Deep in Western Australia's Pilbara region lies a crater unlike any other – a 3-billion-year-old testament to a cosmic collision that shook the very foundations of our planet during its tumultuous formative years.
A team from Curtin University, led by Professor Chris Kirkland, has made this extraordinary discovery using cutting-edge techniques and rigorous analysis. The researchers pinpointed rare geological formations called shatter cones within the North Pole Dome crater as evidence of a massive meteorite strike. These distinctive rock features are only created under immense pressure and heat – a hallmark of such events.
To accurately date the impact, the scientists employed two sophisticated methods. Firstly, they examined tiny zircon crystals embedded in basalt rock, which had been transformed by the intense heat into unusual skeletal patterns reminiscent of those found on the Moon's surface. An Australian-designed Sensitive High-Resolution Ion MicroProbe revealed these crystals to be approximately 3 billion years old.
Secondly, they analysed apatite minerals that grew in fractures formed by post-impact heat and fluids, yielding consistent age results. This 'smoking gun' evidence from both zircon recrystallisation and apatite growth conclusively dates the North Pole Dome crater to a staggering 3 billion years.
This breakthrough pushes back the timeline for known impact events on Earth by an astonishing 800 million years – making it significantly older than the Yarrabubba crater in Western Australia. The research is a significant contribution to our understanding of the Archean eon, when life was first emerging and the planet was vastly different from its current form.
Associate Professor Bruce Schaefer, from Macquarie University, welcomed the findings, praising the team's innovative use of techniques that have helped unravel this ancient geological mystery. The discovery not only advances our knowledge of Earth's past but also highlights the importance of preserving evidence of such events in a world where erosion and plate tectonics often erase similar records.