Researchers from Curtin University have succeeded in determining the most precise age yet for the oldest known meteorite impact crater on our planet. The discovery, published in the journal Geology, provides scientists with a unique opportunity to better understand how cosmic impacts influenced the formation and evolution of Earth during the earliest stages of its history.
The geological structure known as the North Pole Dome is located in the Pilbara region of western Australia. Specialists from the Curtin University’s School of Earth and Planetary Sciences, working in collaboration with the Geological Survey of Western Australia, applied advanced dating techniques and confirmed that a major meteorite impact occurred in the area approximately 3 billion years ago.
A mineral clock hidden in shattered rocks
According to the study’s lead author, Chris Kirkland, the status of North Pole Dome as an impact structure had long been debated, but its precise age remained a mystery. The answer came from what researchers describe as a unique “mineral clock.”
During a major impact, rocks undergo total destruction, but at the same time new minerals form within them. By analyzing these formations, scientists were able to determine the exact moment of the catastrophe.
Zircon and apatite as witnesses to a cosmic impact
The key evidence came from zircon, a remarkably durable mineral capable of preserving records of geological processes for billions of years. Within the impact zone, zircon crystals display a distinctive branched, skeletal-like structure. Scientists explain that the original mineral was damaged by the extreme heat generated during the collision and later partially recrystallized. These deformed crystal structures effectively record the impact event that occurred 3 billion years ago.
To test their hypothesis, the team analyzed another mineral—apatite. It formed as a result of hot fluids circulating through the damaged rocks after the impact. This independent dating method produced exactly the same age estimate. The agreement between two separate lines of evidence gives scientists complete confidence that they are observing the traces of a single large-scale meteorite impact event.
A window into the Archean Eon
The findings make the North Pole Dome the oldest confirmed impact crater in the world and the only known example dating back to the Archean Eon—a period when Earth’s first continents were just beginning to form.
Dating such ancient structures is extremely challenging. Over billions of years, natural heat, immense pressure, and the movement of fluids can completely alter rocks, erasing the original traces of an impact. However, the Australian researchers succeeded in separating the primary signal of the catastrophe from the region’s long and complex geological history.
As emphasized by Simon Johnson, director of geoscience at the Geological Survey of Western Australia, such exceptional results demonstrate the crucial role of scientific collaboration in uncovering the deepest secrets of our planet’s geological past.
Previously, we reported on the five best-preserved impact craters on Earth.
According to phys.org
