An Evaluation of Garnet – Clinopyroxene Geothermometer

Abstract

The garnet-clinopyroxene pair commonly found in upper amphibolite, granulite, and eclogite facies assemblage, as well as in garnet peridotites serves as a basic tool to estimate the equilibrium temperature for these metamorphic rocks. Several empirical and experimental calibrations for garnet-clinopyroxene thermometers have been proposed in the last four decades. Due to several calibrations for this pair, scholars often find difficulty in choosing the most optimum and valid thermometer. In the present study, eleven garnet-clinopyroxene thermometers formulated since 1972 have been evaluated to find the most valid thermometer checked on 89 sample data collated from the published global literature and processed through Gt-Cpx.Exe software. The authors used the relationship of LnKD versus the inverse of temperature and regression values. Out of the eleven geothermometer models, five models showing highest regression values with clustering of data at smaller ranges and less deviation for the collated data have been considered the best one: Raheim and Green (Contributions to Mineralogy and Petrology 48: 179–203, 1974); Mysen and Heier (Contributions to Mineralogy and Petrology 36: 73–94, 1972); Jun Lui (International Geology Review 40: 579–608, 1998); Ganguly and Saxena (Minerals Rocks 19: 1–291, 1987) and Ganguly (Geochimica et Cosmochimica Acta, 43: 1021–1029, 1979).