Geochemistry of Pegmatites from South Delhi Fold Belt: A Case Study from Rajgarh, Ajmer District, Rajasthan

On the basis of geochemical studies, pegmatites emplaced in the Rajgarh Group of Delhi Supergroup in the South Delhi Fold Belt have been classified into three groups. They show a variety of rare earth element enrichment patterns, LREE/HREE values and Eu anomalies. The geochemical affinities of these pegmatites suggest their calc-alkaline nature, volcanic arc granite signature in tectonic discrimination diagrams (Nb vs Y and Rb vs Nb + Y) and a probable S-type parentage as inferred from their high A/CNK value, peraluminous character, presence of high normative corundum and abundance of garnet and muscovite. These features have been related to subductionrelated processes which might have generated the parent granitic melt forming these pegmatites.