Scientists in Australia have uncovered what they say is the biggest asteroid impact area ever discovered.Â The 400 kilometer (250 mile) wide region is buried deep in the Earthâ€™s crust and consists of two different impact scars.â€œIt would have been â€˜curtainsâ€™ for many species in the world at the time,â€ said Dr. Glikson.
However, the team, which released its findings in the geology journal â€˜Tectonophysics,â€™ hasnâ€™t been able to link the event to any known annihilation.Â â€œIt is a puzzle â€“ we cannot find an extinction event that fits this crash,â€ said Dr. Glikson. â€œIâ€™ve a feeling the impact may be older than 300 million years.â€
The stones around the impact zone are about 300 to 600 million years old, however a layer of ashes that would have been thrown up by the impact hasnâ€™t yet been found, as sediment in the stone layers form an identical interval.
â€œSubstantial impacts such as these may have had a lot more important part in the Earthâ€™s development than previously believed,â€ Dr. Glikson said.
The excavation returned bits of stone that were turned into glass by excessive temperature and pressure, consistent with a substantial impact.
The rocks around the impact zone are roughly 300 to 600 million years old, but a layer of ash that would have been thrown up by the impact has not been detected as sediment in rock layers from the same period.
The large meteorite believed to have killed the dinosaurs 66 million years ago corresponds to a layer of sediment in rocks around the world.
â€œLarge impacts like these may have had a far more significant role in the Earthâ€™s evolution than previously thought,â€ Dr Glikson said.
The apparent impact zone in the Warburton Basin was discovered by accident while scientists were drilling 2km under the Earthâ€™s surface for a geothermal research project.
The dig returned traces of rock that had been turned to glass by extreme temperature and pressure, consistent with a massive impact.