New Study Identifies Earth’s Secret Metal Highways beneath Ancient Continents
This discovery highlights new exploration targets essential for supporting a green economy, the journal Nature reported.
New research from Macquarie University has pinpointed likely locations of essential metals crucial for advancing a green economy.
Transitioning to a green economy demands significantly more critical metals—such as copper, rare earth elements, and cobalt—than current supplies can meet. To address this shortage, it is essential to discover new metal resources formed through different geological processes in previously unexplored regions.
New research published on January 8, 2025, in Nature, led by Dr. Chunfei Chen during his postdoctoral work with the Earth Evolution research group at Macquarie University, sheds light on where and how critical metals likely accumulate. The study identifies the margins of ancient continental cores as promising locations for these metal deposits and explains the geological mechanisms behind their formation.
“These cores are the thickest, bowl-shaped, parts of tectonic plates. Melts that form below their centers will flow upwards and outwards towards the edges, so that volcanic activity is common around their edges,” says Chen.
Previous high-pressure experiments in the Earth Evolution group have shown that initial melts at around 200 kilometers depth are rich in carbonate but contain much less silica than most rock melts.
The new experiments by Dr Chen and colleagues show that these melts will lose silica and become almost pure carbonate as they flow upwards and outwards beneath the continental cores.
Distinguished Professor Stephen Foley from Macquarie’s School of Natural Sciences explains the link to critical metals lies in this change in melt composition.
“The initial melts can carry lots of critical metals and sulfur, but our new results show that these are dropped by the melt as it loses silica. This causes concentrations of critical metals and sulfur in linear arrangements around the edges of thick continental cores,” says Professor Foley.
The research also confirms that mantle samples brought to the surface in volcanoes in these areas do indeed contain more sulfur and copper than elsewhere on the continents.
This new work explains recent observations by researchers at the Australian National University and Geoscience Australia that found critical metals are accumulated around the edges of continent cores, and brings these areas into sharp focus for future exploration activities.
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