Early Cretaceous columnar basalts from the Mesoarchean Coorg Block, Southern India: A potential plume-influenced rifting event or a localized magmatic phenomenon?

The role of mantle plume in the final stages of rifting of the East Gondwana crustal fragments remains equivocal with only limited evidence so far reported from the southern part of Peninsular India. Here, we report for the first time a suite of columnar basalts from the Mesoarchean Coorg Block in the Southern Granulite Terrain (SGT) of India and characterize these rocks through field, petrological, geochemical, and isotope geochronological studies. The basalts show porphyritic texture with phenocrysts of pyroxene and plagioclase embedded in fine groundmass. Geochemical data reveal tholeiitic flood basalt affinity with affinities of plume-related magmatism. The zircon U-Pb data of the rocks yield a weighted mean age of 137 Ma, thus corresponding to the Valanginian Age of the Early Cretaceous Period. We suggest the possible geochemical affinity of the studied rocks Kerguelen plume basalts which provide new insights into magmatism associated with the final stages of East Gondwana rifting.