermal deposit.
Keywords : Epithermal, intermediate sulfidation, sulfur isotopes, Zehabad, Alborz, Iran