Deep within the Earth, a thin layer exists just around the molten metal of the outer core. The origin of this layer has remained unclear for decades, but researchers now believe that surface water caused this differentiation in the first place. It is difficult to explain this layer by the concentration of a single element there, but the occurrence of a widespread chemical reaction may help explain it.
Water does not reach here by dripping thousands of kilometers from a small hole. The water is carried downward by descending tectonic plates and reaches the core after a journey of 2,900 kilometers. The process is slow, but over billions of years, water from the surface changes the boundary between the base of the mantle and the upper part of the core.
Considering that the hydrogen-rich, silicate-poor layer is about a few hundred kilometers thick and the core is 6,970 kilometers in diameter, this thickness can be seen as a very thin film. The altered state of water causes this altered layer of liquid metal to result in reactions that form silica crystals that move into the mantle. The layer is also expected to be less dense and have a lower seismic velocity, as measured by geologists.
Co-author Dr. from Arizona State University. “For years, it was believed that the exchange of matter between the Earth’s core and mantle was low,” Dan Shim said in a statement. But our recent high-pressure experiments reveal a different story. “We found that when water reaches the core-mantle boundary, it reacts with the silicon in the core to form silica,” he said. “This discovery, together with our previous observations of diamonds formed from water reacting with carbon in the iron liquid under extreme pressure, points to a much more dynamic core-mantle interaction and “It shows that there was a significant exchange of materials.”
There’s a lot we don’t know about the deep interior of our planet. More precise seismic data and better simulations collected from earthquakes large and small are revealing new details about our planet’s interior. But recently researchers have also found evidence that two regions around the core are left over from the planetary collision that formed the Moon.
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