Nepal Geological Society (NGS)

Nepalese National Group of IAEG Since 20 Years

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Geothermobarometer based on coexisting garnet-orthopyroxene-plagioclase-quartz equilibria

Harel Thomas

Department of Applied Geology, Dr. H. S. G. University, Sagar (MP), India

Lalu P. Paudel

Central Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal

Jour. Nepal Geol. Soc., Vol. 51, 2016, 1-10



The garnet-orthopyroxene-plagiolcase-quartz pairs are commonly found in the assemblages of basic granulites/charnockite and hence are suitable for estimating equilibrium temperature and pressure of most metamorphic rocks. The temperature based on garnet-orthopyroxene Fe-Mg exchange reaction and pressure based on net transfer reaction of garnet-orthopyroxeneplagioclase-quartz equilibria, mainly based on reactions, using the equation given by different workers.

i. 1/2 Ferrosilite + 1/3 Pyrope = 1/2 Enstatite + 1/3 Almandine.

ii.  Ferrosilite + Anorthite = 2/3 Almandine + 1/3 Grossularite + Quartz

iii. Enstatite + Anorthite = 2/3 Pyrope + 1/3 Grossularite + Quartz.

The author developed software in visual basic with the executable code MPET3.EXE

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