Dino-killing asteroid triggered largest lava flow on Earth

Chuck Bednar for redOrbit.com – @BednarChuck

The massive asteroid that crashed into the ocean near the coast of Mexico millions of years ago (and is believed to have wiped out the dinosaurs) was likely the catalyst for a series of worldwide volcanic eruptions contributed to the extinction event, new research claims.

As a team of geophysicists from the University of California, Berkeley explained in The Geological Society of America Bulletin, that the asteroid impact likely triggered the largest eruptions of lava in India – the Deccan Traps.

The Deccan Traps occurred so close to the impact that they led some to doubt that the asteroid was the sole cause of the end-Cretaceous mass extinction event, the study authors explained in a statement Thursday. Now, Mark Richards, a UC Berkeley professor, has found new evidence explaining what may have really happened.

“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. It’s not a very credible coincidence,” Richards said. Instead, he and his colleagues believe that the lava flows started before the asteroid but were re-ignited by its impact.

So, did the lava contribute to extinction?

The researchers calculated that the asteroid responsible for the Chicxulub crater may have been capable of generating a magnitude 9 or larger earthquake throughout the Earth, which would be sufficient to ignite the Deccan flood basalts and potentially cause lava eruptions to occur all over the planet. They also found chemical differences in the Deccan lava, pre- and post-impact.

Those chemical differences indicate that lava rose to the surface more quickly after the asteroid crash-landed, and more randomly-oriented faults from which the lava flowed post-impact were also found. Additional exploration found that there was a span of inactivity in Deccan volcanism prior to the Chicxulub impact, which suggests that the asteroid re-awakened the eruptions.

The Deccan lava flows erupted for several hundred thousand years after the impact, and probably sent tremendous amounts of carbon dioxide and other noxious, climate-modifying gases into the atmosphere. However, it remains uncertain whether or not these events played a role in the extinction of the dinosaurs and most other life on Earth at the time.

“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,” said Richards. He and his colleagues wrote that “high-precision radioisotopic dating” of the Deccan flood basalt formations could be able to determine whether or not the eruptions played a key role in the global extinction events.

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