A new study revealed a fascinating mechanism by which gold, which is formed deep inside the Earth, eventually makes its way to the Earth’s surface.
In the study, "Mantle oxidation by sulphur drives the formation of giant gold deposits in subduction zones," published in the Proceedings of the National Academy of Sciences, a research team, including a University of Michigan scientist has used advanced computer models and numerical techniques to uncover the exact conditions under which magma (molten rock beneath the Earth’s surface) becomes enriched with gold.
A special type of sulphur, which only exists under specific high-pressure and high-temperature conditions found deep below active volcanoes, helps transport gold from the Earth’s interior (mantle) into molten rock (magma).
This gold-rich magma then travels toward the Earth’s surface, where it can form gold deposits.
Although scientists were already aware that gold can bond with various sulphur ions, this study is the first to provide a solid scientific model.
The researchers created a scientific model by conducting experiments in the lab, where they controlled the pressure and temperature to replicate conditions of artificial magma.
Adam Simon, U-M professor of Earth and environmental sciences and co-author of the study, said in a statement, "On all of the continents around the Pacific Ocean, from New Zealand to Indonesia, the Philippines, Japan, Russia, Alaska, the western United States and Canada, all the way down to Chile, we have lots of active volcanoes. All of those active volcanoes form over or in a subduction zone environment. The same types of processes that result in volcanic eruptions are processes that form gold deposits.”
The model they developed can now be used to understand real-world conditions, like those in the Earth’s mantle.
