Vincent Roche
email: vincent.roche@cnrs-orleans.fr

L Jolivet

D Papanikolaou

E Bozkurt

A Menant

G Rimmelé

Slab fragmentation beneath the Aegean/Anatolia transition zone: insights from the tectonic and metamorphic evolution of the Eastern Aegean region

Introduction

Slab rollback and tearing are common features in subduction zones and have a strong impact on the tectonic and metamorphic evolution of the overriding plate [e.g. [START_REF] Dewey | Extensional collapse of orogens[END_REF][START_REF] Royden | Evolution of retreating subduction boundaries formed during continental collision[END_REF]Wortel & Spakman, 2000;[START_REF] Govers | Lithosphere tearing at STEP faults: Response to edges of subduction zones[END_REF][START_REF] Jolivet | Aegean tectonics: Strain localisation, slab tearing and trench retreat[END_REF][START_REF] Sternai | Driving the upper plate surface deformation by slab rollback and mantle flow[END_REF]. One of the best examples to study consequences of this slab dynamics is located in the Eastern Mediterranean region, where numerous mantle tomography studies elucidate the deeper lithosphere structures [Bijward et al., 1998;[START_REF] De Boorder | Late Cenozoic mineralization, orogenic collapse and slab detachment in the European Alpine Belt[END_REF]Piromallo & Morelli, 2003;Wortel & Spakman, 2004;[START_REF] Li | Subduction of the Indian lithosphere beneath the Tibetan Plateau and Burma[END_REF][START_REF] Biryol | Segmented African lithosphere beneath the Anatolian region inferred from teleseismic P-wave tomography[END_REF][START_REF] Salaün | High-resolution surface wave tomography beneath the Aegean-Anatolia region: constraints on upper-mantle structure[END_REF][START_REF] Delph | Shear wave velocity structure of the Anatolian Plate: anomalously slow crust in southwestern Turkey[END_REF]. Although results show a clear ~ 200 km-depth low-velocity anomaly below western Turkey interpreted as a major tear in the Hellenic slab, there is no consensus about the causes of this tearing and its consequences on the time-space tectonic and metamorphic evolution in the overriding plate [e.g. [START_REF] Dilek | Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt[END_REF][START_REF] Papanikolaou | Tectonostratigraphic models of the Alpine terranes and subduction history of the Hellenides[END_REF][START_REF] Jolivet | Neo-Tethys geodynamics and mantle convection: from extension to compression in Africa and a conceptual model for obduction[END_REF]Menant et al., 2016a;Gover & Fichtner 2016]. Some studies suggest the existence of (i) a wide sinistral lithospheric-scale shear zone accommodating different finite rates of back-arc extension due to the slab tear [START_REF] Gessner | What caused the denudation of the Menderes Massif: Review of crustal evolution, lithosphere structure, and dynamic topography in southwest Turkey[END_REF][START_REF] Jolivet | Neo-Tethys geodynamics and mantle convection: from extension to compression in Africa and a conceptual model for obduction[END_REF], (ii) a localized NE-SW striking transfer zone [e.g. [START_REF] Uzel | Paleomagnetic evidence for an inverse rotation history of Western Anatolia during the exhumation of Menderes core complex[END_REF], and (iii) regional variations (e.g. Samos) induced by a sinistral wrench component that was superimposed on the regional NNE-SSW extension [Ring et al., 2017]. However, few field observations of ductile and brittle markers and their link with the metamorphic evolution exist in the Eastern Mediterranean domain that occupies a key-position at the transition between the Aegean domain and western Turkey.

A C C E P T E D M A N U S C R I P T 3

To better understand the crustal consequences of tearing, and thus the geodynamic evolution of the Eastern Mediterranean domain, it appears therefore crucial to clarify (i) the geological correlations between the Cyclades and the Menderes Massif that have often been disputed due to significant lithological differences [e.g. Ring et al., 1999a;Jolivet et al., 2004a] and (ii) the distribution of kinematic indicators and the extent of metamorphic events in this region since the initiation of the tear. However, apart from the recent work of Ring et al. [2017] focusing on brittle deformation, very few geological studies [e.g. [START_REF] Franz | Aragonite-bearing blueschists on Arki island, Dodecanese, Greece[END_REF][START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF]Roche et al., 2018a] were devoted so far to those islands located in the western Aegean domain (e.g. Fourni, Arki, Lipsi and Leros) (Fig. 1). We therefore focus on these islands, by describing for the first time a complete regional scheme of ductile kinematic indicators and associated pressure-temperature (P-T) conditions. We thus shed light on the possible relations between the Cyclades and the Menderes Massif and, finally, we discuss the evolution of the tear in the subducting African lithosphere and its consequences on the upper plate tectonic history.

Geological setting

Geodynamic evolution of the eastern mediteranean region

Since the early Cenozoic at least, a single lithospheric slab has been continuously subducting northward below the Aegean region and the Anatolides -Taurides, accommodating most of the slow convergence between Africa and Eurasia during the closure of the Neotethys oceanic realm [e.g. [START_REF] Spakman | The Hellenic Subduction Zone: A tomographic image and its geodynamic implications[END_REF][START_REF] Faccenna | Subduction and the depth of convection in the Mediterranean mantle[END_REF][START_REF] Jolivet | Subduction tectonics and exhumation of high-pressure metamorphic rocks in the Mediterranean orogens[END_REF][START_REF] Van Hinsbergen | Nappe stacking resulting from subduction of oceanic and continental lithosphere below Greece[END_REF]2010a;[START_REF] Jolivet | Cenozoic geodynamic evolution of the Aegean[END_REF][START_REF] Papanikolaou | Tectonostratigraphic models of the Alpine terranes and subduction history of the Hellenides[END_REF]Pourteau et Africa-derived continental blocks below Eurasia led to the formation of a crustal-scale orogenic wedge (i.e. the Hellenides and the Taurides) [START_REF] Brunn | Contribution a l'etude geologique du Pinde Septenrional et d'une partie de la Macedoine occidentale[END_REF][START_REF] Aubouin | Contribution à l'étude géologique de la Grèce septentrionale: les confins de l'Epire et de la Thessalie; Place des Hellénides parmi les édifices structuraux de la Méditerranée orientale[END_REF][START_REF] Brunn | Structures majeures et corrélations stratigraphiques dans les Taurides occidentales[END_REF][START_REF] Jacobshagen | Structure and geodynamic evolution of the Aegean region[END_REF], by decoupling tectonic nappes from the subducting lithosphere [START_REF] Brunn | Eléments majeurs de liaison entre Taurides et Hellénides[END_REF][START_REF] Bonneau | Subduction, collision et schistes bleus; l'exemple de l'Egee (Grece)[END_REF][START_REF] Jolivet | Subduction tectonics and exhumation of high-pressure metamorphic rocks in the Mediterranean orogens[END_REF][START_REF] Van Hinsbergen | Nappe stacking resulting from subduction of oceanic and continental lithosphere below Greece[END_REF][START_REF] Brun | Exhumation of high-pressure rocks driven by slab rollback[END_REF][START_REF] Jolivet | Cenozoic geodynamic evolution of the Aegean[END_REF][START_REF] Ring | The Hellenic Subduction System: High-Pressure Metamorphism, Exhumation, Normal Faulting, and Large-Scale Extension[END_REF]. These nappes consist of coherent stratigraphic sequences and sedimentary facies, each characterizing a paleogeographic environment. Most of these nappes have also recorded different pressuretemperature (P-T) metamorphic conditions such as (i) high-pressure and low-temperature metamorphism (HP-BT) (e.g. in the Tavşanlı Zone [START_REF] Okay | Distribution and characteristics of the northwest Turkish blueschists[END_REF][START_REF] Okay | Jadeite-chloritoid-glaucophane-lawsonite blueschists in northwest Turkey: unusually high P/T ratios in continental crust[END_REF][START_REF] Plunder | Geodynamics of the Tavşanlı zone, western Turkey: Insights into subduction/obduction processes[END_REF]; in the Afyon Zone [e.g. [START_REF] Candan | Alpine high-P/low-T metamorphism of the Afyon Zone and implications for the metamorphic evolution of Western Anatolia, Turkey[END_REF][START_REF] Pourteau | Multistage growth of Fe-Mg-carpholite and Fe-Mg-chloritoid, from field evidence to thermodynamic modelling[END_REF] and its equivalent in the southwestern part of Turkey, i.e. the HP Lycian Nappe [e.g. [START_REF] Oberhänsli | First occurrence of Fe-Mgcarpholite documenting a high-pressure metamorphism in metasediments of the Lycian Nappes, SW Turkey[END_REF]Rimmelé et al., 2003a] recently renamed Ören unit by [START_REF] Pourteau | Neotethys closure history of Anatolia: insights from 40Ar-39Ar geochronology and P-T estimation in high-pressure metasedimentary rocks[END_REF] (see Appendix for more information); the Cycladic Blueschists Unit (CBU) [e.g [START_REF] Blake | A geological reconnaissance of the Cyclacic blueschist belt, Greece[END_REF][START_REF] Bonneau | Subduction, collision et schistes bleus; l'exemple de l'Egee (Grece)[END_REF][START_REF] Trotet | Exhumation of Syros and Sifnos metamorphic rocks (Cyclades, Greece). New constraints on the P-T paths[END_REF]) and (ii) barrovian-type metamorphism (e.g. in the Tavşanlı Zone [e.g. [START_REF] Seaton | Recrystallization of high-pressure marble (Sivrihisar, Turkey)[END_REF]; in the Menderes Massif [e.g. [START_REF] Sengör | Timing of tectonic events in the Menderes Massif, western Turkey: Implications for tectonic evolution and evidence for pan-African basement in Turkey[END_REF][START_REF] Régnier | Contrasting metamorphic evolution of metasedimentary rocks from the Çine and Selimiye nappes in the Anatolide belt, western Turkey[END_REF]] (see Appendix)). Despite the importance of the post-orogenic overprint on orogenic architecture, various correlations (e.g. stratigraphy, tectono-metamorphic history) have been proposed between Greece and Turkey in the Aegean region [START_REF] Brunn | Eléments majeurs de liaison entre Taurides et Hellénides[END_REF][START_REF] Dürr | The median Aegean crystalline belt: stratigraphy, structure, metamorphism, magmatism. Alps, Apennines[END_REF][START_REF] Papanikolaou | Geological correlations between the alpine segments of the Hellenides-Balkanides and Taurides-Pontides[END_REF][START_REF] Robertson | Palaeogeographic and palaeotectonic evolution of the Eastern Mediterranean Neotethys[END_REF][START_REF] Papanikolaou | The tectonostratigraphic terranes of the Hellenides[END_REF][START_REF] Göncüoğlu | General characteristics of pre-Alpine and Alpine Terranes in Turkey: Explanatory notes to the terrane map of Turkey[END_REF]Ring et al., 1999a;Jolivet et al., 2004b].

A C C E P T E D M

A N U S C R I P T 5 Since the Early Oligocene, the collapse of the Hellenides-Taurides belt and post-orogenic extension in this region have been mainly controlled by the progressive southward retreat of the African slab [e.g. Le [START_REF] Le Pichon | The hellenic arc and trench system: A key to the neotectonic evolution of the eastern mediterranean area[END_REF][START_REF] Lister | Metamorphic core complexes of Cordilleran type in the Cyclades, Aegean Sea, Greece[END_REF][START_REF] Jolivet | Mediterranean extension and the Africa-Eurasia collision[END_REF][START_REF] Jolivet | Cenozoic geodynamic evolution of the Aegean[END_REF], but also by the tear below western Turkey (e.g. see tomographic studies of [START_REF] Spakman | The Hellenic Subduction Zone: A tomographic image and its geodynamic implications[END_REF], [START_REF] Govers | Lithosphere tearing at STEP faults: Response to edges of subduction zones[END_REF] and Berk [START_REF] Biryol | Segmented African lithosphere beneath the Anatolian region inferred from teleseismic P-wave tomography[END_REF]). The nappe stack was cut by extensional low-angle normal faults leading to the exhumation of a series of metamorphic core complexes (MCCs) along a warm geotherm, leading to crustal anatexy [START_REF] Lister | Metamorphic core complexes of Cordilleran type in the Cyclades, Aegean Sea, Greece[END_REF][START_REF] Avigad | Low-angle faults above and below a blueschist belt-Tinos Island, Cyclades, Greece[END_REF][START_REF] Buick | The late Alpine evolution of an extensional shear zone, Naxos, Greece[END_REF][START_REF] Gautier | Crustal-scale geometry and kinematics of late-orogenic extension in the central Aegean (Cyclades and Ewia Island)[END_REF]Jolivet et al., 2004b].

For instance, in the Aegean domain, top-to-the-NE detachments described in the northern part of the Cyclades link up to form the crustal-scale North Cycladic Detachment System [NCDS, Jolivet et al., 2010]. In addition, the Naxos-Paros Detachment System (NPDS) exhumed magmatic gneiss, metapelites and marbles through a top-to-the-NE shearing event in the central part of Cyclades [e.g. Urai et al., 1990;[START_REF] Buick | The late Alpine evolution of an extensional shear zone, Naxos, Greece[END_REF][START_REF] Gautier | Structure and kinematics of Upper Cenozoic extensional detachment on Naxos and Paros (Cyclades Islands, Greece)[END_REF]. Top-to-the-SW kinematics was also described in the western part of the Cyclades linked into a single major detachment system named the West Cycladic Detachment System (WCDS [START_REF] Grasemann | Miocene bivergent crustal extension in the Aegean: Evidence from the western Cyclades (Greece)[END_REF]). In western Anatolia, the exhumation of the Menderes Massif Core Complex is also mainly accommodated by three detachments: (i) the top-to-the-S Büyük Menderes detachment [e.g. Hetzel et al., 1995a;[START_REF] Gessner | An active bivergent rolling-hinge detachment system: Central Menderes metamorphic core complex in western Turkey[END_REF], (ii) the top-to-the-NNE Gediz detachment (also named Alaşehir or Kuzey detachment) [e.g. Hetzel et al., 1995a;1995b;[START_REF] Gessner | An active bivergent rolling-hinge detachment system: Central Menderes metamorphic core complex in western Turkey[END_REF][START_REF] Lips | Multistage exhumation of the Menderes Massif, western Anatolia (Turkey)[END_REF] and (iii) the top-to-the-NE the Simav detachment [e.g. Işık & Tekeli, 2001].

The present-day context is characterized by a more localized extension, notably in the central part of the Menderes Massif [START_REF] Seyítoǧlu | Timing of Cenozoic extensional tectonics in west Turkey[END_REF][START_REF] Seyítoǧlu | The cause of N-S extensional tectonics in western Turkey: Tectonic escape vs back-arc spreading vs orogenic collapse[END_REF] , 2009]. The Cyclades and the Menderes Massif are also part of the Anatolia-Aegean domain that is currently extruding at a fast rate along the dextral North Anatolian Fault (NAF) since 5 Ma (Fig. 1) [START_REF] Mckenzie | Active Tectonics of the Mediterranean Region[END_REF][START_REF] Barka | The north Anatolian fault zone[END_REF][START_REF] Le Pichon | Geodetic determination of the kinematics of central Greece with respect to Europe: Implications for eastern Mediterranean tectonics[END_REF][START_REF] Mcclusky | Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus[END_REF][START_REF] Reilinger | GPS constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications for the dynamics of plate interactions[END_REF][START_REF] Van Hinsbergen | A key extensional metamorphic complex reviewed and restored: The Menderes Massif of western Turkey[END_REF]. In addition, instantaneous GPS velocities further show that the Aegean domain moves faster to the southwest than the Anatolian plate, the difference being accommodated by the active extension [START_REF] Le Pichon | Geodetic determination of the kinematics of central Greece with respect to Europe: Implications for eastern Mediterranean tectonics[END_REF][START_REF] Armijo | Westward propagation of the North Anatolian fault into the northern Aegean: Timing and kinematics[END_REF][START_REF] Mcclusky | Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus[END_REF][START_REF] Jolivet | A comparison of geodetic and finite strain pattern in the Aegean, geodynamic implications[END_REF].

; Aktug et A C C E P T E D M A N U S C R I P T 6 al.
To sum-up, the Aegean-Western Turkey area has recorded the complete succession of tectonic episodes from the Late Cretaceous subduction to the Paleocene-Eocene continental accretion and crustal thickening, and the Late Oligocene to Present back-arc extension [e.g. Le [START_REF] Le Pichon | The Aegean Sea[END_REF][START_REF] Bonneau | Evolution géodynamique de l'arc égéen depuis le Jurassique Supérieur jusqu'au Miocène[END_REF][START_REF] Papanikolaou | Tectonic Evolution of the Cycladic Blueschist Belt (Aegean Sea, Greece)[END_REF][START_REF] Jolivet | Mediterranean extension and the Africa-Eurasia collision[END_REF]Jolivet et al., 2004a]. Most of the history of this region is thus controlled by regional stresses imposed by the retreating and tearing subducting lithosphere [e.g. Le [START_REF] Le Pichon | The hellenic arc and trench system: A key to the neotectonic evolution of the eastern mediterranean area[END_REF][START_REF] Mercier | Extensional tectonic regimes in the Aegean basins during the Cenozoic[END_REF][START_REF] Faccenna | Slab detachment beneath eastern Anatolia: A possible cause for the formation of the North Anatolian fault[END_REF][START_REF] Jolivet | Aegean tectonics: Strain localisation, slab tearing and trench retreat[END_REF][START_REF] Sternai | Driving the upper plate surface deformation by slab rollback and mantle flow[END_REF]. In the following, we present only the main units across the Eastern Aegean domain, other units belonging to the western and central Aegean domain and to Western Turkey are presented in Appendix.

Geology of the Eastern Aegean islands

2.2.1. Samos A C C E P T E D M A N U S C R I P T 7
Several studies were devoted to Samos Island that occupies a key-position at the transition between Aegean domain and western Turkey (Figs. 1, 2a and 2c) [START_REF] Mposkos | Diasporit-und Smirgelvorkommen der Insel Samos (Griechenland)[END_REF][START_REF] Papanikolaou | Unites tectoniques et phases de deformation dans l'ile de Samos, Mer Egee, Grece[END_REF][START_REF] Theodoropoulos | Geological Map of Greece 1: 50000[END_REF][START_REF] Mposkos | Petrology of glaucophane metagabbros and related rocks from Samos, Aegean-Island (Greece)[END_REF][START_REF] Weidmann | Neogene stratigraphy of the Eastern basin, Samos island, Greece[END_REF][START_REF] Mezger | Metamorphism of the variegated sequence at Kallithea, Samos, Greece[END_REF][START_REF] Okrusch | High-pressure rocks of Samos, Greece[END_REF][START_REF] Chen | Evolution of the high-and medium-pressure metamorphic rocks on the island of Samos, Greece (PhD Thesis, University of Wurzburg)[END_REF]Will et al., 1998;Ring et al., 1999b;Ring et al., 2007]. The metamorphic succession of Samos consists of four distinct tectono-metamorphic units, from the base to the top. (i) The Kerketeas marbles crop out in the western part of the island in a tectonic window below the overlying Ampelos unit [START_REF] Papanikolaou | Unites tectoniques et phases de deformation dans l'ile de Samos, Mer Egee, Grece[END_REF][START_REF] Theodoropoulos | Geological Map of Greece 1: 50000[END_REF]Ring et al., 1999b]. The tectonic contact between these units is named Pythagoras Thrust. The Kerketeas unit consists in a monotonous sequence of dolomitic marbles with local schist on top that can be correlated with the Basal Unit [START_REF] Ring | Miocene high-pressure metamorphism in the Cyclades and Crete, Aegean Sea, Greece: Evidence for large-magnitude displacement on the Cretan detachment[END_REF], i.e. the Gavrovo-Tripolitza nappe. Iincipient HP-LT metamorphism and a subsequent greenschist overprint is recorded [START_REF] Mposkos | Diasporit-und Smirgelvorkommen der Insel Samos (Griechenland)[END_REF]. (ii) The Ampelos unit outcrops over the central part of the island (Fig. 2a). We include in this unit the Agios Nikolaos unit distinguished by some authors [Ring et al., 1999b]. It is mainly made of metasediments (e.g. schists and marbles) with minor occurrences of metabasites. The lower part contains slices of gneiss that provided Carboniferous and Triassic radiometric ages on zircons [Ring et al., 1999b]. This unit can be correlated with the lower part of the CBU [Ring et al., 1999b]. The Ampelos nappe underwent an Eocene blueschist-facies metamorphic event (520 °C, 19 kbar), followed by an Oligo-Miocene overprint under greenschist-facies conditions (455 -485 °C, 6 -7 kbar) [START_REF] Okrusch | High-pressure rocks of Samos, Greece[END_REF][START_REF] Chen | Evolution of the high-and medium-pressure metamorphic rocks on the island of Samos, Greece (PhD Thesis, University of Wurzburg)[END_REF][START_REF] Chen | Polymetamorphic evolution of high-pressure rocks on Samos, Greece[END_REF]Will et al., 1998]. (iii) The Selçuk nappe crops out in the center of the island as discontinuous outcrops of metabasites (Fig. 2a) [Ring et al., 1999b]. It is similar in terms of lithology to the ophiolitic mélange metamorphosed in HP-LT conditions in the upper

A C C E P T E D M A N U S C R I P T 8
part of the CBU, for instance in Syros and Sifnos (Fig. 2a) [START_REF] Okrusch | Eclogites associated with high-grade blueschists in the Cyclades archipelago, Greece: a review[END_REF]]. (iv) The Vourliotes nappe crops out in the eastern part of the island where it is mainly made of schists and marbles (Fig. 2a). The upper marble formation has been dated as Upper Cretaceous on the basis of rudists found within the metabauxite outcrops at the eastern part of the island [START_REF] Papanikolaou | Unites tectoniques et phases de deformation dans l'ile de Samos, Mer Egee, Grece[END_REF]. It recorded the same metamorphic conditions as the Ampelos nappe [Ring et al., 1999b].

(v) The Kallithea nappe and the Katavasis Complex are only found in the westernmost part of the island, on top of Kerketeas marbles. Here, we merged both units in the Kallithea nappe that can be correlated with the Upper Cycladic Nappe where no evidence for a Cenozoic HP-LT metamorphism is observed. The Kallithea nappe is made of sandstones, serpentinized peridotite lenses, spilite and diabase with red radiolarites and fossiliferous ammonitico rosso-type limestones overlain by an Upper Triassic to Jurassic massive limestone series [START_REF] Papanikolaou | Unites tectoniques et phases de deformation dans l'ile de Samos, Mer Egee, Grece[END_REF][START_REF] Theodoropoulos | Geological Map of Greece 1: 50000[END_REF]. The underthrusted Katavasis Complex is mainly composed of marbles, amphibolites and quartzites, formed under amphibolite-facies conditions [START_REF] Mezger | Metamorphism of the variegated sequence at Kallithea, Samos, Greece[END_REF][START_REF] Chen | Evolution of the high-and medium-pressure metamorphic rocks on the island of Samos, Greece (PhD Thesis, University of Wurzburg)[END_REF]. It is locally intruded at ~10 Ma by igneous dykes cut by a distinct low-angle normal fault [Ring et al., 1999b], suggesting a younger activity of this fault that is interpreted as an extension of the NCDS [Jolivet et al., 2010].

A large surface of Samos is covered by Mio-Pliocene sedimentary basins [START_REF] Theodoropoulos | Geological Map of Greece 1: 50000[END_REF][START_REF] Weidmann | Neogene stratigraphy of the Eastern basin, Samos island, Greece[END_REF] (Fig. 2a). K-Ar age data (on sanidine and biotite in tuffaceous rocks) of [START_REF] Weidmann | Neogene stratigraphy of the Eastern basin, Samos island, Greece[END_REF] provide age constraints for sedimentary rocks. From 12 Ma and 9 Ma one can observe conglomerates with locally-derived pebbles of basement, then the freshwater limestones Pythagorion formation, volcanoclastic rocks (i.e. basalt and tuff), formed 11 Myrs ago, overlain by the Hora formation grading from thick-bedded

A C C E P T E D M A N U S C R I P T 9
limestones to thin-bedded diatomaceous shales and, finally, thinly bedded limestones deposited some 9 Ma ago. The upper cycle, formed between 8.6 and 6.2 Ma, starts with the Mytilini formation, made of conglomerates and tuffaceous marls that rests unconformably above the Hora or the Pythagorion formation. The upper cycle ends with the Kokkari formation made of lacustrine limestones attributed to the Pliocene.

According to Ring et al. [1999b], the tectono-metamorphic units of Samos have recorded five successive deformation stages. D 1 and D 2 stages are associated with the HP-LT metamorphic event and show a roughly consistent E-W orientation with bivergent sense of shear. They correspond to the thrusting of the Ampelos nappe onto the Kerketeas marbles in the western part of the island. D 3 event corresponds to the greenschist-facies metamorphism associated with crustal extension. This event is mainly associated with ESE-WSW transport direction, except in the core of the Ampelos nappe where D 3 stretching lineation displays a N-S orientation with topto-the-N and top-to-the-S kinematic indicators. Ring et al. [1999b] therefore conclude to a large component of coaxial strain during the exhumation of these units. Finally, D 4 corresponds to a short contractional brittle event between 8.6 and 9 Ma whereas D 5 is extensional, corresponding to the formation of N-S trending high-angle normal faults.

Fourni and Thymaena islands

Whereas Thymaena Island benefited from a map coverage by the study of [START_REF] Papanikolaou | Thrust sheets of the island of Thymaena-indication of northward displacements in the Aegean during miocene[END_REF], there is no geological map available of Fourni Island (Figs. 2b and2c). In Thymaena, the non-metamorphic succession from the middle to upper Triassic consists in sandstones and red

A C C E P T E D M

A N U S C R I P T 10 nodular limestones with mafic igneous rocks, and white dolomites and neritic limestones with megalodon. A series of north-directed thrusts affected this sequence (Fig. 2b). According to [START_REF] Papanikolaou | Thrust sheets of the island of Thymaena-indication of northward displacements in the Aegean during miocene[END_REF], thrusting may be related to the middle-upper Miocene period.

Dodecanese islands

Dodecanese islands (Figs. 1 and3) were mapped by [START_REF] Desio | Le isole italiane dell'Egeo: studi geologici e geografico-fisici[END_REF] and then by the Greek Geological Survey (IGME) (e.g. Leros geological map from [START_REF] Stavropoulos | Geological map of Leros[END_REF]). However, the tectono-metamorphic evolution of Kalymnos, Leros, Lipsi and Arki remains fragmentary. The metamorphic succession consists in the tectonic superimposition of two tectono-metamorphic units, i.e. the Marina and Temenia units from the top to the base, respectively [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF]Roche et al., 2018a]. Furthermore, a thin Neogene to recent sedimentary cover is also present on Leros and Lipsi (Fig. 3).

Outcrops of Marina unit are well exposed in Kalimnos and Leros and locally in the southeastern part of Lipsi (Figs. 3c and3d). The first-order architecture of this unit is defined by crystalline rocks that are transgressively overlain by weakly metamorphosed, violet schists, conglomerates and sandstones, which grade upwards into upper Triassic to Liassic dolomites and limestones. On Leros Island, this contact juxtaposes low-grade metamorphism schists with amphibolites and kyanite-staurolite-garnet micaschist yielding ages between 320 and 230 (amphibole and white micas [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF]). According to [START_REF] Papanikolaou | Tectonostratigraphic models of the Alpine terranes and subduction history of the Hellenides[END_REF], these formations are similar to the volcano-sedimentary-type Tyros Beds at the base of the Tripolis unit in the Hellenides. Conversely, [START_REF] Dürr | The median Aegean crystalline belt: stratigraphy, structure, metamorphism, magmatism. Alps, Apennines[END_REF] suggest that the sedimentary formation of

A C C E P T E D M A N U S C R I P T 11
Marina unit correspond to units of the Lycian Nappes in SW Turkey, which consists, from base to top, of (i) a parautochthonous unit, mainly composed of shallow-water and pelagic limestones from Late Cretaceous to Early Miocene age; (2) an intermediate complex consisting of thrust sheets comprising shallow-water limestones, dolomites, pelagic and turbiditic cherty limestones and flysch from Middle Triassic to Cenomanian, topped by an assemblage of basaltic pillow lavas and (3) a large peridotite nappe with serpentinites and fragments of doleritic dykes [START_REF] Bernoulli | The extension of the Lycian Nappes (SW Turkey) into the southeastern Aegean Islands[END_REF]. It is followed by well-bedded upper Jurassic to lower Cretaceous (?) limestone with cherty replacement [START_REF] Dürr | Über Alter und geotektonische Stellung des Menderes Kristallins/SW Anatolien und seine Äquivalente in der Mittleren Aegean[END_REF][START_REF] Dürr | The median Aegean crystalline belt: stratigraphy, structure, metamorphism, magmatism. Alps, Apennines[END_REF][START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF].

Crystalline rocks are represented by the Panormos and Emporios units [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF]. The first consists mostly in a succession of marbles, plagioclase gneisses and kyanite-staurolite-garnet micaschists with intercalations of banded epidote and garnet amphibolites. The base of this unit is formed of fine-grained schist and minor coarse-grained massive amphibolite with a thickness of about 100 m. The overlying Emporios unit is made of albite gneisses and chloritoid-biotite schists [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF]. K-Ar dating of the basement rocks of the Dodecanese islands shows Variscan ages partially reset by a very low-grade Alpine overprint, suggesting a polyphased deformation [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF].

The underlying Temenia unit is mainly exposed in Arki, Lipsi and Leros (Fig. 3) and consists of late Paleozoic to Mesozoic sediments affected by an Alpine HP-LT metamorphism [START_REF] Franz | Aragonite-bearing blueschists on Arki island, Dodecanese, Greece[END_REF]. It consists of interlayered phyllites, micaschists, quarzites and marbles with rare occurrences of metabasites. The presence of Mg-riebeckite, glaucophane and aragonite in Leros and Arki islands [START_REF] Katagas | Petrochemistry of low and medium grade mafic metamorphic rocks from Leros island, Greece[END_REF][START_REF] Katagas | Metamorphic zones and physical conditions of metamorphism in Leros Island[END_REF][START_REF] Franz | Aragonite-bearing blueschists on Arki island, Dodecanese, Greece[END_REF]Roche et al., 2018a], implies a subduction-related metamorphism with a Roche et al. [2018a] show that glaucophane/Mg-riebeckite is locally preserved and may destabilize into winchite, suggesting a greenschist-facies overprint. [START_REF] Dürr | Über Alter und geotektonische Stellung des Menderes Kristallins/SW Anatolien und seine Äquivalente in der Mittleren Aegean[END_REF] considers this unit as an equivalent of the Kara Dag unit in the Lycian Nappes of western Turkey (Fig. 1). However, Roche et al. [2018a] challenged this hypothesis, suggesting that this unit belongs to the Lower Cycladic Blueschist Nappe (LCB) as attested by the similar P-T conditions as on Folegandros and Milos islands [START_REF] Augier | Exhumation kinematics of the Cycladic Blueschists unit and back-arc extension, insight from the Southern Cyclades (Sikinos and Folegandros Islands, Greece)[END_REF][START_REF] Grasemann | Miocene postorogenic extension of the Eocene synorogenic imbricated Hellenic subduction channel: New constraints from Milos (Cyclades, Greece)[END_REF].

A C C E P T E D M A N U S C R I P T 12 minimum pressure of ~ 8 kbar.
For more information about this sub-unit which belonging to the CBU, it is possible to refer to the studies of [START_REF] Grasemann | Miocene postorogenic extension of the Eocene synorogenic imbricated Hellenic subduction channel: New constraints from Milos (Cyclades, Greece)[END_REF] and Roche et al. [2018a].

Crustal-scale tectonic evolution of Dodecanse islands is still poorly known. Nonethess, a recent study of Roche et al. [2018a] on Leros reveals that Temenia unit has been exhumed under Marina unit through a top-to-the-NE ductile shearing. Deformation is thus preferentially localized along the main tectonic contact (i.e. Temenia shear zone), although second-order ductile shear zones with similar kinematics are also evidenced, especially along lithological contacts such as marble -schist lithologies (e.g. Xirokampos shear zone, Fig. 3d). In addition, top-to-the-SW ductile-brittle deformation is also recognized at different places (see Fig. 6 in Roche et al. [2018a]), suggesting a significant component of coaxial flow in the latest increment of deformation.

New field data

We carried out several field surveys in the eastern Aegean region, including field mapping in order to complement the existing IGME geological maps or to realize new geological maps

A C C E P T E D M A N U S C R I P T
13 (e.g. Fourni Island). Geological mapping was complemented by a detailed study of metamorphic evidences in all islands. Large-scale analysis of the distribution of metamorphic markers thus leads to roughly constrained P-T conditions for several deformation events. Results also include maps of finite strain markers, foliation trajectories, kinematic indicators and field measurements on stereographic plots.

Samos

Distribution of metamorphic record

On Samos, our study provides additional data for the distribution of HP-LT assemblages, notably well expressed in metabasite boudins of the Ampelos and Vourliotes nappes (Fig. 4a).

There, glaucophane, epidote ± chloritoid and white mica are common and well preserved (Fig. 4b). Depending on the areas, epidote-chlorite-albite assemblage is evidenced and indicate retrogression to greenschist-facies conditions (Fig. 4c). Although [START_REF] Okrusch | High-pressure rocks of Samos, Greece[END_REF] described the paragenesis carpholite-kyanite in a pebble collected on Psili Amos beach (Fig. 4a), we were not able to recognize any in-situ Fe-Mg-carpholite occurrence in the field. In old metabauxites mines along the eastern coast of Samos, we however observed the chloritoid-diaspore assemblage and the diaspore-quartz association (Figs. 4d and4e). The latter has only been found in Sulawesi (New Caledonia), Amorgos (Cyclades) and Vanoise Massif (Western Alps) [START_REF] Theye | The assemblage diaspore+quartz in metamorphic rocks: a petrological, experimental and thermodynamic study[END_REF].

It leads to a minimum pressure of 13 kbar and maximum temperatures of 430 °C, i.e. about 100 °C colder than previously published P-T estimates (Fig. 4a) [Ring et al., 1999b]. Such cold HP-

A C C E P T E D M A N U S C R I P T 14
LT conditions are compatible with the Fe-Mg-carpholite reported by [START_REF] Okrusch | High-pressure rocks of Samos, Greece[END_REF], but are not common in the Cyclades.

Structural geology

At first glance, our observations on Samos confirm the conclusions of Ring et al. [1999b] for the main trends of stretching lineation and shearing associated with blueschist-to greenschistfacies assemblages (Fig. 5a). The best examples of shear sense observed in the field are located near the Pythagoras Thrust in the Ampelos nappe (Fig. 5a). There, blueschist parageneses are associated with E-W or WNW-ESE stretching lineations and top-to-the-W-WNW shear bands (Fig. 5b). These observations suggest that the fabric formed together with the Pythagoras Thrust (probably Eocene) has been preserved here and not severely reworked by the subsequent extension, except for the recent normal fault controlling the topography. This localized shearing along this thrust confirms that it is the major tectonic contact in the island as proposed by Ring et al. [1999b]. Nonetheless, our study show some N-S stretching lineations and rather clear top-tothe-N shear sense associated with greenschist-facies parageneses near Kumarradei and Marathokambos in the Ampelos nappe (Figs. 5c and5d). The same kinematics is also observed in the southwestern part of Samos in the Vourliotes nappe (Fig. 5a). However, these criteria are very local and do not allow any definite conclusion. If these observations were confirmed, it would mean that the kinematic direction during the HP-LT event and the retrogression were almost perpendicular to each other, at least locally, in contrast to the interpretation of Ring et al. [1999b] that suggest a continuum of ENE-WSW-directed transport during exhumation.

A C C E P T E D M

A N U S C R I P T 15 Furthermore, although the contact between the Kallithea nappe and the Kerketeas unit does not crop out continuously, it is characterized in the field by thin dark-grey marble ultramylonites (approximately 10 cm high) at the top of dolomites (Fig. 5e). This thin layer carries a NEtrending stretching lineation with locally some normal-sense shear bands spaced a few centimeters apart, and sigmoidal foliation indicating top-to-the-NE shearing (Fig. 5f). This ductile deformation is then overprinted by brittle deformation as suggested by the presence of ultracataclasites and brittle low-angle faults. Locally, centimetric antithetic high-angle normal fault also affected the penetrative foliation. Below this contact, the dolomite is not affected by this deformation indicating a strongly localized deformation.

Fourni and Thymaena islands

We present in Figure 2b the first geological map of Fourni and Thymaena islands. The geology of the two islands is characterized by a metamorphic sequence comprising three main units (Fig. 2b). (i) The Korakas unit crops out in the eastern part of the island and mainly consists of dolomitic marbles with local schists on top. (ii) The overlying Chrisomilia unit, is mainly made of metabasites with minor occurrences of marbles in the upper part. The lower part of this unit is exposed in southeastern, and consists in thin marble layers. (iii) The uppermost Fourni unit mostly crops out in the central part of the island. It includes mainly schists, marbles, quartzites and minor occurrences of metabasites. Finally, above these tectono-metamorphic units, a nonmetamorphic nappe (i.e. the Thymaena unit) is observed [START_REF] Papanikolaou | Thrust sheets of the island of Thymaena-indication of northward displacements in the Aegean during miocene[END_REF].

We distinguish three main contacts between these units: (i) Chrisomilia thrust cropping out in the north of Fourni Island and separating Chrisomilia unit from Korakas unit, (ii) Plagia thrust

Distribution of metamorphic record

We report here preliminary results on metamorphic conditions recorded on Fourni and Thymaena islands. Observed metamorphic parageneses from metabasites in the Chrisomilia unit mainly consist of porphyroblasts of albite -quartz -white mica -chlorite -kyanite, indicating a greenschist-facies metamorphic event (Fig. 6a). Locally, some chloritoid pods are also observed in quartzitic levels (Fig. 6b) that may suggest a former higher-pressure event. The Fourni unit seems to have also recorded the greenschist-facies event. Foliation within schist layers is marked by quartz -white mica -chlorite with locally stretched albite surrounded by chlorite pressure shadows (Fig. 6c). It is noteworthy that both units (i.e. Chrisomilia and Fourni units) seem to have recorded lower peak-metamorphic conditions than the nearby Cyclades and Samos islands.

Structural geology

On Fourni and Thymaena islands, foliation trajectories are given in Figure 2b. The main foliation strikes E-W with moderate dips towards north or south in the central and western parts of the island. In the south, the foliation in both Fourni and Chrisomilia units turns with an average strike around N45°E, whereas it appears more variable in the north, and particularly within Chrisomilia unit. In addition, the foliation is locally deflected in the vicinity of late steep faults 6d). A later folding event is also observed in the landscape with the main foliation that is affected by a series of large-scale open folds with E-W axes (Fig. 2b). In addition, kink structures are well developed in both Fourni and Chrisomilia units, showing a N50°E strike (Fig. 6e). Locally, dykes crosscut the main foliation of the Fourni unit which strikes NE-SW (Fig. 6f).

Stretching lineation is mainly underlined by stretched calcite in marbles layers and by elongated aggregates of albite and white micas in metapelites and metabasites. Its orientation is centered on a value of N150°E with a dominant southwestward plunge in the lower structural level, whereas the orientation of stretching is around N0°E to N10°E in the upper levels (Fourni unit, Fig. 7). Lineation and foliation are, however, bent by the main brittle faults, especially strike-slip faults, resulting in a slight scattering of the stretching direction. For instance, in the eastern part of the island, the orientation of stretching lineation is around N90°E with a dominant eastward plunge (Fig. 7) whereas it trends NW-SE in other areas.

Fourni unit is affected by two shearing events, top-to-the-SE and top-to-the-NNE with kinematic indicators often unambiguous at all scales (Fig. 8). As shown in Figure 7, top-to-the-NNE pervasive shearing deformation affected the upper part of this unit, below the Thymaena Detachment, whereas top-to-the-SE kinematic indicators are well preserved in deeper structural levels. In the top of this unit, top-to-the-NNE shear bands are particularly abundant in metapelites and calcschists (Fig. 8a; see stereographic projection in Fig. 7). Depending on areas, their spacing ranges from a few millimeters in the weakest lithologies in the vicinity of the main contacts (e.g.

A C C E P T E D M

A N U S C R I P T 18 close to the Thymeana Detachment) to decimeters in more competent levels. Locally, the angle between shear bands and the main foliation varies, from high-angle in the upper levels of Fourni unit, suggesting an increasingly brittle behavior, to 20 -35° at the base of this unit. Non-coaxial deformation is also accommodated by sheared quartz veins (Fig. 8a) and asymmetric boudinage of competent levels (e.g. marbles, metabasites) into a weaker, generally metapelitic matrix.

Controversy, top-to-the-SE kinematic indicators are well preserved in deeper structural levels of this unit with common kinematic criteria including quartz-and white mica-bearing pressure shadows on pyrites (Fig. 8b), shear bands and asymmetric quartz veins. In addition, top-to-the-SE more localized brittle-ductile deformation is locally observed (Fig. 8c). Chrisomilia unit is only affected by top-to-the-SE ductile deformation. For instance, metric shear bands affecting foliation are abundant (Figs. 8d and8e). The relative timing of these two episodes of shearing appears clearly in the field. In the whole island of Fourni, below the Thymaena Detachment, shallow or steep north-dipping shear bands deform the main regional foliation associated with ductile top-tothe-SE shearing, showing that the-top-to-the-NNE shearing event overprints the-top-to-the-SE deformation.

On Fourni and Thymaena islands, the main contact between Fourni unit and the upper nonmetamorphic Thymaena unit is marked by breccia and cataclasites (Fig. 9a) over a thickness of approximately 20 meters. Yellowish foliated cataclasites associated with fluid circulations are folded asymetricaly, and locally show sigmoidal foliation compatible with the top-to-the-NNE shearing (Fig. 9b). Below this contact, top-to-the-NNE deformation gradually decreases, while the-top-to-the-SE deformation is totally erased. In addition, in the vicinity of strike-slip faults, top-to-the-E ductile deformation is also recorded in the Chrisomilia unit (Fig. 7) and overprinted

A C C E P T E D M A N U S C R I P T
19 by a clear top-to-the-N brittle deformation (Fig. 9c). A new set of major SE-NW to E-W striking faults with a strike-slip component offset the contacts between the main units (e.g. Chrisomilia and Korakas units, Fig. 7; Chrisomilia and Fourni units, Fig. 9d). Shallow-dipping striae along the main fault planes (Fig. 9e) and on smaller-scale faults in the breccia in the north are consistent with a NW-SE extension (see stereogram on Figs. 7 and9g). This set of faults is crosscut by steeply N-S striking high-angle normal faults (Fig. 7). According to Ring et al. [2017], this set of faults represents the youngest increment, related to the late Miocene to recent extension (for complementary informations, see detailed study of Ring et al. [2017]).

Dodecanese islands

Distribution of metamorphic record

We propose here new maps of Arki and Lipsi islands (Fig. 3) where the metamorphic record was investigated by studing parageneses from metabasites belonging to Temenia and Marina units (Fig. 10). The geology of Leros and the associated metamorphic record are detailed in Roche et al. [2018a] and also summarized in this study.

Near the lighthouse of Arki harbor, an outcrop of Temenia unit shows several bands of blueschists bearing porphyroblastic blue amphibole, interlayered with micaschists, quartzmicaschists and marbles. In other parts of the island, microscopic observations have revealed blue amphiboles (Fig. 10b). Greenschist-facies intercalations are also observed and chloritoids mark a stretching lineation around N60°E (Fig. 10c). On Lipsi Island, metamorphic assemblages present in metabasites and schists of Temenia unit show chlorite -phengite ± epidote ± quartz ± sphene

A C C E P T E D M A N U S C R I P T 20
(e.g. Fig. 10d). The absence of blue amphiboles on Lipsi does not allow ascribing these rocks to the blueschists-facies. Nonetheless, the lithologies are very similar as those found in Leros and Arki islands where HP-LT parageneses have been recorded [e.g. Franz & Okrush, 1992;Roche et al., 2018a;this study]. This suggests that the Temenia unit outcropping on Lipsi was probably not far from the blueschists-facies conditions. The whole Temenia unit would then have been affected by an HP-LT alpine event followed by a retrogression stage in greenschist-facies conditions where chlorite -albite -winchite -epidote -phengite are generally observed.

Conversely, Marina unit shows mainly chloritized garnet-bearing rocks and well-preserved amphibolites showing hornblende and plagioclase parageneses (Figs. 10e and10f). This unit crops out in Leros and Lipsi islands (Figs. 4 and10a). These rocks are consistent with the Barrovian medium-temperature and medium-pressure (MT-MP) conditions described by [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF].

Structural geology

In Temenia unit of Dodecanese islands, foliation trajectories and lineations are given in 4d and12a). There, metabasites are located in the core of schist and marble antiforms (Fig. 4d). Foliation in Marina unit is also characterized by a N90°E to N135°E strike, and is gently to steeply dipping. Furthermore, the main foliation tends to increase in intensity toward the Marina -Temenia contact in both units, while the strike and These events are thus apparently related to layer-normal thinning during shear deformation. This overall strain gradient is complicated by strain localization over a limited number of ductile shear zones developed along lithological contacts (e.g. Arki and Gatis shear zones, Figs. 3b and3c), including a well-developed mylonitic foliation at the contact between marbles and schists in Arki or in Lipsi (e.g. Fig. 12d). In the following, we focus mainly on the study of the deformation within the Temenia unit, which recorded HP-LT Alpine parageneses on Arki and Leros islands, and problably on Lipsi Island even if HP-LT evidences were not found.

Stretching lineation is marked by various types of indicators, depending upon lithology, deformation and P-T conditions. Lineation is outlined by stretched quartz and elongated phyllosilicates aggregates such as chlorites and white micas in metapelites, epidote and rare blue amphiboles in metabasites and chloritoids in quartzite levels (e.g. Fig. 10b). On Arki, the direction of stretching appears more scattered than on Lipsi, with an average trend around N-S (Fig. 11). On Lipsi, the orientation of stretching lineation is centered on a value of N45°E with a dominant northeastward plunge, whereas on Leros it shows a larger dispersion between N0° and N90°E with an average around NE-SW and a variable plunge depending on the area (Fig. 11).

A C C E P T E D M A N U S C R I P T 22

At first glance, the whole Temenia unit is affected by a pervasive top-to-the-NE ductile shearing attested by numerous kinematic indicators in the three islands (Figs. 11 and 12, see also Roche et al. [2018a] for Leros field pictures). Shear bands are well developed at all scales (Figs.

10d, 12e and 12f) and are associated with large-scale asymmetric boudinage in alternating lithologies and cm-scale top-to-the-NE kinematic indicators well preserved in metaconglomerate levels (Fig. 12g). At the scale of the outcrop, the rarity of HP-LT rocks occurrences in the field makes difficult any discussion about the kinematics of deformation active during the HP event.

Conversely, greenschist-facies parageneses appear conspicuously associated with top-to-the-NE shearing deformation (e.g. Fig. 10d). Indeed, the regional foliation is made of greenschist-facies minerals such as epidote and chlorite concentrates in pressure shadows or in folded layers in both metapelites and metabasites.

Althoug predominant top-to-the-NE ductile kinematics are present in all Dodecanese islands, the distribution of ductile-brittle criteria appears more complex in all units. On Lipsi, Neogene sediments are often in fault contact with the metamorphic rocks. There, the contact is characterized by a low-angle normal fault parallel to the regional foliation (Fig. 13a). Locally, striae along the main fault plane are compatible with the same NE-SW direction of extension (Fig. 13b). This major contact may therefore be interpreted as a low-angle detachment, which we name the Ghialos Detachment. Hence, the observed Alpine structures within metamorphic rocks (Fig. 12g) and at their contact with Neogene sediments (Fig. 13b) suggests a continuum of stretching from ductile to brittle conditions with top-to-the-NE shearing. Similar ductile-brittle deformation is recorded within the main contact (i.e. Temenia shear zone) on Leros, but with a top-to-the-SW sense of shear. In the area of Agios Isidoros (Fig. 3d), ductile deformation within

A C C E P T E D M A N U S C R I P T 23
Temenia is intense as attested by numerous low-angle shear zones spaced of a few meters. Topto-the-WSW shear bands become more brittle approaching the base of Marina unit (Figs. 13c and13d). The coexistence of opposite kinematic indicators is thus ascribed to the coaxial component of deformation, as also illustrated by large-scale boudinage on Leros [Roche et al. 2018a].

Brittle deformation is fairly consistent through all Dodecanese islands showing N-S to NE-SW direction of extension (see stereographic projection on Fig. 11). On Lipsi, brittle deformation is well-developed, overprinting ductile deformation and controlling relationships between the different units (i.e. Neogene sediments, Temenia and Marina units). For instance, although the tectonic contact between Neogene sediments and Temenia unit is well exposed (strikes N80°E dipping gently toward the north), it is transected by NW-SE striking high-angle normal faults with a strike-slip component (Fig. 13e). Displacement on faults ranges typically between a few meters to decameters. The stress tensor analysis shows a subvertical orientation for the maximum principal stress axis (σ1) whereas the minimum principal stress axis (σ3) is horizontal striking approximately NE-SW (see stereographic plot #4 in Fig. 13g). Similar faults are also observed in the southern part of Lipsi where a thick damage zone affects marbles and schists of Temenia unit (Fig. 13f). There, foliation strikes N-S and dips deeply toward the north (~ 60°), and turns close to the fault, suggesting a dextral component (Fig. 13f). On Leros, low-angle brittle normal faults, dipping 20 -30°, may also control the deposition of Neogene sediments (the Lakki detachment, see Roche et al. [2018a]). Here, brittle indicators are again compatible with a NE-SW to N-S extension (see stereographic projections on Figs. 11 and13g, #6a and #6b).

A C C E P T E D M

A N U S C R I P T 24

Discussion

Correlations between western Anatolia and the Aegean region

The location of the eastern Aegean islands and the Dodecanese at the transition between the Aegean and western Anatolian regions allows discussing the correlations between these two domains based on our new field observations. Two main criteria can be used for these correlations. (i) One can correlate units with similar stratigraphic successions, and thus preorogenic paleogeographic domains, but these domains may have very large areal extents and be involved in different parts of the same belt (Fig. 14). (ii) One may alternatively correlate units with approximately similar stratigraphic succession and similar P-T-time evolution or, rather, similar peak pressure-temperature conditions (Fig. 15). In this case, the emphasis is put on the position of these units within the subduction channel or accretionary wedge, thus on a synorogenic situation. Although the complex evolution before the Eocene is not in the scope of the present paper, it might have had some consequences in differentiating two domains with two different lithospheres. Therefore, some general comparisons have to be recalled about the ophiolite emplacement and the nature of the continental basement.

General correlations

According to the literature [e.g. [START_REF] Papanikolaou | Geological correlations between the alpine segments of the Hellenides-Balkanides and Taurides-Pontides[END_REF][START_REF] Papanikolaou | Timing of tectonic emplacement of the ophiolites and terrane paleogeography in the Hellenides[END_REF][START_REF] Papanikolaou | Tectonostratigraphic models of the Alpine terranes and subduction history of the Hellenides[END_REF], the following lateral correlations can be made: 1) The Late Triassic-Early Jurassic event The late Jurassic -early Cretaceous event, corresponding to the obduction of the Axios/Vardar oceanic basin, is widespread in the so-called internal Hellenides of [START_REF] Brunn | Les zones helléniques internes et leur extension. Réflexions sur l'orogénèse alpine[END_REF] in continental Greece with sparse outcrops in the Aegean, especially in Crete below the Asteroussia nappe [e.g. [START_REF] Bonneau | La nappe métamorphique de l'Asteroussia, lambeau d'affinités pélagoniennes charrié jusque sur la zone de Tripolitza de la Crète moyenne (Grèce)[END_REF] (see Appendix). 3) The late Cretaceous second obduction event can be followed through the Anatolides-Taurides [e.g. [START_REF] Okay | Obduction, subduction and collision as reflected in the Upper Cretaceous-Lower Eocene sedimentary record of western Turkey[END_REF]] (e.g. Tavşanlı Zones, Afyon and Ören units, the Kurudere-Nebiler units, see Appendix for more information) to the Aegean and from the internal Hellenides in the Vardar region [e.g. [START_REF] Bonneau | Correlation of the Hellenide nappes in the south-east Aegean and their tectonic reconstruction[END_REF]. In the Cyclades, the Upper Cycladic Nappe shows large units of ophiolite with associated amphibolites yielding Late Cretaceous ages [e.g. [START_REF] Patzak | The Akrotiri Unit on the island of Tinos, Cyclades, Greece: Witness to a lost terrane of Late Cretaceous age.(with 18 figures and 8 tables in the text)[END_REF][START_REF] Bröcker | Rb-Sr isotope studies on Tinos Island (Cyclades, Greece): additional time constraints for metamorphism, extent of infiltration-controlled overprinting and deformational activity[END_REF]].

Furthermore, a crucial point is the correlation of the Variscan basement below the Southern Cyclades (Paros, Naxos, Ios) with the "Menderes core" nappes in Turkey. Indeed, the limited outcropping surfaces of basement rocks in the Cyclades and the Hellenides shows that most of the basement has been subducted [Jolivet et al., 2004a], while the widely outcropping continental basement in the Menderes Massif shows that the crustal wedge is made of basement units to a large extent (see Appendix). Although this continental basement has a similar structural position as the Variscan basement seen in Ios or Naxos [e.g. [START_REF] Henjes-Kunst | Isotopic dating of pre-alpidic rocks from the island of Ios (Cyclades, Greece)[END_REF][START_REF] Andriessen | Isotopic age study of pre-Alpine rocks in the basal units on Naxos, Sikinos and Ios, Greek Cyclades[END_REF], it is mostly of Panafrican age and no trace of a Panafrican event has been detected in the Aegean domain [e.g. [START_REF] Bonneau | Subduction, collision et schistes bleus; l'exemple de l'Egee (Grece)[END_REF][START_REF] Candan | Supra-Pan-African unconformity between core and cover series of the Menderes Massif/Turkey and its geological implications[END_REF].

However, occurrence of Triassic intrusions and the presence of a common Mesozoic sedimentary cover affinity in both regions suggest a common evolution since this period [Jolivet et al., 2004a]. In addition, according to [START_REF] Dürr | The median Aegean crystalline belt: stratigraphy, structure, metamorphism, magmatism. Alps, Apennines[END_REF], the sedimentary formations of the Marina

A C C E P T E D M

A N U S C R I P T 26 unit resemble the SW Lycian Nappes. In this framework, a solution is to see the presence of the large amount of basement on Leros and Kalymnos as a lateral equivalent of Lycian Nappes (without HP-LT evidences), but with a preserved Paleozoic basement that would have overthrust the Menderes Massif and its cover, a basement that is so far unknown in western Turkey.

Nonetheless, [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF] suggest that the pre-Alpidic basement rocks in the Dodecanese islands reveals similarities with the basement in Eastern Crete (i.e. similar lithologies and pre-Alpidic metamorphic evolution). In all cases, while the Cycladic Basement was clearly involved in the Hellenic orogenic wedge, associated with an HP-LT Alpine metamorphic overprint, this event was less severe in the Dodecanese islands (300 -370 °C at 1 -3 kbar [Franz & Okrush, 1992]), and in Eastern Crete (250 -330 °C at 4.5 -8 kbar [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF]). In addition, this HP-LT Alpine event is not recognized within the basement of the Menderes Massif.

Fourni, Samos, western Anatolia and the Cyclades

The nappe stack of Fourni and Samos offers possible correlations with the nearby Menderes Massif and the Lycian Nappes. From top to bottom, the Kallithea nappe can be correlated with the upper Cycladic Nappe and its Pelagonian basement when looking west, and with the Lycian ophiolite or Lycian ophiolitic mélange that root in the Izmir-Ankara suture zone, when looking east in western Turkey (Fig. 14). The presence of a late Cretaceous HT-LP metamorphism associated with an ophiolite on several Cycladic islands (e.g. Anafi [START_REF] Reinecke | Remnants of a late Cretaceous high temperature bet on the island of Anafi (Cyclades, Greece)[END_REF]) shows that the Vardar Ocean ophiolite was once distributed over a large part of the Aegean domain. In addition, the non-metamorphic Thymaena unit on Fourni [Papanikolaou,

A C C E P T E D M A N U S C R I P T

27 1980] and Kefala-Fanari units on Ikaria, may also belong to this Upper Cycladic Nappe/Pelagonian domain (Fig. 14) (see Appendix).

The underlying Fourni unit on Fourni Island and Agios-Kirikos unit on Ikaria present similar lithostratigraphic successions and an apparent lack of a significant HP-LT imprint [START_REF] Papanikolaou | Contribution to the geology of Ikaria Island, Aegean Sea[END_REF], excluding correlation with the CBU. Indeed, Agios-Kirikos unit is made of marbles and metapelites intercalations, and Raman spectroscopy on carbonaceous material (RSCM) results displayed lower temperature ranging between 390 and 450 °C [START_REF] Beaudoin | The ikaria high-temperature metamorphic core complex (Cyclades, Greece): geometry, kinematics and thermal structure[END_REF]. These two units could thus be lateral equivalents of the Menderes cover series, having escaped deep burial and stacked together with the Cycladic Blueschists nappes in a late stage of accretion of the orogenic wedge. In this frame, the Ikaria unit which is tectonically located under the Agios-Kirikos unit, may also correlate with the Menderes cover series (Fig. 14) [START_REF] Kumerics | The extensional Messaria shear zone and associated brittle detachment faults, Aegean Sea, Greece[END_REF].

In the eastern part of Samos Island, the preservation of HP-LT parageneses in Vourliotes nappe with the paragenesis diaspore -quartz suggests that this unit was equilibrated along a very low-temperature and high-pressure gradient (Fig. 15a), similar to the gradient observed on Amorgos (i.e. Amorgos unit), in the cover of the Menderes Massif, or in the Ören unit, three areas where Fe-Mg carpholite has been observed [Minoux et al, 1981;Rimmelé et al., 2003a;2003b;Jolivet et al., 2004a] (Fig. 15a). However, this cold HP unit overlies on Samos the Upper Cycladic Blueschist Nappe (UCB), which has recorded eclogite-facies parageneses. Hence, this structural position differs from the classic structural position of the CBU described first by [START_REF] Grasemann | Miocene postorogenic extension of the Eocene synorogenic imbricated Hellenic subduction channel: New constraints from Milos (Cyclades, Greece)[END_REF] where the LCB nappe overlies the UCB Nappe (see also Roche et al. [2018a]). Therefore the correlation in this area is difficult. It could be an equivalent of the Afyon

A C C E P T E D M A N U S C R I P T 28
and Ören units where HP-LT parageneses have been found (Fig. 14) [e.g. [START_REF] Okay | Distribution and characteristics of the northwest Turkish blueschists[END_REF]Rimmelé et al., 2003a;[START_REF] Pourteau | Multistage growth of Fe-Mg-carpholite and Fe-Mg-chloritoid, from field evidence to thermodynamic modelling[END_REF]]. An alternative solution is that this unit is an equivalent of the LCB Nappe, overthrusted in a late stage of formation of the accretionary wedge on top of the UCB Nappe.

The underlying Ampelos nappe and Selçuk nappe on Samos are similar to the metasediments and ophiolitic mélange of the CBU of the Dilek Peninsula (see Appendix for more information), resting on top of the Menderes Massif [START_REF] Candan | Blueschist relics in the Mesozoic series of the Menderes Massif and correlation with Samos Island, Cyclades[END_REF][START_REF] Oberhänsli | The age of blueschist metamorphism in the Mesozoic cover series of the Menderes massif[END_REF]Ring et al., 1999a]. It may therefore be correlated with the UCB Nappe that crops out mainly on Syros, Sifnos and Tinos (Fig. 14). Even though Chrisomilia unit of Fourni shows a strong retrogression in greenschist-facies conditions, it can be either correlated with the Ampelos nappe (and hence with the UCB Nappe) because of the significant amount of metabasite or it would be a part of the LCB Nappe that crops out in more external zones of the CBU (e.g. Folegandros, Leros) (Figs. 14 and15b).

Finally, a thick marble sequence is recognized in both the lowermost Kerketeas (Samos) and Korakas (Fourni) units. We can correlate these units with the Basal Unit (Fig. 14), which can be observed in the Olympos, Ossa and Almyropotamos tectonic windows [START_REF] Godfriaux | L'Olympe, une fenêtre tectonique dans les Hellénides internes[END_REF][START_REF] Godfriaux | Etude géologique de la région de l'Olympe[END_REF][START_REF] Godfriaux | Sur l'importance des événements tectoniques et métamorphiques d'âge tertiaire en Thessalie septentrionale (L'Olympe, Ossa et Flamburon)[END_REF] and also possibly the Panormos marbles on Tinos [START_REF] Avigad | Low-angle faults above and below a blueschist belt-Tinos Island, Cyclades, Greece[END_REF]], all lateral equivalents of the Gavrovo-Tripolitza nappe.

Dodecaneses islands, Menderes cover and Amorgos Island

Before discussing all possible correlations, it has to be recalled that no consensus exists on the belonging of the HP-LT sequences of the Kurudere-Nebiler units (south Menderes, see

A C C E P T E D M A N U S C R I P T 29
Appendix). This unit has indeed recorded peak conditions of ~ 440 -570 °C and 10 -12 kbar [e.g. Rimmelé et al., 2003b;2005;Whitney et al., 2008] while the UCB Nappe were buried at deeper depths of 530 ± 30 °C and 22 ± 2 kbar (Fig. 15a) [e.g. [START_REF] Laurent | Exhumation of eclogite and blueschist (Cyclades, Greece): Pressure-temperature evolution determined by thermobarometry and garnet equilibrium modelling[END_REF]. In [START_REF] Pourteau | High-pressure metasediments in central Turkey: Constraints on the Neotethyan closure history[END_REF][START_REF] Papanikolaou | Tectonostratigraphic models of the Alpine terranes and subduction history of the Hellenides[END_REF], the Kurudere unit is correlated with the CBU as a whole, but the lithologies and P-T conditions are not equivalent to the typical occurrence of the CBU (Fig. 15) that should show a large amount of metabasites and well-preserved eclogites. It seems more reasonable to consider the cover of the Menderes Massif as an equivalent of the LCB Nappe (Figs. 14 and15a).

The ubiquitous presence of blueschist-facies parageneses in Temenia unit in Leros and Arki islands consolidates the hypothesis of [START_REF] Franz | Polymetamorphic evolution of pre-Alpidic basement relics in the external Hellenides, Greece[END_REF] suggesting that the whole Temenia unit was affected by an HP-LT alpine event, although it was not clearly evidenced in Lipsi Island. The preservation of aragonite, the absence of garnet together with RSCM results (T max conditions around 368 to 487 °C) [Roche et al., 2018a] however show that Temenia unit has recorded lower peak-metamorphic conditions than the nearby Cyclades islands where the UCB Nappe is cropping out (Fig. 15a). In this framework, Temenia unit could be either an equivalent of (i) the metamorphic Ören unit (and hence the lower part of the Lycian Nappes) where HP-LT parageneses with Fe-Mg carpholite have been reported or (ii) the LCB Nappe (Figs. 14 and15b).

Because of similar lithologies and metamorphic conditions between the Temenia unit and the LCB Nappe, we are on the same line as Roche et al. [2018a], suggesting that this unit can be compared with the LCB Nappe, which could in turn be correlated with the cover of the Menderes Massif.

Amorgos exposes a sequence of HP-LT rocks that have undergone two different blueschistfacies metamorphic events (Fig. 15a). A first event is estimated at < 13 kbar and 500 -600 °C

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A N U S C R I P T 30 [START_REF] Rosenbaum | Tectonometamorphic evolution of high-pressure rocks from the island of Amorgos (Central Aegean, Greece)[END_REF] and may correspond to the eclogite-blueschists-facies observed in the UCB Nappe. The second event is associated with Fe-Mg-carpholite and saliotite found in metabauxites and is estimated at 8 -12 kbar and 300 -350 °C [START_REF] Theye | The assemblage diaspore+quartz in metamorphic rocks: a petrological, experimental and thermodynamic study[END_REF]. This unit (i.e. named Amorgos unit) consists of a thick Mesozoic marble sequence capped by an early Tertiary metaflysch, and may be correlated with the cover of the Menderes Massif in terms of lithology and metamorphism (Figs. 14 and15a).

This discussion emphasizes the difficulty of correlating the different nappes of the Hellenides once they have been dispersed by the Oligo-Miocene Aegean extension. The complexity of the situation in the Eastern Aegean region is also due to a lack of metamorphic age constraints on a number of these islands. Further works should thus focus on enlarging the radiochronological data set there. Although all these units have followed different P-T evolutions, a similar structural position is recognized through the entire region. From bottom to top, one then finds (i) the colder units such as the Amorgos unit and the Menderes and its cover before the Main Menderes Metamorphism overprint [START_REF] Sengör | Timing of tectonic events in the Menderes Massif, western Turkey: Implications for tectonic evolution and evidence for pan-African basement in Turkey[END_REF], the LCB Nappe (i.e. Folegandros, the lower unit of Milos, the western Cyclades, a part of the Dodecanese islands, and probably Fourni unit), (ii) the eclogitic rocks observed mainly in the central part of the Cyclades, in Samos and on Dilek peninsula (i.e. the UCB Nappe), and (iii) the Lycian units and Vourliotes nappe in Samos (?) that were buried and exhumed earlier (Figs. 14 and 15). This overall vertical succession can be locally modified suggesting late out-of-sequence thrusting. [START_REF] Walcott | Constraints on the kinematics of post-orogenic extension imposed by stretching lineations in the Aegean region[END_REF][START_REF] Van Hinsbergen | Exhumation with a twist: Paleomagnetic constraints on the evolution of the Menderes metamorphic core complex, western Turkey[END_REF][START_REF] Uzel | Paleomagnetic evidence for an inverse rotation history of Western Anatolia during the exhumation of Menderes core complex[END_REF]. The first stage of deformation corresponds to the stacking of units by thrusting, probably during prograde evolution or at peak pressure. Most kinematic indicators related to this episode of nappe stacking have been erased during subsequent exhumation and further extension, but a limited number of outcrops evidence this kinematics in the Cyclades and in the Olympos-Ossa region. On Syros, [START_REF] Philippon | Tectonics of the Syros blueschists (Cyclades, Greece): From subduction to Aegean extension[END_REF] suggest that the sense of shear was toward the south during the prograde episode (Fig. 16a). Syn-orogenic top-to-the-SW shear sense criteria have also been preserved in the Olympos-Ossa region [START_REF] Schermer | Temperature-time history of subducted continental crust, Mount Olympos Region, Greece[END_REF][START_REF] Ricou | Rhodope and Vardar: the metamorphic and the olistostromic paired belts related to the Cretaceous subduction under Europe[END_REF]Jolivet et al., 2004a;[START_REF] Lacassin | Syn-and post-orogenic exhumation of metamorphic rocks in North Aegean[END_REF]. In addition, our study shows that top-to-the-SE kinematic indicators associated with thrusts are also well preserved on Fourni Island, in the lower part of Fourni unit (Figs. 7 and 16a). Although no clear P-T conditions are established on Fourni, we suggest that these kinematic indicators were recorded during the prograde compressional event.

Tectonic evolution of the Aegean-Anatolia region

A C C E P T E D M A N U S C R I P T 32

The overall architecture of the Menderes Massif and Lycian Nappes also calls for a top-tothe-S emplacement of nappes. The Lycian Nappes, including the lowermost Ören metamorphic unit, was tectonically transported from the northern margin of the Menderes, as the thrusting front was propagating southward [START_REF] Collins | Processes of Late Cretaceous to Late Miocene episodic thrust-sheet translation in the Lycian Taurides, SW Turkey[END_REF]Rimmelé et al., 2003a;2005;[START_REF] Pourteau | Neotethys closure history of Anatolia: insights from 40Ar-39Ar geochronology and P-T estimation in high-pressure metasedimentary rocks[END_REF]. Similarly, large-scale top-to-the-S shear zone are described within the Menderes Massif (i.e. Selimiye Shear Zone (SSZ); Fig. 16a), between the basement and the cover [e.g. [START_REF] Bozkurt | Southern Menderes Massif: an incipient metamorphic core complex in western Anatolia, Turkey[END_REF][START_REF] Hetzel | Intrusion age of Pan-African augen gneisses in the southern Menderes Massif and the age of cooling after Alpine ductile extensional deformation[END_REF], which may be ascribed to this prograpde phase, although their significance, whether they are thrusts or detachments or both, is still debated [e.g. [START_REF] Bozkurt | Southern Menderes Massif: an incipient metamorphic core complex in western Anatolia, Turkey[END_REF][START_REF] Whitney | Metamorphic history of the southern Menderes massif, western Turkey[END_REF]Ring et al., 1999a;2003].

Syn-orogenic deformation

The exhumation process encompassed the syn-orogenic stage through different extensional and compressional structures. Extensional structures are observed in the Cyclades domain within the CBU and in southern Turkey. On Samos Island, a continuum from ductile blueschist-to greenschist-facies deformation is preserved across the contact between the Kerketeas and the Ampelos units with a top-to-the-W-NW shearing (Fig. 16a) [Ring et al., 1999b], suggesting that the Pythagoras shear zone has accommodated a part of the syn-orogenic exhumation during the HP-LT metamorphic event. Top-to-the-E shearing deformation along the Vari Detachment (in Syros Island) also allowed the exhumation of the CBU sequence within the subduction channel (Fig. 16a) [e.g. [START_REF] Jolivet | Subduction tectonics and exhumation of high-pressure metamorphic rocks in the Mediterranean orogens[END_REF][START_REF] Van Hinsbergen | A key extensional metamorphic complex reviewed and restored: The Menderes Massif of western Turkey[END_REF][START_REF] Huet | Thrust or detachment? Exhumation processes in the Aegean: Insight from a field study on Ios (Cyclades, Greece)[END_REF][START_REF] Laurent | Strain localization in a fossilized subduction channel: Insights from the Cycladic Blueschist Unit (Syros, Greece)[END_REF]. However, the apparent inconsistency between N-S and E-W lineation at the base and to the top of the CBU, respectively, is difficult to explain. One may assume that the original trend of the lineation is not

A C C E P T E D M A N U S C R I P T 33
known in the absence of paleomagnetic data and it could be envisaged that is was more NE (or N?)-trending, according to HP lineations recorded on the neighboring Sifnos Island [e.g. Roche et al., 2016]. In the HP-LT Lycian Nappes in Western Turkey, contrasted P-T conditions indicate the existence of numerous shear zones accommodating their exhumation [Rimmelé et al., 2003a].

Top-to-the-E shear senses are recorded within the entire HP-LT sequence, and deformation appears more localized close to the contact between the Lycian and Menderes Massif [START_REF] Rimmelé | Exhumation Paths of High-Pressure-Low-Temperature Metamorphic Rocks from the Lycian Nappes and the Menderes Massif (SW Turkey): a Multi-Equilibrium Approach[END_REF]. Hence, this deformation post-dated the early southward translation of the Lycian Nappes and corresponds to the exhumation of HP-LT rocks that was aided by the reactivation of major thrusts with a new top-to-the-NE to -E shearing.

Compressional structures are mainly recorded in the southern Cyclades. For instance, topto-the-S thrusting in Ios Island is also coeval with the extensional shear zone of Vari (Fig. 16a) [START_REF] Huet | Thrust or detachment? Exhumation processes in the Aegean: Insight from a field study on Ios (Cyclades, Greece)[END_REF]. According to this study, an extrusion structure is proposed to explain exhumation of the CBU [see also [START_REF] Ring | Early exhumation of high-pressure rocks in extrusion wedges: Cycladic blueschist unit in the eastern Aegean, Greece, and Turkey[END_REF][START_REF] Huet | Thrust or detachment? Exhumation processes in the Aegean: Insight from a field study on Ios (Cyclades, Greece)[END_REF]. However, recent studies [e.g. [START_REF] Grasemann | Miocene postorogenic extension of the Eocene synorogenic imbricated Hellenic subduction channel: New constraints from Milos (Cyclades, Greece)[END_REF]Roche et al., 2018a] show the existence of a LCB Nappe outcropping in the southern Cycaldes (Fig. 16a), as a consequence this basal thrust cannot explain the entire exhumation of CBU. This short discussion emphasizes the 3-D complexity of the wedge, where HP-LT synorogenic exhumation shearing may be approximately E-W in some places (i.e. parallel to the trench; e.g. Syros, Samos, Ören unit) whereas it is for instance N-S in other areas (e.g. Ios Island) (Fig. 16a). In any case, the accretionary complex is particularly wide and made of different tectonic slices such as continental basement (e.g. Menderes Massif, Cycladic Basement), oceanic (e.g. the CBU) and cover units (e.g. Kurudere-Nebiler units, Ören unit). The overall picture of the extensional kinematics of the Aegean Sea and western Anatolia shows that the direction and sense of displacement along the main detachments during slab retreat is consistent over the entire eastern and central Cyclades. This area presents a pervasive network of large-scale to small-scale ductile-brittle shear zones in all metamorphic units and ductile and brittle criteria show an overall consistent top-to-the-NNE kinematics from the Central Aegean (Paros-Naxos) to the Dodecanese and Eastern Aegean islands with rare top-to-the-SW (e.g. locally on Leros) and top-to-the-WNW kinematics (e.g. locally on Samos) (Fig. 16b).

Because the top-NNE kinematics of the eastern and central Cyclades is associated with HT-LP metamorphic overprint (with local anatexy) at many places (e.g. in Ikaria, Mykonos and Naxos from ~ 20 Ma to the Late Miocene) (e.g. a-type domes [Jolivet et al., 2004b], and with the emplacement of the Aegean granitoids [e.g. [START_REF] Altherr | I-type plutonism in a continental back-arc setting: Miocene granitoids and monzonites from the central Aegean Sea, Greece[END_REF][START_REF] Rabillard | Synextensional Granitoids and Detachment Systems Within Cycladic Metamorphic Core Complexes (Aegean Sea, Greece): Toward a Regional Tectonomagmatic Model[END_REF], we suggest that most of post-orogenic exention is accommodated by top-to-the-NNE shearing in this large area. However, this is not the case further west (western Cyclades), south (southern Cyclades) and east (Menderes Massif). There, deformation appears more symmetrical, characterized by several detachment systems exhibiting opposing kinematics (e.g. the WCDS and NCDS in the Cyclades [e.g. Jolivet et al., 2010;[START_REF] Grasemann | Miocene bivergent crustal extension in the Aegean: Evidence from the western Cyclades (Greece)[END_REF], the Santorini detachment [START_REF] Grasemann | Miocene postorogenic extension of the Eocene synorogenic imbricated Hellenic subduction channel: New constraints from Milos (Cyclades, Greece)[END_REF], the Büyük Menderes and the Gediz detachments [e.g. Hetzel et al., 1995a;[START_REF] Gessner | An active bivergent rolling-hinge detachment system: Central Menderes metamorphic core complex in western Turkey[END_REF]; Fig. 16b). However, the bivergent pattern in the Menderes Massif is mostly due to the most recent part of extension, from ~ 20 Ma to the present [e.g. Hetzel et al., 1995b;[START_REF] Gessner | An active bivergent rolling-hinge detachment system: Central Menderes metamorphic core complex in western Turkey[END_REF]. Before this event, the main detachment exhuming the [START_REF] Ring | Tectonic denudation of a Late Cretaceous-Tertiary collisional belt: regionally symmetric cooling patterns and their relation to extensional faults in the Anatolide belt of western Turkey[END_REF]Seyítoǧlu et al., 2004;[START_REF] Bozkurt | Surprisingly young Rb/Sr ages from the Simav extensional detachment fault zone, northern Menderes Massif, Turkey[END_REF][START_REF] Cenki-Tok | Complete Alpine reworking of the northern Menderes Massif, western Turkey[END_REF]. Furthermore, according to Ring et al. [1999b], NNE extension was interrupted by a shortlived phase of E-W shortening between 9 and 8.6 Ma, essentially recorded in the brittle crust.

This compressional event, which may also be associated with some strike-slip component [START_REF] Papanikolaou | Unites tectoniques et phases de deformation dans l'ile de Samos, Mer Egee, Grece[END_REF], is ascertained in Samos by the presence a several reverse faults that affect both the margins of the Miocene basin and the basin itself. Folds formed in the Miocene deposits before the deposition of the Mytilini formation are also compatible with this event. This Miocene compressional event has also been recognized on Mykonos during the late stages of cooling of the intrusion some 9 Ma ago [START_REF] Menant | The North Cycladic Detachment System and associated mineralization, Mykonos, Greece: Insights on the evolution of the Aegean domain[END_REF]. Following [START_REF] Menant | The North Cycladic Detachment System and associated mineralization, Mykonos, Greece: Insights on the evolution of the Aegean domain[END_REF], we suggest that the extrusion of Anatolia may be responsible for this regional compressional event in the brittle crust of the central Cyclades, before strike-slip deformation localized on the edge of the Aegean domain when the NAF reached the north Aegean Sea in the Late Miocene [START_REF] Armijo | Westward propagation of the North Anatolian fault into the northern Aegean: Timing and kinematics[END_REF][START_REF] Koukouvelas | Fault structure and related basins of the North Aegean Sea and its surroundings[END_REF]. [START_REF] Armijo | Linear elastic fracture mechanics explains the past and present evolution of the Aegean[END_REF] proposed that propagation of the NAF and its satellites would produce a compressional stress regime, just south of the western tip of the faults, while an extensional regime would be active north of the fault. The short compressional event could then be due to the propagation of such a strike-slip system, just north of Samos. However, this would make the NAF propagate earlier than usually postulated (~ 5 Ma) as the age of the compression is estimated ~ 9 Ma. It is thus important to obtain more data to precise this point.

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A N U S C R I P T 36 Finally, the late stage of brittle deformation is compatible with a N-S to NNE-SSW extension over large areas [e.g. [START_REF] Brun | The two-stage Aegean extension, from localized to distributed, a result of slab rollback acceleration[END_REF]Ring et al., 2017]. For instance, in the Menderes massif, E-W striking high-angle normal faults control the structure of Neogene basins. These set of faults, seismically active, started to operate around ~ 5 Ma ago [START_REF] Ring | Tectonic denudation of a Late Cretaceous-Tertiary collisional belt: regionally symmetric cooling patterns and their relation to extensional faults in the Anatolide belt of western Turkey[END_REF],

and are co-directional with the extension direction of earlier low-angle normal faults. In addition, inversion of GPS data that estimates the present-day strain field [START_REF] Pérouse | Bridging onshore and offshore present-day kinematics of central and eastern Mediterranean: Implications for crustal dynamics and mantle flow[END_REF][START_REF] Aktug | Deformation of western Turkey from a combination of permanent and campaign GPS data: Limits to block-like behavior[END_REF], and fault mechanism from the earthquake on Lesbos (data from the USGS Earthquake Hazards Program) showing a normal component, are both consistent with a N-S extension. 4.3. Slab tearing: which consequences in the overriding plate? Before discussing tectonic and thermal consequences of slab tearing, we need to clarify the timing of the tear formation below western Turkey. Paleomagnetic measurements show that the main differential rotation between the Hellenides and western Anatolia took place between 15 and 8 Ma [e.g. [START_REF] Morris | First palaeomagnetic results from the Cycladic Massif, Greece, and their implications for Miocene extension directions and tectonic models in the Aegean[END_REF][START_REF] Van Hinsbergen | Exhumation with a twist: Paleomagnetic constraints on the evolution of the Menderes metamorphic core complex, western Turkey[END_REF][START_REF] Van Hinsbergen | Map view restoration of Aegean-West Anatolian accretion and extension since the Eocene[END_REF]. This timing also corresponds to the exhumation of high-temperature metamorphic domes below top-NE detachments in the central and eastern Aegean Sea and emplacement of the Aegean granitoids. Accordingly, [START_REF] Jolivet | Neo-Tethys geodynamics and mantle convection: from extension to compression in Africa and a conceptual model for obduction[END_REF] suggested a ~ 15 Ma age for the main slab tearing event, which is consistent with the timing of a K-rich magmatic pulse in western Turkey [e.g. [START_REF] Dilek | Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt[END_REF][START_REF] Ersoy | Eocene-Quaternary magmatic activity in the Aegean: implications for mantle metasomatism and magma genesis in an evolving orogeny[END_REF]. Alternatively, [START_REF] Govers | Signature of slab fragmentation beneath Anatolia from fullwaveform tomography[END_REF] suggested that the slab tear started to forms earlier (i. Within the transition zone from the Menderes Massif to the Cyclades, we showed that the direction of extension is consistently NNE-SSW with no major change in trend, and the sense of shear is predominantly top-to-the-NNE (Fig. 16b). Most of the observed deformation relates to low-angle normal faults and ductile shear zones, without any clear large-scale strike-slip fault systems that could have been expected above a slab tear. This confirms the ideas put forward by [START_REF] Gessner | What caused the denudation of the Menderes Massif: Review of crustal evolution, lithosphere structure, and dynamic topography in southwest Turkey[END_REF] and [START_REF] Jolivet | Neo-Tethys geodynamics and mantle convection: from extension to compression in Africa and a conceptual model for obduction[END_REF] of a wide zone of gradient of extension accommodating the left-lateral displacement imposed by the faster retreat south of the Aegean Sea than of the Menderes Massif. Most of the related deformation in the lower crust is then accommodated by low-angle shear zones, which is compatible with the idea that the deformation in this region is largely controlled by the flow of asthenospheric mantle underneath [START_REF] Jolivet | From mantle to crust: Stretching the Mediterranean[END_REF]2015;Menant et al., 2016b]. Seismic anisotropy data [START_REF] Endrun | Complex layered deformation within the Aegean crust and mantle revealed by seismic anisotropy[END_REF] are also compatible with this hypothesis, suggesting a strong coupling between SW-NE mantle fabrics and the frozen-in fabric in the lower crust. We therefore challenge the hypothesis of Ring et al. [2017] which suggest an important change in strain pattern in this region. Nonetheless, it is noteworthy that different fission-track age patterns have been recorded in both regions (i.e.

Cyclades and Menderes Massif) (see the compilation of Ring et al. [2017]), suggesting a difference of exhumation and erosion rates. Alternatively, to reconcile complex deformation pattern recorded in the brittle crust and in sedimentary basins during the Miocene [Ring et al., 1999b;2017] to the consistent NE-SW ductile flow in the metamorphic crust (Fig. 16b), one may suggest a possible decoupling between the brittle upper and the ductile lower crust at some The thermal effects induced by slab dynamics (i.e. mantle flows and shear heating) appear clearly since the Miocene (e.g. numerous K-rich magmatic pulses [START_REF] Dilek | Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt[END_REF][START_REF] Ersoy | Eocene-Quaternary magmatic activity in the Aegean: implications for mantle metasomatism and magma genesis in an evolving orogeny[END_REF]) and are essential in the eastern Aegean domain [e.g. see Roche et al., 2018b]. Slab dynamics controls the bulk of heat source at the base of the crust and therefore explains (i) the different pattern of deformation, asymmetrical in the central and eastern Aegean Sea versus symmetrical in the western Cyclades and in the Menderes Massif, which may be related to the activity of asthenospheric flow underneath [START_REF] Jolivet | Neo-Tethys geodynamics and mantle convection: from extension to compression in Africa and a conceptual model for obduction[END_REF], (ii) the retrogression in greenschist-facies or amphibolite-facies conditions within the metamorphic domes in the Aegean domain, (ii) the current localization of geothermal resources in the Menderes Massif [Gessener et al., 2018;Roche et al., 2018c].

Conclusion

Based on a field study in the eastern part of the Cyclades (Eastern Aegean islands and Dodecanese), we (i) produce new geological maps and describe the tectonic evolution of this region, (ii) clarify the correlations and differences between the Aegean Sea and the Menderes Massif in terms of lithological and tectonic units and metamorphic evolution and we (iii) complete the description of extensional shearing direction and sense over the entire back-arc region. We highlight the structure of the accretionary complex that may be defined by three main

  After the closure of the Vardar Ocean in the late Cretaceous-Paleocene, subduction of

  A C C E P T E D M A N U S C R I P T 16 separating Fourni unit from Chrisomilia unit, and (iii) Thymaena Detachment between Thymaena and Fourni units, cropping out only on Thymaena Island and possibly in the central part of Fourni (Fig. 2b).

  A C C E P T E D M A N U S C R I P T 17 associated with strike-slip kinematic indicators. The original lithological contacts are generally transposed into the main penetrative foliation, as shown by isoclinal folds locally observed within dolomitic marble layers (Fig.

Figures 4

 4 Figures 4 and 11. The main foliation strikes N90°E to N135°E with variable dips. It is affected by

  foliation do not change significantly across it. There, folded foliation develops a new crenulation with fold axes almost parallel to the main stretching lineation (see stereogram on Fig.12b). Depending on localities, isoclinal folds with axes perpendicular to stretching lineation (trending ENE-WSW to E-W, see stereogram on Fig.12c) are also observed. Both folding events are located close to the main contact (i.e. the Temenia shear zone) and thus probably contemporaneous with the mylonitic foliation localized between the Temenia and Marina units.

  (i.e. closure basin stage & subduction) known as the Cimmerides orogeny occurs only in the A C C E P T E D M A N U S C R I P T 25 eastern Aegean islands of Lesvos and Chios and possibly also in the Circum Rhodope belt. 2)

Figure 16

 16 Figure 16 is a map of kinematic indicators covering the Aegean Sea and the Menderes

  4.2.1. Kinematics of deformation from the Cretaceous to the Oligocene 4.2.1.1. Prograde deformation

  2. An overall NNE-SSW gradient of extension from Oligo-Miocene to Present

  active in the north (Simav Detachment) with a top-to-the-N kinematics [e.g.Işık & Tekeli, 2001], exhuming partially molten crust (Fig.16b). Characterized by episodic activities, this detachment fault started in the late Oligocene and have continued until 8 Ma [e.g.

  e. ~ 35 Ma) following the arrival of A C C E P T E D M A N U S C R I P T 37 the Central Anatolian Crystalline Complex in the accretionary complex. Therefore, we cannot rule out that slab tearing might start earlier, but at a slower pace.

  hypothesis have to be further investigated but it would imply that the overall geometry and kinematics revealed by this study mainly results from basal drag due to the underlying asthenospheric flow.

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Acknowledgement:

This work has received funding from the Labex Voltaire (ANR-10-LABX-100-01) homed at Orléans University and BRGM, from the European Research Council (ERC) under the seventh Framework Programme of the European Union (ERC Advanced Grant, grant agreement No 290864, RHEOLITH), and from the Institut Universitaire de France. The authors are grateful to S. Janiec and J.G. Badin (ISTO) for the preparation of thin sections and to Clément Conand for fieldwork together in Leros. We are gratefull to Bernhard Grasemann and an anonymous reviewer for their relevant suggestions.

Abstract

Slab tearing below western Turkey had first-order tectonic and magmatic consequences by inducing a lateral gradient of extension in the upper plate and toroidal flow of asthenosphere that affected the typology and distribution of melts at the surface. But the coupling mechanisms between the 3D mantle flow at depth and deformation in the upper plate above a slab tear have received little attention so far. This paper is focused on the description of the distribution and kinematics of deformation in the eastern part of the Aegean Sea, within the transition zone between the Cyclades and the Menderes Massif, which have been little studied. By investigating the Dodecanese and Eastern Aegean islands, we thus complete the description of the extensional strain field in the overriding plate around the slab tear. There, extension related to slab retreat and tearing keeps a constant NNE-SSW direction accommodating the difference in finite rates of extension, without localized crustal-scale strike-slip faults and block rotations above the tear. In addition, despite the complexity involved in the Aegean-Anatolian orogenic wedge, a similar structural position is recognized through the entire region. From top to bottom, we found that (i) the Lycian units which were exhumed earlier, in the Late Cretaceous, (ii) the higher-pressure and higher-temperature units (i.e. the Upper Cycladic Blueschist Nappe), with exception of the Vourliotes nappe in Samos, and finally (iii) the colder units such as Amorgos unit, the Menderes and its cover before the Main Menderes Metamorphism overprint and the Lower Cycladic Blueschist Nappe (e.g. Milos, Folegandros, a part of the Dodecanese and Fourni islands).

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