Lower Mantle Mineralogy and Geophysics

The lower mantle extends from a depth of approximately 660 to 2,900 km beneath Earth’s surface and is composed primarily of silicate perovskite (bridgmanite), ferropericlase and calcium silicate perovskite (davemaoite). Its mineral assemblages and physical properties govern large-scale mantle convection, heat transport and chemical differentiation. Variations in mineral composition, grain size and iron spin and valence states affect density, elasticity and viscosity, thereby shaping seismic heterogeneity and geodynamic processes. Seismological imaging, experimental petrology and theoretical modelling have converged to reveal complex interactions between temperature, pressure and composition, including phase transitions and spin crossovers in ferropericlase and bridgmanite. These phenomena influence slab subduction, plume ascent and the preservation of chemical reservoirs at the core–mantle boundary. Understanding the interplay between mineral physics and geophysics in the lower mantle is essential for constraining Earth’s thermal history, tectonic evolution and the cycling of volatiles and trace elements on a global scale.

Research from Nature Portfolio

Recent studies have shown that heterogeneity in bridgmanite grain size can account for the mid-mantle viscosity jump at 800–1,200 km depth; experiments indicate that bridgmanite-rich domains develop grain sizes an order of magnitude larger than surrounding rocks, yielding viscosities sufficient to impede slab descent and plume ascent. Advances in full-waveform tomography have enabled quantitative three-dimensional mapping of bulk and shear wave speeds, isolating signatures of an iron spin crossover in ferropericlase between 1,000 and 2,500 km depth; this transition reconciles seismic velocities with realistic temperature and composition models and implies silica enrichment nearer the core–mantle boundary. Experimental work under ultrahigh pressure confirms the stability of davemaoite in the lower mantle, demonstrating limited calcium solubility in bridgmanite and predicting persistent davemaoite-enriched domains that may host incompatible elements and contribute to ultralow-velocity provinces above the core–mantle boundary.

Lower Mantle Mineralogy and Geophysics publication trend

The graph below shows the total number of articles in lower mantle mineralogy and geophysics across all publications each year (not limited to Nature Index journals).

Technical terms

Bridgmanite: The silicate perovskite (Mg,Fe)SiO₃, the most abundant mineral phase in the lower mantle.

Ferropericlase: A magnesium–iron oxide (Mg,Fe)O that coexists with bridgmanite and undergoes a spin crossover at depth.

Davemaoite: Calcium silicate perovskite (CaSiO₃), stable under lower-mantle pressures and a potential reservoir for incompatible elements.

Spin crossover: A pressure-driven change in the electronic spin state of iron in minerals, affecting density and elastic properties.

Full-waveform tomography: A seismic imaging method using complete seismic waveforms to reconstruct three-dimensional velocity structures.

Viscosity jump: A sudden increase in mantle viscosity at mid-lower-mantle depths, influencing slab stagnation and plume dynamics.

Core–mantle boundary (CMB): The interface at ~2,900 km depth separating Earth’s molten outer core from the solid lower mantle.

References

1. Variation in bridgmanite grain size accounts for the mid-mantle viscosity jump. Nature (2023).
2. Full-waveform tomography reveals iron spin crossover in Earth’s lower mantle. Nature Communications (2024).
3. Persistence of davemaoite at lower-mantle conditions. Nature Geoscience (2025).
4. Influence of Al, C, N and H on the iron redox state in the Earth’s lower mantle: A geochemical quantum model. Geochimica et Cosmochimica Acta (2025).
5. Radiative thermal conductivity of single-crystal bridgmanite at the core-mantle boundary with implications for thermal evolution of the Earth. Earth and Planetary Science Letters (2022).
6. Stability and Solubility of the FeAlO3 Component in Bridgmanite at Uppermost Lower Mantle Conditions. Journal of Geophysical Research: Solid Earth (2020).