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Authors
Affiliations
1 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur - 721 302, IN
2 EASC, 8888 University Drive, Simon Fraser University, Burnabay, B.C., Canada V5A156, CA
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 61, No 1 (2003), Pagination: 51-60
Abstract
Fluid inclusions in quartz from the mineralized quartz veins from the Mosabani and Rakha copper deposits were investigated. On the basis of petrography, two distinct types of primary inclusions were identified. These are low saline aqueous biphase inclusions and high saline halite-bearing polyphase inclusions. The halite-bearing inclusions mostly homogenized by halite dissolution; barring instances where homogenization was manifest by disappearance of the vapour bubble. Minimum entrapment pressure values were eslimated by intersection of the halite liquid with the corresponding incIusion isochores. The ranges in P-T at the ternpcratures of halite dissolution are: 2.6 kb / 370°C - 0.8 kb / 263°C for Mosabani and 2.1 kb 1 270°C - 0.65kb / 217°C for Rakha. Temperature-salinity plots fot both the deposits is suggestive of restricted mixing (and simple cooling) of a hot saline magmatic fluid with cooler low saline meteoric water that caused precipitatin of sulphide minerals. Stable isotope data (δ18O and D) from Changkakoti et al. (1987) are re-interpreted in the present study, leading to the conclusion that the main fluid component for Mosabani mineralization was either of magmatic/metasomatic parentage or an evolved meteoric water at a low water/rock ratio, after its interaction with a granitic pluton. The observed high saline nature of fluids in both the deposits compels us to choose an initial magmatic/metasomatic fluid that evolved by restricted mixing and simple cooling.
Keywords
Fluid inclusions, Microthermornetry, Copper Ores, Mosabani, Rakha, Singhbhum, Jharkhand.
