• M K Panigrahi

      Articles written in Journal of Earth System Science

    • Fluid evolution in quartz vein-hosted tungsten mineralization in Chhendapathar, Bankura District, West Bengal: Evidence from fluid inclusion study

      B Mishra D C Pal M K Panigrahi

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      Tungsten mineralization in Chhendapathar area is hosted by quartz veins that traverse mostly the metasediments in and around Jikhu Nala. Fluid inclusion microthermometric experiments reveal the presence of four distinct types of inclusions. These are: aqueous biphase, monophase carbonic, aqueouscarbonic and halite-bearing polyphase inclusions. Salinity-temperature variation points towards the presence of two fluids of contrasting salinities and both independently followed simple cooling paths without any indication of fluid mixing. The P-T of mineralization was calculated from the intersection of coexisting and coeval aqueous biphase, carbonic and halite-bearing inclusions. The deduced values range from 1.63kb/361°C to 2.30kb/385°C. However, the initial temperature must have been much higher as indicated from the high dissolution temperature (> 450°C) of halite. Transportation of tungsten in the high saline fluid was facilitated by cation-tungstate ion pairing, i.e., with the help of Na2WO4 and/or NaHWO4 complexes. A rapid fall in solubility in such fluid with falling temperature (in the range of 300–400°C), and by occasional fluid-rock interaction triggered precipitation of wolframite.

    • Granite-hosted molybdenite mineralization from Archean Bundelkhand cratonmolybdenite characterization, host rock mineralogy, petrology, and fluid inclusion characteristics of Mo-bearing quartz

      J K Pati M K Panigrahi M Chakarborty

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      The dominantly high-K, moderate to high SiO2 containing, variably fractionated, volcanic-arc granitoids (± sheared) from parts of Bundelkhand craton, northcentral India are observed to contain molybdenite (Mo) in widely separated 23 locations in the form of specks, pockets, clots and stringers along with quartz ± pyrite ± arsenopyrite ± chalcopyrite ± bornite ± covellite ± galena ± sphalerite and in invisible form as well. The molybdenite mineralization is predominantly associated with Bundelkhand Tectonic Zone, Raksa Shear Zone, and localized shear zones. The incidence of molybdenite is also observed within sheared quartz and tonalite–trondhjemite–granodiorite (TTG) gneisses. The fluid inclusion data show the presence of bi-phase (H2O–CO2), hypersaline and moderate temperature (100°–300°C) primary stretched fluid inclusions suggesting a possible hydrothermal origin for the Mo-bearing quartz occurring within variably deformed different granitoids variants of Archean Bundelkhand craton.

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