Deep Earth’s icy silica-rich slabs reach the core-mantle boundary

AI Insight

This study uses the phase boundary of seifertite, a high-pressure form of silica (SiO2), to trace the descent of cold oceanic slabs through Earth's mantle to the core-mantle boundary (CMB). The researchers demonstrate that seifertite's formation conditions serve as a thermal marker, revealing that some subducted slabs retain significantly lower temperatures than surrounding mantle material even after sinking approximately 2,900 kilometers to the CMB. This provides direct evidence that cold, silica-rich crustal material from Earth's surface can reach the deepest parts of the mantle while maintaining distinct thermal and chemical signatures.

Why it matters

These findings improve our understanding of Earth's deep carbon cycle, heat distribution, and chemical circulation between the surface and core. The ability to track cold slabs to the CMB has implications for understanding mantle convection patterns, the long-term evolution of Earth's interior, and potentially the dynamics that drive plate tectonics and volcanic activity.