Water penetrates to alter the structure of the earth’s core

2023-11-14 17:32:50

Illustration of silica crystals emerging from the liquid metal of the Earth’s outer core due to a water-induced chemical reaction. – DAN SHIM/ASU

MADRID, 14 Nov. (EUROPA PRESS) –

Water from the Earth’s surface can penetrate deep into the planet, altering the composition of the outermost region of the metallic liquid core and creating a thin and distinct layer.

It is the conclusion of new research published in Nature Geoscience.

For billions of years, surface water has been transported to the depths of the Earth by descending or subducting tectonic plates. Upon reaching the boundary between the core and the mantle, about 2,900 kilometers below the surface, This water triggers a deep chemical interaction that alters the structure of the nucleus.

Scientists at Arizona State University and Yonsei University (South Korea) have demonstrated through high-pressure experiments that subducted water reacts chemically with core materials. This reaction forms a hydrogen-rich, silicon-depleted layer, altering the upper region of the outer core into a film-like structure. In addition, the reaction generates silica crystals that rise and integrate into the mantle.

This modified liquid metallic layer is predicted to be less dense, with reduced seismic velocities, consistent with the anomalous features mapped by seismologists.

“For years, it has been believed that the exchange of material between the Earth’s core and mantle is small. However, our recent high-pressure experiments reveal a different story. We discovered that when water reaches the boundary between the core and the mantle, reacts with the silicon in the core, forming silica,” he said it’s a statement Dan Shim, del School of Earth and Space Exploration en Arizona State y couator del estudio.

“This discovery, together with our previous observation of diamonds forming from water reacting with carbon in liquid iron under extreme pressure, points to a much more dynamic core-mantle interaction, suggesting a substantial exchange of material,” he added.

This finding improves our understanding of Earth’s internal processes, suggesting a more extensive global water cycle than previously recognized. The altered “film” of the core has profound implications for the geochemical cycles that connect the surface water cycle to the deep metallic core.

This study was conducted by an international team of geoscientists using advanced experimental techniques at the Argonne National Laboratory’s Advanced Photon Source and PETRA III at the Deutsches Elektronen-Synchrotron in Germany to replicate the extreme conditions at the core-mantle boundary.