Groundbreaking Study Reveals Earth’s Surface Water Reaches Core, Altering Composition
A groundbreaking study published in the journal Nature Geoscience has revealed that Earth’s surface water is capable of reaching the planet’s core, altering its composition and sparking a more dynamic core-mantle interaction, hinting at a complex global water cycle.
A team of researchers, including scientists Dan Shim, Taehyun Kim, and Joseph O’Rourke from Arizona State University’s School of Earth and Space Exploration, have uncovered the deep-seated interaction between the Earth’s surface water and the core.
For years, the origin of a thin layer just over a few hundred kilometers thick, known as the E prime layer, has puzzled seismologists. However, the recent study has shed light on this mystery, attributing it to the interaction of water from the Earth’s surface with the metallic liquid core.
The study, conducted by an international team of geoscientists, utilized advanced experimental techniques at the Advanced Photon Source of Argonne National Lab and PETRA III of Deutsches Elektronen-Synchrotron in Germany to replicate the extreme conditions at the core-mantle boundary.
Research indicates that over billions of years, subducted tectonic plates have transported surface water deep into the Earth. When this water reaches the core-mantle boundary, which is approximately 1,800 miles below the surface, a profound chemical interaction occurs, resulting in a shift in the core’s structure.
The team’s high-pressure experiments demonstrated that subducted water chemically reacts with core materials, leading to the formation of a hydrogen-rich, silicon-depleted layer in the topmost outer core region and silica crystals that integrate into the mantle. This discovery suggests a far more dynamic core-mantle interaction than previously believed, hinting at substantial material exchange between the core and mantle.
“These recent high-pressure experiments reveal a different story about the material exchange between Earth’s core and mantle. We found that when water reaches the core-mantle boundary, it reacts with silicon in the core, forming silica,” explained Dan Shim. “This, 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.”
This groundbreaking finding not only advances our understanding of Earth’s internal processes but also suggests 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 with the deep metallic core.
The international team of geoscientists involved in the study included members from Arizona State University and Yonsei University in South Korea, as well as research scientists from the Advanced Photon Source and Deutsches Elektronen-Synchrotron. The work was supported by the NSF Earth Science Program.
The study’s findings have far-reaching implications for our understanding of Earth’s internal dynamics and the intricate processes that govern the planet’s core-mantle interaction. With the advancement of this research, scientists are poised to uncover even more mysteries of the Earth’s deep-seated secrets.
Reference: “A hydrogen-enriched layer in the topmost outer core sourced from deeply subducted water” by Taehyun Kim, Joseph G. O’Rourke, Jeongmin Lee, Stella Chariton, Vitali Prakapenka, Rachel J. Husband, Nico Giordano, Hanns-Peter Liermann, Sang-Heon Shim and Yongjae Lee, 13 November 2023, Nature Geoscience. DOI: 10.1038/s41561-023-01324-x