UWA research offers insight into how early continents formed billions of years ago

UWA researchers have helped to unearth more about how ancient continents formed on Earth 3.5 billion years ago.

A team of researchers from the University of Western Australia and Nanjing University in China wanted to gain a better understanding of how early continental crust formed on Earth.

“The two competing points of view are subduction, when two tectonic plates meet and the denser one gets pushed underneath the other and sinks into the Earth, and non-subduction, when hot material from deep within the Earth rises upwards and melts or large meteorites impact and melt Earth’s crust,” UWA professor and co-author of the study Tony Kemp said.

The researchers sought answers from the granitic rocks of the Pilbara Craton — one of the most ancient and best-preserved geological formations on the planet.

Analysing the tiny crystals of the mineral zircon within these ancient rocks, they found evidence that the magmas which formed these rocks had become more oxidised and richer in water over time, between 3.2 billion and 3.5 billion years ago.

“For this finding to be a true, a mechanism must have existed on early Earth to transport water into the deep crust and mantle,” Professor Kemp said.

“On modern Earth this is achieved along the boundaries of tectonic plates through subduction — as one plate sinks beneath the other — a process unique to Earth and responsible for forming continents.”

The findings, published in Science Advances, underscore the role of subduction-driven water recycling in the formation of continental crust billions of years ago.