Arizona, US

Recent research delves into the intricate relationship between Earth's surface water and the outermost layer of its metallic liquid core. According to this research, water transported through tectonic plate subduction zones over billions of years reaches the lower mantle, instigating a significant chemical reaction upon reaching the core-mantle boundary, situated 2,900 kilometres beneath the surface.

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This chemical interplay results in the creation of a top core layer enriched in hydrogen, while simultaneously dispatching silica to the lower mantle. Contrary to prior beliefs, the study posits a more extensive material exchange between the core and mantle.

Understanding this process is pivotal, given that the outer core's composition, predominantly iron and nickel, plays a pivotal role in generating Earth's magnetic field. This field acts as a shield, safeguarding the planet from solar winds and radiation.

The findings challenge conventional wisdom, indicating that material exchange between the core and mantle is more dynamic than previously assumed. 

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"For years, it has been believed that material exchange between Earth's core and mantle is small," materials scientist Dan Shim from Arizona State University told Science Alert. 

"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," he added. 

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What's the mystery of 'E Prime' layer?

The study proposes that prolonged chemical exchanges between the core and mantle contribute to the formation of the elusive 'E prime' layer, a phenomenon identified but unexplained at the core-mantle boundary.

Laser-heated diamond-anvil cells were employed to simulate the rigorous conditions at the core-mantle boundary. These experiments demonstrated that subducted water undergoes a transformative chemical reaction with core materials, morphing the outer core into a hydrogen-rich film and dispersing silica crystals to the mantle.

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The altered core film results in a less dense and slower seismic speed layer at the core's apex, aligning with seismic wave observations. This revelation challenges preconceived notions and deepens our comprehension of Earth's internal dynamics.

The study's findings suggest a more intricate global water cycle than previously envisioned. The potential repercussions of the altered core film on the deep water cycle highlight the interconnected nature of Earth's internal processes.

(With inputs from agencies)