Scientists have found glass spheres in the Australian desert that point to an ancient asteroid impact that no one had previously known about. A new study has shown that the particles have a unique composition and were formed about 11 million years ago.
A team led by geoscientist Anna Mussolino of the University of Aix-Marseille in France has discovered that the small glass spheres from South Australia are a new type of impact glass, called ananguite. They are unlike any other on Earth.
The glass could have formed when a large asteroid hit Earth, melting the surface and scattering material thousands of kilometers. But the crater that would have been left behind by such an impact has not yet been found.
Geochronologist Fred Jourdan of Curtin University in Australia explains:
“These glass beads are unique to Australia and preserve an ancient event that we didn’t know about. They formed when an asteroid hit the Earth, melting rocks and scattering debris over vast distances.”
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He also adds:
“The impact was very strong, but the crater has not yet been discovered.”
Similar glass beads, called tektites, are already known from this region. They formed after another meteorite fell about 788 thousand years ago. But the new finds differ in composition: less silica, more oxides of iron, magnesium and calcium, a different density and shape of the bubbles.
This means they come from a different impact.
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Scientists performed radio-argon dating and determined: the age of the particles is 11 million years.
The place where the asteroid fell is still unknown. Perhaps the crater was destroyed by erosion or it could have been confused with a volcano, for example in areas like Papua New Guinea. It could also have simply been hidden under the soil for millions of years.
In a scientific article, the researchers write that further analysis may help narrow down the search for the impact site, but for now the answer remains a mystery.
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