Magmatic Sulfide Deposit Formation and Geochemistry

Magmatic sulfide deposits arise when sulphur‐rich melts separate from silicate magmas and accumulate dense, metal‐bearing sulphide liquids within the crust or mantle. Sulphide saturation may be triggered by magma cooling, oxidation changes, or addition of external sulphur, leading to segregation of an immiscible sulphide phase. Chalcophile elements—chiefly nickel, copper and platinum‐group elements (PGE)—concentrate in the sulphide melt according to element‐specific partition coefficients and the mass ratio of silicate magma to sulphide liquid (the R factor). Physical processes such as droplet coalescence, crystal scavenging and volatile‐driven transport govern the ascent and emplacement of sulphide liquids into conduits, sills or layered intrusions. Crustal contamination, metasomatism of the lithospheric mantle and volatile fluxes (CO₂, H₂O) further modulate the redox state, sulphur source and metal budget of evolving magmas. The interplay of geochemical partitioning and fluid dynamics yields a spectrum of deposit styles—from stratiform layers in large igneous provinces to small high‐grade pods in ultramafic dykes. Understanding these processes is vital for exploration of critical metals and for constraining mantle‐to‐crust metal cycling on both ancient and modern Earth.

Research from Nature Portfolio

Recent studies have revealed the importance of nanoscale and fluid‐mediated mechanisms in metal transfer. High‐resolution imaging of sulphide droplets transported from the subcontinental lithospheric mantle demonstrates that nanometre‐scale immiscible metal‐rich melts can be mechanically scavenged and carried upward by alkaline magmas, challenging classical equilibrium models of metal flux. Experimental work has shown that exsolution of a fluid phase (e.g. supercritical CO₂ or H₂O) enhances droplet coalescence and drives sulphide melt accumulation independent of sulphide generation mechanisms, thereby upgrading metal tenors. Investigations of mantle‐derived carbonates interacting with sulphide liquids indicate that buoyant supercritical CO₂ fluids may envelop sulphide droplets, promoting their ascent across the mantle–crust transition with minimal metal loss. These findings collectively highlight a trans‐lithospheric continuum in which volatile-rich phases and mechanical transport of nanomelts are key controls on global metal fertilisation of the crust.

Magmatic Sulfide Deposit Formation and Geochemistry publication trend

The graph below shows the total number of articles in magmatic sulfide deposit formation and geochemistry across all publications each year (not limited to Nature Index journals).

Technical terms

Sulfide melt: A molten phase rich in sulfur and chalcophile metals that separates from silicate magma.

Immiscibility: The inability of two liquids, such as sulfide and silicate melts, to mix into a single homogeneous phase.

R factor: Ratio of silicate magma mass to segregated sulfide melt mass, influencing the degree of metal enrichment.

Chalcophile elements: Elements with an affinity for sulfur, including nickel, copper and platinum‐group elements.

Metasomatism: Chemical alteration of mantle or crustal rocks by fluid or melt infiltration.

Supercritical CO₂: A fluid state of carbon dioxide at high pressure and temperature, with properties intermediate between gas and liquid.

References

1. Mantle-to-crust metal transfer by nanomelts. Communications Earth & Environment (2023).
2. The critical role of magma degassing in sulphide melt mobility and metal enrichment. Nature Communications (2022).
3. Fluxing of mantle carbon as a physical agent for metallogenic fertilization of the crust. Nature Communications (2020).
4. Incorporation of palladium into pyrite: Insights from X-ray absorption spectroscopy analysis and modelling. The Science of The Total Environment (2024).
5. The Roles of Various Types of Crustal Contamination in the Genesis of the Jinchuan Magmatic Ni-Cu-PGE Deposit: New Mineralogical and C-S-Sr-Nd Isotope Constraints. Economic Geology (2023).
6. Caught in the moment: interaction of immiscible carbonate and sulfide liquids in mafic silicate magma—insights from the Rudniy intrusion (NW Mongolia). Mineralium Deposita (2023).