Geologists find 3.47-billion-year-old impact crater in Western Australia

Researchers in Western Australia’s Pilbara region have discovered the world’s oldest known meteorite impact crater, pushing back the previous record by more than one billion years.

The newly identified crater is estimated to be around 3.47 billion years old, a discovery that offers significant insight into early Earth’s geological history and the possible origins of life.

The crater, which spans at least 100 kilometres (62 miles), was formed by a massive space rock striking Earth when the planet was almost entirely covered by water.

The impact, which occurred at a speed of 36,000 km/h, scattered debris across the planet, leaving behind evidence of shock waves that significantly altered the surrounding rocks.

Chris Kirkland, a geologist at Curtin University and the lead researcher behind the discovery, emphasised the importance of this find, calling it a major breakthrough in understanding Earth’s early conditions. “Given how rare such evidence is due to Earth’s geological recycling processes, this is a major breakthrough in understanding early Earth,” Kirkland explained.

The discovery pushes back the previous record for the oldest impact crater, which was 2.2 billion years old and located in the same region of Western Australia, known as the Yarrabubba impact structure.

The study, published in Nature Communications, details the discovery of unusual rock formations, known as shatter cones, which are unique markers of meteorite impacts.

These cone-shaped features were found in the North Pole Dome area of Pilbara, suggesting a significant collision in Earth’s early history. While the team did not find a complete crater basin due to erosion over the billions of years, the shatter cones provided strong evidence of a massive impact event.

The impact is believed to have had a significant effect on early Earth’s environment, creating conditions that may have fostered the development of life. Kirkland noted that meteorite impacts, like the one that created the crater, could have provided the right physical and chemical conditions for microbial life to thrive, such as hot water pools formed in the aftermath of the collision.

This discovery aligns with the theory that meteorite impacts played a vital role in the formation of Earth’s first continents. Researchers have previously suggested that such impacts could have contributed to the formation of volcanic material, which later became the continental crust.

The newly found crater could provide further insights into how life might have originated on Earth and offer a valuable clue in the search for past life on Mars, as scientists suggest that impact craters on the Red Planet could similarly have played a role in shaping conditions for life.

While some experts, including planetary scientist Marc Norman from Australian National University, have questioned the exact size and impact of the crater, the researchers remain confident in the significance of their findings.

The study provides hard evidence to support the idea that meteorite impacts were instrumental in shaping both Earth’s geology and the potential for early life on our planet.

This groundbreaking discovery not only rewrites Earth’s geological history but also opens new avenues for further research into the conditions that may have allowed life to emerge and evolve.