Abstract
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.
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Srikantappa, C., Kumar, G.R.R. Gneiss-charnockite relation around Ponmudi, southern Kerala: evidences and implications of prograde charnockite formation in southern India. Proc. Indian Acad. Sci. (Earth Planet Sci.) 96, 1–10 (1987). https://doi.org/10.1007/BF02842632
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DOI: https://doi.org/10.1007/BF02842632