Australian crater may be world's oldest asteroid impact site, scientists say

Scientists say they have confirmed that a crater in the Australian outback is the world's oldest known asteroid impact site, dating back to around 3 billion years, though the claim remains contested by some researchers.

A team led by scientists at Curtin University used advanced dating techniques to determine the age of the impact structure at North Pole Dome in Western Australia, ABC News reported.

The findings build on research published last year that identified the site as an ancient impact crater but left uncertainty about when the collision occurred.

Lead author Chris Kirkland said researchers examined tiny zircon crystals preserved within the rocks and identified unusual skeletal structures formed under extreme heat.

"We were able to date the age of those very special grains that relate to the impact event," Kirkland said.

The team also analyzed a second mineral, apatite, which formed when hot fluids moved through rocks damaged by the impact. According to the researchers, both methods produced the same age estimate of about 3 billion years.

If confirmed, the discovery would make North Pole Dome the oldest known asteroid impact structure on Earth.

However, the findings have been challenged by some scientists.

Alec Brenner, a postdoctoral fellow at Harvard University, argued that nearby rock formations suggest the impact may have occurred significantly later.

"We've already documented shatter cones in nearby 2.77-billion-year-old rocks," Brenner said, adding that the impact would therefore have had to occur after those rocks formed.

He also questioned whether the minerals used in the study were altered by the asteroid impact or by unrelated hydrothermal activity that occurred later in the region's geological history.

The debate highlights the challenges of reconstructing events from Earth's distant past, particularly in the Pilbara region of Western Australia, which contains some of the planet's oldest surviving rocks.

Asteroid impacts played a major role in shaping early Earth, influencing its geology, atmosphere and potentially even the conditions under which life emerged. Determining when such impacts occurred helps scientists better understand the planet's evolution during its earliest history.