New Research Uncovers How Water Changes Earth’s Core
Scientists have long been puzzled by the presence of a thin layer of material inside the Earth that seemed unexplainable. Now, new research has shed light on this mystery, revealing how water from the planet’s surface can find its way deep into the core and change its outermost layer.
The study, carried out by a team from South Korea, the US, and Germany, shows that water transported to the lower mantle through subduction zones sets off a powerful chemical interaction when it reaches the core-mantle boundary, some 2,900 kilometers below the surface. This interaction creates a top core layer rich in hydrogen and sends silica to the lower mantle.
“For years, it has been believed that material exchange between Earth’s core and mantle is small,” says materials scientist Dan Shim from Arizona State University. “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 findings are significant as the mix of iron and nickel in the outer core plays a crucial role in generating Earth’s magnetic field, which protects the planet from solar winds and radiation. Understanding how Earth’s core has evolved over time is essential for studying the planet’s dynamics.
The team’s research also suggests that the chemical exchange between the core and mantle over billions of years may have contributed to the formation of the proposed ‘E prime’ layer, which has confounded researchers for decades.
Moreover, the study has implications for the deep water cycle, suggesting that it is far more complex than previously thought.
“This discovery, along with our previous observation of diamonds forming from water reacting with carbon in iron liquid under extreme pressure, points to a far more dynamic core-mantle interaction, suggesting substantial material exchange,” Shim says.
The study, titled “Deep hydrous mantle reservoir implies a major role of subducted water in Earth’s deep water cycle,” has been published in Nature Geoscience.