New Delhi, March 23 Approximately 70 per cent of volcanic eruptions in India's Deccan Plateau occurred at the end of the Maastrichtian period, which represents the last few hundred thousand years of the Cretaceous Period and immediately preceding the Cretaceous-Paleogene boundary, a study has found.
The volcanic activity primarily contributed to environmental toxicity, resulting in the mass extinction event, according to findings published in the journal, The Geological Society of America Bulletin.
Dating back 66 million years, the Cretaceous-Paleogene boundary marks the mass extinction event, completely destroying non-avian dinosaurs, pterosaurs, and many marine organisms. The event is attributed to an asteroid impact.
Researchers, including those from the Advanced Center for Water Resources Development and Management and Fergusson College, Pune, said their analysis of the space-time distribution shows that 1.5 million cubic kilometers of Deccan flood basalts erupted during the 700,000 years within the geological time range of 66.31-65.73 Ma (Mega-annum), straddling the Cretaceous-Paleogene boundary event.
"Unlike earlier projections, we demonstrate that (nearly) 70 per cent of these lavas erupted in the terminal Maastrichtian before the KPgB (Cretaceous-Paleogene boundary)," the authors wrote.
The toxic degassing of the lavas over the 300,000 years prior to the KPgB set the stage for the mass extinction, they said. Hazardous gases and aerosols are released into the atmosphere both during and after an eruption as part of the degassing process.
The researchers coupled geochronology with previously published paleomagnetics and paleontological data of sediments associated with the Deccan volcanics.
The analysis "concludes that the earlier temporal distribution of the Deccan lavas was open to revision and that the late Maastrichtian flood basalt volcanism was magnitudes larger than the Danian volcanism in this province (Deccan Volcanic Province)."
The findings remove ambiguity about the environmental impact of the volcanism during the terminal Cretaceous times, the authors said.
"We conclude that the late Maastrichtian Deccan volcanism was the dominant contributor to the environmental crisis resulting in the TCME (Terminal Cretaceous Mass Extinction)," they said.
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