Geologists have identified the world’s oldest known impact crater in the Pilbara region of Western Australia. The crater, estimated to be at least 100 kilometres wide, was formed around 3.47 billion years ago when a large space rock struck Earth.
The discovery surpasses the previous record held by the Yarrabubba impact structure, also in Western Australia, by more than a billion years. The finding provides rare evidence of early impact events due to Earth’s continuous geological recycling.
Researchers suggest that the impact may have influenced early life on Earth. The collision could have created hot, mineral-rich pools of water and altered rock structures, providing conditions that may have supported microbial life.
In May 2021, geologists identified “shatter cones” in the North Pole Dome area of Pilbara. These formations, shaped like inverted shuttlecocks, are considered direct evidence of an impact event. Further fieldwork in 2023 confirmed the crater’s estimated age.
Some scientists remain sceptical about the crater’s estimated size and its role in shaping early Earth. Critics argue that while the discovery is significant, it does not substantially advance understanding of how impacts influenced Earth’s formation and evolution.
The finding suggests that other similarly ancient impact craters may exist but remain undiscovered. Scientists emphasise the need to re-examine ancient geological terrains for further evidence of early impacts.
The research, led by Chris Kirkland of Curtin University, was published on 6 March in Nature Communications. The study highlights the challenges of identifying ancient impact craters due to erosion and geological changes over time.