Groundbreaking discovery: How researchers found remnants of Earth's primordial crust near Perth
Our planet was born around 4.5 billion years ago. To understand this mind-bendingly long history, we need to study rocks and the minerals they are made of.
The oldest rocks in Australia, which are some of the oldest on Earth, are found in the Murchison district of Western Australia, 700 kilometers north of Perth. They have been dated at almost 4 billion years old.
In a new study published in Communications Earth & Environment, we have found evidence of rocks of a similar age near Collie, south of Perth. This suggests the ancient rocks of Western Australia cover a far greater area than we knew, buried deep in the crust.
The ancient continental crust
The ancient crust of Australia is crucial for understanding the early Earth, because it tells us about how the continental crust formed and evolved.
Continental crust forms the foundation of landmasses where humans live, supporting ecosystems, and providing essential resources for civilization. Without it there would be no fresh water. It is rich in mineral resources such as gold and iron, making it economically significant.
Dykes in Norway cutting into older layered sandstone rocks. Credit: Cato Andersen/Mapillary, CC BY-SA
Microscope image of titanite grain with zircon crystals trapped inside and protected. The scale bar in the right bottom of image is 100 microns, about the width of a human hair. Credit: Adapted from Communications Earth & Environment (2024). DOI: 10.1038/s43247-024-01469-6
Cross-section of the crust south of Perth showing dykes picking up 3.4 billion-year-old zircon from depth and bringing it to the surface. The inset zoom-in shows the armouring of this ancient zircon by a shield of the mineral titanite. Credit: Communications Earth & Environment (2024). DOI: 10.1038/s43247-024-01469-6