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Differentiated dyke rocks of Mer Mundwara, Rajasthan and their metallogenic significance

Published online by Cambridge University Press:  01 May 2009

Sivaramasubramania Viswanathan
Sivaramasubramania Viswanathan
Affiliation:
Indian Institute of Technology, Bombay-400 076, India
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Summary

The differentiated dyke rocks of Mer Mundwara comprise a subalkaline series which includes basalts and dolerites, and an alkaline series which includes theralites, porphyritic alkali syenites and nepheline syenites. These intrude into the coarse grained Precambrian granites which, in their turn, are subjacent bodies in the Aravalli system of metamorphic complex of archaean age. Absolute age of basic volcanics is 56±8 Ma, thus relating their emplacement to Deccan Trap volcanism in the Cretaceo-Eocene times in Central and Western India. Petrochemical characteristics of the basic rocks exemplify an alkaline character and so indicate that the basaltic magma of Mer Mundwara is tectonically and genetically different from the Deccan basalts which are in the main tholeiitic. The geological setting, petrography and major and minor element chemistry (Na > K and abundance of Nb, Co, Sn and V) relegate the dyke rock suite to the alkaligabbroic formations of Borodin (1974) with their parent magmatic source in the upper mantle. The alkaline igneous rocks of Mer Mundwara strongly suggest a possible occurrence of rare earths, niobium, zirconium and fluorine in industrial concentrations and also thorium and phosphorus.

Type
Articles
Information
Geological Magazine , Volume 114 , Issue 4 , July 1977 , pp. 291 - 298
Copyright
Copyright © Cambridge University Press 1977

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