Earth is composed of four distinct layers, based on their density. The outermost layer is called crust, then comes the mantle, followed by the outer core and finally, the inner core, which is mostly liquid. Except for the crust, no one has ever explored other layers in person. Scientists have been studying other layers, particularly the core, in details for decades but are yet to fully understand it. Now, a research by international team of researchers has revealed that water from Earth’s surface can reach deep into the planet and cause changes in the outer core.
The study also shed light on a thin layer within the Earth – called E Prime – that has mystified geologists for decades.
“For years, it has been believed that material exchange between Earth’s core and mantle is small,” Arizona State University scientist Dan Shim, part of the research team, said about the study published in Nature Geoscience.
“Yet, our recent high-pressure experiments reveal a different story. We found that when water reaches the core-mantle boundary, it reacts with silicon in the core, forming silica,” the expert further said.
Since its formation billions of years ago, Earth’s tectonic plates have been transporting water to lower mantle through subduction zones. When the water reaches the core-mantle boundary, about 2,900 kilometres beneath the surface, it triggers a powerful chemical reaction.
The research team studied this reaction and came to the conclusion that the reaction creates results a hydrogen-enriched top core layer and transports silica to the lower mantle.
The Earth’s core-mantle boundary undergoes a sharp transition from silicate to metal, creating a film-like layer.
“We suggest that such chemical exchange between the core and mantle over gigayears of deep transport of water may have contributed to the formation of the putative E prime layer,” the team wrote in the study.
The team used laser-heated diamond-anvil cells to mimic pressure-temperature conditions at the core-mantle boundary.