Mantle Dynamics and Pacific Seamount Volcanism

The dynamics of Earth’s mantle underpin the genesis of seamounts across the Pacific basin. Buoyant upwellings, known as mantle plumes, ascend from deep within the mantle and impinge upon the base of the lithosphere, producing age-progressive volcanic chains. These seamounts record the interplay between plate motion, plume buoyancy flux and lithospheric architecture. In regions of plate flexure, partial melts formed in the asthenosphere can exploit fractures in the overlying lithosphere, giving rise to small “petit-spot” volcanoes in otherwise quiescent oceanic crust. Hydrothermal circulation around these edifices drives mineralisation processes that may influence global geochemical cycles. Plate-mantle interactions also govern the long-term evolution of hotspot tracks, constraining models of absolute plate motion and the wandering of large low shear-velocity provinces in the lowermost mantle. Advances in geophysical imaging, geochemical analysis and numerical modelling have together refined our understanding of how mantle flow, lithospheric thickness and surface topography combine to shape Pacific seamount volcanism and its broader significance for Earth’s thermal and chemical regimes.

Research from Nature Portfolio

Investigations of a petit-spot volcano on old, flexed Pacific crust have revealed low-temperature hydrothermal ferromanganese deposits at depths approaching 6 km. Geochemical and isotopic data indicate interaction between volatile-rich melts and marine sediments, suggesting carbon dioxide-driven partial melting in the asthenosphere and potential implications for the deep carbon cycle.

New age constraints on the Rurutu, Louisville and Hawaiian chains demonstrate that long-lived mantle plumes are not laterally fixed. High-precision geochronology shows rapid southward drift of the Hawaiian plume between 60 and 50 Ma, whereas the Rurutu and Louisville plumes remained relatively stationary. These findings reconcile plume motions with plate reconstructions and seismic tomography of deep mantle structures.

Palaeomagnetic studies of the Hawaiian-Emperor Bend have confirmed that southward motion of the Hawaiian plume, rather than abrupt plate reorganisation alone, produced the distinctive angular change in the seamount chain. Concurrent analysis indicates that large low shear-velocity provinces in the lowermost mantle also display mobility, refining models of deep mantle convection and plume sourcing.

Mantle Dynamics and Pacific Seamount Volcanism publication trend

The graph below shows the total number of articles in mantle dynamics and pacific seamount volcanism across all publications each year (not limited to Nature Index journals).

Technical terms

Mantle plume: A column of hot, buoyant rock rising from the deep mantle that can generate volcanic chains.

Seamount: An underwater mountain of volcanic origin that does not reach the sea surface.

Asthenosphere: The ductile layer of the upper mantle beneath the lithosphere that allows tectonic plates to move.

Lithosphere: The rigid outer shell of the Earth, including the crust and uppermost mantle.

Hotspot track: A linear chain of volcanic edifices formed as a tectonic plate moves over a relatively stationary mantle plume.

LLSVP: A large region in the lowermost mantle with anomalously low seismic shear-wave velocities, implicated in plume generation.

Petit-spot volcano: A small volcanic edifice formed by melt generated in the asthenosphere at sites of plate flexure far from plate boundaries.

References

1. Hydrothermal ferromanganese oxides around a petit-spot volcano on old and cold oceanic crust. Communications Earth & Environment (2023).
2. Petit-spot as definitive evidence for partial melting in the asthenosphere caused by CO2. Nature Communications (2017).
3. On the relative motions of long-lived Pacific mantle plumes. Nature Communications (2018).
4. Hotspot motion caused the Hawaiian-Emperor Bend and LLSVPs are not fixed. Nature Communications (2019).
5. When a Plateau Suppresses a Plume: Disappearance of the Samoan Plume Under the Ontong Java Plateau. AGU Advances (2024).
6. Evaluation of Shipboard and Satellite‐Derived Bathymetry and Gravity Data Over Seamounts in the Northwest Pacific Ocean. Journal of Geophysical Research: Solid Earth (2020).
7. Absolute plate motions relative to deep mantle plumes. Earth and Planetary Science Letters (2018).