Lithium-enriched Sibagaon pegmatites of Rajasthan,India and their economic potentiality: Geospatial,geochemical and petrological insights for Li–Cs–Ta (LCT) pegmatite exploration

Abstract

Sibagaon pegmatites in Northwest India demonstrate transition from barren granitic magmatism to LCT mineralization, offering geochemical insights to refine rare metal exploration models. Hosted in calc-silicate rocks, these pegmatites are highly fractionated, peraluminous, LCT-type, show syn- to post-collisional signatures and feature lepidolite (contain up to 2.34 w-t% Li₂O) as primary Li- mineral, followed by elbaite to liddicoatite tourmalines. Geochemical markers distinguishing them from barren granites include low Nb/Ta ratios, REE tetrad effects, non-CHARAC behavior, and linear Li-F correlation. Lepidolite and tourmaline exhibit core to rim Li and F enrichment. Tourmalines with liddicoatite rims and feldspar replacement textures indicate late stage CaO rich fluid contamination. This study illustrates a continuum from fractional crystallization to magmatic-hydrothermal interaction with late Li-F fluid influx causing rare metal mineralization. These signatures with inferred resource of 91,295 tonnes at 0.673 wt-% Li₂O provide a quantitative framework for identifying similar prospects in evolved collisional granitic systems.