Barika Gold Mineralization: a Gold-Rich Volcanogenic Massive Sulfide Deposit in Iran

Barika gold mineralization occurred in a Cretaceous metavolcano-sedimentary sequence at northwestern Sanandaj-Sirjan zone. Major units in this area include Cretaceous Submarine volcano-sedimentary rocks. Host rock of mineralization is rhyolite to rhyolitic tuff unit which is completely in Barika shear zone. Mineralization occurred as lenticular ore bodies that has developed parallel to Barika shear zone foliation. Mineralization from footwall to hanging wall consists of: 1- Silica-Sulfide zone, which includes two part, pyrite-rich part and quartz with sulfide veins that crossed with shear zone foliation. Gold grade in pyrite-rich part is between 0.02 to 5 ppm and in quartz sulfide-bearing veins is between 0.05 to 0.5 ppm. 2- Sulfide and sulfosalt-rich zone. This zone contains of two part, pyrite-sphalerite-sulfosalt and massive pyrite part. Gold grade in this zone is 0.02 to more than 100 ppm. 3- Massive barite ore zone. This zone included of some barite lenses that longer lens has 10 thickness and about 60 m length. This zone is contained two parts, a sulfide and sulfosalt-rich part and sulfide and sulfosalt-poor part. Gold grade in sulfide and sulfosalt-rich part is between 0.02 to 25 ppm. Major minerals in mineralization zones are pyrite, sphalerite, galena, tetrahedrite-tenantite, bournonite-boulangerite, twinnite-veenite, stibnite, electrom, chalcopyrite and covelite. Electron microprobe studies on different minerals showed that gold occurs as electrom, and in minerals compose such as pyrite, galena and sulfosalts. The most important characteristics of mineralization of the Barika gold mineralization such as tectonic setting, host rocks, mineralogy, metal contents and metal zonation, wall rock alterations, shows similarities with gold-rich volcanogenic massive sulfide (VMS) deposits, e.g. , Rosbery, Hellyer and Que River deposits in Tasmania and some Kuroko type deposits at Hokuroko Basin, Japan.