Wednesday, May 10, 2017

Crater Potentially Linked to the Biggest Mass Extinction Event in Earth’s History is Discovered

[Newsweek] Scientists have discovered what they believe is one of the biggest impact craters in the world near the Falklands Islands. They say the crater appears to date to between 270 and 250 million years ago, which, if confirmed, would link it to the world’s biggest mass extinction event, where 96 percent of life on Earth was wiped out.
The presence of a massive crater in the Falklands was first proposed by Michael Rampino, a professor in New York University, in 1992 after he noticed similarities with the Chicxulub crater in Mexico—the asteroid that created this crater is thought to have played a major role in the extinction of the dinosaurs 66 million years ago.
But after a brief report at the Falklands site, very little research was carried out. Now, a team of scientists—including Rampino—have returned to the area to perform an “exhaustive search for additional new geophysical information” that would indicate the presence of an impact crater.
Their findings, published in the journal Terra Nova, suggest the huge circular depression just northwest of the islands is indeed the result of the massive impact of an asteroid or meteorite. The basin, which is now buried under sediments, measures over 150 miles in diameter.
To analyze the site, the team, from the U.S., Argentina and Paraguay, looked at various aspects of the crater, including gravity anomalies and seismic reflection, which allows them to estimate sub-surface properties, along with differences in the chemistry of the rocks.
Their findings were consistent with other impact craters, with certain features being “very similar to that of the Chicxulub multi-ring impact structure.” They found there was a large magnetic anomaly, suggesting significant variation in rocks at the site, as well as gravitational variations “typical of very large impact structures.” Read More