There may be a zone of silicon snow nestled between the Earth’s core and its mantle. This is a topic that has been highlighted by the press office of Arizona State University as researchers explore what lies beneath our feet.
Deep beneath the planet’s surface sits the outer core, a vast 2,000-kilometer-thick layer composed mainly of a liquid metal alloy. Although this layer lies about 3,000 kilometers below the surface, its dynamics shape surface life by driving the planet’s magnetic field. That connection makes the boundary where silicate mantle meets metallic core a focal point for scientists, who seek to explain several seismic mysteries and irregularities observed in deep Earth studies.
To probe this boundary directly, American geologists conducted a set of laboratory experiments that mimic the extreme conditions found at depth. A iron-silicon alloy was placed between diamond anvils and infused with hydrogen and argon impurities. By compressing this material to pressures comparable to those thousands of kilometers beneath Earth and heating it with a laser to around 3,200 degrees, the researchers recreated the high-pressure, high-temperature environment of the deep interior. Under these conditions, iron-silicon crystals formed and gradually settled toward the deeper core.
The researchers explain that if the outer layers of the Earth’s core contain ample hydrogen and silicon, unusual silicon snow particles could materialize inside the planet. Their calculations indicate that such exotic silicon flakes begin to precipitate at the core-mantle boundary and may play a significant role in cooling processes occurring at great depths within the Earth.
Beyond the cooling aspect, the presence of this silicon snow could help account for a number of seismic anomalies. Variations in how seismic waves travel through the planet have puzzled scientists for years, and the introduction of silicon-rich phases at the boundary offers a plausible mechanism for some of these irregularities. In short, the silicon snow at the core-mantle interface might influence both heat transfer and wave propagation, linking deep Earth dynamics to observable surface phenomena.