Evolution of the ultramafic rocks of the Rakhabdev and Jharol belts in southeastern Rajasthan, India: New evidences from imagery mapping, petro-minerological and O-H stable isotope studies

The Rakhabdev and Jharol ultramafics occur within the Palaeoproterozoic Aravalli Supergroup in northwestern Indian shield. A discontinuous curvilinear regional outcrop pattern of the ultramafics of the Rakhabdev lineament and Jharol belts is observed in LANDSAT imagery. Ultramafics of both the belts show similar mineral assemblages comprising mainly antigorite and serpentine both of which have undergone extensive chloritization. Serpentine often shows alteration to dolomite and talc. Dominance of olivine and lizardite is observed in the Rakhabdev ultramafics, whereas magnetite and actinolite-tremolite are predominantly present in the Jharol ultramafics. Coherence is observed in the O and H stable isotope of ultramafics in both the belts which suggests uniformity in the process of serpentinization. Similar mineral assemblages and stable isotope compositions imply that serpentinization of ultramafics in both the belts evolved from same source under analogous coexisting conditions.