The asteroid that slammed into the ocean off Mexico 66 million years ago and may have killed off the dinosaurs probably rang the Earth like a bell, triggering volcanic eruptions around the globe that may have contributed to the devastation, it has been claimed.

A new study says the impact may have triggered most of the immense eruptions of lava in India known as the Deccan Traps.

The 'uncomfortably close' coincidence between the Deccan Traps eruptions and the impact, has previously cast doubt on the theory that the asteroid was the sole cause of the mass extinction.

UK researchers studied the asteroid impact 66 million years ago (illustration shown). They found the heat near the impact site in Mexico was not intense enough to ignite plant material. A heat pulse lasted less than a minute, too short to set plants alight

A VAST IMPACT SITE The impact site is believed to be the 125 mile (200km) wide Chicxulub crater buried underneath the Yucatán Peninsula in Mexico. When the six-mile-wide (10km) asteroid hit what is now Mexico approximately 66 million years ago, dinosaurs were experiencing environmental upheaval, which left them vulnerable. Previous researcher has questioned the theory that a global firestorm accompanied the asteroid that killed off the dinosaurs. A team of researchers has found that heat near the impact site would not have been sufficient to ignite plants. It suggests our understanding of the mass extinction event that wiped out the dinosaurs may not be as complete as thought. Advertisement

'If you try to explain why the largest impact we know of in the last billion years happened within 100,000 years of these massive lava flows at Deccan … the chances of that occurring at random are minuscule,' said team leader Mark Richards, UC Berkeley professor of earth and planetary science.

'It's not a very credible coincidence.'

Richards and his colleagues marshal evidence for their theory that the impact reignited the Deccan flood lavas in a paper to be published in The Geological Society of America Bulletin.

While the Deccan lava flows, which started before the impact but erupted for several hundred thousand years after re-ignition, probably spewed immense amounts of carbon dioxide and other noxious, climate-modifying gases into the atmosphere, it's still unclear if this contributed to the demise of most of life on Earth at the end of the Age of Dinosaurs, Richards said.

'This connection between the impact and the Deccan lava flows is a great story and might even be true, but it doesn't yet take us closer to understanding what actually killed the dinosaurs and the 'forams,' he said, referring to tiny sea creatures called foraminifera, many of which disappeared from the fossil record virtually overnight at the boundary between the Cretaceous and Tertiary periods, called the KT boundary.

The disappearance of the landscape-dominating dinosaurs is widely credited with ushering in the age of mammals, eventually including humans.

He stresses that his proposal differs from an earlier hypothesis that the energy of the impact was focused around Earth to a spot directly opposite, or antipodal, to the impact, triggering the eruption of the Deccan Traps.

The 'antipodal focusing' theory died when the impact crater, called Chicxulub, was found off the Yucatán coast of Mexico, which is about 5,000 kilometers from the antipode of the Deccan traps.

Richards proposed in 1989 that plumes of hot rock, called 'plume heads,' rise through Earth's mantle every 20-30 million years and generate huge lava flows, called flood basalts, like the Deccan Traps.

It struck him as more than coincidence that the last four of the six known mass extinctions of life occurred at the same time as one of these massive eruptions.

Illustration of a hot mantle plume “head” pancaked beneath the Indian Plate. The theory by Richards and his colleagues suggests that existing magma within this plume head was mobilized by strong seismic shaking from the Chicxulub asteroid impact, resulting in the largest of the Deccan Traps flood basalt eruptions.

Richards calculates that the asteroid that created the Chicxulub crater might have generated the equivalent of a magnitude 9 or larger earthquake everywhere on Earth, sufficient to ignite the Deccan flood basalts and perhaps eruptions many places around the globe, including at mid-ocean ridges.

'It's inconceivable that the impact could have melted a whole lot of rock away from the impact site itself, but if you had a system that already had magma and you gave it a little extra kick, it could produce a big eruption,' Manga said.

Similarly, Deccan lava from before the impact is chemically different from that after the impact, indicating a faster rise to the surface after the impact, while the pattern of dikes from which the supercharged lava flowed – 'like cracks in a soufflé,' Renne said – are more randomly oriented post-impact.

Part of the main stack of 66 million year old Deccan Traps lava flows near the city of Mahabaleshwar, India. The entire volume of the Deccan Traps could have covered an area as large as the state of California in a mile deep pile of lava flows

'There is a profound break in the style of eruptions and the volume and composition of the eruptions,' said Renne. 'The whole question is, 'Is that discontinuity synchronous with the impact?'

Richards, Renne and graduate student Courtney Sprain, along with Deccan volcanology experts Steven Self and Loÿc Vanderkluysen, visited India in April 2014 to obtain lava samples for dating, and noticed that there are pronounced weathering surfaces, or terraces, marking the onset of the huge Wai subgroup flows.

Geological evidence suggests that these terraces may signal a period of quiescence in Deccan volcanism prior to the Chicxulub impact.

Apparently never before noticed, these terraces are part of the western Ghats, a mountain chain named after the Hindu word for steps.

Further away from the impact site in Mexico (shown), in places like New Zealand, the heat could have lasted up to seven minutes and caused some localised fires. But the theory that a global firestorm accompanied the asteroid impact is not correct, according to the scientists

'This was an existing massive volcanic system that had been there probably several million years, and the impact gave this thing a shake and it mobilized a huge amount of magma over a short amount of time,' Richards said.