New evidence unearthed on extinction of dinosaurs

Mansourasaurus shahinae
Representational picture Andrew McAfee, Carnegie Museum of Natural History

An asteroid that hit Earth 66 million years ago may have possibly triggered a worldwide release of volcanic magma that could have sealed the fate of the dinosaurs, researchers have claimed.

A six-mile-wide asteroid crashed into Mexico's Yucatan Peninsula, nearly 66 million years ago, causing a massive earthquake both on land and sea.

The impact might have also caused underwater volcanoes to spit up magma more ferociously, further intensifying the devastating environmental impact of the event, revealed a study published in the journal Science Advances.

"We found evidence for a previously unknown period of globally heightened volcanic activity during the mass-extinction event," said Joseph Byrnes from the University of Minnesota.

Since 1980s when the evidence of the meteor strike near present-day Chicxulub in Mexico surfaced, scientists have been debating whether the asteroid or eruptions from a particularly volcanic region in India called the Deccan Traps drove the extinction event that killed off all nonavian dinosaurs.

Various studies indicated that the Deccan Traps volcanoes were already active when the meteor struck. Hence, the seismic waves moving through the planet from the meteor strike, probably fuelled an acceleration of those eruptions, explained Leif Karlstrom, Professor at the University of Oregon.

For the study, the team analysed available global data sets on free-air gravity, ocean floor topography and tectonic spreading rates.

They divided the seafloor into one-million-year-old groupings, constructing a record back to 100 million years ago.

At about 66 million years, they found evidence of a "short-lived pulse of marine magmatism" along ancient ocean ridges. This pulse is suggested by a spike in the rate of the occurrence of free-air gravity anomalies seen in the data set.

Byrnes found changes in free-air gravity anomalies of between five and 20 milligals associated with seafloor created in the first million years after the meteor.

"Our work suggests a connection between these exceedingly rare and catastrophic events, distributed over the entire planet. The meteorite's impact may have influenced volcanic eruptions that were already going on, making for a one-two punch," Karlstrom said.

The meteorite may have modulated distant volcanism by generating powerful seismic waves that produced shaking worldwide and proposed that seismic shaking liberated magma stored in the mantle beneath the Deccan Traps and caused the largest eruptions there, researchers said.

Source: IANS