A giant asteroid hit Earth, but its crater is missing

The discovery focuses on rare natural glass called tektites, which form when a meteorite hits Earth with enough force to melt the surface and fling molten material vast distances. This newly identified variety of tektites has so far been discovered only across parts of South Australia.

Co-author Professor Fred Jourdan from Curtin’s School of Earth and Planetary Sciences compared the finding to uncovering a new chapter in Earth’s turbulent past.

"These glasses are unique to Australia and have recorded an ancient impact event we did not even know about," Professor Jourdan said.

"They formed when an asteroid slammed into Earth, melting surface rock and scattering debris for thousands of kilometers. These tiny pieces of glass are like little time capsules from deep in our planet's history.

"What makes the discovery even more intriguing is that, although the impact must have been immense, scientists are yet to locate the crater.

"Understanding when and how often large asteroids have struck Earth also helps us assess the risk of future impacts, which is important for planetary defense."

Lead author Anna Musolino, a PhD student at Aix-Marseille University, said the glasses stand apart from all previously known tektites.

"These tektites are unique because of their unusual chemistry and their age, which is about 11 million years," Ms. Musolino said.

"They record a completely separate impact event from the famous Australasian tektite-strewn field.

"While the Australasian tektites formed about 780,000 years ago and are spread across half the globe, these tektites are much older and their discovery suggests a previously unrecognized giant impact."

The study was part of a larger research project led by Emeritus Professor Pierre Rochette from Aix-Marseille University and highlights both the destructive power of past impacts and the importance of studying them.

The full research paper, 'A new tektite strewn field in Australia ejected from a volcanic arc impact crater 11 Myr ago', is published in Earth and Planetary Science Letters.