Where did gold come from and how did it disappear in the Earth's interior? Science provides answers for the story of gold: A team of scientist
Where did gold come from and how did it disappear in the Earth’s interior?
Science provides answers for the story of gold:
A team of scientists has proposed a new theory about how gold, platinum, and other precious metals arrived on Earth.
Scientists at Yale University and the Southwest Research Institute (SwRI) gained valuable insights into the story of gold.
The story begins with violent collisions of large objects in space, continues in a partially molten region of Earth’s mantle, and ends with precious metals finding an unexpected resting place much closer to the planet’s surface than scientists had expected.
The study of John Corrigan, a professor of Earth and planetary sciences at Yale’s Faculty of Arts and Sciences, and Simon Marchildon, a researcher at SwRI in Boulder, Colorado, was published in the Proceedings of the National Academy of Sciences.
The new theory provides possible answers to the puzzling question of how gold, platinum, and other precious metals found their way to shallow pockets within Earth’s mantle instead of reaching the depths of the planet’s core. On a broader scale, the new theory offers insights into the formation of planets throughout the universe.
“Our research is a good example of making an unexpected discovery after rethinking conventional wisdom,” Corrigan said.
Recent research by scientists around the world:
It shows that precious metals such as gold and platinum arrived on Earth billions of years ago after the early Earth collided with large objects the size of the moon in space. It is leaving behind deposits of material that sank into the planet’s interior.
However, the process of this absorption has remained somewhat unclear.
In addition to their value due to their rarity, beauty, and use in high-tech products, gold and platinum are attracted to the element iron to the point that they are expected to almost completely accumulate in the Earth’s metallic core, either by directly merging with the metallic core at the impact, or by quickly sinking from the mantle to the core.
By this logic, they were not expected to accumulate near the surface of the Earth or around it. But that’s what happened.
“By working with Simon, the expert in impact dynamics, I was able to come up with a new solution to this dilemma,” Corrigan said.
Corrigan and Marchildon’s theory:
It centers on a thin “transient” region of the mantle, where the shallow part of the mantle melts and the deeper part remains solid. The researchers found that this region has strange dynamic properties that can efficiently trap falling metal components. The dynamic properties can also slowly deliver them to the rest of the mantle.
The theory assumes that this delivery is still ongoing, as remnants of the transient region appear as “large low-shear velocity provinces” – known geophysical anomalies in the deep mantle.
“This transient region is almost always formed when a large impact hits the early Earth, which makes our theory very strong,” Marchildon said.
The researchers say the new theory not only explains previously obscure aspects of Earth’s geochemical and geophysical evolution, but it also highlights the wide range of timescales involved in Earth’s formation.
“One of the great things we found is that the dynamics of the transient mantle region happen over a very short period of time – about a day. Its impact on Earth’s subsequent evolution has lasted for billions of years,” Corrigan said.
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