Geologists have announced the discovery of silicon “snow” at the boundary of the core and mantle
Between the earth’s core and the mantle there may be a zone of silicon “snow”. This was reported by the press service of the University of Arizona.
Deep below the surface of the Earth is the outer core, which consists of a layer of liquid metal alloy 2000 km thick. Even though the outer core is located at a depth of 3000 km from the surface, it affects life on the surface because it is associated with the generation of a magnetic field. Therefore, scientists are interested in how the contact zone between the silicate mantle and the metal core is arranged, including explaining a number of anomalies identified during seismic studies.
American geologists conducted a series of laboratory experiments in which they recreated the conditions at this boundary. An iron-silicon alloy loaded with impurities of hydrogen and argon was placed between diamond anvils. With their help, the material was compressed to pressures typical for a depth of thousands of kilometers (1.23 million atmospheres), and heated with a laser to 3.2 thousand degrees. It turned out that under such conditions, iron-silicon crystals are formed, which gradually settle on the core.
“If there is a sufficient amount of hydrogen and silicon in the outer layers of the Earth’s core, then peculiar particles of silicon “snow” can appear inside it. Our calculations show that such exotic silicon “snows” begin to fall at the boundary between the core and the mantle, and also indicate that they can play a significant role in cooling the Earth’s interior at great depths,” the authors explain.
Scientists believe that the existence of such snow can explain many of the anomalies that slow down the propagation of seismic waves.