G R Ravindra Kumar
Articles written in Journal of Earth System Science
Volume 95 Issue 3 November 1986 pp 397-407
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.
Volume 96 Issue 1 March 1987 pp 1-10
Isochemical conversion of garnet-biotite bearing paragneiss to charnockite in the Precambrian Khondalite belt of southern Kerala is described from Ponmudi area. Petrographic evidences indicate the formation of hypersthene by the breakdown of biotite in the presence of quartz following the reaction: Biotite + quartz → hypersthene + K-feldspar + vapour. The estimated pressure — temperature conditions of metamorphism are around 5–7 kbars and 750° ± 40°C. Presence of CO2-rich, mixed CO2-H2O and H2O-rich inclusions were noticed in gneiss as well as in charnockites. Charnockites contain abundant CO2-rich inclusions.