Valid garnet-biotite thermometer: A comparative study

What is it about?

The abundance of garnet-biotite pair in a wide range of rocks mainly from upper green schist to granulite facies has made it one of the most widely used pairs for estimation of temperature at which once rocks equilibrated. In last four decades, more than 20 thermometer models of garnet-biotite pair have been proposed. To find the suitability of models, twenty-one thermometers formulated by a number of scholars since 1976 is considered. 27 sample data of granulites from the global literature were collected and processed through the “Gt-Bio.EXE” software. We conclude that four models are the most valid and reliable of these kinds of thermometers: Perchuk and Lavrente’va (1983); Thompson (1976); Ferry and Spear (1978) and Holdaway and Lee (1977)

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Why is it important?

Among the twenty-one geothermometer models of garnetbiotite equilibrium considered for this comparative study, Perchuk and Lavrente’va (1983); Thompson (1976); Ferry and Spear (1978) and Holdaway and Lee (1977) are showing the highest regression values and maximum points (values of temperature) are coming in best fit lines (Figs. 1a-d). So, these models can be considered empirically as the most appropriate ones to be used for the calculation of temperature.