‘Unequivocal evidence’ of the age of Earth’s oldest impact crater turns out to be off by half a billion years
A new study shows that Earth’s oldest known impact crater was formed about 3 billion years ago when a meteorite struck what is now Australia – 470 million years later than scientists previously claimed.
The impact crater, known as the North Pole Dome Crater, is located in the Pilbara region of Western Australia, home to some of the oldest rocks on the planet. It remains a record-breaking structure, surpassing the world Next oldest known meteorite impact crater – Yarrabubba impact structure, also in Western Australia – about 800 million years old.
“Although the site was previously identified as an ancient impact structure, its exact age remains uncertain,” said the study’s first author. chris kirklandThe professor, from the School of Earth and Planetary Sciences at Curtin University in Australia, said in a statement. “The impact left behind a ‘mineral clock’. By dating reworked or newly evolved minerals in the damaged rocks, we can now find out when this extraordinary event occurred.”
However, a study published four months later in the journal Science Advances described the other team’s results as “false”, arguing that The impact occurred 2.7 billion years ago.
For the new study, Kirkland and colleagues used advanced mineral dating techniques to estimate the ages of zircon, apatite, calcite and muscovite in broken cones from the North Pole Dome crater. The researchers analyzed two samples of shattered-cone-bearing rocks, as well as a shocked quartz vein – a sheet-like deposit that typically forms when superhot, mineral-rich water expands into cracks between shocked rocks.
Researchers analyzed zircon and other minerals in North Pole dome rocks.
(Image credit: Curtin University)
“The key evidence comes from zircon, a small but exceptionally flexible mineral that can span billions of years across geological time,” Kirkland said. “Some of the zircons on the North Pole Dome have unusual branched, skeletal shapes. We interpret these as impact-modified crystals, which formed when older zircons were disrupted, partially recrystallized, and regrown in places during the intense heat caused by the impact.”
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The age recorded in the zircon was similar to the age locked inside the apatite minerals, leading researchers to believe the impact occurred a little more than 3 billion years ago. The young shatter cones in the Science Advances study may have formed later due to tectonic and thermal activity, the team wrote in the new paper, which was published Tuesday (June 23) in the journal Science Advances. Geology.
“Ancient impact craters are incredibly difficult to detect because over billions of years, rocks are altered by heat, pressure and fluids, which can obscure or reset the original impact signatures,” Kirkland said. “The new age places the North Pole Dome Structure as Earth’s oldest known impact crater and the only recognized example from the Archean era. [4 billion to 2.5 billion years ago]The time when the planet’s earliest continents were forming.”
Kirkland, CL, Kampf, J., Johnson, TE, Ribeiro, BV, Zametzer, A., Smithies, RH and McDonald, BJ (2026). How old is the North Pole Dome5Impact, Western Australia? Geology. https://doi.org/10.1130/G54866.1
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