Sydney, Australia (BBN)-Scientists have discovered a giant asteroid impact zone spanning 400km in the central Australian outback, the largest ever recorded.
The impact was caused by an enormous meteorite that split into two 10km-wide chunks before it slammed into Earth around what is now the Warburton basin, lead researcher Andrew Glikson, from the Australian National University, said, reports The Guardian.
“It would have been curtains for many life species on the planet at the time,” he said.
Two huge bruises in the earth caused by the collisions were discovered 3km deep in the mantle and twin scars extending more than 190km long and 30km deep still mark the impact zone, which encompasses parts of Queensland, South Australia and the Northern Territory.
The easternmost scar was identified by chance in 2013 when geothermal drilling revealed traces of rocks that had been turned to glass by an extreme shock.
The impact zone was thought to span 200km, making world headlines at the time as the third-largest ever found.
Glikson had been aware of a second scar in the west of the basin that showed “similar seismic and magnetic signatures”, but which had not been sufficiently tested.
Evidence the two were caused by the same asteroid was published this month in the journal Tectonophysics.
The discovery doubled estimates of the size of the impact of the asteroid to 400km, more than four times the size of the zone created by the asteroid that struck Mexico’s Yucatan peninsula, which many scientists believe caused the “KT extinction event” that wiped out the dinosaurs.
This asteroid may have caused a similar mass extinction, but scientists will first need to figure out when it struck.
Curiously, telltale evidence that usually accompanies large impacts- such as the plume of ash that blanketed the atmosphere following the Yucatan collision and settled in the surrounding area- has yet to be found in the 300m to 600m-year-old rocks around the Warburton site.
Glikson said: “It’s a mystery – we can’t find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300m years.”
Answering these questions could lead to new theories about the Earth’s origins. “Large impacts like these may have had a far more significant role in the Earth’s evolution than previously thought,” he said.
BBN/SK/AD-24Mar15-12:40pm (BST)