A few decades ago seismologists Images of the planet’s deepest interior detect a thin layer just over a few hundred kilometers thick, was unknown until then. The origin of this layer, known as primary layer E, remains a mystery to this day. However, this riddle has largely been solved and has provided scientists with surprises.
An international team of researchers, including Arizona State University scientists Dan Shim, Taehyun Kim, and Joseph O’Rourke of the School of Earth and Space Exploration, discovered: Water found on Earth’s surface can penetrate surprising depths of the planet, to the point that the metallic liquid will change the composition of the outermost region of the core and create a thin and differentiated layer.
published research, Natural Geologydetails of surface water transported to Earth’s deepest depths over billions of years Through descending tectonic plates (subduction) that sink deep into the planet’s interior.
Interaction with the Earth’s core
When the boundary between the core and mantle is reached, This water, located approximately 2,900 kilometers below the surface, triggers a profound chemical interaction that changes the structure of the core.
Shim and his team, along with Yong Jae Lee of Yonsei University in South Korea, demonstrated through high-pressure experiments that water chemically reacts with core materials. This reaction results in the formation of a hydrogen-rich and silicon-poor layer. converting the upper region of the outer core into a film-like structure. Additionally, this reaction produces silica crystals that rise until they integrate into the mantle.
The study authors believe that this altered liquid metallic layer will be less dense and seismic velocities will decrease, consistent with the anomalous features that seismologists have detected and mapped.
“For years it was thought that the exchange of matter between the Earth’s core and mantle was small. But our recent high-pressure experiments reveal a different story. “We found that when water reaches the boundary between the core and the mantle, it reacts with the silicon in the core to form silica,” Shim said. said.
“This discovery, together with our previous observation that diamonds form from water reacting with carbon in liquid iron under extreme pressure, It points to a much more dynamic core-mantle interaction than previously thought, indicating significant material exchange“added.
This discovery sheds light on Earth’s complex and still unknown internal processes. Reveals a broader global water cycle than previously known. The altered ‘film’ or layer of the core has profound effects on geochemical cycles linking the surface water cycle to the deep metallic core.
This work was carried out by an international team of geoscientists who used advanced experimental techniques at Argonne National Laboratory’s Advanced Photon Source and PETRA III at the Deutsches Elektronen-Synchrotron in Germany to replicate extreme conditions at the core-mantle boundary.
Reference work: https://www.nature.com/articles/s41561-023-01324-x
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