Volume : III, Issue : III, March - 2014

Geochemistry of The Basement Gneissic Rocks Around Sumer–Umsning Area, Meghalaya India

Tapos Kumar Goswami

Abstract :

The Basement Gneissic and Migmatitic Complex (BGMC) of the Assam Meghalaya craton studied in and around Sumer , Nayabunglow and Umsning areas of the Ribhoy Distrct of Meghalaya indicate that the quartzofeldspathic gneisses are the most abundant rock types. Besides the two verities of grey and pink gneisses, discontinuous but persistent bands of amphibolites and discontinuous quartz and aplitic veins also occur in the area. Microcline is less dominat in grey gneiss while it is dominant in pink gneiss apart from dominant phases of quartz, plagioclase and biotite. Hornblende, zircon apatite, magnetite and sphene occur as accessory phases in both verities. Modal composition of quartz varies between 31.5 to 35.3% in the gneisses. Geochemical analysis of the gneisses indicates that they are metaluminous to peraluminous granite of calc alkaline type with high Si and alk and low mg and c values. The gneisses might be the product of metamorphism of the siliceous shale under lower amphibolites facies condition.

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Article: Download PDF   DOI : 10.36106/ijsr  

Cite This Article:

Tapos Kumar Goswami Geochemistry of The Basement Gneissic Rocks Around Sumer-Umsning Area, Meghalaya India International Journal of Scientific Research, Vol.III, Issue.III March 2014

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