Volcanic Geology and Geodynamics of Oceanic Islands

Oceanic islands arise at intraplate and plate-margin settings through mantle upwelling and lithospheric thinning, giving rise to volcanic edifices that evolve over millions of years. Their geological architecture reflects complex interactions between magma supply rate, compositional differentiation and tectonic stresses. Magma generation commonly involves low-degree partial melting of enriched mantle sources, followed by extended fractional crystallisation within shallow reservoirs. Structural deformation includes caldera collapse, flank instability and rifting, which shape island morphology and modulate eruptive behaviour. Dynamically, many islands sit atop mantle plumes or along rift zones, leading to episodic volcanic phases interspersed with tectonically dominated extension. Surface expressions such as parasitic cones, lava flow fields and pyroclastic deposits record shifts in magma composition, eruption style and external triggers. Understanding the geodynamics of oceanic islands is critical for assessing volcanic hazards—flank collapses, landslides and tsunamis—and for reconstructing past environmental changes encoded in lavas and sedimentary records. Moreover, ocean islands serve as natural laboratories for studying crust–mantle interaction, magma chamber evolution and the influence of lithospheric structure on volcanic systems worldwide.

Research from Nature Portfolio

Recent studies have harnessed high-precision geochronology to refine the timing of large-scale flank collapse events, revealing that major edifice failures coincide with shifts in magmatic differentiation and reservoir pressure fluctuations. In one example, single-grain argon–argon dating of pyroclastic deposits has constrained collapse events on an Atlantic island to within a few tens of thousands of years, offering new insights into the coupling of magmatic processes and structural destabilisation. Another investigation along a slow-spreading oceanic plateau has documented alternating phases of magmatic activity and tectonic rifting, identifying distinct basanitic and alkali-basalt units that record episodic volcanic pulses and lithospheric extension. These findings emphasise the interplay between mantle source dynamics, crustal stress regimes and surface evolution in shaping island geology.

Volcanic Geology and Geodynamics of Oceanic Islands publication trend

The graph below shows the total number of articles in volcanic geology and geodynamics of oceanic islands across all publications each year (not limited to Nature Index journals).

Technical terms

Caldera: A large volcanic depression formed by collapse of the summit area following magma chamber evacuation.

Flank collapse: Sudden failure of a volcano’s side, often producing landslides and co-blast deposits.

Rifting: Extension of the crust leading to fault formation and magma ascent along linear zones.

Fractional crystallisation: Progressive removal of early-forming minerals from a magma, altering its composition.

Peralkaline magmatism: Generation of silica-undersaturated felsic melts with high alkali content due to extreme differentiation.

Magma reservoir: A subsurface body of molten rock that supplies volcanic eruptions and evolves compositionally over time.

References

1. Precise dating of large flank collapses by single-grain 40Ar/39Ar on pyroclastic deposits from the example of Flores Island (Azores). Scientific Reports (2024).
2. Rifting of the oceanic Azores Plateau with episodic volcanic activity. Scientific Reports (2020).
3. Spatial distribution, temporal trends and impact of landslides on São Miguel Island from 1900 to 2020 based on an analysis of the Azores historical natural hazards database. Natural Hazards (2023).
4. Peralkaline Felsic Magmatism of the Atlantic Islands. Frontiers in Earth Science (2018).