Scientists say asteroid-powered volcanoes killed dinosaurs



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It's been almost 40 years since scientists discovered what destroyed dinosaurs: an asteroid hitting the Earthnear modern Mexico. That was it or that's what we thought.An article published today in Science supports an alternative hypothesis: catastrophic events following the impact could have contributed to the disappearance of dinosaurs and many other forms of life.

This builds on previous work – including some published last year – suggesting a link between the impact of the asteroid, the increase in volcanic eruptions and the impact of the earthquake. mass extinction event.

Brutal shock

In 1980, the American experimental physicist Luis Alvarez, his son geologist Walter and their colleagues published an influential article in the journal Science. They expose the evidence of a global catastrophe, buried in a layer scattered all over the planet, about 66 million years ago.

They found high levels of iridium – a rare element in the earth's crust, but common in meteorites. They found shocked quartz grains containing fractures indicative of the shock wave of impact, as well as traces of molten rock projection from impact shock.

With the subsequent discovery of the Chicxulub impact crater on the Yucatan Peninsula, Mexico, the case seemed closed. The reign of the dinosaurs ended with a meteorite impact, marking the end of the Cretaceous and the beginning of the paleogenic period, called the K-Pg limit.

Was there anything else?

Yet within the Earth Sciences community, discontent has continued to simmer. Two of the largest mass extinctions of the geologic register coincide with the largest basalt episodes exposed to continental flooding over the past 542 million years.

It's the end of the Permian 251 million years ago and, as the scientific paper of today points out, the extinction of the dinosaurs at the end of the Cretaceous 66 million years ago. The coincidence seems too great.

To understand the link between flood volcanism, meteorite impacts and extinctions, the moment is crucial.

In the new Science article, a team from the United States and India presents some of the most accurate dates for the huge eruptions in India, in a unit known as Deccan Traps – a huge province of basalt flooded in western India covering more than 500,000 km2 and in places is more than 2 km thick.