Mineral Chemistry and Geothermobarometry of Ore-Host Minerals in the Sulphide Mineralization in a Part of Subansiri District, Arunachal Pradesh

Sulphide mineralization in a thin shear of about 25 mts wide locating in the Potin - Yazali road section of Subansiri district, Arunachal Pradesh has been reappraised. The mineralization is structurally controlled. Structural elements include shear fractures and shear foliations; lithological variant is confined to garnetiferous quartz-biotite-schist. A comprehensive EPMA analysis of host minerals viz., garnet and biotite has been evaluated and P&T condition for the host rock has also been determined by garnet-biotite geothermometry. Ore mineralogical study revealed dominance of chalcopyrite and pyrrhotite with minor quantities of sphalerite, occasional patches of arsenopyrite and isolated finely disseminated bodies of pyrite. From the EPMA analysis of sphalerite, sphalerite geobarometry has been evaluated. The equilibrium temperature estimated for the peak metamorphic assemblages are 480°c ± 24°c while the pressure value might be higher than estimated value of 2.5 Kbar.