A few thoughts on the diamondiferous nature of lamprophyres from Wajrakarur Kimberlite Field, Southern India

Abstract Lamprophyre Clan Rocks (LCRs) such as lamprophyres, lamproites and kimberlites are reported from many parts of the cratonic areas in India, especially the diamondiferous Eastern Dharwar Craton (EDC). Although the most common hosts of diamonds are kimberlites and lamproites, different types of lamprophyres elsewhere in the world are also reported to contain diamonds. Owing to the fact that the lamprophyres and kimberlites in the Wajrakarur Kimberlite Field (WKF) are cogengetic, this study attempts for the first time to validate the diamond potentiality of WKF lamprophyres situated at Korrakodu, Kadiri, Kalagalla, Udiripikonda, Sivarampet, Khaderpet, Lattavaram (P-8) and Mudigubba using geochemical data. The geochemical plots of selected cationic wt.% for major oxides and trace elements show that Khaderpet and Lattavaram aillikites (ultramafic lamprophyres) are diamondiferous, with plausible chances of diamond incidences in the Kadiri and Mudigubba calc-alkaline lamprophyres. The trace-element plot of Ta and Sc also shows that the Khaderpet and Lattavaram lamprophyres are diamondiferous. The geochemical data reveal that diamond grade (DG) values are inversely proportional to TiO 2 content. It is also observed that the WKF lamprophyres contain some of the diamond indicator minerals. This study shows that the ultramafic lamprophyres of Khaderpet and Lattavaram, have DG values of Kadiri and Mudigubba lamprophyres showing DG values of 5.42 and 7.32 respectively and warrant detailed investigation. The higher DG values for Khaderpet (6.73) and Lattavaram (3.84) are consistent with exploration results. To date, no drilling has been conducted on the WKF lamprophyres except Khaderpet and Lattavaram; all the other lamprophyre outcrops are amenable for further exploration and drilling to ascertain their diamond potential and enhance understanding of the mantle systematics of this region.