Pink Sapphire from Southern Kerala, S. India: Implications on India-Madagascar Correlation Within Gondwana Assembly

Abstract

We report here the occurrence of pink sapphires in association with a variety of gemstones from the Trivandrum Granulite Block south of the Achankovil Shear Zone in southern India. The mineralization is associated with pegmatites or veins emplaced within granulite facies aluminous supracrustals. The sapphires show near-pure Al2O3 composition (98.43-99.48 wt.%) with traces of Cr2O3 (0.02-0.12 wt.%) and FeO (0.01-0.12 wt.%). The available radiometric age of 513+/-2 Ma for gem quality zircon associated with pink sapphire in the Melankode locality confirms that the mineralization is of late Pan-African age. Pink sapphires have been widely reported from a number of localities in southern Madagascar including Betroka, Illakaka, Antranondambo and Ambossary. Sapphires of various hues also occur in the Ratnapura gem district in the southwestern part of Sri Lanka. The pink sapphire occurrences in southern Madagascar and southern Kerala provide strong evidence for India-Madagascar juxtaposition in the Gondwana assembly with the Ranotsara Shear Zone in southern Madagascar extending into the Achankovil Shear Zone in southern India.