Occurrence of rhyolitic dykes within the Mt. Abu Batholith, southwestern Rajasthan

Abstract

The occurrence of Malani rhyolites as dykes within the Mt. Abu batholith has been studied. The Mt. Abu rhyolitic dykes are peraluminous and of subalkaline nature. These are enriched in trace elements such as Rb, Nb, Zr, Y, Ga, Th and Zn, and depleted in Ba and Sr resulting in high K/Rb, Rb/Sr, Ba/Sr and Ga/Al ratios. The geochemical characters indicate Mt. Abu rhyolitic dykes to be A-type, within-plate granites (WPG) with high SiO2, Na2O + K2O and Fe/Mg. These rhyolites are likely to have formed in anorogenic rift-related setting and the volcanism may be correlated to early stages of Pan-African magmatic event (850-750 Ma). © Geol. Soc. India.