World's oldest meteorite impact crater found, rewriting Earth's ancient history

Curtin University researchers have discovered the world's oldest known meteorite impact crater, which could significantly redefine our understanding of the origins of life and how our planet was shaped.

"A Paleoarchean impact crater in the Pilbara Craton, Western Australia" is published in Nature Communications.

The team from Curtin's School of Earth and Planetary Sciences investigated rock layers in the North Pole Dome—an area of the Pilbara region of Western Australia—and found evidence of a major meteorite impact 3.5 billion years ago.

Study co-lead Professor Tim Johnson, from Curtin University, said the discovery significantly challenged previous assumptions about our planet's ancient history.

"Before our discovery, the oldest impact crater was 2.2 billion years old, so this is by far the oldest known crater ever found on Earth," Professor Johnson said.

Researchers discovered the crater thanks to "shatter cones," distinctive rock formations only formed under the intense pressure of a meteorite strike.

The shatter cones at the site, about 40 kilometers west of Marble Bar in WA's Pilbara region, were formed when a meteorite slammed into the area at more than 36,000km/h.

This would have been a major planetary event, resulting in a crater more than 100km wide that would have sent debris flying across the globe.

"We know large impacts were common in the early solar system from looking at the moon," Professor Johnson said.

"Until now, the absence of any truly ancient craters means they are largely ignored by geologists.

"This study provides a crucial piece of the puzzle of Earth's impact history and suggests there may be many other ancient craters that could be discovered over time."

Co-lead author Professor Chris Kirkland, also from Curtin's School of Earth and Planetary Sciences, said the discovery shed new light on how meteorites shaped Earth's early environment.

"Uncovering this impact and finding more from the same time period could explain a lot about how life may have got started, as impact craters created environments friendly to microbial life such as hot water pools," Professor Kirkland said.

"It also radically refines our understanding of crust formation: the tremendous amount of energy from this impact could have played a role in shaping early Earth's crust by pushing one part of the Earth's crust under another, or by forcing magma to rise from deep within the Earth's mantle toward the surface.

"It may have even contributed to the formation of cratons, which are large, stable landmasses that became the foundation of continents."