Tag: Subduction polarity reversal

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SZI Events Tonga-Kermadec

Tonga-Kermadec subduction zone initiation

Schematic tectonic reconstruction of the Tonga-Kermadec SZI event (modified from Whattam et al., 2008). The collision of the Papua New Guinea continental block with the Loyalty-Three Kings trench is suggested to have caused a flip in subduction polarity, initiating the new Tonga-Kermadec subduction zone, possibly exploiting a weakness due to the presence of an old 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).
Schematic tectonic reconstruction of the Tonga-Kermadec SZI event (modified from Whattam et al., 2008). The collision of the Papua New Guinea continental block with the Loyalty-Three Kings trench is suggested to have caused a flip in subduction polarity, initiating the new Tonga-Kermadec subduction zone, possibly exploiting a weakness due to the presence of an old 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).

The Tonga-Kermadec subduction zone’s initiation is a debated topic, with suggestions ranging from 30 to 100 Ma. Collision events, back-arc magmatism, and tectonic models contribute to understanding this geological phenomenon. Seismic data indicate a deep slab anomaly, reflecting complex geological processes in the region over millions of years.

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Sunda-Java SZI Events

Sunda-Java subduction zone initiation

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).
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).

The Sunda-Java SZI event likely re-initiated subduction at Sundaland’s southern margin between 60–40 Ma. The evolving subduction zone’s history includes earlier accretion of the Woyla arc, a hiatus in subduction, and evidence from seismic tomography suggesting the current slab’s depth aligns with historical models, indicating significant tectonic interactions over time.

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South Sandwich SZI Events

South Sandwich subduction zone initiation

Schematic tectonic reconstruction of the South Sandwich SZI event (modified from Dalziel et al., 2013b). The arrival of the Chile ridge at the South America trench might have triggered a flip in subduction polarity, but the South Sandwich subduction zone is suggested to have initiated as a newly destructive boundary. Shown are the new subduction zone (pink line), other active subduction zones (solid purple lines), spreading ridges (solid red lines), and transform faults (red dashed lines).
Schematic tectonic reconstruction of the South Sandwich SZI event (modified from Dalziel et al., 2013b). The arrival of the Chile ridge at the South America trench might have triggered a flip in subduction polarity, but the South Sandwich subduction zone is suggested to have initiated as a newly destructive boundary. Shown are the new subduction zone (pink line), other active subduction zones (solid purple lines), spreading ridges (solid red lines), and transform faults (red dashed lines).

The South Sandwich subduction zone (SZI) marks the westward subduction of the South American plate beneath the Scotia plate, estimated to have started between 39 and 29 Ma. Debates regarding its age and implications highlight tectonic interactions and magmatic activities, driven by geologic evidence and seismic models, revealing complex plate dynamics.

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Ryukyu SZI Events

Ryukyu subduction zone initiation

Schematic tectonic reconstruction of the Ryukyu SZI event (modified from Faccenna et al., 2018). A slab break-off event caused a pause in arc activity. Subduction of the Philippine Sea plate started again along the same margin, initiating the new Ryukyu 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).
Schematic tectonic reconstruction of the Ryukyu SZI event (modified from Faccenna et al., 2018). A slab break-off event caused a pause in arc activity. Subduction of the Philippine Sea plate started again along the same margin, initiating the new Ryukyu 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).

The Ryukyu SZI event marks the reinitiation of subduction of the Philippine Sea plate beneath the Eurasian plate, evidenced by two distinct SZI events. The older event lacks significant geological evidence, while the younger event, occurring around 6 Ma, has associated volcanic activity. Current plate models do not include this SZI event.

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Philippine SZI Events

Philippine subduction zone initiation

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.
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.

The Philippine subduction zone began around 9 million years ago after the Palawan block collided with the Philippine Mobile Belt, triggering a polarity flip in subduction. This region features ongoing volcanic activity, with evidence of younger magmatism and significant seismic activity, indicating a dynamic geological history influenced by complex tectonic processes.

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Oman SZI Events

Oman subduction zone initiation

Schematic tectonic reconstruction of the Oman 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).
Schematic tectonic reconstruction of the Oman 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).

The Oman subduction zone, part of the Western Neotethyan subduction system, originated around 104 Ma, likely along a fracture zone. Its formation involved the subduction of the ‘Anadolu plate’ beneath the Africa-Arabia continental plate, resulting in significant geological features like the Semail ophiolite by 70 Ma.

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New Hebrides-New Britain SZI Events

New Hebrides-New Britain subduction zone initiation

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.
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.

The New Hebrides – New Britain subduction zone (NHNB SZI) formed from a polarity reversal of subduction around 10 million years ago, impacting volcanic activity. Geological evidence shows a cyclical pattern of arc volcanism, with evidence of the North Fiji basin opening dating back to 12-8 million years. Seismic data confirm significant slab structures today.

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Lesser Antilles SZI Events

Lesser Antilles subduction zone initiation

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 subduction zone. 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).
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 subduction zone. 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).

The Lesser Antilles SZI event, occurring between 59–38 Ma, marks the transition from the Greater Caribbean Arc to the Lesser Antilles subduction zone, with debates on whether it was episodic or continuous. Geological evidence includes varying volcanic rock ages and the formation of the Barbados Accretionary Prism, indicating complex tectonic interactions.

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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.

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Halmahera SZI Events

Halmahera (East Molucca) subduction zone initiation

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).

The Halmahera subduction zone initiation (SZI) was previously dated at 17-15 Ma but is now suggested to be around 10-7 Ma based on recent evidence. This event is linked to the subduction of the Molucca Sea plate beneath the Philippine Sea plate. Geological findings indicate a complex history of volcanic activity related to both recent and older subduction processes.

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Aleutian SZI Events

Aleutian subduction zone initiation

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).
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).

The Aleutian subduction zone initiation event, starting around 53 Ma as a subduction, marked the formation of the Aleutian trench as the Pacific and Kula plates began subducting. This event possibly involved a subduction polarity reversal linked to the Olutorsky arc’s arrival, influencing regional tectonic activity and magma production along northeastern Asia and northwestern North America.