Scientists shed light on Earth's hidden layer: water's core connection

For many decades, geologists have remained fascinated by a unique thin layer found in the outer region of Earth's metallic core. Current research suggests that the existence of this layer could be related to the process of water seeping from the surface deep into the core of our planet.

The Earth's crust is made up of tectonic plates, which rub against each other and move relative to one another. Over billions of years, the cracks formed by these movements allowed water to reach the core of the planet. When this water reaches the boundary between the core and the mantle, situated approximately 1,801 miles beneath the surface, it sparks a powerful chemical reaction that transports silica to the lower mantle.

Researchers from South Korea, the United States, and Germany have published their research findings in the journal Nature Geoscience.

"For years, it has been believed that material exchange between Earth's core and mantle is small. 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," states materials scientist Dan Shim from Arizona State University.

The relatively thin layer, several hundred miles thick (known as "E prime"), was first observed by scientists studying seismic wave recordings passing through the Earth's interior a few decades ago. For a long time, scientists wondered about its origin. But they now propose that its formation could result from the chemical reaction triggered by water penetrating the core.

In order to substantiate this, the research team conducted a series of experiments using a laser-heated diamond anvil cell, enabling them to replicate the pressure and temperature conditions at the core-mantle boundary. The results indicate that water seeping into the Earth's core can indeed interact chemically with the material inside, producing silica, which is then integrated with the mantle.