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Authors
Affiliations
1 Dept. of Earth Sciences, Indian Institute of Technology, Powai, Mumbai, 400 076, IN
2 Department of Geology, MLS University, Udaipur, IN
3 Analytical Chemistry Division, BARC, Bombay, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 52, No 6 (1998), Pagination: 721-732
Abstract
The granulitic terrain of Proterozoic Delhi Supergroup exposed between Balaram and Mawal in Gujarat carries a suite of plutonic basic intrusive rocks consisting of gabbro, norite and basic granulites. Chronologically the suite is younger than metabasic rocks of north and central Rajasthan and occurs as melt intrusion within the host of pelitic granulites, calc granulites and granite gneisses. The suite ranges in chemical composition from alkaline to tholeiite through calc alkaline with characteristic major elemental distribution. Rare earth element chemistry shows Eu anomaly with LREE and LILE enrichment over HREE and HFSE. On the basis of the above enrichment it is invoked that the rocks are possibly derived from an enriched mantle beneath a subduction zone. Further, the Hf / 3-Th-Ta and Th / Yb-Ta / Yb systematics reflect a compositional match with calc alkaline basalt of present arc setting. These lead to suggest that the gabbro-norite-basic granulite suite signifies continental are magmatism in Delhi Supergroup and the Aravalli mountain had been evolved through continental collision and subduction during upper Proterozoic time.
Keywords
Geochemistry, Proterozoic, Tectonic Setting, Basic Granulites, Delhi Supergroup, Rajasthan.
