Sunday, May 03, 2015

Did dinosaur-killing asteroid trigger largest lava flows on Earth?

I have wondered about this for some years.

The headline refers to it being a "new" theory. Actually a woman scientist proposed this already. What is "new" is that males are proposing it.

http://www.eurekalert.org/pub_releases/2015-04/uoc--dda043015.php

Public Release: 30-Apr-2015
University of California - Berkeley

The asteroid that slammed into the ocean off Mexico 66 million years ago and killed off the dinosaurs probably rang the Earth like a bell, triggering volcanic eruptions around the globe that may have contributed to the devastation, according to a team of University of California, Berkeley, geophysicists.

Specifically, the researchers argue that the impact likely triggered most of the immense eruptions of lava in India known as the Deccan Traps, explaining the "uncomfortably close" coincidence between the Deccan Traps eruptions and the impact, which has always cast doubt on the theory that the asteroid was the sole cause of the end-Cretaceous mass extinction.

"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, available online today (April 30) in advance of publication.

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.

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tags: historical global warming, historical climate change,

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