New evidence implicates one of Earth's biggest impact craters in a mass extinction that occurred 33.7 million years ago, according to research presented here Wednesday (June 11) at the annual Goldschmidt geochemistry conference.
Researchers from the University of California, Los Angeles precisely dated rocks from beneath the Popigai impact crater in remote Siberia to the Eocene epoch mass extinction that occurred 33.7 million years ago. Popigai crater is one of the 10 biggest impact craters on Earth, and in 2012, Russian scientists claimed the crater harbors a gigantic industrial diamond deposit.
The new age, which is later than other estimates, means the Eocene extinction — long blamed on climate change — now has another prime suspect: an "impact winter." Meteorite blasts can trigger a deadly global chill by blanketing the Earth's atmosphere with tiny particles that reflect the sun's heat. [Crash! 10 Biggest Impact Craters on Earth]
"I don't think this will be the smoking gun, but it reopens the door to Popigai being involved in the mass extinction," said lead study author Matt Wielicki, a UCLA graduate student.
This isn't the first time flying space rocks have been implicated in the Eocene's mass die-offs. Other possible culprits besides Popigai crater include three smaller Earth-meteorite smashups between 35 million and 36 million years ago: Chesapeake Bay crater offshore Virginia, Toms Canyon crater offshore New Jersey and Mistastin crater in Labrador, Canada.
Previously, all four craters were ruled out because of their ages. Earlier dating attempts had pinned Popigai's impact age at 35.7 million years ago, Wielicki said. And 2 million years is too much of a time lag between a meteorite blast and disappearing species, he said. The cosmic impact that killed the dinosaurs 65 million years ago coincides in time with its extinction by just 33,000 years, according to the most precise dating techniques available.