Precambrian Carbonatites of Tamil Nadu, South India

Abstract The newly discovered carbonatites of Tamil Nadu are Upper Precambrian in age. They are associated with alkali syenite massifs in Tirupattur area, where the fault system directed NE-SW, very likely represents an ancient deeply eroded trough or rift valley. The carbonatites are mostly beforsitic (para-ankeritic); and pyrochlore mineralization found here is unique in the world, as in general pyrochlore is not reported from beforsitic carbonatites. Both geological setting and petrological features support the view that the Tamil Nadu carbonatite province differs in many respects from Narmada Valley province in India as well as from other carbonatite provinces all the world over.