Scientists discover massive ancient asteroid strike

Researchers have discovered evidence of an enormous asteroid that hit the Earth early in its existence with an impact greater than anything humans have ever seen, according to a new study published in the journal Precambrian Research.

The new study is based on small glass beads known as spherules that were discovered in northwestern Australia and determined to be created from vaporized material kicked up by the asteroid impact that occurred around 3.5 billion years ago.

“The impact would have triggered earthquakes orders of magnitude greater than terrestrial earthquakes, it would have caused huge tsunamis and would have made cliffs crumble,” study author Andrew Glikson from The Australian National University’s Planetary Institute, said in a news release. “Material from the impact would have spread worldwide. These spherules were found in sea floor sediments that date from 3.46 billion years ago.”

A massive ancient impact

The second oldest known to have struck the Earth and one of the most massive, the asteroid was between about 13 and 18 miles wide and it created an impact crater hundreds of miles across.

“Exactly where this asteroid struck the earth remains a mystery,” Glikson said. “Any craters from this time on Earth’s surface have been obliterated by volcanic activity and tectonic movements.”

The spherules in the study were extracted from a drill core from Marble Bar, a place in northwestern Australia that has some of the oldest known sediments on the planet.

The sediment layer, which was initially located on the sea floor, was conserved between two volcanic layers, which allowed very accurate dating of its source.

Glikson has been trying to find proof of ancient impacts for over 20 years and said he immediately thought the glass beads came from an asteroid strike. Tests revealed trace amounts of telltale elements like platinum, nickel and chromium that can be found in asteroids.

Glikson said there could be more currently-unknown impact that may be discovered using methods like the one used in his study.

“This is just the tip of the iceberg,” he said. “We’ve only found evidence for 17 impacts older than 2.5 billion years, but there could have been hundreds.

“Asteroid strikes this big result in major tectonic shifts and extensive magma flows. They could have significantly affected the way the Earth evolved.”

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Image credit: A. Gliksoin

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