Author: <span>Fabio Crameri</span>

Schematic tectonic reconstruction of the Anatolia SZI event (modified from van Hinsbergen et al., 2019a,b). Shown are the new subduction zone (pink line), other active subduction zones (solid purple lines), and transform faults (red dashed lines).

Anatolia subduction zone initiation

The Anatolia subduction zone (or ‘Anatolian Neotethys’) started at around 104 Ma as a consequence of fracture zone inversion.

Oman subduction zone initiation

The Oman subduction zone, together with the Anatolian subduction zone, started at around 104 Ma as a consequence of fracture zone inversion.

Schematic tectonic reconstruction of the New Hebrides-New Britain SZI event (modified from Schellart et al., 2006 and Holm et al., 2016). The collision of the Ontong Java plateau with the trench of the Melanesian subduction zone is suggested to have caused a flip in subduction polarity, initiating the New Hebrides-New Britain subduction zone. Shown are the new subduction zone (pink line) and other active (solid purple lines) and inactive (dashed purple lines) subduction zones.

New Hebrides-New Britain subduction zone initiation

The New Hebrides-New Britain (NHNB) SZI event evolved into the New Hebrides, San Cristobal, and New Britain trenches by subduction polarity reversal at around 10 Ma.

Schematic tectonic reconstruction of the Lesser Antilles SZI event (modified from van Benthem et al., 2013 and Boschman et al., 2014). Subduction of the North and South America plates beneath the Caribbean plate was probably already active earlier on. At 58-39 Ma, subduction jumped eastwards, creating the new Lesser Antilles SZ. Shown are the new subduction zone (pink line), other active (solid purple lines) and inactive (dashed purple lines) subduction zones, and transform faults (red dashed lines).

Lesser Antilles subduction zone initiation

The Lesser Antilles SZI event that formed the present-day Lesser Antilles subduction zone likely occurred between 59–38 Ma and might be an episodic event.

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).

Izu-Bonin-Mariana subduction zone initiation

The onset of the Izu-Bonin-Mariana (IBM) subduction zone likely occurred at around 52 Ma likely along a pre-existing fracture zone after a plate reorganisation.