Geochemistry of Mantle Xenoliths and Siderophile Elements

The geochemical study of mantle xenoliths and the behaviour of siderophile elements provides unique insights into the composition, evolution and dynamics of the Earth’s lithospheric and asthenospheric mantle. Mantle xenoliths, fragments of deep peridotitic and pyroxenitic lithologies entrained in volcanic host rocks, preserve records of melt depletion, metasomatism and melt–rock interaction. Siderophile elements—iron-loving trace metals including the platinum-group elements (PGEs) and gold-group elements—partition strongly into metallic and sulphide phases, making them sensitive tracers of mantle melting, sulphide stability and redox conditions. Analysis of isotopic ratios, trace-element abundances and mineral hosts in xenolithic peridotites and associated sulphides reveals patterns of mantle depletion and enrichment, the role of fluids in metasomatic overprinting, and the provenance of recycled lithospheric domains. These findings inform global mass-exchange processes, the fate of subducted materials and the metallogenic fertility of the continental lithosphere, with implications for resource exploration and models of mantle convection.

Research from Nature Portfolio

One study of peridotites sampled near mid-ocean ridges has employed high-precision hafnium and neodymium isotope measurements to trace ancient melt-depletion events in mantle fragments beneath Iceland. These data reveal heterogeneously depleted domains, some aged by billion-year histories of melting, that contribute density-driven pulses to mantle plumes and influence ridge morphology and basalt chemistry. Insights into the thermochemical buoyancy of plume material challenge conventional plume temperature models by emphasising compositional controls on upwelling processes.

Another investigation reports supra-subduction-zone peridotite fragments recovered from the Mid-Atlantic Ridge that bear geochemical signatures of hydrous flux melting. Clinopyroxene retention at high melt fractions and trace-element patterns inconsistent with dry melting demonstrate entrainment of refractory arc mantle in the convecting upper mantle. Estimates suggest such buoyant, hydrous domains may constitute a majority of the upper mantle by volume, yet remain under-represented in basalt-derived compositional models.

Geochemistry of Mantle Xenoliths and Siderophile Elements publication trend

The graph below shows the total number of articles in geochemistry of mantle xenoliths and siderophile elements across all publications each year (not limited to Nature Index journals).

Technical terms

Mantle xenolith: A fragment of mantle rock (typically peridotite) carried to the surface by volcanic eruptions, preserving deep-seated chemical signatures.

Siderophile element: A metal that preferentially partitions into metallic or sulphide phases, used to trace core–mantle differentiation and mantle processes.

Platinum-group elements (PGEs): A subset of highly siderophile elements including Pt, Pd, Rh, Ru, Ir and Os, notable for their strong affinity for sulphides and alloys.

Metasomatism: Chemical modification of a rock by percolating fluids or melts, resulting in the addition or removal of elements and formation of new minerals.

Serpentinization: The hydration of ultramafic minerals (e.g. olivine, pyroxene) to form serpentine minerals, often affecting the distribution of siderophile elements.

Hydrous flux melting: Partial melting of mantle peridotite induced by addition of water-rich fluids, lowering the solidus and altering melt compositions.

References

1. Upwelling of melt-depleted mantle under Iceland. Nature Geoscience (2024).
2. The origin of platinum group minerals in oceanic crust. Geology (2023).
3. Recycled arc mantle recovered from the Mid-Atlantic Ridge. Nature Communications (2020).
4. Siderophile and chalcophile elements in spinels, sulphides and native Ni in strongly metasomatised xenoliths from the Bultfontein kimberlite (South Africa). Lithos (2021).