Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

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Mawpyut Intrusive Complex of Jaintia Hills District, Meghalaya, Northeastern India: A Case Study for Magmatic Differentiation


Affiliations
1 Department of Geology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata - 700 019, India
2 Geological Survey of India, Eastern Region, Salt Lake City, Kolkata - 700 091, India
     

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The petrological details of the ultramafic-mafic-alkaline complex related to Sylhet Trap occurring near to Mawpyut (25°25'N:92°10'E) of Jaintia hills district Meghalaya, northeastern India, are poorly known. Field investigations indicate that the Mawpyut body occurs as a pluton distinctly intrusive into adjacent low grade metasedimentary Shillong Group of rocks. This body reveals development of two broad lithotypes namely ultramafic (olivine clinopyroxenite, clinopyroxenite and plagioclase bearing ultramafic) and mafic (mostly gabbro, orthopyroxene gabbro, olivine gabbronorite, mela gabbro and mela-gabbro-norite) with minor presence of later syenitic veins. Though, in general, the pluton shows mineralogical variations, the field boundaries among those petrographic types are not discernible. Careful consideration of major and trace element chemistry of the constituent lithomembers clearly suggest progressive insitu fractionation of a common parent magma.

Keywords

Sylhet Traps, Mawpyut Complex, Major and Trace Element Characters, Differentiation History, Meghalaya.
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  • Mawpyut Intrusive Complex of Jaintia Hills District, Meghalaya, Northeastern India: A Case Study for Magmatic Differentiation

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Authors

Srinanda Chaudhuri
Department of Geology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata - 700 019, India
Rajarshi Saha
Department of Geology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata - 700 019, India
Jyotisankar Ray
Department of Geology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata - 700 019, India
S. K. Bhaduri
Geological Survey of India, Eastern Region, Salt Lake City, Kolkata - 700 091, India

Abstract


The petrological details of the ultramafic-mafic-alkaline complex related to Sylhet Trap occurring near to Mawpyut (25°25'N:92°10'E) of Jaintia hills district Meghalaya, northeastern India, are poorly known. Field investigations indicate that the Mawpyut body occurs as a pluton distinctly intrusive into adjacent low grade metasedimentary Shillong Group of rocks. This body reveals development of two broad lithotypes namely ultramafic (olivine clinopyroxenite, clinopyroxenite and plagioclase bearing ultramafic) and mafic (mostly gabbro, orthopyroxene gabbro, olivine gabbronorite, mela gabbro and mela-gabbro-norite) with minor presence of later syenitic veins. Though, in general, the pluton shows mineralogical variations, the field boundaries among those petrographic types are not discernible. Careful consideration of major and trace element chemistry of the constituent lithomembers clearly suggest progressive insitu fractionation of a common parent magma.

Keywords


Sylhet Traps, Mawpyut Complex, Major and Trace Element Characters, Differentiation History, Meghalaya.

References