Tholeiitic basalts of Deccan large igneous province, India: An overview

The Deccan large igneous province (DLIP) of Peninsular India is predominantly composed of tholeiitic basalts with a minor amount of alkaline, carbonatite, and silicic rocks. The tholeiitic basalts of DLIP are enriched in incompatible trace elements and divisible into low-Ti basalts (TiO2 < 2.5; Ti/Y < 500) and high-Ti basalts (TiO2 > 2.5; Ti/Y > 500). Despite variable total REE content, both low-Ti and high-Ti basalts exhibit almost similar geochemical patterns in the chondrite- and primitive- mantle-normalized diagrams. The mantle potential temperature (T-p) of high-Ti tholeiites estimated at Ca.1368 degrees C, which is consistent with an ambient mantle temperature (1300-1400 degrees C) whereas the T-p of low-Ti tholeiites is around 1553 degrees C, which indicates its derivation from the mantle plume axis. Extensive assimilation of the crustal components into the ascending plume have masked the nature and compositional characteristics of both high- and low-Ti basalts. The low-Ti basalts indicate significant contamination with crustal components than the high-Ti basalts. The geochemical and isotopic compositions indicate the involvement of multiple mantle components. In general, the differentiated tholeiites of DLIP are the products of plume and depleted sections of the mantle with or without contributions from the continental crust. The main phase of Deccan magmatism intensely affected the atmosphere and hydrosphere, which was a possible trigger for the mass extinction event at the K-Pg boundary.