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.
The studied manganese prospects are located in ophiolitic complex of Birjand, east of Iran. The ophiolitic sequence in this region hosts manganese ores occurring as lens associated with radiolarian cherts and as veinlets with shales. The main gangue minerals are calcite, silica and gypsum. The major manganese ore minerals are pyrolusite, braunite, bixbyite, ramsdellite, and romanechite showing replacement, colloidal, and brecciated textures. High concentration values of Si, Fe, Mn, Ba, Zn, Sr, and As in the studied manganese ores can be applied as evidence for sea-floor Mn-rich hydrothermal exhalatives responsible for the formation of the ores. Investigations on fluid inclusions of calcites demonstrated that the ore-forming 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/cm 3 . The pressure was estimated to be about 50 bars which corresponds with a depth of ~150 meters at the time of formation manganese prospects that fluid inclusions datas approved hydrothermal processes in the studied manganese prospects can be applied as evidence for sea-floor Mn-rich hydrothermal exhalatives responsible for the formation of the ores. The geological and geochemical results also revealed that deposition of the ores occurred on upper parts of the ophiolitic sequence by submarine exhalatives. The hydrothermal activities caused leaching of elements such as Mn, Fe, Si, Ba, As, and Sr from basaltic lavas (spilites) through concurrent faults with deposition, elements entered to sedimentary basin and during the retreat of the sea with the expansion of oxidation conditions are formed the primary manganese minerals were Mn oxides and hydroxides which have gradually been converted to psilomelane and finally pyrolusite, braunite and bixbyite.
The studied ophiolite-hosted manganese prospects are located in southeast of Birjand, South Khorasan, in the east of Iran. The manganese ores within the ophiolitic sequence in this region occur as small discrete patches, associated with radiolarian chert and shale. Manganese ores in the host rocks are recognizable as three distinct syngenetic, diagenetic, and epigenetic features. The syngenetic manganese ores occurred as bands associated with light-red radiolarian chert. The diagenetic Mn ores occurred as lenses accompanied by dark-red to brown radiolarian chert. The epigenetic Mn ores occurred as veins/veinlets within the green radiolarian shale. The major manganese ore minerals are pyrolusite, braunite, bixbyite, ramsdellite, and romanechite showing replacement, colloidal, and brecciated textures. The high mean values of Mn/Fe (15.32) and Si/Al (15.65), and the low mean concentration values of trace elements, such as Cu (85.9 ppm), Ni (249.9 ppm), and Zn (149 ppm), as well as the high concentration values of Si, Fe, Mn, Ba, Zn, Sr, and As in the studied manganese ores furnished sufficient evidence to postulate that the sea-floor Mn-rich hydrothermal exhalatives were chiefly responsible for the ore formation, and the hydrogenous processes had negligible role in generation of the ores. The further geological and geochemical evidence also revealed that the ores deposited on the upper parts of the ophiolitic sequence by submarine exhalatives. The intense hydrothermal activities caused leaching of elements such as Mn, Fe, Si, Ba, As and Sr from the basaltic lavas (spilites). After debouching of the sea-floor exhalatives, these elements entered the sedimentary basin. The redox conditions were responsible for separation of Fe from Mn.
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