Ancient Meteorite Impact in Western Australia Revealed as Earth’s Oldest Crater
Discovery of a 3‑billion‑year‑old impact crater in Western Australia
Scientists from Curtin University have identified the world’s oldest confirmed meteorite impact crater in the Pilbara region’s North Pole Dome, dating back roughly 3 billion years to the Archean eon.
Dating the strike with shatter cones, zircon and apatite
- Shatter cones in the basalt were examined to confirm impact origin.
- “Little lightning bolts” of zircon recrystallised by the shock were dated using the Sensitive High‑Resolution Ion MicroProbe.
- Growth of apatite in post‑impact fractures provided a second, independent age estimate.
Why this finding reshapes our view of early Earth
The crater predates the previously oldest known Australian impact, the Yarrabubba crater (≈ 2.2 billion years), pushing back the record of large collisions by ~800 million years. Researchers say the event occurred when Earth was a “water world” with limited continental crust, a dimmer Sun and early stromatolite life.
Broader implications for Archean geology and planetary science
According to Prof Chris Kirkland, the well‑preserved rocks offer a rare “glimpse of the violent processes that shaped the early Earth”. The study also demonstrates that impact signatures can survive deep erosion, subduction and plate‑tectonic recycling.
Next steps for uncovering ancient impact histories
Geochemist Bruce Schaefer notes that many Archean impacts remain hidden; combining zircon and apatite dating may become a standard “detective‑story” approach to locate and age other primordial craters.