Geochemical studies and economic perspective of light rare earth element (LREE) enriched carbonatite from Khaderpet, Eastern Dharwar Craton

An account of petrographic features, geochemical character, enriched light rare earth elements (LREEs), and stable isotope (C–O) concentrations in carbonatite occurring in association with lamprophyre clan rock (LCR) from Khaderpet is presented here. The Khaderpet carbonatite (KC) intrudes as a plug into LCR (ultramafic lamprophyre or aillikite) which is emplaced in granites of Archaean age forming granitoid breccia. A total of 10 fresh outcrop samples of carbonatite have been analysed. Petrographically, the carbonatites are dominated by calcite crystals showing an equigranular texture with accessory minerals like phlogopite, fluorite, chlorite, apatite along with REE bearing minerals such as monazite, titanite and allanite. Geochemical analyses reveal that the major element content shows high proportions of CaO (46.8–53.8 wt.%), with MgO (0.11–0.48 wt.%), FeO (0.21–0.23 wt.%), classifying the rock as a calcio-carbonatite. The ∑REE ranges from 4100 to 4500 ppm of which ∑LREE contributes maximum, (4092 to 4509 ppm) and Y ranges from 43 to 50 ppm. The δ 18 O values range from 6.6 to 8.76‰ and δ 13 C ranges from −7.45 to −6.33‰ indicating its primary carbonatite character. Geochemistry and stable isotopes have confirmed that carbonatite is of magmatic origin. KC shows ‘mineralised’ nature in geochemical diagrams. The enriched LREE relative to HREE indicates low degree of partial melting of source magma. Although the intrusion is smaller in outcrop magnitude, it warrants detailed testing in terms of quality and quantity with reference to its anomalously enriched LREE content and presence of diamonds.