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Geochemistry and Origin of Neoproterozoic Granitoids of Meghalaya, Northeast India: Implications for Linkage with Amalgamation of Gondwana Supercontinent

Ghosh, S.; Fallick, A. E.; Paul, D. K. and Potts, P. (2005). Geochemistry and Origin of Neoproterozoic Granitoids of Meghalaya, Northeast India: Implications for Linkage with Amalgamation of Gondwana Supercontinent. Gondwana Research, 8(3) pp. 421–432.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/S1342-937X(05)71144-8
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Abstract

Many granitic bodies intrude the basement gneisses in Meghalaya Plateau, Northeast India. Rb-Sr whole-rock isotopic ages of the granitoids range from 881 to 479 Ma while the ages of the basement orthogneisses vary from 1714 to 1150 Ma. All the plutons are dominantly metaluminous and show geochemical variation. Oxygen isotopic compositions in the granitoids and gneisses are concordant (delta(18)O: + 5.78% to + 8.70%). However, the gneisses from high-grade terrain have low delta(18)O value of +2.52%o to +5.31%o. Initial Sr-87/Sr-86 (I-Sr) ratios of the plutons vary from 0.70459 to 0.71487 and tend to increase with progressive younging in age. The geochemical characters suggest derivation of the granites from lower crustal source. The fractionated rare earth patterns observed in the granitoids can be obtained by partial melting of gneisses or diorites. Some gneiss samples have experienced interaction with hydrothermal fluids resulting in lowering delta(18)O. The isotopic ages of granite plutonism in Meghalaya are similar to the plutonic and tectonothermal events in other parts of India, southwestern Australia and document final amalgamation events of the Gondwana Supercontinent.

Item Type: Journal Article
ISSN: 1342-937X
Keywords: Neoproterozoic granite; oxygen isotope; petrogenesis; Meghalaya; Northeast India
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 8889
Depositing User: Astrid Peterkin
Date Deposited: 09 Aug 2007
Last Modified: 02 Dec 2010 20:03
URI: http://oro.open.ac.uk/id/eprint/8889
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