Oxygen Isotope Geochemistry in Terrestrial Systems

Oxygen isotope geochemistry examines the natural abundance variations of stable oxygen isotopes—principally 16O, 17O and 18O—in minerals, rocks and fluids across Earth’s crust, lithospheric mantle and surface environments. Fractionation of these isotopes occurs during equilibrium exchange and kinetic processes such as crystallisation, fluid–rock interaction, diffusion and evaporation. The δ18O values of terrestrial materials record the imprint of past temperatures, fluid sources and crustal evolution, underpinning applications in palaeoclimate reconstruction, water-cycle modelling and geothermometry. The Δ′17O parameter offers an additional tracer of mass-independent fractionation driven by atmospheric or photochemical reactions. Combined oxygen isotope ratios have illuminated the dynamics of weathering, erosion and subduction-driven crust–mantle recycling, as well as signatures of magmatic-hydrothermal systems. Advances in high-precision mass spectrometry and robust calibration protocols have refined our ability to interpret δ-values within a global context, linking surface processes to mantle exchange over geological time.

Research from Nature Portfolio

Recent work has documented a subtle but significant decrease in δ18O of shallow continental lithospheric mantle olivine and bulk peridotite since the Archean, attributed to the onset and intensification of plate tectonics and subduction. By establishing baseline mantle δ18O values—approximately 5.37‰ for olivine and 5.57‰ for peridotite—this research quantifies the progressive heterogeneity introduced by recycled surface materials. It demonstrates how even minor shifts in the vast lithospheric mantle reservoir can influence continental crust δ18O through fluid-mediated sediment accretion at convergent margins and low-δ18O mantle inputs in subduction zones, offering a quantitative framework for long-term crust–mantle oxygen exchange.

Oxygen Isotope Geochemistry in Terrestrial Systems publication trend

The graph below shows the total number of articles in oxygen isotope geochemistry in terrestrial systems across all publications each year (not limited to Nature Index journals).

Technical terms

δ18O: Per mil deviation of a sample’s 18O/16O ratio relative to a standard, indicating isotopic enrichment or depletion in natural materials.

Δ′17O: Deviation of a sample’s 17O/16O ratio from a defined mass-dependent fractionation line, reflecting mass-independent isotopic processes.

Fractionation factor: Equilibrium coefficient describing isotopic separation between two phases or substances under given conditions.

VSMOW-SLAP scale: Dual-point calibration framework based on Vienna Standard Mean Ocean Water and Standard Light Antarctic Precipitation for normalising δ-values across laboratories.

References

1. Oxygen isotope (δ18O, Δ′17O) insights into continental mantle evolution since the Archean. Nature Communications (2022).
2. An Internally-Consistent Database for Oxygen Isotope Fractionation Between Minerals. Journal of Petrology (2019).
3. Seawater-oceanic crust interaction constrained by triple oxygen and hydrogen isotopes in rocks from the Saglek-Hebron complex, NE Canada: Implications for moderately low-δ18O Eoarchean Ocean. Chemical Geology (2024).