Seminar: Experimental Exploration of the Core-Mantle Boundary Region: Insights into the Dynamics and Mineralogy of the Lowermost Mantle
Abstract
The core-mantle boundary (CMB) constitutes the most prominent thermal and density interface within the Earth’s interior. As a critical gateway for heat transfer from the core, it serves as a key region that fundamentally governs deep Earth dynamics. The D » layer, situated immediately above the CMB, exhibits a suite of enigmatic seismic features that remain inadequately explained, including the D » seismic discontinuity, Large Low-Shear-Velocity Provinces (LLSVPs), shear wave polarization anisotropy, and Ultra-Low Velocity Zones (ULVZs). To elucidate the physical origins of these seismological anomalies, we have conducted high-pressure experimental investigations into the elastic wave velocities of mantle minerals, enabling a direct comparison between laboratory data and seismic observations.
In this presentation, I will discuss the dynamics and chemical heterogeneity of the lowermost mantle based on our recent experimental breakthroughs in determining the elasticity of the textured-post-perovskite phase (Murakami et al. 2025*) and SiO2 high-pressure polymorphs (Krymarys et al. 2025**) under megabar pressure conditions. Our results provide new constraints on the mineralogical interpretation of seismic structures and offer insights into the complex thermochemical evolution of the Earth’s deepest mantle.