Ancient meteorite impact blasted debris across the globe, reshaping early Earth
Scientists in Australia have identified what is now the world’s oldest known impact crater, a 3.5-billion-year-old geological structure that could reshape our understanding of Earth’s early history.
An approximately one metre tall shatter cone ‘hut’, with the rolling hills of the Pilbara in the background. Image credit: Curtin University
- The object impacted Earth at a speed of 36 000 km/h (22 400 mph), with the original crater estimated at more than 100 km (62 miles) in diameter.
- This was a major planetary event, with debris set flying across the globe.
- The impact likely modified the early Earth’s crust, influenced the formation of early cratons, and contributed to the conditions necessary for life.
The study, conducted by scientists from Curtin University, the Geological Survey of Western Australia, and partner institutions, confirms the presence of shatter cones in the Antarctic Creek Member (ACM), providing direct evidence of hypervelocity meteorite impact.
“The discovery of shatter cones in the Antarctic Creek Member provides unequivocal evidence for a hypervelocity meteorite impact,” Christopher L. Kirkland, lead researcher, said.
“This finding not only extends the known impact record but also suggests that large-scale impacts played a crucial role in shaping the early Earth.”
The impact structure is located at the North Pole Dome, in the East Pilbara Terrane (EPT), a region characterized by a Paleoarchaean (3.53–3.23 billion years ago) cratonic crust. The site contains metasedimentary layers, including the ACM, with evidence of impact-related processes such as spherules and shocked rocks. Shatter cones, a diagnostic feature of impact structures, were found throughout the ACM, extending over several hundred meters.
The EPT is an exceptionally well-preserved fragment of early Earth’s crust, composed of granite domes and intervening greenstone belts, covering an area roughly 200 km (124 miles) in diameter.
Before this discovery, the oldest confirmed impact structure on Earth was Yarrabubba in Western Australia, dated at 2.23 billion years.
Geological and stratigraphic context
The Warrawoona Group, which forms the base of the Pilbara Supergroup, consists of ultramafic to mafic volcanic rocks with minor felsic volcanic material. Pillow basalts in the lower sections are overlain by sedimentary sequences, including the ACM. The ACM contains quartz-rich layers interbedded with volcaniclastic rocks, chert, and carbonate deposits.
Field observations revealed shatter cones within the ACM, featuring well-defined radial striations and an average apical angle of 90°. The structures are consistent with those found in confirmed impact craters worldwide, including Steinheim in Germany. The presence of impact spherules, quenched and devitrified melt droplets, within the same stratigraphic horizon further supports the meteorite impact hypothesis.
Evidence for large-scale impact
The discovery of shatter cones, along with impact-related spherules and brecciated rocks, indicates that the North Pole Dome represents the central uplift of a large impact crater. The dome has a diameter of 40–45 km (25–28 miles), suggesting that the original impact crater may have exceeded 100 km (62 miles) in diameter.
The impact likely played a role in modifying the early Earth’s crust. Large meteorite impacts generate immense heat, leading to crustal melting, hydrothermal alteration, and mineralization. This process may have influenced the formation of early cratons and contributed to the conditions necessary for life.
Comparisons with lunar impact rates
The Moon, with its relatively undisturbed surface, provides a record of early solar system impacts. Craters such as Atlas, approximately 3.6 billion years old, are comparable in size to the East Pilbara Terrane.
Given the Moon’s impact history, it is expected that early Earth experienced a much higher impact flux. The lack of known Archaean craters may be because of erosion, subduction, or underrecognition of impact structures within ancient terrains.
“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.”
References:
1 A Paleoarchaean impact crater in the Pilbara Craton, Western Australia – Christopher L. Kirkland, Tim E. Johnson, Jonas Kaempf, et, al., – nature – March 6, 2025 – https://doi.org/10.1038/s41467-025-57558-3 – OPEN ACCESS
2 World’s oldest impact crater found, rewriting Earth’s ancient history – Curtin University – March 6, 2025
Rishika holds a Master’s in International Studies from Stella Maris College, Chennai, India, where she earned a gold medal, and an MCA from the University of Mysore, Karnataka, India. Previously, she served as a Research Assistant at the National Institute of Advanced Studies, Indian Institute of Science, Bengaluru, India. During her tenure, she contributed as a Junior Writer for Europe Monitor on the Global Politics website and as an Assistant Editor for The World This Week. Her work has also been published in The Hindu newspaper, showing her expertise in global affairs. Rishika is also a recipient of the Women Empowerment Award at the district level in Haryana, India, in 2022.
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