Contemporary researches and issues related to the deccan volcanism

Abstract

In the past few decades, late Cretaceous Deccan volcanism witnessed extensive researches, focused on nature, variety and genesis of magma, emplacement span [entail Cretaceous /Palaeogene (K/Pg) transition] and attendant faunal crisis; however several issues remain to be addressed. In this gamut, researches in the past five years have been reviewed, encompassing petrochemical, Nd-Sr-Pb isotopic, and geochronology studies to comprehend origin, age and duration of volcanism and attendant K/Pg transition events. Low/high TiO2 tholeiites of Deccan Traps and associated rocks from a rifted basin revealed existence of varied mantle sources for synchronously formed tholeiitic and alkaline magma involved sub-continental lithospheric mantle. Moreover, later magma type ascended with faster rate through the lithosphere and subsequently led to rapid gaseous release, accounted for the Cretaceous/Palaeogene boundary (KPB) mass extinction. Flow-by-flow palaeomagnetic measurements for the Mandla basalt revealed multiple magnetic polarity events: implying for C29n-C28rC28n magnetostratigraphy. 40Ar/39Ar ages for Mundwara and Sarnu-Dandali complexes assign polychronous emplacement, concomitant with the post-breakup of Indo-Madagascar. Both complexes show comparable evolution from early to late Cretaceous Period. U-Pb zircon age data based Deccan eruption rates when combined with the Chicxulub impact triggered seismicity, inferred four major eruptive phases, each lasted for ≤100 ka. In the second eruptive phase, Poladpur Formation eruption began tens of thousands of years before, but peaked out at K/Pg mass extinction event. Consequently, carbonate dissolution, climatic cooling and late Maastrichtian global warming attendant to Deccan volcanism, induced ocean acidification which led to high environmental stress worldwide. Present review also covers applied aspects, including CO2 sequestration in Deccan basalt and suitability of silicic phase for nuclear waste disposal. Additionally, it ends-up with a note on future direction of researches in Deccan basalt.