Petrogenesis of the protolith for the Tirodi gneiss by A-type granite magmatism: The geochemical evidence

In the Central Indian region, the Tirodi gneisses occur intimately associated with the Sausar Group metasediments. The protoliths for these gneisses might have originated by rift-related intracontinental felsic A-type (anorogenic) magmatism. The geochemical signatures in them like high Zr + Nb + Y +...

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Bibliographic Details
Published in:Current science (Bangalore) 1999-05, Vol.76 (9), p.1258-1264
Main Authors: Rao, M. V. Subba, Narayana, B. L., Rao, V. Divakara, Reddy, G. L. N.
Format: Article
Language:English
Subjects:
Fractionation
Geochemistry
Gneiss
Granite
Magmatism
Petrogenesis
Plate tectonics
Protoliths
Rare earth elements
RESEARCH COMMUNICATIONS
Tectonics
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Summary:In the Central Indian region, the Tirodi gneisses occur intimately associated with the Sausar Group metasediments. The protoliths for these gneisses might have originated by rift-related intracontinental felsic A-type (anorogenic) magmatism. The geochemical signatures in them like high Zr + Nb + Y + Ce, Ga/Al, Zr/Ni, Rb/Sr and Y/Sc, are quite similar to the A-type granite characteristics and point to the derivation of the protoliths by the melting of lower crustal dehydrated assemblages at high temperatures attained as a result of possible ponding of basaltic magma/magma underplating. The occurrence of mafic rocks related to subduction zone magmatism and back-arc environment in the vicinity of these gneisses in the Central Indian region attest to such an origin for the protoliths of the Tirodi gneisses.
ISSN:0011-3891