Geochemical characteristics, discrimination and petrogenesis of Neoproterozoic peralkaline granites, Barmer District, SW Rajasthan, India

The Malani Igneous Suite is characterized by discontinuous, ring-shaped outcrops of peralkaline granite associated with minor exposures of volcanic rocks around Barmer town in southwestern Rajasthan, India. These granites are defined as peralkaline, within plate, and A-type based on their bulk rock compositions. The most distinctive geochemical characteristics of these A-type granites are enrichments in Na2O + K2O, Fe/Mg, Zr, Nb, Y, depletions in Al2O3, CaO, Sr, and low-absolute abundances of incompatible trace elements compared to granites from adjoining areas. The igneous activity is considered as a reflection of the ` Pan-African Event'. The correlative mineralogy, chemical characteristics, and tectonic setting of the peralkaline granites from the study area, and comparison with data from adjoining areas, suggest their generation under a common thermal event.