Geologists find “strong candidate for the cause of mass extinction” 250 million years ago

The 480-kilometer (300-mile) -wide crater lies hidden more than 1.5 kilometers (a mile) beneath a sheet of ice and was discovered by scientists using satellite data, Ohio State University geologist Ralph von Frese said.

Von Frese said the satellite data suggests the crater could date back about 250 million years to the time of the Permian-Triassic extinction, when almost all animal life on Earth died out, paving the way for dinosaurs to rise to prominence, the AP reports.

The crater was found in what's known as the Wilkes Land region of the East Antarctic Ice Sheet.

Similar claims were made in 2004 when a team led by Luann Becker of the University of California reported that a crater off the northwest coast of Australia showed evidence of a large meteor impact at the time of the early extinction.

That team relied heavily on core samples provided by an oil company drilling in the region as evidence for its findings.

Von Frese, who announced his findings last month at an American Geophysical Union meeting in Baltimore, acknowledged his discovery lacks such hard evidence. He said he wanted to visit Antarctica to hunt for rocks at the base of the ice along the coast that could be dated.

Von Frese's findings so far rely on data from a NASA satellite that can measure fluctations in gravity fields beneath the ice.

The data revealed a 200-mile-wide (320-kilometer-wide) area where the Earth's denser mantle layer bounced up into the planet's crust. This is what would happen in reaction to such a big impact, in the planetary equivalent of a bump on the head, Von Frese said.

The prevailing theory holds that the Permian-Triassic extinction was caused by a series of volcanic eruptions over thousands of years that buried what is now Siberia in molten rock and released tons of toxic gases into the atmosphere, changing the Earth's climate.

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