Rb-Sr Age determinations for the Mount Abu granite and related rocks of Gujarat

Abstract The mount Abu Granite of south-western Rajasthan and related 'Erinpura type' granites in Gujarat give Rb-Sr total rock ages of about 735 m.y. They are therefore of the same age as the Malani Igneous Suite of western and south-western Rajasthan and not older as previously believed. Though possibly updated by re-heating related to emplacement of that Suite, it seems more probable that the two were emplaced at about the same time. This could have taken place in a tectonic environment created by sinistral shear of what are now northern and southern Peninsular India along the Narmada-Son lineament, with bending of the southern end of a rectilinear Aravalli orogenic belt by major fault drag.