Dec 27, 2024 20:00:00

The process by which gold produced deep in the mantle emerges on the Earth's surface has been revealed

Gold , which is also used in accessories and electronic components, is thought to be generated in the mantle on Earth. A research team from the University of Michigan investigated how gold generated deep underground appears on the surface as gold deposits .

Mantle oxidation by sulfur drives the formation of giant gold deposits in subduction zones | PNAS
https://www.pnas.org/doi/10.1073/pnas.2404731121

Study identifies how gold reaches Earth's surface | University of Michigan News
https://news.umich.edu/study-identifies-how-gold-reaches-earths-surface/

Previous research has shown that gold deposits associated with volcanoes around the Ring of Fire originate from the Earth's mantle and are transported to the surface by magma, and that very high concentrations of gold are found in minerals in

subduction zone environments.

A subduction zone is a place on the Earth where two plates collide and the lower plate slides down into the mantle. Near the subduction zone, the mantle rises to the surface as magma, forming volcanoes.

However, it was unclear how the transported gold appears on the Earth's surface. Professor Adam Simon of the University of Michigan and his colleagues used numerical modeling to investigate the specific conditions under which gold is concentrated in magma rising from the Earth's mantle to the surface.

They found that while gold is generally inert in the mantle and tends to remain there, it becomes more mobile when it combines with

trisulfur ions to form gold-trisulfur complexes, which are then transported from the mantle to magma and transported to the Earth's surface, where they cool and solidify, eventually becoming gold deposits.

'There are a lot of active volcanoes in the Pacific Ocean, in countries and regions like New Zealand, Indonesia, the Philippines, Japan, Russia, Alaska, and all of these active volcanoes are formed in subduction zone environments. The process by which these volcanoes erupt is almost the same as the process by which gold deposits form,' Simon said.

Simon added: 'Our findings provide a very definitive answer as to what factors cause certain subduction zones to produce extremely gold-rich deposits. Combining the results of this study with existing research will ultimately improve our understanding of how gold deposits form and whether they can have a positive impact on underground exploration.'