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Gold and platinum: their cosmic history and path to Earth.
Scientists from Yale University and the Southwest Research Institute (SRI) have provided valuable data on the origin of gold. The study begins with violent collisions of large objects in space, continues in the semi-thawed region of the Earth's mantle, and ends with precious metals being much closer to the surface of the planet than scientists expected.
June Korenaga, a professor of Earth and planetary sciences at Yale University, and Simone Marchi, a researcher at SRI, detailed their findings in the journal Proceedings of the National Academy of Sciences. Their new theory provides possible answers to long-standing questions about how gold, platinum, and other precious metals ended up in shallow pockets in Earth's mantle, rather than deep in the planet's core. More broadly, the new theory offers insight into the formation of planets in the universe.
"Our study is a good example of an unexpected discovery after revising conventional wisdom," Corenaga said.
Recent research by scientists from around the world has established that precious metals such as gold and platinum arrived on Earth billions of years ago after the early proto-Earth collided with large, moon-sized bodies in space. However, the process of this takeover still remained a mystery.
In addition to being prized for their rarity, aesthetic beauty, and use in high-tech products, gold and platinum are so-called "siderophilic" elements. They are attracted to the iron element to such an extent that one would expect them to almost completely congregate in the Earth's metal core - either by merging directly with the metal core on impact, or by rapidly sinking from the mantle into the core.
Korenaga and Marchi's theory centers around a thin, "transitional" 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 peculiar dynamic properties that can effectively capture falling metal components and slowly deliver them to the rest of the mantle.
The researchers said the new theory not only explains previously mysterious aspects of Earth's geochemical and geophysical evolution, but also highlights the wide range of time scales involved in Earth's formation.
"One of the great things we found was that the dynamics of the transition mantle region occur over a very short period of time — about a day — but its impact on the subsequent evolution of the Earth lasted for several billion years," said Corenaga.
Scientists from Yale University and the Southwest Research Institute (SRI) have provided valuable data on the origin of gold. The study begins with violent collisions of large objects in space, continues in the semi-thawed region of the Earth's mantle, and ends with precious metals being much closer to the surface of the planet than scientists expected.
June Korenaga, a professor of Earth and planetary sciences at Yale University, and Simone Marchi, a researcher at SRI, detailed their findings in the journal Proceedings of the National Academy of Sciences. Their new theory provides possible answers to long-standing questions about how gold, platinum, and other precious metals ended up in shallow pockets in Earth's mantle, rather than deep in the planet's core. More broadly, the new theory offers insight into the formation of planets in the universe.
"Our study is a good example of an unexpected discovery after revising conventional wisdom," Corenaga said.
Recent research by scientists from around the world has established that precious metals such as gold and platinum arrived on Earth billions of years ago after the early proto-Earth collided with large, moon-sized bodies in space. However, the process of this takeover still remained a mystery.
In addition to being prized for their rarity, aesthetic beauty, and use in high-tech products, gold and platinum are so-called "siderophilic" elements. They are attracted to the iron element to such an extent that one would expect them to almost completely congregate in the Earth's metal core - either by merging directly with the metal core on impact, or by rapidly sinking from the mantle into the core.
Korenaga and Marchi's theory centers around a thin, "transitional" 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 peculiar dynamic properties that can effectively capture falling metal components and slowly deliver them to the rest of the mantle.
The researchers said the new theory not only explains previously mysterious aspects of Earth's geochemical and geophysical evolution, but also highlights the wide range of time scales involved in Earth's formation.
"One of the great things we found was that the dynamics of the transition mantle region occur over a very short period of time — about a day — but its impact on the subsequent evolution of the Earth lasted for several billion years," said Corenaga.
