Water from the Earth’s surface can reach deep into the Earth, and a new study explains how water changes the outermost regions of the metallic liquid core.
The discovery could explain the existence of a thin layer of material inside the planet, which has puzzled geologists for decades.
The Earth’s crust is made up of tectonic plates that grind and slide beneath each other.Over billions of years, these sinking The zone transported water to the lower layers mantle.
When this water reaches the core-mantle boundary, about 2,900 kilometers (1,800 miles) from Earth’s surface, powerful chemical interactions begin. A team from South Korea, the United States, and Germany showed that this creates a hydrogen-rich upper core layer that sends silica to the lower mantle.
“For many years, the exchange of material between Earth’s core and mantle was thought to be small.” To tell Dan Sim, a materials scientist at Arizona State University, says:
“But our recent high-pressure experiments revealed a different story. We found that when water reaches the core-mantle boundary, it reacts with silicon in the core to form silica. .”
of outer coreA mixture of iron and nickel plays an important role in generating Earth’s magnetic field, essentially protecting life on Earth from solar wind and radiation. Therefore, it is important to understand how the Earth’s interior functions and has evolved over time.
The Earth’s core-mantle boundary changes very rapidly from silicates to metals, but little is known about the chemical exchange.
decades agoresearchers have recorded seismic waves A thin layer just over a few hundred kilometers thick has been recorded from Earth’s slimy interior, but until now no one knows where this proposed “E Prime” layer came from. did.
“We suggest that such chemical exchange between the core and mantle over several giga-years of deep transport of water may have contributed to the formation of the putative E-prime layer.” says the research team. write.
Seismologists have mapped several unusual features that suggest this altered liquid metal layer is less dense and has slower seismic velocities. These density differences are thought to be related to differences in the concentration of light elements such as hydrogen and silicon.
However, as the concentration of a single light element increases, the density decreases while the velocity increases, making it difficult to reconcile seismic observations with the dynamic stability of the E-prime layer.
A possible explanation has been proposed that the concentration of one light element increases while the concentration of another light element decreases. However, scientists were not aware of such an exchange process.
The team used laser heating diamond anvil cell It mimics the pressure and temperature conditions at the core-mantle boundary.
They say that water that sinks into the Earth’s core can chemically react with materials there, turning the outer core into a hydrogen-rich film and dispersing the silica crystals that rise and bind to the mantle. showed that.
![crystal-like structures rising from a fiery liquid](https://www.sciencealert.com/images/2023/11/WaterAndEarthCoreReactionConceptPicSquare.jpg)
A layer of hydrogen-rich, silicon-poor material that forms on top of the core has lower density and velocity, consistent with seismic wave observations.
The modified core film is then deep water circulationAnd the research team says their results suggest a more complex global water cycle than we thought.
“This discovery is our previous observations “Diamonds are formed when water and carbon in a ferrous liquid react under extreme pressure,” Sim said. To tell“points to a much more dynamic core-mantle interaction, suggesting substantial mass exchange.”
This research natural earth science.