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Konilov, A. N.
- Conditions of Metamorphism of the Garnet-Cordierite Gneisses from Malai Mahadeswara Hills, South India and the Origin of Zn-Cr-Rich Spinel
Authors
1 Institute of Experimental Mineralogy of the Russian Academy of Sciences, Chernogolovka, Moscow district, 142432, RU
2 Department of Geology, University of Mysore, Mysore 570 006, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 51, No 1 (1998), Pagination: 75-86Abstract
A spinel phase with unusually high ZnO (8.8-11.0) and Cr2O3 (13.2-15.8%) contents is found in garnet-cordierite-sillimanite bearing migmatised pelitic bands interbedded with tonalitic charnockites of Malai Mahadeswara (MM) Hills. The textural and microprobe data indicate that this spinel phase is associated with late iron-rich garnet (rim)-cordierite-sillimanite assemblage.
P-T conditions of cordierite-garnet assemblages vary from peak metamorphic conditions of greater than 8 kbar and 750°C to 6.7±1.4 kbar and 685 ±20°C. The last retrograde phase of metamorphism took place at P of 4.5 kbar and at T of 580°C. The formation of Zn and Cr rich spinel phase must have taken place during this waning stages of metamorphism by the activity of hydrothermal fluids.
Keywords
Geothermobarometry, Mineralogy, Metamorphism, MM Hills, Karnataka.- Electron Microprobe Dating of Monazite from Spinel Granulite in the Eastern Ghats Belt, India
Authors
1 Department of Geology, Andhra University, Visakhapatnam-530 003, IN
2 Institute of Experimental Mineralogy, 1142432, Chernogolovka, Moscow District, RU