Traces of the earliest asteroid impact on Earth have been found in Australia

This is not your typical crater with a circular funnel. Over billions of years, such features are almost completely erased by erosion, heat and the movement of the Earth’s crust. However, in the rocks of the North Pole Dome in the Pilbara region of Western Australia, minerals have been preserved that have acted as geological ‘clocks’. It is these that have helped scientists determine the age of the ancient impact.

The study has been published in the journal *Geology*.

The authors believe that the North Pole Dome remains the oldest known impact structure on Earth, and the new dating provides the most accurate age for this event — around 3 billion years.

Details

Scientists from Curtin University and the Geological Survey of Western Australia have studied ancient rocks in the North Pole Dome area. This site has long been discussed as a possible structure formed following the impact of a large celestial body.

The key evidence lies not in the shape of the crater itself, but in the minerals within the damaged rocks. The researchers analysed zircon and apatite. Zircon is particularly valuable to geologists: it is capable of preserving information about the age of events over billions of years.

Unusual branching, ‘skeletal’ forms were found in some of the zircon crystals. The authors believe that such structures arose when the old crystals were damaged, partially recrystallised and, in places, regrew under the influence of intense heating following the impact.

Why are the scientists confident?

A single dating result in such ancient rocks could be controversial. The researchers therefore verified the result using a second mineral — apatite. This formed when hot fluids passed through the impact-damaged rocks.

Both zircon and apatite indicated roughly the same age — around 3 billion years. The agreement between these two independent mineral systems reinforced the conclusion: the scientists see evidence of a single major event, most likely an asteroid impact.

Put simply, the rocks did not preserve the ‘moment of the explosion’ itself, but rather its aftermath: minerals that were altered or reformed due to the heat, pressure and circulation of hot fluids following the impact.

Why this is not a typical ‘asteroid crater’

When we hear the word ‘crater’, it is easy to picture a smooth, round funnel. But we are talking here about an event that took place around 3 billion years ago. Over such a long period, the Earth’s surface has changed many times over.

Ancient craters on Earth are rarely preserved in their original, pristine form. They are eroded by water, wind, volcanism, tectonics, pressure and the reheating of rocks. Geologists therefore look not only for the shape, but also for internal signs of an impact: altered minerals, crystal deformations, impact structures and traces of hot fluids.

This is precisely why the discovery is significant: it shows that even in very ancient rocks, it is possible to distinguish the traces of an asteroid impact from the subsequent complex geological history.

Why this is important

The North Pole Dome is located in the Pilbara – one of the regions where very ancient rocks of the Earth’s crust have been preserved. Such places offer a glimpse into the Archaean era, when the Earth looked very different from how it does today.

Asteroid impacts may have played a major role in the planet’s early history: altering the surface, influencing the formation of the crust, creating extreme conditions and triggering hydrothermal systems. Whilst they may have been destructive, they simultaneously created new geological and chemical environments.

The new dating pushes Earth’s impact chronology further back in time. Previously, Yarrabubba in Western Australia, aged around 2.2 billion years, was considered one of the oldest well-known craters. If the interpretation is correct, the North Pole Dome is approximately hundreds of millions of years older.

Background

Unlike the Moon, the Earth does not preserve ancient craters well. On the Moon, impact traces can remain virtually unchanged for billions of years because there is no active atmosphere, no oceans and no plate tectonics. On Earth, things are different: the surface is constantly being reshaped.

Therefore, any very ancient impact feature is a rarity. It helps us understand how often the young Earth collided with asteroids and how such events might have affected the early crust, oceans and conditions for life.

Source

Study: “How old is the North Pole Dome impact, Western Australia?”, Geology, 2026.