Carbonatite Veins of Mundwara Igneous Complex, Rajasthan

Lenticular veins of carbonatite are located in the pheripheral Erinpura granites E of Alkalic Mer pluton in Mundwara igneous complex, Sirohi District, Rajasthan. These veins vary in length from 20' to 200' and are composed of discontinuous lenses arranged en echelon. Calcite is the principal mineral of these veins and the associated accessory minerals are ankerite, hematite, magnetite, aegirine, apatite, feldspar, quartz and baryte. Frothy and fluidal textures as well as chilled marginal and fenitisation effects are observed in these veins. Martitised magnetite and chalcedony indicate low temperature of formation whereas the vesicular nature of these veins indicates low confining pressures (may be as low as I bar). These veins.are having high Sr, Ba and RE contents. The calcites from these are enriched in Sr, Ba, RE, Mo, Mg and P compared to their sedimentary counterparts. Thus, these veins are alvikites formed under pneumatolytic-hydrothermal conditions.

Lenticular veins are not reported by earlier workers and the Mundwara veins seem to be unique in this respect.