A Late Cretaceous (ca. 90 Ma) kimberlite event in southern India: implication for sub-continental lithospheric mantle evolution and diamond exploration

摘要: Abstract We report groundmass perovskite U–Pb (SIMS) ages, Nd isotopic (LA-ICPMS) composition and bulk-rock geochemical data of the Timmasamudram diamondiferous kimberlite cluster, Wajrakarur field, in Eastern Dharwar craton southern India. The pipes gave similar Mesoproterozoic ages 1086 ± 19 Ma (TK-1, microcrystic variant) 1119 ± 12 Ma (TK-3). However, a population sampled from macrocrystic variant TK-1 much younger Late Cretaceous age ca. 90 Ma. This phase intrudes has distinct geochemistry. Nd-isotope ~ 1100 Ma perovskites cluster show depleted eNd(T) values 2.1 ± 0.6 to 6.7 ± 0.3 whereas ~ 90 Ma have enriched − 6.3 ± 1.3. depleted-mantle (DM) model is 1.2 Ga, DM Proterozoic 1.2 1.5 Ga. Bulk-rock incompatible trace element ratios (La/Sm, Gd/Lu, La/Nb Th/Nb) all kimberlites strong affinity with those Group II Bastar (India) Kaapvaal (southern Africa). As indistinguishable that Marion hotspot-linked extrusive intrusive igneous rocks Madagascar India, we infer may be part single Large Igneous Province. Our finding constitutes first activity India significant implications for its sub-continental lithospheric mantle evolution diamond exploration programs.