Cold SiO2-rich slabs reaching the CMB revealed by the seifertite phase boundary
A cold silica (SiO2)-rich subducted slab creates notable heterogeneity above the core-mantle boundary (CMB), influencing the evolution of the Earth’s mantle. This slab may exhibit characteristic anomalies in the longitudinal and shear wave seismic velocity above the CMB, attributed to the SiO2 phase transition into its dense polymorph, seifertite. However, the transition depth remains unclear due to the often-observed metastable phases in experiments. To address this long-sta
Scientists have discovered evidence suggesting that cold, silica-rich slabs are reaching the Earth's core-mantle boundary. Using advanced experimental techniques and theoretical calculations, researchers determined the phase boundary for seifertite, a dense form of silica. Their findings indicate that the slope of this boundary is less steep than previously thought, allowing a cold slab to cross it twice as it descends.
This discovery helps explain observed seismic anomalies near the Earth's core and provides crucial insights into the dynamics and evolution of our planet's deep interior.
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