Inside the Earth, around the molten metal of the outer core, there is a thin layer, the composition of which has been a mystery to geologists for decades. However, scientists have now found a probable cause of its appearance.
In a study published in the journal Nature Geoscience, an international group of scientists claims that water from the Earth’s surface can penetrate deep into the planet, changing the composition of the outermost region of the metallic liquid core and creating a distinctive thin layer, write Science Alert and Arizona State University.
The Earth’s crust is made up of tectonic plates that move and sink. For billions of years, during such subsidence, surface water was transported deep into the Earth, to the lower mantle.
Having reached the boundary between the core and the mantle (at a depth of about 2,900 kilometers from the Earth’s surface), this water causes a deep chemical interaction that changes the structure of the core.
Using experiments under high pressure, a team of scientists demonstrated the interaction of submerged water and core materials. The result of this reaction is the formation of a hydrogen-rich and silicon-depleted layer, which turns the upper outer region of the core into a film-like structure.
As a result of the reaction, silicon dioxide crystals (silica) are also formed, which rise and integrate into the mantle.
“For many years, it was thought that the material exchange between the Earth’s core and the mantle is small. However, our recent high-pressure experiments show otherwise.” – said one of the authors of the study, Dan Shim from Arizona State University.
Scientists hypothesize that this modified liquid metal layer will be less dense and with a reduced seismic velocity: waves generated in the Earth’s crust and mantle due to earthquakes, explosions and impacts will propagate more slowly.
The mixture of iron and nickel in the outer core plays an important role in creating the Earth’s magnetic field, because it actually protects life on the planet from solar winds and radiation. It is important for scientists to understand how the interior of the Earth is organized and develops over time.
“This discovery, along with our previous observations of the formation of diamonds from water reacting with carbon in liquid iron under extreme pressure, points to a much more dynamic interaction of the core and mantle, involving significant exchange of substances.” – explained Dan Shim.
We will remind you that earlier we wrote that a robot chemist found a way to get oxygen on Mars.
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