The geological signature of a slab tear below the Aegean

Abstract

Mediterranean Highlights-Rotation of Hellenides is coeval with granite migration -Migration of granitoids signs a slab tear in the Cyclades -HT domes and a left-lateral gradient of extension also sign the tear AbstractIn this paper we explore the geology of the Aegean region in the Miocene to identify the geological signature of a first-order slab tear observed in all tomographic models. From 15 to 8 Ma, the tear is associated, spatially and timely, with a fast clockwise rotation of the External Hellenides, alkaline volcanism, high-temperature metamorphic domes with a predominance of north-dipping detachments, south-westward migration of granitoids intrusions. These features suggest a warmer geodynamic environment during the rotation and the impact of a hot mantle flow associated with the tear. The ~8 Ma duration between the first hightemperature metamorphic domes in the centre of the archipelago and the beginning of the fast rotation may correspond to the time needed for the slab to bend, stretch and finally tear.

Kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern Mediterranean region since the late Cretaceous

“…In addition, the westward emplacement of syn-tectonic intrusions from the Menderes massif to the Cyclades in the Miocene (figure 11), associated with an increase of the mantle source component of these magmas [Stouraiti et al, 2010;Jolivet et al, 2015], can be correlated with this slab tear. Indeed, as shown by analog and numerical modeling [Funiciello et al, 2003Piromallo et al, 2006;Faccenda and Capitanio, 2012;Sternai et al, 2014], slab tearing-related asthenospheric flow displays a significant toroidal component that could progressively heat the base of the stretched lithosphere inducing partial melting.…”

“…Recently, Jolivet et al [2015] proposed instead a left-lateral transfer zone, accommodated as a gradient of finite extension across a large part of the central Aegean domain.…”

Multiphase boudinage: a case study of amphibolites in marble in the Naxos migmatite core

“…Jolivet et al, 2013;Philippon et al, 2011), or normal faulting in an overall extensional regime (Gautier et al, 1999;Hinsbergen and Schmid, 2012) including vertical axis rotations in the footwall (Malandri et al, 2017). Field evi-dence is controversial, as there seems that there is neither support for a major detachment (Brun et al, 2016;Jolivet et al, 2015;Philippon et al, 2014) nor is strike-slip faulting observed on Paros, where the Mid-Cycladic Lineament might be exposed (Malandri et al, 2017;Walcott and White, 1998a). Additional complexity is added due to interaction of slab roll-back with westward migration of the Anatolian Plate since ∼ 11 Ma Ring et al, 2010).…”

An extensional and transtensional origin of elongated magmatic domes and localised transfer faults in the northern Menderes metamorphic core complex, western Turkey

“…Strike-slip-dominated shear zones bordering the western and eastern margins of the Menderes MCC have been recognised as NE-trending and crustal-scale transfer zones, which lie parallel to the regional extension direction (Brun & Sokoutis, 2010;Gessner et al, 2016;Jolivet et al, 2015;Ring et al, 1999). The shear zones on the western margin are inferred to have been active since Late Cretaceous and are comprised of major NE-trending dextral and sinistral fault sets accompanied by NW-and E-W-trending faults (İzmir-Balıkesir Transfer Zone, (Erkül, Helvacı, & Sözbilir, 2005); İzmir shear zone, (Brun & Sokoutis, 2010); the West Anatolia Transfer Zone, (Gessner, Gallardo, Markwitz, Ring, & Thomson, 2013)).…”