What is it about?
The abundance of garnet - hornblende pair in a wide range of rocks primarily 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. Several models of garnet- hornblende thermometer have been formulated by a number of researchers in last four decades. In this contribution, four thermometers: Graham & Powell (1984); Perchuk et al., (1985); Powell, (1985) and Ravna, (2000) formulated since 1984 have been applied.
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Why is it important?
Based on the present study, the best among all the four models have been identified where the regression bearing on inverse of temperature verses LnKD of each model as well as relation of distribution coefficient on composition were compared. It is concluded that Perchuk et al., (1985) is the most valid and reliable thermometers for a wide range of rock types such as greenschist to eclogite facies.
Perspectives
Although it is always necessary to do further experimental work to refine the calibration of the Garnet-Hornblende thermometer using garnet and hornblende with chemical compositions and comparable to natural minerals due to its high variable chemistry . However, it is equally important to improve our knowledge of the various chemical interactions within minerals such as garnet and hornblende over the occurrence in very different conditions in both igneous and metamorphic facies, so that we can improve the activity models for these minerals over the large span of chemical equilibrium and physical condition
Professor Harel Thomas
Doctor Harisingh Gour Vishwavidyalaya, Sagar (M.P.) 470003, INDIA (A Central University)
Read the Original
This page is a summary of: Garnet-Hornblende Geothermometer: A Comparative Study, Journal of the Geological Society of India, December 2020, Springer Science + Business Media,
DOI: 10.1007/s12594-020-1607-9.
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