Bombolai Continental Pillow Lavas (Neoproterozoic) from Trans-Aravalli Region, Pali District, Rajasthan and their Tectonic Significance

Neoproterozoic Bombolai volcanics of Trans - Aravalli terrain of western Rajasthan, consist of three distinct flows separated by metasediments including bedded chert, phyllite and quartzite In terms of their major oxides and trace and rare earth element abundances, all these flows are compositionall identical and evolved (Mg No 0 397-0 474, Ni - 61-92 ppm and Cr - 172-234 ppm) Major and trace element contents permi one to classify them as subalkaine basalts having enriched LREE abundances However, MORB and PM- nomalised spidergrams characterize them as within plate tholeites On the basis of their TiO 2 , content (1 84-2 43), Ti/Y ratio (294-347) and Zr/Y ratio (2 9-3 7), the Bombolai volcanics are classified as low Ti-continental tholentes The general geology geochemistry and associated lithologies indicate that the Bombolai volcanics were erupted in a reactivated nit environment (Pali lineament) which probably occurred as a precursor event to a large magmatic activity ie Malani volcanism in Trans-Aravalli region.