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 onset of the presently active Izu-Bonin-Mariana (IBM) subduction zone likely occurred at around 52 Ma with the subduction of the Pacific plate under the Proto-Philippine Sea plate, which was mostly formed of arc terranes at the time of subduction initiation (e.g., Ishizuka et al., 2018). The age of this SZI event is mostly based on the age of the oldest Early basalts (e.g., Reagan et al., 2019), which are considered to be the first magmatic product of SZI and to erupt very soon after the onset of subduction.
The most common view is that subduction initiated along a pre-existing fracture zone after a plate reorganisation due to the subduction of the Izanagi-Pacific ridge beneath Asia at around 60–55 Ma (O’Connor et al., 2013; Lallemand, 2016) or the collision of the Olutorsky arc (Domeier et al., 2017). Regardless of the cause, these stress changes might have caused compression across a transform fault (or a pre-existing fracture zone) and locally initiated subduction (Hall et al., 2003). Additionally, ocean-island basalt (OIB) magmatism in the West Philippine basin indicates the presence of a mantle plume (the Oki-Daito plume) that started its activity almost at the same time as the IBM SZI (Ishizuka et al., 2013).
For more details on the geologic record, corresponding plate reconstruction, and seismic tomography, see the SZI Database.
- Creators: Fabio Crameri, Valentina Magni, Matthew Domeier, Ágnes Király, Grace Shephard
- This version: 17.06.2025
- License: Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
- Specific citation: These graphics from Crameri et al. (2020) are available via the open-access s-ink.org repository.
- Related reference: Crameri, F., V. Magni, M. Domeier, G.E. Shephard, K. Chotalia, G. Cooper, C. Eakin, A.G. Grima, D. Gürer, A. Király, E. Mulyukova, K. Peters, B. Robert, and M. Thielmann (2020), A transdisciplinary and community-driven database to unravel subduction zone initiation, Nature Communications, 11, 3750. doi:10.1038/s41467-020-17522-9
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