Conceptual illustrations

Conceptual illustrations in science are “freehand” drawings to portray certain concepts qualitatively. Instead of directly representing data, they are visualising the current knowledge.

Subduction zone initiation reconstructions

Subduction zone initiation (SZI) reconstructions for selected events since around 100 Ma. The reconstructed events are based on the whole Earth Sciences community point-of-view of the SZI database.

Schematic tectonic reconstruction of the Halmahera SZI event (modified from Hall, 1996 and Hall and Smyth, 2008). Subduction of the Molucca Sea plate started close to a transform boundary, initiating the new Halmahera subduction zone. Shown are the new subduction zone (pink line), other active subduction zones (solid purple lines), and transform faults (red dashed lines).

Halmahera (East Molucca) subduction zone initiation

The Halmahera SZI event is suggested to have occurred at ~15 Ma, which is still controversial, possibly through episodic subduction.

Schematic tectonic reconstruction of the Aleutian SZI event (modified from Domeier et al., 2017). The collision of the Olutorsky arc with the trench of the south-dipping subduction of the Eurasia plate below the Pacific Plate is suggested to have caused a flip in subduction polarity, initiating the new Aleutian subduction zone. 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).

Aleutian subduction zone initiation

The Aleutian subduction zone initiation event formed today’s Aleutian trench, occurred at around 53 Ma through subduction polarity reversal.

Tonga-Kermadec subduction zone initiation

The Tonga-Kermadec subduction zone initiated likely due to a subduction-polarity reversal at around 50 Ma.

Schematic tectonic reconstruction of the Sunda-Java SZI event (modified from Hall, 2012). Subduction of the Indo-Australian plate at the Sundaland margin has been episodically ongoing since >100 Ma. The most recent episode occurred at ca. 40–60 Ma and it initiated the new Sunda-Java subduction zone. 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).

Sunda-Java subduction zone initiation

The Sunda-Java SZI event might have re-started subduction at the southern margin of Sundaland at around 60–40 Ma.

Schematic tectonic reconstruction of the Philippine SZI event (modified from Hall, 1996 and Wu et al., 2016). The collision of the Palawan continental block with the trench of the east-dipping subduction of the Eurasia plate below the Philippine Sea Plate is suggested to have caused a flip in subduction polarity, initiating the new Philippine subduction zone. Shown are the new subduction zone (pink line) and other active (solid purple lines) and inactive (dashed purple lines) subduction zones.

Philippine subduction zone initiation

The present-day Philippine subduction zone is thought to have started at about 9 Ma via a subduction polarity flip.

Schematic tectonic reconstruction of the Cascadia SZI event (modified from Stern and Dumitru et al., 2019 and Wells et al., 2014). A trench jump occurred due to the accretion of the Siletzia and Yakutat large igneous province (LIP) formed by the Yellowstone plume, initiating the new Cascadia subduction zone. Shown are the new subduction zone (pink line), other active (solid purple lines) and inactive (dashed purple lines) subduction zones, and spreading ridges (solid red lines).

Cascadia subduction zone initiation

The Cascadia subduction zone initiation event formed at around 53–43 Ma likely as an episodic subduction via a trench jump after the large igneous province (LIP) Siletzia accreted.