The nature of the crust obscured beneath the Deccan Traps has remained enigmatic, largely because of the voluminous lava pile that deters access to the concealed basement. The paper present in situ zircon U–Pb geochronology and bulk-rock geochemistry of a volcanic sequence discovered at – 400 m in the deep bore-hole well-core KBH-5 of the southwestern Deccan Traps, India.
The ~300 m thick 2.58 Ga metavolcanic succession includes a basalt – Nb-enriched basalt – andesite – Mg-andesite – dacite – adakite suite. The geochemical attributes of the metavolcanic rocks are identical to those reported in the Medur Formation of the Shimoga greenstone belt, ~300 km south of KBH-5 in the western Dharwar craton. The study provides the first physical evidence of Dharwar greenstone belt(s) extending further beneath the Deccan Traps.
Th/Nb vs. Ce/Nb tectonic discrimination diagram for the KBH-5 metavolcanic rocks, after Saunders et al. (1988). The diagram illustrates mixing between the mantle components: DMM (depleted MORB mantle), SDC (subduction zone component) and the RSC (residual slab component).