• N G K Nair

      Articles written in Journal of Earth System Science

    • Granite-molybdenite association in Kerala in relation to taphrogenic metallogeny

      M Santosh N G K Nair

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      Two molybdenite-bearing granites from the Kerala region, namely, the Chengannoor and the Ambalavayal granites are discussed here in terms of their salient geochemical characters. The geochemistry of the host rocks indicates a peraluminous, calc-alkaline to alkali-calcic nature and the element levels show good fit with the proposed ‘finger-prints’ for granite-molybdenite systems. Fluid inclusion studies suggest that Mo was probably partitioned in vapour phase, which subsequently combined with available sulphur. Regional distribution of molybdenite strongly favours the view of a molybdenum province in the southern part of the Indian shield. Associations of rare metal mineralization with the riftcontrolled acid magmatic phase in the Kerala region are suggestive of a late Precambrian —Early Palaeozoic taphrogenic metallogeny.

    • Natural radioactivity distribution studies in Trivandrum district, Kerala, India

      G K Raju John Mathai G R Ravindra Kumar N G K Nair

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      The distribution pattern of radioactive minerals in Trivandrum district of Kerala has been investigated. The surface radioactivity was measured employing a jeep-mounted four-channel gamma-ray spectrometer coupled to a high volume Na I (T1) crystal detector. The distribution of radioactivity has been correlated with the corresponding litho-units and major structures of the study area. The total countrate from sedimentaries including beach sands and pegmatite rich zones (∼ 3,500 CPS) are significantly higher than that of the laterites and gneisses which are substantiated by laboratory studies.

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