Friday, September 30, 2022

A 4-Billion-year-old ancient piece of Earth’s crust found underneath Western Australia

Lasers light the way to the discovery of ancient crust.

Using lasers smaller than human hair to target microscopic grains of a mineral extracted from beach sand, researchers from Curtin University have discovered an approximately four billion-year-old piece of the Earth’s crust beneath the South-West of Western Australia. They used the lasers to vaporize portions of individual grains of the mineral zircon. It revealed the geological history of the region and also disclosed where the grains were originally eroded from.

Ph.D. student Maximilian Droellner said, “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.”

“This piece of the 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 worldwide 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.”

“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. Still, it is deeply important for understanding life’s significance on Earth and our quest to find it on other planets.”

Journal Reference:

  1. Maximilian Dröllner, Christopher L. Kirkland et al. A persistent Hadean–Eoarchean protocrust in the western Yilgarn Craton, Western Australia. Terra Nova. DOI: 10.1111/ter.12610
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