Volcanoes, asteroid wiped out dinosaurs

The theory, although widely supported, is now being revisited due to new research that points to the occurrence of a double catastrophe. Previous studies showed that while eruptions in western India’s Deccan Traps began millions of years before the impact, volcanic activity surged closer to the time of the asteroid collision. For example, Princeton Professor of Geosciences Gerta Keller argued in a 2011 report appearing in the Journal of the Geological Society of India that a combination of volcanic eruptions and meteor strikes was responsible for the mass extinction.

Combined with the hefty impact, the increase in volcanic activity would have pumped enough dust and noxious fumes into the atmosphere to blanket the Earth and drive many species to extinction. But Renne and his colleagues wondered if the two were related; after all, having such massive volcanic flows around the same time as a devastating asteroid impact seemed like an unlikely coincidence.

Professor Paul Renne said, “Based on our dating of the lavas, we can be pretty certain that the volcanism and the impact occurred within 50,000 years of the extinction, so it becomes somewhat artificial to distinguish between them as killing mechanisms: both phenomena were clearly at work at the same time”. “It is going to be basically impossible to ascribe actual atmospheric effects to one or the other”. “We are proposing that the volcanism unleashed and accelerated right at the KT boundary suppressed the recovery until the volcanoes waned”. What’s more, the researchers were able to determine the size and strength of each major eruption, based on lava flow estimates. Others insisted the death knell had been the impact, which left behind a large crater dubbed Chicxulub off Mexico’s Yucatan peninsula, and viewed the Deccan Traps eruptions as a minor sideshow.

The asteroid impact that triggered the mass extinction event that killed off the dinosaurs accelerated one of the planet’s largest volcanic eruptions, further compounding the disaster, a new study suggests.

What are the Deccan Traps?

Even though the rate of lava flow more than doubled, the frequency of eruptions-as measured by the number of lava and soil layers-dropped.

It took a half-million years before Earth and all its creatures began to recover from the world’s most recent mass extinction a few 66 million years ago, scientists report, and it took all that time for volcanoes that contributed to it to quiet down after erupting mountainous surges of lava across almost half the Asian continent.

The impact abruptly changed the volcanoes’ plumbing system. “Our data don’t conclusively prove that the impact caused these changes, but the connection looks increasingly clear”.

One factor supporting the Deccan-traps theory is that giant lava floods have also been pointed to as a likely culprit in the mass extinction at the end of the Permian, and between the Triassic and Jurassic periods.

In fact it was possible that large earthquakes had triggered volcanic eruptions throughout the Earth’s history.

Although the asteroid impact would have caused massive disruption to the climate it would have been relatively short-lived compared to the long-term impacts caused by the Deccan Traps erupting for thousands of years, the scientists said.

Such a change in the nature of eruptions – from frequent but small to occasional but enormous – could have been brought on by the shock of the asteroid impact, he said. The famous asteroid or comet that hastened their demise touched down in the middle of a period of climate change caused by burbling volcanoes.