Magnetic Properties of Marine Sediments

Marine sediments contain a record of magnetic minerals derived from detrital input, authigenic precipitation and biogenic production. Magnetic phases such as magnetite, greigite and iron oxides accumulate on the seabed through riverine supply, hydrothermal fluxes and microbial activity. Their concentration, grain size and magnetic domain state are shaped by sedimentation rate, redox conditions and early diagenesis. Measurements of magnetic susceptibility, remanent magnetisation and hysteresis properties offer insights into sediment provenance, palaeoceanographic currents, bottom-water oxygenation and geomagnetic field variations. Biogenic magnetite produced by magnetotactic bacteria leaves diagnostic magnetofossil signatures that reflect past nutrient availability and oxygen levels. Transformations during burial can overprint primary magnetic signals, requiring careful discrimination between detrital, authigenic and diagenetic carriers. Advances in high-resolution environmental magnetism, micromagnetic imaging and numerical modelling have refined interpretations of complex magnetic assemblages. Globally, magnetic studies of marine sediments underpin reconstructions of climate transitions, carbon cycling and ocean circulation, with applications spanning resource exploration, environmental monitoring and climate modelling.

Research from Nature Portfolio

Recent studies have reconstructed glacial–interglacial variations in ocean oxygenation by analysing redox-sensitive magnetofossils from Indian Ocean sediment cores. Observations of coeval magnetic hardening, increased elongation of magnetite crystals and elevated magnetofossil concentrations across multiple isotope stages over the past 900 ka provide robust evidence for repeated deoxygenation events and enhanced glacial carbon storage. In parallel, a high-resolution multiscale magnetic approach to Palaeocene–Eocene Thermal Maximum sediments has revealed transient microbial blooms and a gradual decline in bottom-water oxygenation, establishing magnetofossils as reliable indicators of rapid environmental perturbations and nutrient dynamics.

Magnetic Properties of Marine Sediments publication trend

The graph below shows the total number of articles in magnetic properties of marine sediments across all publications each year (not limited to Nature Index journals).

Technical terms

Magnetofossil: A biogenic magnetic particle, typically magnetite, produced by magnetotactic bacteria and preserved in sedimentary records.

Magnetic susceptibility: A measure of how much a material becomes magnetised when subjected to an external magnetic field.

Magnetic remanence: The residual magnetisation retained in a material after removal of an applied magnetic field.

First-order reversal curve (FORC): A family of partial hysteresis loops used to characterise magnetic domain-state distributions in complex assemblages.

Pseudo-single-domain (PSD): A magnetic grain state exhibiting intermediate behaviour between single-domain and multidomain structures, often dominating bulk sediment magnetism.

References

1. Indian Ocean glacial deoxygenation and respired carbon accumulation during mid-late Quaternary ice ages. Nature Communications (2023).
2. Coupled microbial bloom and oxygenation decline recorded by magnetofossils during the Palaeocene–Eocene Thermal Maximum. Nature Communications (2018).
3. Magnetic unmixing of first‐order reversal curve diagrams using principal component analysis. Geochemistry Geophysics Geosystems (2015).
4. Primordial magnetotaxis in putative giant paleoproterozoic magnetofossils. Proceedings of the National Academy of Sciences of the United States of America (2024).