Scientists find ancient piece of Earth’s crust 4 billion years old under Western Australia

The lasers pave the way for finding the ancient crust.

Curtin University researchers have uncovered evidence of a roughly four billion year old piece of Earth’s crust that exists beneath the southwest of Western Australia using lasers smaller than a human hair to target microscopic grains of a mineral mined from beach sand.

The Mineral Systems Timescales Group at Curtin’s School of Earth and Planetary Sciences, led by Ph.D. student Maximilian Droellner, said lasers were used to vaporize portions of individual grains of the mineral zircon and have revealed where the grains were originally eroded from as well as the geological history of the area. This new discovery helps explain how the planet went from uninhabitable to living.

“There is evidence that a piece of crust up to four billion years old the size of Ireland has influenced the geological evolution of WA over the past billion years and is a key ingredient in rocks formed in WA at that time,” says Droellner.

“This piece of crust has survived several mountain-building events between Australia, India and Antarctica and still appears to exist tens of kilometers deep below the southwest corner of WA. Comparing our results to existing data, it appears that many parts of the world experienced a similar time of early crustal formation and preservation.This suggests a significant change in Earth’s evolution around four billion years ago, so that the meteor bombardment was waning, the crust was stabilizing, and life on Earth was beginning to establish itself.

Research leader Dr Milo Barham, also from the Timescales of Mineral Systems group at Curtin’s School of Earth and Planetary Sciences, said that no large-scale studies of this region had been done before and that the results, compared to existing data, had revealed exciting results. new ideas.

“The edge of the ancient piece of crust appears to define an important crustal boundary controlling where economically important minerals are found,” Dr Barham said.

“Recognizing these ancient crustal remnants is important for the future of optimized sustainable resource exploration. Studying early Earth is challenging given the enormity of time that has passed, but it has profound significance for understanding the meaning of life on Earth and our quest to find it on other planets.

Reference: “A persistent Hadean–Eoarchean protocrust in the western Yilgarn Craton, Western Australia” by Maximilian Dröllner, Christopher L. Kirkland, Milo Barham, Noreen J. Evans and Bradley J. McDonald, June 17, 2022, Terranova.
DOI: 10.1111/ter.12610

Dr. Droellner, Dr. Barham and co-supervisor Professor Chris Kirkland are affiliated with the Institute for Geoscience Research (TIGeR). Curtin’s flagship Earth Science and Research Institute was funded by the Minerals Research Institute of Western Australia.