Petrogenesis of Subduction-Related Magmas

Subduction-related magmas arise where oceanic lithosphere descends beneath another plate, releasing fluids and heat that trigger melting in the overlying mantle wedge and lower crust. Dehydration of the slab induces flux melting of mantle peridotite, generating basaltic magmas that evolve by fractional crystallisation, assimilation and mixing. In some cases, high-pressure melting of subducted oceanic crust or garnet-bearing lower crust produces adakitic magmas, characterised by high Sr/Y and La/Yb ratios. Variations in slab age, dip angle, convergence rate and sediment input control the depth and degree of melting, and thereby magma chemistry. These magmas feed volcanic arcs, form plutons, and play a key role in continental crust growth, metallogenesis and volatile cycling. Recent advances integrate geophysical imaging, experimental petrology and geochemical modelling to resolve melt generation depth, source heterogeneity and temporal evolution. This synthesis emphasises global diversity—from hot young slabs yielding deep slab melts to cold old slabs promoting mantle-wedge flux melting—and illustrates links between subduction parameters, melt chemistry and resource formation.

Research from Nature Portfolio

A study of Quaternary volcanoes in central Myanmar demonstrates that medium-K basaltic magmas formed by partial melting of a hydrated mantle wedge under normal potential temperatures. Tomographic images indicate asthenospheric upwelling beneath old lithosphere. High-pressure fractional crystallisation of garnet and amphibole in primitive basalt produced mafic adakitic compositions, while mid-crustal assimilation–fractional crystallisation generated felsic adakitic melts. This model circumvents slab melting and emphasises mantle‐wedge dynamics in subduction zones of variable thermal regimes.

Petrogenesis of Subduction-Related Magmas publication trend

The graph below shows the total number of articles in petrogenesis of subduction-related magmas across all publications each year (not limited to Nature Index journals).

Technical terms

Adakite: A silica-rich magma with high Sr/Y and La/Yb ratios, often ascribed to melting of subducted basaltic crust or garnet-bearing lower crust.

Fractional crystallisation: Differentiation process in which early-forming minerals are removed from a melt, altering its composition.

Slab melting: Partial melting of the subducted oceanic plate, generating magmas with distinctive trace-element signatures.

Metasomatism: Chemical alteration of mantle peridotite by fluids or melts derived from the subducting slab.

Sr/Y ratio: Geochemical proxy indicating garnet presence in the source; elevated values suggest high-pressure melting environments.

References

1. K‐Rich Adakite‐Like Rocks in Central Tibet: Fractional Crystallization of a Hydrous, Alkaline Primitive Melt. Geophysical Research Letters (2023).
2. Adakites, High-Nb Basalts and Copper–Gold Deposits in Magmatic Arcs and Collisional Orogens: An Overview. Geosciences (2022).
3. Petrogenesis of isotopically enriched Quaternary magma with adakitic affinity associated with subduction of old lithosphere beneath central Myanmar. Scientific Reports (2022).
4. Permian–Triassic adakitic igneous activity at Northern Mongolia: Implication for Permian–Triassic subduction system at the Siberian continental margin. Journal of Geodynamics (2022).