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

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