Origin of Gold: Precious Metal Comes From Ancient Chemical Factory in Deepest Part of Earth's Mantle

Peridotite from the deep mantle (green) enclosed in lava (black) from a Patagonian volcano, which was found by the researchers. Their work throws possible light on the origins of gold. UGR

Gold has, in one way or another, been at the heart of much human history for thousands of years. It has sparked wars, alliances and massacres, and it still holds a central place in many cultures. But despite all this, scientists know very little about how it came to exist.

Now, an international team of scientists has published research in Nature Communications that could shed new light on how the iconic metal first came into being in the Earth's crust.

The team studied the Deseado Massif at the Argentinean Patagonia, part of one of the world's largest gold-producing regions, according to Phys.org.

While the Earth's mantle, the layer below the crust which begins around 70 kilometers below the land, is still unreachable by humans, the team was able to examine material that had surfaced from the depths of the Earth during volcanic eruptions.

Inside such material, the researchers discovered tiny traces of gold, the deepest ever found beneath the South American continent.

"[The region's] history dates back 200 million years, when Africa and South America were part of the same continent," González Jiménez, of the University of Granada, explained.

"Their separation was caused by the ascent of a 'mantle plume' from the deep mantle, which broke the much thinner and more fragile crust and caused the separation of the two continents.

"The ascent of the deep mantle plume generated a true chemical factory that enriched the mantle with metals, which would later generate the conditions for the creation of gold deposits.

"This time, the process was caused by the movement of one tectonic plate under another, allowing the circulation of metal-rich fluids through the cracks, which precipitated the metals and concentrated them near the surface."

The research is novel, according to the release, because most theories about the origin of mineral deposits "are generally attributed to an origin in the crust itself, without taking into account the role of a deeper root from the mantle."