A 400 km-wide (250 mile-wide) impact basin from a massive asteroid that broke in two moments before it slammed into our planet has been found in north-eastern South Australia by a team of scientists, led by Dr Andrew Glikson of the Australian National University’s Planetary Science Institute.
Warburton East and West sub-basins, northeast South Australia; the Birdsville Track Ridge divides the Warburton East Basin from the Warburton West Basin. Image credit: A.Y. Glikson et al.
The twin scars of the impacts – the largest impact zone ever found on Earth – were discovered during drilling as part of geothermal research, in the Warburton Basin – an area near the borders of South Australia, Queensland and the Northern Territory.
“The two parts of the asteroid must each have been over 10 km (6.4 mile) across – it would have been curtains for many life species on the planet at the time,” said Dr Glikson, who is the lead author of the paper published in the journal Tectonophysics.
“Large impacts like these may have had a far more significant role in the Earth’s evolution than previously thought.”
According to Dr Glikson and his colleagues from the Research School of Earth Science in Canberra, the University of Queensland, and Geoscience Australia, the exact date of the asteroid impact remains unclear.
The surrounding rocks are 300 to 600 million years old, but evidence of the type left by other meteorite strikes is lacking.
Dr 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 300 million years,”
“There are two huge deep domes in the crust, formed by the Earth’s crust rebounding after the huge impacts, and bringing up rock from the mantle below,” he added.
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A.Y. Glikson et al. 2015. Geophysical anomalies and quartz deformation of the Warburton West structure, central Australia. Tectonophysics, vol. 643, pp. 55–72; doi: 10.1016/j.tecto.2014.12.010
