Portuguese 
English 
Spanish 
5 min of reading 
0 comments 
Rare traces in Australian rocks reignite debate on early Earth impacts, with evidence that could redefine the age of the oldest identified crater and raise new questions about the planet’s formation.
Geologists have identified evidence of an ancient meteorite impact in rocks from the Pilbara region in Western Australia, in a study published in Nature Communications that attributed an age of 3.47 billion years to the event and suggested a crater more than 100 kilometers wide.
The interpretation is based on the discovery of shatter cones, conical structures formed by extremely high-pressure shock waves and considered one of the most reliable signs of meteoric impacts.
The marks were found in the North Pole Dome, within the East Pilbara Terrane, an area that preserves some of Earth’s oldest continental rocks.
-
A Nature study puts the planet on alert by revealing that even a warming of 2 °C can trigger droughts, extreme rainfall, and fire risk in more severe global patterns than averages projected for 3 °C or 4 °C, with crops, forests, and densely populated areas under simultaneous threat.
-
Singapore has just unveiled an all-electric cargo drone that takes off vertically, carries up to 100 kg for over 70 km, and could change unmanned deliveries and inspections.
-
The Brazilian Army raised an alert and is preparing a R$400 billion plan until 2040 with drones at all levels, 20% of troops at maximum readiness, 5 strategic brigades, and new multi-domain warfare.
-
Arctic city that loses up to 2 meters of land per year enters a countdown against permafrost thaw: Tuktoyaktuk tries to hold houses, roads and its own natural barrier, which could be breached by 2050, with a US$ 53.7 million containment project against the advance of the sea.
Earth’s oldest crater enters scientific debate
The discovery was presented as a possible new milestone in the record of terrestrial impacts, as it would shift the boundary previously associated with the Yarrabubba crater, also in Western Australia, dated at approximately 2.23 billion years, by more than 1 billion years.
However, the age and size of the structure began to be debated after a subsequent study published in Science Advances in July 2025.
This work agreed that there is evidence of impact in the North Pole Dome, but questioned whether the collision occurred 3.47 billion years ago and estimated a smaller structure, about 16 kilometers in diameter.
Even with the controversy, the identification of shatter cones keeps the region at the center of research on early Earth.
The debate now involves not only the existence of the impact, but also when it occurred, what its real extent was, and how the rocks preserved this record for so long.
Where the impact marks were found in Pilbara
The features were described in the Antarctic Creek Member, a sedimentary unit within the Mount Ada Basalt, in the heart of the East Pilbara Terrane.
This area brings together granitic domes and volcanic rock belts formed in the Paleoarchean, an interval when the Earth’s crust was still undergoing intense transformation processes.
The authors of the original study stated that the cones appear in a layer dominated by siliciclastic materials, with curved surfaces, branched grooves, and delicate fractures.
The distribution of the marks over hundreds of meters reinforced the interpretation that they do not result from common rock deformation.
Another point cited by the researchers is the presence of spherules in the same geological unit.
These small particles had previously been interpreted in earlier works as droplets of molten and cooled material after impacts, although this type of evidence can be transported over long distances.
Impact age and challenges of geological interpretation
The date of 3.47 billion years was associated with the stratigraphic position of the analyzed rocks.
In the original study, researchers indicated that rocks with signs of shock appear below layers without these marks, which would help to constrain the timing of the impact within the Paleoarchean.
This interpretation, however, is not consensual.
Later research also found shatter cones in younger rocks, which led its authors to argue that the impact would have occurred after the formation of these layers, and not necessarily at the same time as the 3.47-billion-year-old rocks.
The divergence shows the difficulty of interpreting Archean terrains, which have undergone erosion, metamorphism, intrusions, and deformations over billions of years.
In such ancient regions, the preservation of a complete crater is unlikely, and scientists rely on fragmented signs to reconstruct the event.
Why ancient craters disappeared from Earth
The importance of the discovery also appears when comparing Earth to the Moon.
While the lunar surface preserves millions of craters, the planet has lost much of this record due to erosion, plate tectonics, and the continuous recycling of the crust.
Therefore, any reliable trace of a very ancient impact helps to fill a gap about the bombardment that hit the bodies of the inner Solar System.
Earth certainly suffered frequent collisions in its early stages, but few records have survived in conditions that allow for safe identification.
In Pilbara, the exceptional preservation of the rocks made it possible to recognize marks that would normally disappear.
This context explains why the North Pole Dome is treated as a rare window into processes that occurred before the formation of continents in their current configuration.
Crater size still divides experts
In the Nature Communications study, the authors suggested that if shatter cones were distributed throughout the mapped area of the Antarctic Creek Member, the North Pole Dome could correspond to the central uplift of a crater at least 100 kilometers in diameter.
The subsequent estimate from Science Advances was more cautious and reduced the structure to about 16 kilometers.
This difference alters the geological weight of the event, as a 100-kilometer crater would indicate a much broader global or regional-scale collision.
Still, even a smaller structure would have scientific relevance for being preserved in an extremely ancient terrain.
The discussion about size depends on new mappings, structural analyses, and studies capable of separating the effects of impact from other geological processes.
Impacts and possible effects on early Earth
The Pilbara region is already important for holding some of the oldest evidence of environments associated with microbial life.
The original study does not present the crater as proof of the origin of life, but it reminds us that impacts can generate fractures, heat, and hydrothermal circulation.
These conditions are of interest to researchers because fluid-heated environments, common in impact zones, can modify rocks and concentrate chemical compounds.
The connection expands the scientific value of the finding, without replacing the main focus, which remains on the identification and interpretation of shock marks.
The dispute surrounding the North Pole Dome shows that Earth’s early history still depends on rare and often difficult-to-interpret evidence.
Preserved fragments of the Archean crust may hold records of ancient impacts, but each new interpretation must withstand confrontation with field data, dating, and independent analyses.
Be the first to react!