"E Prime" Layer Discovered in in Earth's Core

• 22 Nov 2023

Earth's composition, consisting of an inner core, outer core, mantle, and crust, sees the addition of a newly discovered layer, termed "E Prime," at the outermost part of the core, as unveiled by an international research team.

Key Points

• Nature Geoscience Revelations: Citing findings from Nature Geoscience, researchers, particularly from ASU, challenge the long-held belief that material exchange between the Earth's core and mantle is minimal.
• Instead, experiments reveal significant reactions occurring when surface water reaches the core-mantle boundary.
• Tectonic Plates and Water Transport: The study proposes that tectonic plates, transporting surface water over billions of years, carry it deep into the Earth.
• Upon reaching the core-mantle boundary, approximately 1,800 miles below the surface, water induces chemical changes that influence the structure of the core.
• Water-Induced Chemical Reactions: Observations by ASU scientists and collaborators indicate that subducted water chemically reacts with core materials under high pressure, leading to the formation of a unique hydrogen-rich, silicon-depleted layer resembling a film-like structure at the outer core.
• Ascension and Impact on Composition: Silica crystals generated in this process ascend into the mantle, impacting the overall composition.
• These alterations in the liquid metallic layer may result in reduced density and altered seismic characteristics, aligning with anomalies detected by seismologists.
• Implications for Earth's Understanding: The researchers emphasize that this discovery significantly enhances our understanding of Earth's internal mechanisms, shedding light on a more intricate global water cycle than previously acknowledged.
• The transformed core layer has profound implications for the interconnected geochemical processes linking surface water cycles with the deep metallic core.