Western Neotethys subduction system
New destructive boundary
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).
The Anatolia subduction zone (also referred to as ‘Anatolian Neotethys’ or ‘southern strand of the Neotethys’) started at around 104 Ma. It initiated within the oceanic lithosphere of the Neotethys and, together with the Oman SZI event, represents the western Neotethyan subduction system. SZI has been proposed to be the consequence of fracture zone inversion (van Hinsbergen et al., 2019a, Maffione et al., 2017), though this remains a matter of debate (Agard et al., 2007; van Hinsbergen et al., 2019a).
At the time of SZI, both downgoing and overriding plates were oceanic lithosphere of the Neotethys, the overriding oceanic lithosphere has also been termed ‘Anadolu plate’ (Gürer et al., 2016). The final stages of subduction of the downgoing plate saw the arrival and accretion of continental lithosphere (the Africa-Arabia plate), including several microcontinents of ‘Greater Adria’ (Gaina et al., 2015; van Hinsbergen et al., 2019b).
Presently, the only remnant of this subduction system is represented by the Cyprus trench (Biryol et al., 2011; Portner et al., 2018). The collision along strike of the paleo-trench resulted in widespread ophiolite obduction. The timing of subduction initiation at ~104 Ma (based on Lu-Hf) is inferred from prograde garnet growth in metamorphic soles underlying Anatolian ophiolites (Pourteau et al., 2018; Peters et al., 2018). The time lag between pro-grade metamorphism and the crystallisation of supra-subduction forearc crust, based on zircon U-Pb ages (94-90 Ma; e.g. van Hinsbergen et al., 2016, and references therein), argue for a horizontally forced SZI event contemporaneous and in the northwestward continuation of Oman (Guilmette et al., 2018; van Hinsbergen et al., 2019a). The oldest arc age from the Uckapılı granite in the Central Anatolian Crystalline Complex (or Kirsehir arc) is ~91 Ma (Whitney et al. 2003; Lefebvre et al., 2013).
The model of Müller et al. (2016) does not implement this SZI event; the northern margin of ‘Greater Adria’ in this model is passive at ~104 Ma, lying in the middle of the ‘Dinaride plate’, which was subducting to the north beneath Eurasia at this time. The northern margin of ‘Greater Adria’ remained passive until ~80 Ma, when north-dipping subduction locally appeared to the south of the Kirsehir Block (between the Kirsehir Block and the Menderes-Taurides Block), and elsewhere the margin remained passive until its arrival to the southern active margin of Eurasia.
In the Atlas of the Underworld (van der Meer et al. 2018), Anatolian subduction is related to both the Antalya and Cyprus slabs (which are difficult to tomographically distinguish from each other). In the vote maps, a slab is identified between 250 – 1550 km depth.
Seismic tomography VoteMap (Shephard et al., 2017) analysis of the Anatolia SZI event.
This SZI event is not implemented in the model of Müller et al. (2016).
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