Petrology of High Grade Migmatitic Gneisses of the Lesser-Higher Himalayan Rocks of Western Sikkim, India

Jindal, Jayprakash (2013) Petrology of High Grade Migmatitic Gneisses of the Lesser-Higher Himalayan Rocks of Western Sikkim, India. Masters thesis, Indian Institute of Scienc e Education and Research Kolkata.

PDF (MS Dissertation of Jayprakash Jindal (08MS13)) Jayprakash_Jindal-08Ms13-MSThesis.pdf - Submitted Version Restricted to Repository staff only Download (702kB)

Abstract

This dissertation was carried out in the Lesser-Higher Himalayan migmatitic gneisses in western Sikkim, India. The study area is represented dominantly by thick sequence of pelitic migmatites, characterized by quartzofeldspathic leucosomes alternating with melanosomes, containing a combination of garnet, biotite, sillimanite, and the metapelites are completely devoid of muscovite. Textural features establish operation of Muscovite dehydration-melting reactions. Modeling of phase equilibria was carried out with the help of pseudosections using average bulk composition of pelites. In the present dissertation peak as well as retrograde pressure-temperature conditions of metamorphism were deduced using conventional geothermobarometric method. The results of individual thermobarometry shows that the rocks of Higher Himalaya in the study region has suffered a peak pressure-temperature of 9.6 kbar, 900⁰C were as the peak conditions for Lesser Himalayan rocks were 8.9kbar, 750⁰C.

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