Deccan volcanism killed dinosaur: Study

Geologists have uncovered compelling evidence that an asteroid impact on earth 66 million years ago accelerated the eruptions of volcanos in India for thousands of years, and the two catastrophes led to the extinction of many animals, including the dinosaurs.

For 35 years, paleontologists and geologists debated the role these two global events played in the last mass extinction, with one side claiming the eruptions were irrelevant, whereas the other side asserting the impact was a blip in a long-term die-off.

The new evidence suggests the pace of eruptions accelerated within 50,000 years of the asteroid impact.

The impact and volcanism blanketed the planet with dust and noxious fumes, drastically changing the climate and sending many species to an early grave.

"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. , It becomes somewhat artificial to distinguish between them as killing mechanisms: both phenomena were clearly at work at the same time," said lead researcher Paul Renne, a University of California, Berkeley professor-in-residence of earth and planetary science.

The geologists argue that the impact abruptly changed the volcanos' underground plumbing system, which produced major changes in the chemistry and frequency of the eruption.

"We are showing the viability of a scenario in which the impact and accelerated volcanism - which would be especially potent - are genetically related. Previous 'one-two punch' hypotheses have not proposed this," said Renne. The findings are published in the October 2 issue of Science.

Since the 1980s, when researchers discovered the evidence of a comet or asteroid impact on earth 66 million years ago, scientists wondered if the impact was the main cause of the mass extinction.

The counter-theory gives prominence to the huge Indian volcanic eruptions known as the Deccan Traps, which occurred around the same time.

Earlier this year, Richards, Renne and eight other geoscientists proposed a new scenario - the impact ignited volcanos around the globe, most catastrophically in India, and the two events combined to cause the extinction.

To test this hypothesis, the team tested lava samples from Deccan Traps collected from east of Mumbai. The analysis demonstrate major changes in the Deccan Traps volcanism, which was probably bubbling along happily, continuously and relatively slowly before the extinction.

After the impact, the eruption rate more than doubled and the volcanism became more punctuated, consistent with a change in the underground mechanism feeding the flows.

"Our data don't conclusively prove that the impact caused these changes, but the connection looks increasingly clear," he added.