Asteroid-powered volcanoes killed the dinosaurs, scientists say


It’s almost 40 years since scientists discovered what wiped out the dinosaurs: an asteroid hitting Earthnear modern-dayMexico. That was it, or so we thought.A paper published today in Science further supports an alternative hypothesis: that catastrophic events following the impact could have helped cause the end of the dinosaurs and many other forms of life.

This builds on earlier work – including some published last year – suggesting a connection between the asteroid impact, increased volcanic eruptions, and the mass extinction event.

Sudden impact

Back in 1980, the American experimental physicist Luis Alvarez, his geologist son Walter and their colleagues published an influential paper in the journal Science. In it, they outlined evidence of a global catastrophe, buried in a layer spread all over the planet, about 66 million years ago.

They found high levels of iridium – a rare element in Earth’s crust, but common in meteorites. They found shocked quartz – grains of quartz with telltale fractures from the blast wave of the impact, as well as evidence of molten rock thrown out from the impact blast.

With the later discovery of the Chicxulub impact crater on the Yucatan Peninsula, Mexico, the case seemed sealed. The reign of the dinosaurs ended with a meteorite impact, marking the end of the Cretaceous, and start of the Paleogene period, called the K-Pg boundary.

Was there something else?

Yet within the Earth science community, discontent continued to simmer. Two of the largest mass extinctions in the geological record both coincide with the largest exposed continental flood basalt events in the past 542 million years.

They are the end of the Permian 251 million years ago, and – as today’s Science paper highlights – the dinosaur extinction at the end of the Cretaceous 66 million years ago. The coincidence seems too great.

In understanding the link between flood volcanism, meteorite impacts and extinctions, timing is everything.

In the new Science paper, a team from the United States and India present some of the most precise dates yet for the enormous eruptions in India, in a unit known as the Deccan Traps – an enormous flood basalt province in Western India that covers more than 500,000 km2 and in places is more than 2 km thick.