Earth Slice Interior Core

Scientists Discover a 4-Billion-Year-Old Ancient Piece of Earth’s Crust Underneath Western Australia

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

Lasers pave the path for finding ancient crust.

Curtin University researchers have discovered evidence of an approximately four billion-year-old piece of the Earth’s crust that exists beneath the South-West of Western Australia by using lasers smaller than a human hair to target microscopic grains of a 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 the lasers were used to vaporize portions of individual grains of the mineral zircon and revealed where the grains were originally eroded from as well as the geological history of the region. This new discovery helps explains how the planet evolved from being uninhabitable to supporting life.

“There is evidence that an up to four billion-year-old piece of crust about the size of Ireland has been influencing the geological evolution of WA for the past few billions of years and is a key ingredient of rocks formed in WA across this time,” Mr. Droellner states.

“This piece of crust has survived multiple mountain-building events between Australia, India, and Antarctica and appears to still exist at tens of kilometers of depth under the South-West corner of WA. When comparing our findings to existing data, it appears many regions around the world experienced a similar timing of early crust formation and preservation. This suggests a significant change in the evolution of the Earth some four billion years ago, as meteorite bombardment waned, crust stabilized and life on Earth began to establish.”

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

“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.

“Recognising these ancient crustal remnants is important for the future of optimized sustainable resource exploration. Studying the early Earth is challenging given the enormity of time that has elapsed, but it has a profound importance for understanding life’s significance 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 June 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 Earth Sciences research institute and the research were funded by the Minerals Research Institute of Western Australia.

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