Miocene Aegean T-A-BA system

As argued earlier, another effect of the extrusion of the Tethyan, in front of the Arabian indenter, was the westward displacement and southward bending of the Aegean arc (Figures 2b and 2c). Due to this deformation, the Aegean massifs (Cyclades) and the Hellenides belt separated from the Balkanides, causing extensional deformation in the north Aegean and northwestern Anatolian regions (Figures 2b and 2c), as indicated by geological and volcanological evidence (Fitykas et al., 1985; Sengor et al., 1985; Mercier et al., 1989; Jolivet et al. 1994; Seyitoglu and Scott, 1996), which suggests a progressive south to SWward migration of extension. The southward bowing of the Aegean arc and the consequent consumption of the Ionian-Levantine lithosphere, is testified by the Miocenic accretionary activity recorded along the Hellenic trench zone (e.g; Finetti, 1976; Le Pichon and Angelier, 1979; Le Pichon et al., 1988; Mercier et al., 1989).

The westernmost edge (and hinge zone) of the Aegean arc roughly corresponded to the Albanides, i.e. the transition zone between the Dinaric sector of the belt, where the Adriatic plate was already sutured to the Tethyan system, and the Hellenic sector, where the consumption of the last part of the pre-Apulian zone was still going on (e.g., Mercier et al., 1989). This interpretation is suggested by geological, morphological and paleomagnetic data (Kissel et al., 1995) which indicate a clockwise rotation of the Albanides-Western Greece zone with respect to the Dinarides, since the lower-middle Miocene.

Some authors (e.g., Le Pichon and Angelier, 1979; Jolivet et al., 1994; Le Pichon et al., 1995) argued that the occurrence of extensional strain in the Aegean region during the lower-middle Miocene demonstrates that the tectonic evolution of this region cannot be taken as an effect of the westward escape of Anatolia, since at that time the western segment of the North Anatolian fault (NAF) was not formed yet. However, we think that this argument could be uncorrect since the kinematic reconstruction reported in Figure 2 shows that even the Miocenic extension in the Aegean zone may causally be linked with the lateral escape of Anatolia (and of the Tethyan belt). In fact, during this phase the westward motion of Anatolia did not require any decoupling from the northern domain (Pontides), since this last chain was participating the migration of the whole Tethyan belt. The activation of the western NAF, as right-lateral guide of the westward escape of Anatolia, became instead unavoidable around the late Miocene, when the mobility of the Pontides decreased considerably after the continental collision of the Carpathian arc with Eurasia (Sengor, 1993).