From: Andrew Johnson
Date: 2006-06-04 14:24:49
Attachments : Source: www.news24.com/News2…,,2-13-1443_1944659,00.html Huge meteor spawns Australia02/06/2006 21:20 – (SA) A meteor’s roaring crash into Antarctica – larger and earlier than the impact that killed the dinosaurs – caused the biggest mass extinction in Earth’s history and more than likely spawned the Australian continent. Ohio State University scientists said the 483km wide crater is now hidden more than 1.6km beneath the East Antarctic Ice Sheet. “Gravity measurements that reveal its existence suggest it could date back about 250 million years – the time of the Permian-Triassic extinction, when almost all animal life on Earth died out,” said the scientists. “Its size and location – in the Wilkes Land region of East Antarctica, south of Australia – also suggest it could have begun the break-up of the Gondwana super-continent by creating the tectonic rift that pushed Australia northward.” Scientists believe the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence. Wilkes Land meteor was 48.3km wide The Wilkes Land crater is more than twice the size of the Chicxulub crater in Mexico’s Yucatan peninsula, which marks the impact that may have killed the dinosaurs 65 million years ago. The Chicxulub meteor is thought to have been 9.6km wide. The Wilkes Land meteor could have been up to 48.3km wide. That is, four or five times wider. “This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time,” said Ralph von Frese, a professor of geological sciences at Ohio State. He and Laramie Potts, a postdoctoral researcher in geological sciences, led the team that discovered the crater. Impact could have helped rift form They collaborated with other Ohio State and Nasa scientists, as well as scientists from Russia and South Korea. They reported their preliminary results in a recent American Geophysical Union joint assembly meeting in Baltimore, United States. Some 100 million years ago, Australia split from the ancient Gondwana super-continent, pushed away by expansion of a rift valley, and began drifting north into the eastern Indian Ocean. The rift cuts directly through the crater, so the impact may have helped the rift to form, said von Frese. The more immediate effects of the impact, however, would have devastated life on Earth. “All the environmental changes that would have resulted from the impact would have created a highly caustic environment that was really hard to endure. So it makes sense that a lot of life went extinct at that time,” said von Frese. Source: www.news24.com/News2…,,2-13-1443_1944659,00.html Does a giant crater lie beneath the Antarctic ice?Signs of an ancient impact could help to explain a mass extinction. Mark Peplow Evidence of a cataclysmic meteorite impact has been unearthed in Antarctica, according to researchers who say the collision could possibly explain the greatest mass extinction ever seen on our planet. But scientists contacted by news@nature.com say they are sceptical, as no signs of such an enormous impact have been found in other, well-studied areas of Antarctica.The first sign of this possible impact was spotted by NASA’s GRACE satellites, a pair of orbiting probes that sense slight variations in the Earth’s gravity field. They revealed a 320-kilometre-wide plug of dense mantle material more than 1.6 kilometres beneath the East Antarctic ice sheet in an area known as Wilkes Land. A dense bit of rock in the Antarctic (orange circle) seems to be circled by a crater.© Ohio State UniversityRead full article here: www.nature.com/news/… Gigantic Meteor Crater Found in Antarctica The 300-mile-wide crater lies more than a mile beneath the East Antarctic Ice Sheet and might date to about 250 million years ago — the time of the Permian-Triassic extinction, when nearly all animal life on Earth became extinct. all 31 related »
