Microthermometric Considerations for the Kanif (SE Birjand) and Basiran (SW Birjand) Manganese Prospects, Birjand, South-Khorasan, Eastern Iran.

Abstract

The studied manganese prospects (1) Kanif is in ophiolitic complex are located in 110 km southeast of Birjand, Southern Khorasan province (east of Iran). The ophiolitic sequence in this region hosts manganese ore occurring as small discrete patche associated with radiolarian cherts. Ore minerals identified by XRD method and petrographic studies are pyrolusite, hematite, and goethite showing replacement, colloidal and brecciated textures. Carbonate and silica are the gangue minerals. Based on the ICP-ES-MS methods, the average grade of Mn in Kanif is 33.92%. Microthermometry considerations of calcite in Kanif, fluid inclusions demonstrated that the oreforming solutions had salinities within the range of 0.5-4.5 wt% NaCl eq., homogenization temperature range of 100-220˚C and density about 0.8-1 g/cm3. The pressure was estimated to be about 50 bars which corresponds with a depth of ~150 meters at the time of formation ophiolitehosted manganese prospects.(2) Basiran veins/veinlets are located in 212 km southwest of Birjand, Southern Khorasan province (east of Iran). These veins/veinlets are hosted by andesitic rocks of Eocene to Oligocene ages. Ore minerals identified by XRD method and petrographic studies are pyrolusite, psilomelane, hematite, goethite and limonite, displaying colloform and open-space filling textures. Gypsum, carbonate and silica are the gangue minerals. Alteration zones, specifically argillic alteration zone, are developed along the veins/veinlets within the andesitic wall rocks. Based on the mineralogical and geochemical data, the primary manganese minerals were Mn oxides and hydroxides, which have gradually been converted to psilomelane and finally pyrolusite. The average grade of Mn within the veins/veinlets are 25.95%. Microthermometry considerations of calcite in Kanif, fluid inclusions demonstrated that the ore-forming solutions had salinities within the range of 0.5-5.5 wt% NaCl eq., TH range of 120-220˚C and density about 0.8-1 g/cm3. The pressure was estimated to be less 50 bars which corresponds with a depth of ~150 meters that in this area show hydrothermal origin. The Major purpose this study are investigation fluid inclusions based on petrography, Variety, morphologies, salinity, Homogenization temperature for polykind of the manganese prospects in different locations: Kanif is located in sistan zone and Basiran is located in lut block that Results and Interpretation of microthermometric data suggested a hydrothermal origin for the Kanif and Basiran Mn prospects.