Abstract

Jarin barite- fluorite deposit lies in the Alborz structural zone, 140 km southeast of Zanjan. Mineralization occurs as epigenetic hydrothermal veins in Cretaceous dolomitized limestone (Kl unit), and is structurally and lithologically controlled. Barite and fluorite are the main ore-forming minerals accompanied with subordinate quartz, calcite, dolomite, galena and pyrite. Five mineralization stages occur in the Jarin deposit (from early to late): fluorite veins, fine-grained barite‒cemented veins and breccias, coarse-grained barite infilling veins, quartz-galena-pyrite veins, and vug infill calcite veins. Microthermometric investigations indicate that barite- fluorite veins at Jarin deposit are formed during mixing of basinal brines with meteoritic waters. Characteristics of Jarin deposit are comparable with MVT type deposits. Investigation of fault zones within carbonate rocks of K1 unit which accompanied with dolomitization, is, therefore, of major importance in exploration of MVT type deposits at Alborz zone.