Scientists discover Earth’s 'Gold Kitchen' hidden under Pacific Ocean

Veiled by the waves of the ocean, and sheilded from the life on ground, scientists discovered Earth's "gold kitchen" during a study conducted on the Kermadec Island Arc in the South Pacific region.

It was found that the island arcs are a suitable area for gold production as it was where volcanoes form above subduction zones, regions where a tectonic plate sinks beneath another.

In a press statement, the lead author of the study from the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany, Christian Timm said, "Our research shows that hydrous mantle melting beneath island arcs is a key driver of gold enrichment."

"In these settings, the mantle behaves like a multi-stage melting system that progressively concentrates gold," he added.

The team analysed 66 glass samples from the ocean floor along the Kermadec island arc, and the adjacent Havre Trough north of New Zealand, a statement read.

The volcanic glasses originate when lava rapidly cools underwater, maintaining the original magma's chemical composition.

"When we analysed these samples, we found that their gold concentrations are often several times higher than those of comparable magmas from mid-ocean ridges," Timm informed.

"This raised the key question: which processes are responsible for this enrichment?"

To seek an answer, the group examined the concentrations of gold and estimated its behaviour alongside other elements, such as silver, copper, selenium and platinum. As these elements exhibit similar behaviour during melting, the experiments provided insights into the conditions inside the mantle.

The data revealed that the mantle under the Kermadec island arc undergoes hydrous melting at high temperatures, and in such environments, magmas demonstrate silver-to-copper ratios similar to those of the mantle.

Simultaneously, researchers observed elevated original gold concentrations of up to six nanograms per gram of rock. The gold-to-copper ratios also exceeded those of fertile mantle and primitive mid-ocean ridge basalts.

"We initially assumed that water released from the subduction zone directly controlled gold enrichment," Timm said.

"However, our data show that water mainly facilitates mantle melting. The key factor for high gold concentrations is the high – and in part repeated – degree of melting."

"Gold in the mantle is commonly bound in sulphide minerals. At high degrees of melting, these minerals break down, releasing their gold completely into the melt," the lead author explained.

"Our results demonstrate that gold enrichment is not the result of a single melting event, but of multiple stages," he added. "Only repeated melting allows gold to become strongly concentrated in the magma."

The study, published in the journal Communications Earth & Environment, immediately gained spotlight, setting a milestone in researching on gold-rice deposits found in intra-oceanic island arcs.

"We are effectively looking at the first step in the life cycle of gold," Timm said. "It begins with the transfer of gold from the mantle into a melt that eventually forms volcanoes. The alchemy starts long before the metal reaches the surface."