Consideration of mineralogy, fluid inclusions and type of Pb-Zn-Ba mineralization of the Neyzar deposit, Tabas-Poshte Badam metallogenic belt, east of Iran

The Neyzar lead-zinc-barium deposit is located about 20 km east of Eshgabad city (South-Khorasan Province, east Iran) and is a part of Tabas-Pushte Badam metallogenic belt. This deposit is hosted by carbonate units of Jamal (Permian) and Shotori (Triassic) Formations. Mineralization was mainly controlled by structural factors (thrust faults) in this deposit. Galena, sphalerite and barite are the principal ore minerals with minor amounts of minerals such as calcite, dolomite, quartz, fluorite, malachite, cerussite, covellite, hemimorphite, hematite, goethite, and manganese oxides. The micro-thermometric studies, using fluid inclusions, on calcite and barite crystals were carried out in this deposit. Both calcite and barite minerals are co-existed and co-genetic with Pb-Zn sulfide mineralization occurrence. Petrographic observations of fluid inclusions show that most of them are of liquid-rich two-phase type. Based upon micro-thermometric analysis, the homogenization temperatures of the fluid inclusions in calcite and barite crystals vary from 120 to 220ºC and from 119 to 199ºC, respectively. The salinities of the fluid inclusions in calcite and barite crystals also show changes within the range of 10.12-23.5 and 19.6-23.1 wt% NaCl eq., respectively. In general, the microthermometric investigations revealed that simple cooling and boiling were the main evolutionary trend for deposition of the ore and gangue minerals by sedimentary-derived hydrothermal fluids. Based on the results obtained from field observations, mineralogy, structure and texture and micro-thermometric data, the Pb-Zn-Ba deposit in the Neyzar area is very similar to those of the Mississippi Valley-type (MVT).