Category: Izu-Bonin-Mariana

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Izu-Bonin-Mariana SZI Events

Izu-Bonin-Mariana subduction zone initiation

Schematic tectonic reconstruction of the Izu-Bonin-Mariana SZI event (modified from Lallemand, 2016). A plate reorganisation, possibly due to the arrival of the Izanagi ridge at the trench, is suggested to trigger SZI along a pre-existing transform fault in the south, initiating the Izu-Bonin-Mariana subduction zone. The orange circle shows the location of the Oki-Daito plume. Shown are the new subduction zone (pink line), other active (solid purple lines) and inactive (dashed purple lines) subduction zones, spreading ridges (solid red lines), and transform faults (red dashed lines).
Schematic tectonic reconstruction of the Izu-Bonin-Mariana SZI event (modified from Lallemand, 2016). A plate reorganisation, possibly due to the arrival of the Izanagi ridge at the trench, is suggested to trigger SZI along a pre-existing transform fault in the south, initiating the Izu-Bonin-Mariana subduction zone. The orange circle shows the location of the Oki-Daito plume. Shown are the new subduction zone (pink line), other active (solid purple lines) and inactive (dashed purple lines) subduction zones, spreading ridges (solid red lines), and transform faults (red dashed lines).

The Izu-Bonin-Mariana subduction zone began around 52 Ma with the Pacific plate subducting beneath the Proto-Philippine Sea plate, leading to Early basalt eruptions. Geologic evidence suggests simultaneous subduction initiation along the trench, marked by subsequent boninite eruptions and tholeiitic lavas, supporting a complex tectonic history.