Scientists discover 4-billion-year-old chunk of Earth’s crust beneath Western Australia

Earth Slice Interior Core

The earth is made up of three main layers: the crust, the mantle and the core.

Lasers pave the way to finding ancient bark.

Curtin University researchers have discovered evidence of an approximately four-billion-year-old piece of Earth’s crust that exists beneath southwestern Western Australia using lasers smaller than a hair human to target microscopic grains of a mineral extracted from beach sand.

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

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

“This piece of crust has survived multiple 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 of the world experienced a similar time of formation and preservation of the early crust.This suggests a significant change in the evolution of the Earth about four billion years ago, as the meteorite bombardment subsided, the crust stabilized, and life on Earth began to establish itself.”

Research supervisor Dr Milo Barham, also from the Mineral Systems Group in Curtin’s School of Earth and Planetary Sciences, said no large-scale study of this region had been done before and that the results, compared to existing data, had revealed interesting new insights.

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

“Recognizing these ancient remnants of the crust is important for the future of optimized exploration of sustainable resources. Studying the early Earth is challenging given the enormity of time that has passed, but it is of great importance for understanding the importance 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, 17 Jun 2022, Terra Nova
DOI: 10.1111/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 research institute in Earth Sciences and the research was funded by the Minerals Research Institute of Western Australia.

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