Lasers pave the way to finding ancient crust.
Curtin University researchers have discovered evidence of a roughly four-billion-year-old piece of the Earth’s crust that exists beneath SW Western Australia by using lasers smaller than a human hair to target tiny grains of mineral extracted from beach sand. The Timescales of Mineral Systems Group at Curtin’s School of Earth and Planetary Sciences, led by Ph.D. student Maximilian Droellner, said lasers were used to vaporize sections of individual grains of the mineral zircon and revealed where the grains had originally eroded from as well as the geological history of the area. This new discovery explains how the planet evolved from being uninhabitable to supporting life. “There is evidence that a piece of crust up to four billion years old about the size of Ireland has influenced the geological evolution of WA over the last billion years and is a key component of the rocks formed in WA during this time. ”, says Mr. Droellner. “This piece of crust has survived many mountain-building events between Australia, India and Antarctica and appears to still exist tens of kilometers deep beneath the south-west corner of WA. When we compare our findings with existing data, it appears that many regions around the world experienced a similar timing of early crustal formation and preservation. This suggests a major change in Earth’s evolution about four billion years ago, as the meteorite bombardment waned, the crust stabilized, and life on Earth began to emerge.” The research supervisor Dr. Milo Barham, also from the Timescales of Mineral Systems Group at Curtin’s School of Earth and Planetary Sciences, said no large-scale study of this region had been done before and the results, compared with existing data, had revealed exciting new insights . “The edge of the ancient piece of crust appears to define an important crustal boundary that controls where economically important minerals are located,” Dr Barham said. “Identifying these ancient crustal remnants is important for the future of optimized sustainable resource exploration. Studying the early Earth is challenging, given the vast amount of time that has passed, but it is hugely important for understanding the importance of life on Earth and our quest to find it on other planets.” Citation: “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, 17 June 2022, Terra Nova.11: Terra Nova.11: /ter.12610 Mr. Droellner, Dr. Barham and research co-supervisor Professor Chris Kirkland are affiliated with The Institute for Geoscience Research (TIGeR). Curtin’s flagship Earth Sciences research institute and the research was funded by the Minerals Research Institute of Western Australia.
