Mantle-Source Geochemistry of Oceanic Basalts

Oceanic basalts, including mid-ocean ridge basalts (MORB) and ocean island basalts (OIB), provide fundamental insights into the chemical and physical state of Earth’s mantle. Their major, trace-element and isotopic compositions record the depth and degree of partial melting, the extent of mantle heterogeneity and the influence of recycled crustal components. MORB typically reflect decompression melting of a depleted upper mantle beneath spreading centres, whereas OIB derive from plume-fed sources that sample deeper or more enriched domains. Studies of these lavas inform on global geodynamics, crustal growth rates, deep carbon cycling and the evolution of the lithosphere–asthenosphere system.

Research from Nature Portfolio

Recent studies have shown that Hawaiian tholeiitic basalts derive from primary picritic magmas that undergo a two-stage evolution before olivine fractionation. First, clinopyroxene and garnet crystallise at the base of the lithosphere, modifying the major- and rare‐earth-element signatures. Second, ascent through lithospheric harzburgite leads to re-equilibration that further depletes certain elements. This refined model reconciles discrepancies between experimental peridotite melts and observed basalt compositions, emphasises the role of lithospheric overprinting on plume-related magmas and advances our understanding of OIB generation.

Mantle-Source Geochemistry of Oceanic Basalts publication trend

The graph below shows the total number of articles in mantle-source geochemistry of oceanic basalts across all publications each year (not limited to Nature Index journals).

Technical terms

Partial melting: The process by which only a fraction of a solid mantle mineral assemblage melts to produce basaltic magma.

Peridotite: A dense ultramafic rock composed mainly of olivine and pyroxenes, representing the dominant mantle lithology.

Pyroxenite: A mantle lithology rich in pyroxene minerals, often formed by melt metasomatism and contributing distinct geochemical signatures.

Carbonated melt: A fluid or melt in the mantle enriched in CO₂ that lowers the solidus temperature and fluxes melting.

Melt inclusion: A tiny pocket of melt trapped within a growing crystal that preserves the composition of primitive magma.

Mid-Ocean Ridge Basalt (MORB): Basaltic magma produced by decompression melting at spreading centres, typically depleted in incompatible elements.

Ocean Island Basalt (OIB): Basalt erupted at intraplate ocean islands, often enriched in incompatible elements and indicating heterogeneous deep mantle sources.

Isotopic ratio: The proportion of isotopes of elements such as Sr, Nd, Pb and Hf used to trace source reservoirs and melting processes.

References

1. Genesis of Hawaiian lavas by crystallization of picritic magma in the deep mantle. Nature Communications (2023).
2. Geochemistry of Olivine Melt Inclusion Reveals Interactions Between Deeply Derived Carbonated Melts From the Big Mantle Wedge and Pyroxenite in the Lithospheric Mantle Beneath Eastern Asia. Geophysical Research Letters (2024).
3. Hainan mantle plume produced late Cenozoic basaltic rocks in Thailand, Southeast Asia. Scientific Reports (2018).