Lasers have been used to find ancient crust beneath WA. 

By firing lasers finer than a human hair at tiny grains of a mineral extracted from beach sand, Curtin researchers have found evidence of an almost four billion-year-old piece of the Earth’s crust that lies beneath the South-West of WA.

The new finding helps explain the planet’s evolution from uninhabitable to life supporting, according lead researcher and PhD student Maximilian Droellner.

The study involved using lasers to vaporise portions of individual grains of the mineral zircon and reveal where the grains were originally eroded from, as well as the geological history of the region.

“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 says.

“This piece of crust has survived multiple mountain-building events between Australia, India and Antarctica and appears to still exist at tens of kilometres 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 stabilised and life on Earth began to establish.”

Research supervisor Dr Milo Barham says the study is the first to reveal some 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 optimised sustainable resource exploration.

“Studying the early Earth is challenging given the enormity of time that has elapsed, but it has profound importance for understanding life’s significance on Earth and our quest to find it on other planets.”

The full study is accessible here.