A new study has identified the presence of the mineral phase seifertite, a high-pressure form of silicon dioxide (SiO₂), in Earth's lower mantle. This finding, based on molecular dynamics simulations and laboratory experiments, suggests that subducted SiO₂-rich oceanic slabs can penetrate as far as the core-mantle boundary (CMB), a region much deeper than previously thought. Seifertite forms under extreme pressures and temperatures, indicating that these slabs maintain a distinctive composition and structure even at depths of thousands of kilometers.

Traditionally, subducted slabs were thought to stagnate or mix with the surrounding mantle at intermediate depths. However, the persistence of seifertite under these extreme conditions provides key evidence that oceanic crustal material can descend much further. Seifertite is an SiO₂ polymorph that forms at pressures exceeding 120 GPa and temperatures of thousands of Kelvin, conditions found in the deep lower mantle. This discovery is crucial for understanding Earth's mantle dynamics and the geochemical cycle of elements.

The identification of seifertite in these deep slabs has significant implications for models of mantle convection, the transport of water and carbon into Earth's interior, and the planet's thermal evolution. The presence of cold, SiO₂-rich material at the CMB could influence the generation of Earth's magnetic field and surface volcanic activity. Next steps include searching for direct seismic evidence of these seifertite-rich structures and improving geodynamic models to incorporate these new observations on the composition and behavior of subducted slabs in the lower mantle.