Why are gold and platinum in the mantle and not sunk into the core?
Precious metals, such as gold and platinum, have long fascinated humanity with their scarcity, beauty and industrial applications. A recent discovery sheds light on the formation of celestial bodies in the universe and how these molecules ended up in the bowels of the earth.
Scientists at Yale University and the Southwest Research Institute (SwRI) have uncovered a remarkable story that traces the origins of these precious materials from the depths of space to Earth's mantle.
The story begins with violent collisions of celestial bodies in space, setting the stage for a cosmic drama that ends with precious metals resting on the planet's surface much closer to the surface than previously thought.
Jun Korenaga, a professor of Earth and planetary sciences at Yale, and Simone Marchi, a researcher at SwRI in Boulder, Colorado, revealed their groundbreaking findings in a study published in the journal Proceedings of the National Academy of Sciences.
Their research challenges conventional wisdom and presents a new theory that redefines our understanding of how precious metals, including gold and platinum, ended up in Earth's mantle.
Gold and platinum reemergence cycle
“Our research is a good example of an unexpected discovery after re-examining conventional wisdom,” Korenaga noted in a statement, underscoring the transformative nature of their findings.
The enigmatic attraction of shiny metals
A recent scientific consensus has established that precious metals such as gold and platinum arrived on Earth billions of years ago, after a series of collisions of the proto-Earth with other large terrestrial bodies.
These impacts left deposits of materials that eventually coalesced into the Earth we know today. However, the process by which these precious elements were absorbed into the composition of the Earth remained a mystery.
Gold and platinum are highly “siderophilic” elements, showing a strong affinity with iron. Logically, they should have fused directly with the iron core on impact or rapidly sunk from the mantle into the core.
This phenomenon should have prevented these precious metals from accumulating near the Earth's surface, but, surprisingly, this happened.
Simone Marchi, an expert in impact dynamics, collaborated with Korenaga to propose a solution to this conundrum. Their theory centers on a thin, “transitional” region within the Earth's mantle, where the surface melts while the deeper section remains solid.
Surprisingly, this region exhibits dynamic properties that effectively trap infalling metallic components, gradually releasing them to the rest of the mantle.
According to their theory, this process is still ongoing, with the remnants of the transitional region manifesting as “large low-shear provinces,” widely known geophysical anomalies deep in the mantle.
“This transient region almost always forms when a large object hits the early Earth in a simulation, making our theory quite robust,” Marchi explained.
Unraveling the formation of the Earth
The implications of this research extend far beyond the origins of gold and platinum, offering valuable insights into the formation of celestial bodies throughout the universe. The new theory explains many puzzling aspects of the Earth's geochemical and geophysical evolution.
Korenaga highlighted the extraordinary time scales involved in the formation of the Earth, stating: “One of the extraordinary things we discovered was that the dynamics of the transitional mantle region take place over a very short period of time – about a day – and yet its influence on the subsequent Earth, evolution lasted a few billion years”.
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The article Why are gold and platinum in the mantle and not sunk into the core? comes from Economic Scenarios .
This is a machine translation of a post published on Scenari Economici at the URL https://scenarieconomici.it/come-mai-oro-e-platino-sono-nel-mantello-e-non-sono-affondati-nel-nucleo/ on Tue, 24 Oct 2023 10:00:10 +0000.