Responsible Permian-Triassic Extinction Meteorite Found?
A massive meteorite impact, traces of which have now been discovered, may not only have caused the mass extinction of animals on the Permian-Triassic border. Furthermore, the energy of the impact could have accelerated or triggered the breakup of the supercontinent Gondwana and with it the formation of Australia.
At least that's the opinion of Ohio State University's Ralph von Frese and his colleagues who discovered the impact crater in East Antarctica's Wilkes Land. The location was revealed by satellite measurements of the regionally fluctuating force of gravity and by radar images: In Wilkes Land they not only found a ring-shaped structure with a diameter of around 480 kilometers, but also a so-called mascon measuring 320 kilometers - a gravity anomaly in the earth's surface that in this case formed by the ascent of material from the Earth's mantle.
Mascons form when very large objects impact the surface of a planet, pushing mantle material up through the Earth's crust while displaced crustal rock encapsulates it down and holds it in place. Ring and Mascon together clearly point to a violent impact for the researchers about 250 million years ago. Since nearly ninety percent of the existing marine and seventy percent of the terrestrial fauna disappeared at the same time, the hit may have been as devastating as that of the better-known Chicxulub crater in the Yucatan. Chicxulub is often blamed for the extinction of the dinosaurs.
Since a rift valley runs through the middle of the crater, which separated Australia from Gondwana 100 million years ago, the impact could also have initiated or facilitated the break-up of the supercontinent, according to von Frese.
