At the interface where subducting water fulfills the core, a chemical exchange occurs to form a hydrogen-rich layer in the upper external core and dense silica in the bottom of the mantle. Along with Yong Jae Lee of Yonsei University in South Korea, Shim and his group have shown through high-pressure experiments that subducted water chemically reacts with core materials. This response forms a hydrogen-rich, silicon-depleted layer, altering the topmost outer core region into a film-like structure.” For years, it has been thought that product exchange between Earths core and mantle is small. We found that when water reaches the core-mantle limit, it responds with silicon in the core, forming silica,” said Shim.
Illustration of silica crystals coming out from the liquid metal of the Earths external core due to a water-induced chain reaction. Credit: Dan Shim/ASU
An innovative study exposes that Earths surface area water reaches the core, modifying its composition and recommending a more dynamic core-mantle interaction and a complex global water cycle.
A few years earlier, seismologists imaging the deep world determined a thin layer, simply over a few hundred kilometers thick. The origin of this layer, referred to as the E prime layer, has actually been a secret– previously.
A global group of scientists, consisting of Arizona State University researchers Dan Shim, Taehyun Kim, and Joseph ORourke of the School of Earth and Space Exploration, has revealed that water from the Earths surface area can penetrate deep into the world, modifying the structure of the outer region of the metal liquid core and producing a distinct, thin layer.
Their research was released on November 13 in the journal Nature Geoscience.
The Process of Deep Water Transport
Research study shows that over billions of years, surface water has been transferred deep into the Earth by coming down, or subducted, tectonic plates. Upon reaching the core-mantle limit, about 1,800 miles below the surface area, this water triggers an extensive chemical interaction, changing the cores structure.
Illustration of Earths interior exposing subducting water and a rising plume of magma. At the interface where subducting water satisfies the core, a chemical exchange strikes form a hydrogen-rich layer in the upper external core and thick silica in the bottom of the mantle. Credit: Yonsei University
Chemical Interactions at the Core-Mantle Boundary
Along with Yong Jae Lee of Yonsei University in South Korea, Shim and his group have actually shown through high-pressure experiments that subducted water chemically reacts with core products. This reaction forms a hydrogen-rich, silicon-depleted layer, modifying the upper outer core region into a film-like structure.
Core-Mantle Interaction and Global Implications
” For years, it has been believed that material exchange between Earths core and mantle is little. We found that when water reaches the core-mantle boundary, it reacts with silicon in the core, forming silica,” stated Shim.
This finding advances our understanding of Earths internal procedures, suggesting a more substantial international water cycle than formerly acknowledged. The transformed “movie” of the core has profound ramifications for the geochemical cycles that connect the surface-water cycle with the deep metallic core.
Referral: “A hydrogen-enriched layer in the topmost external core sourced from deeply subducted water” by Taehyun Kim, Joseph G. ORourke, 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.
This study was conducted by a worldwide team of geoscientists utilizing advanced experimental strategies 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 limit.
Members of the group and their key roles from ASU are Kim, who started this job as a visiting PhD student and is now a postdoctoral scientist at the School of Earth and Space Exploration; Shim, a professor at the School of Earth and Space Exploration, who spearheaded the high-pressure experimental work; and ORourke, an assistant teacher at the School of Earth and Space Exploration, who performed computational simulations to understand the formation and persistence of the cores modified thin layer. Lee led the research study team from Yonsei University, in addition to crucial research researchers Vitali Prakapenka and Stella Chariton at the Advanced Photon Source and Rachel Husband, Nico Giordano, and Hanns-Peter Liermann at the Deutsches Elektronen-Synchrotron.
This work was supported by the NSF Earth Science program.