Gondwana Research 24 (2013) 243–274 Contents lists available at SciVerse ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr GR Focus Review What caused the denudation of the Menderes Massif: Review of crustal evolution, lithosphere structure, and dynamic topography in southwest Turkey Klaus Gessner a,⁎, Luis A. Gallardo b, Vanessa Markwitz c, Uwe Ring d, Stuart N. Thomson e a Western Australian Geothermal Centre of Excellence, and Centre for Exploration Targeting, The University of Western Australia, M006, 35 Stirling Highway, Crawley 6009, Australia Earth Science Division, CICESE, Carretera Ensenada-Tijuana No. 3918, CP 22860, Ensenada, Mexico Centre for Exploration Targeting, The University of Western Australia, M006, 35 Stirling Highway, Crawley 6009, Australia d Department of Geological Sciences, Stockholm University, SE-106 91 Stockholm, Sweden e Department of Geosciences, University of Arizona, Gould-Simpson Building, 1040 E. 4th St., Tucson, AZ 85721-0077, USA b c a r t i c l e i n f o Article history: Received 31 March 2012 Received in revised form 28 January 2013 Accepted 31 January 2013 Available online 16 February 2013 Handling Editor: M. Santosh Keywords: Metamorphic core complex Continental extension Turkey Aegean Sea Menderes Massif Lithosphere delamination Dynamic topography a b s t r a c t The deformation of Earth's lithosphere in orogenic belts is largely forced externally by the sinking slab, but can also be driven by internal delamination processes caused by mechanical instabilities. Here we present an integrated analysis of geophysical and geological data to show how these processes can act contemporaneously and in close proximity to each other, along a lithosphere scale discontinuity that defines the lateral boundary between the Hellenide and Anatolide segments of the Tethyan orogen in western Turkey. The Hellenides and Anatolides have experienced similar rates of convergence, but display remarkable differences in the structure of Earth's crust and lithospheric mantle across the Aegean coast of the Anatolian peninsula. We review the tectonics of southwest Turkey in the light of new and published data on crustal structure, cooling history, topography evolution, gravity, Moho topography, earthquake distribution and seismic tomography. Geological data constrain that one of Earth's largest metamorphic core complexes, the Menderes Massif, experienced early Miocene tectonic denudation and surface uplift in the footwall of a north-directed extensional detachment system, followed by late Miocene to recent fragmentation by E–W and NW–SE trending graben systems. Gravity data, earthquake locations and seismic velocity anomalies highlight a north–south oriented boundary in the upper mantle between a fast slab below the Aegean and a slow asthenospheric region below western Turkey. Based on the interpretation of geological and geophysical data we propose that the tectonic denudation of the Menderes Massif and the delamination of its subcontinental lithospheric mantle reflect the late Oligocene/early Miocene onset of transtension along a lithosphere scale shear zone, the West Anatolia Transfer Zone (WATZ). We argue that the WATZ localised along the boundary of the Adriatic and Anatolian lithospheric domains in the Miocene, when southward rollback of the Aegean slab started to affect the central Aegean–Menderes portion of the Tethyan orogen. Transtension across the West Anatolia Transfer Zone affected the entire Menderes Massif in the Early Miocene. The current crustal expression of this boundary is a NNE-trending, distributed brittle deformation zone that localised at the western margin of the denuded massif. Here, sinistral transtension accommodates the continuing velocity difference between relatively slow removal of lithospheric mantle below western Anatolia and trench retreat in the rapidly extending Aegean Sea region. Our review highlights the significance of lateral variations of the lower plate in subduction–collision systems for evolving structure and surface processes in orogenic belts, particularly in relation to the formation of continental plateaux and metamorphic core complexes. © 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. Contents 1. 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . Regional tectonic overview . . . . . . . . . . . . . . . . . . 2.1. Structure of the Hellenides in the Aegean Sea region . . 2.2. Structure of the Anatolides in western Turkey . . . . . 2.3. Controversies on Alpine tectonics of the Menderes Massif . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 245 246 246 249 ⁎ Corresponding author at: Geological Survey of Western Australia, Department of Mines and Petroleum, 100 Plain Street, East Perth, WA 6004, Australia. E-mail addresses: [email protected] (K. Gessner), [email protected] (L.A. Gallardo), [email protected] (V. Markwitz), [email protected] (U. Ring), [email protected] (S.N. Thomson). 1342-937X/$ – see front matter © 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gr.2013.01.005 244 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 2.3.1. Alpine crustal shortening and the age of deformation fabrics . . . . . . . . . . 2.3.2. Significance of the Selimiye shear zone . . . . . . . . . . . . . . . . . . . . . 2.3.3. Stratigraphic position of low grade metasediments . . . . . . . . . . . . . . . 2.4. Miocene to recent extension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.1. Extension of the Anatolide belt . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2. Magmatic record of crustal extension . . . . . . . . . . . . . . . . . . . . . 2.5. Controversies on crustal extension . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.1. Fabric overprinting — extension or contraction? . . . . . . . . . . . . . . . . 2.5.2. Exhumation of the Gördes submassif and the role of the Simav detachment . . . 2.5.3. Block rotation versus diffuse extension . . . . . . . . . . . . . . . . . . . . . 3. Topographic response to crustal extension . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Methods and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Topographic profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3. Drainage channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4. Interpretation of topography and river channel data . . . . . . . . . . . . . . . . . . . 4. Upper mantle structure and active deformation . . . . . . . . . . . . . . . . . . . . . . . . 4.1. Geophysical evidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1. Gravity anomaly and Moho depth . . . . . . . . . . . . . . . . . . . . . . . 4.1.2. Earthquake hypocentres . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.3. 3D model of seismic tomography and earthquake hypocenters . . . . . . . . . 4.2. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Tectonic synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1. Lateral differences in lithospheric structure . . . . . . . . . . . . . . . . . . . . . . . 5.2. Sinistral transtension across West Anatolian Transfer Zone as a driver for Menderes extension 5.3. Continuous versus punctuated crustal extension . . . . . . . . . . . . . . . . . . . . . 5.4. Open questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Summary points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix A. Supplementary data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Introduction Lithosphere architecture and strain distribution can vary substantially in orogenic belts, both across and along strike. Along-strike variations and structural complexity are common features of mountain belts such as the European Alps (e.g. Schmid et al., 2004), the Andes (e.g. Allmendinger et al., 1997), the Himalayas (e.g. An, 2006) and the Hellenide–Anatolide orogen in southeastern Europe (Ring et al., 1999a; Gessner et al., 2001c; Gessner et al., 2011; van Hinsbergen and Schmid, 2012). The causes for along-strike variations are likely to differ in individual orogenic belts, but will generally be a consequence of compositional and architectural variations in the accreting or colliding continental lithosphere fragments. Along-strike variations, however, depend not only on the composition and architecture of these fragments, but also on the differential dynamics generated by the sinking slab, and by mechanical instabilities that affect the accretion of continental arcs even at distances far from the actual tectonic margin, and shape the geology, topography and the lithosphere structure sensed by geophysical data. It has been recognised that throughout the Earth's history tectonic and magmatic accretion of continental arcs not only have played an important role in the growth of continents (Rudnick, 1995), but also as regions of long-lived thermally weakened mobile belts (Hyndman et al., 2005). Conceptual and numerical models of generic and regionally specific continental arcs suggest that deformation is not only mainly driven by external forcing by the sinking slab (Royden, 1993; Collins, 2002; Schellart et al., 2007; Spakman and Hall, 2010), but also internally, by gravitational instabilities within thermally weakened lithosphere (Houseman et al., 1981; England and Houseman, 1989; Molnar et al., 1993; Platt and England, 1993; Houseman and Molnar, 1997; Stern et al., 2006), with mechanical and thermal coupling across the subduction zone determining how these processes interact (Faccenda et al., 2009). The significance of considering ‘internal drivers’ such as gravitational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 249 249 250 250 252 255 255 255 255 256 256 256 256 257 259 261 261 261 262 263 264 265 266 268 269 269 270 270 270 instabilities in addition to ‘external drivers’ such as sinking slabs, is that synchronous contraction and extension can be accommodated in the Earth's crust over relatively short across-strike distances (Gögüs and Pysklywec, 2008; Faccenda et al., 2009). Such internal driving processes pose a challenge to the existence of regional or far-field force continua across orogens, an assumption that is often made a priori when deformation fabrics are linked with geodynamic processes in ancient orogenic belts. The partition of deformation along active continental collision zones such as the Tethyan orogen in the Eastern Mediterranean provide a natural laboratory where the recent and current evolution of geological structures can be studied and interpreted in the context of surface processes, gravity anomalies, seismicity, geodetic measurements, and mantle tomography. In the Eastern Mediterranean the southward rollback of the Hellenic subduction zone and the westward motion of Anatolia dominate the kinematics of continental plate fragments as they occur at much higher rates than the convergence between Africa and Eurasia (e.g. Reilinger et al., 2006; Pérouse et al., 2012) (Fig. 1). This study focuses on southwest Turkey, where the westward movement of Anatolia changes to the southward movement of the Aegean, where the Anatolian plateau gives way to the Aegean Sea, and where the Hellenide and Anatolide segments of the Tethyan orogen meet. We describe the regional structure across the Hellenide–Anatolide transition and, in the light of new and published apatite fission track data, discuss the tectonic models put forward for the Menderes Massif, particularly with regard to key structures like the Simav detachment and the Selimiye shear zone. We then use the structure of the Alpine nappe stack as a marker to track the deformation imposed on western Anatolia by the late Miocene to recent extension, as evidenced by topography and drainage channel morphology. Using geophysical data such as gravity, seismic velocity anomaly, and earthquake hypocentre locations we show how the geological along-strike-differences between the Hellenic and the Anatolide crustal domains relate to the K. Gessner et al. / Gondwana Research 24 (2013) 243–274 245 the Eastern Mediterranean. We propose that a lithospheric scale transfer zone, the West Anatolia Transfer Zone (WATZ) defines the lateral boundary between the Hellenide and Anatolide orogens, where slab rollback in the Aegean and delamination of the lithospheric mantle in western Anatolia have operated contemporaneously and in close proximity to each other; causing tectonic denudation of the lower crust in the Aegean and in the Menderes Massif. 2. Regional tectonic overview Fig. 1. Kinematic configuration and geodetic measurements of continental fragments in the Eastern Mediterranean, Arabia and the Caucasus relative to a fixed Eurasia; notice the relatively high velocities of Anatolia and the Aegean — driven by suction of the Aegean slab — relative to the convergence between Nubia/Arabia and Eurasia — driven by slab pull, and the uncertainty of how the difference in movement direction between Anatolia and the Aegean is accommodated. Modified from Reilinger et al. (2006). upper mantle structure below western Turkey. Finally, we synthesise our evidence to discuss the lateral differences in lithosphere structure as the driver of the Menderes extension and in the geodynamics of The Hellenide orogen of Greece and the Anatolide belt of western Turkey form an arcuate orogenic belt north of the Hellenic subduction zone (Fig. 2). Both the Hellenides and the Anatolides consist of stacked tectonic units that are overlain by the Late Cretaceous to Paleogene Vardar–İzmir–Ankara suture zone to the north. The Adriatic plate has played a key role in the tectonic development of the Mediterranean region. It has rifted from the northern margin of Gondwana in the Cretaceous and still moves independently of the Eurasian Plate. In the eastern Mediterranean little is known about the Mesozoic to early Tertiary paleogeography of the Adriatic plate, which appears to pinch out eastwards. In the Mesozoic, continental crust of the Adriatic plate as exposed today on the Attic Peninsula and in the Aegean, varied between normal thickness, highly stretched and thinned; and locally may have been oceanic (Jacobshagen, 1986; Robertson et al., 1991). The continental fragment directly east of the Adriatic plate was termed Anatolide–Tauride platform (Sengör and Yilmaz, 1981), or — following Gessner et al. (2001c) — also as Anatolia. Tectonic units within the Hellenide–Anatolide orogen are aligned Fig. 2. Simplified tectonic overview of the Aegean Sea region, with Adriatic plate units in blue, Anatolian plate units in pink, Eurasian plate units in brown, and Vardar–İzmir–Ankara oceanic units in green. The Pindos unit, including widespread high-pressure metamorphic rocks, overlies the External Hellenides in the west. In the east the equivalent Cycladic Blueschist unit overlies the Menderes Massif, which lacks Alpine high-pressure metamorphism. The box shows the extent of Figs. 4, 15, 16, and 17. 246 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 parallel to the present-day Hellenic subduction zone. Once believed to be a ‘Median Crystalline Belt’ (Dürr et al., 1978), the metamorphic rocks of the Pelagonian zone (Aubouin, 1959), the Cycladic zone, and the Menderes Massif (Paréjas, 1940; Brinkmann, 1971) are now known to be different tectonic units (Robertson and Dixon, 1984; Erdogan and Güngör, 1992; Robertson et al., 1996; Ring et al., 1999b; Gessner et al., 2001c; Jolivet and Brun, 2010; Ring et al., 2010; van Hinsbergen and Schmid, 2012). Rather than representing an eastern extension of the Carboniferous basement and Permo-Mesozoic cover of the Adriatic plate, the Anatolide belt is made up of two different units that do not share the same Alpine tectono-metamorphic history, the Cycladic Blueschist unit and the underlying Menderes nappes (Ring et al., 1999a; Gessner et al., 2001a; Gessner et al., 2001c; Regnier et al., 2003). In the Menderes nappes, pronounced magmatic activity occurred at the Proterozoic/Cambrian boundary (Hetzel and Reischmann, 1996; Dannat and Reischmann, 1999; Gessner et al., 2001a; Reischmann and Loos, 2001; Zlatkin et al., 2012), the mid-Triassic (Dannat, 1997; Koralay et al., 2001) and the Miocene (Hetzel et al., 1995b; Seyitoglu and Scott, 1996; Isik and Tekeli, 2001; Ring and Collins, 2005; Glodny and Hetzel, 2007; Ersoy et al., 2008; Akay, 2009; Dilek and Altunkaynak, 2009; Hasozbek et al., 2010; Prelevic et al., 2010a; Prelevic et al., 2010b; Hasozbek et al., 2011; Öner and Dilek, 2011; Altunkaynak et al., 2012a, 2012b; Catlos et al., 2012; Hasozbek et al., 2012). In the Cycladic zone, the granitic basement is of Carboniferous age (Reischmann, 1997; Engel and Reischmann, 1998). In addition, there are Triassic intrusions (Reischmann, 1997; Ring et al., 1999b) and prominent Miocene to recent magmatic activity (Altherr et al., 1982). 2.1. Structure of the Hellenides in the Aegean Sea region The Hellenides consist of five tectonic units. These are from top (north) to bottom (south), (1) the Eurasian plate units, such as for example the Serbo-Macedonian Block, (2) the Vardar–İzmir–Ankara Oceanic units, (3) the Pelagonian Zone, (4) the Pindos Unit (including the Cycladic Blueschist Unit), (5) the External Hellenides, including the Gavrovo–Tripolitza Block and the underlying Ionian Block, and (6) the Mediterranean Ridge Accretionary Complex (Fig. 2). Of these, only the top three units can be correlated across from the Hellenides to the Anatolides in western Turkey (Ring et al., 1999a). The Pindos unit is a subduction complex that formed between ca. 55 Ma and 30 Ma (Ring and Layer, 2003; Jolivet and Brun, 2010; Ring et al., 2010) and comprises normal-thickness continental basement–cover sequences, as well as thick radiolarite sequences indicating that locally it was underlain by oceanic crust, or by thinned continental crust (Pe-Piper and Piper, 1984; Robertson et al., 1991). In the Cyclades, the uppermost unit of the Pindos Unit is the highly attenuated ophiolitic Selçuk Mélange (Okrusch and Bröcker, 1990; Ring et al., 1999b; Katzir et al., 2000), which forms the upper part of the Cycladic Blueschist Unit. The lower part of the Cycladic Blueschist Unit comprises Carboniferous schist and orthogneiss, and a late- to post-Carboniferous passive-margin sequence of marble, metapelite and volcanics (Dürr et al., 1978). The Gavrovo–Tripolitza Block is a continental platform unit of Triassic to Eocene age, partly overlain by late Eocene to early Oligocene turbidites (Jacobshagen, 1986). Subduction of the Gavrovo–Tripolitza Block commenced at ca. 35–30 Ma (Thomson et al., 1998; Sotiropoulos and Kamberis, 2003). In the Cyclades, high-pressure rocks of the Gavrovo– Tripolitza Block that are locally exposed in tectonic windows below the Cycladic Blueschist Unit are usually referred to as the Basal Unit (Godfriaux, 1968; Shaked et al., 2000; Ring et al., 2001a). In the Peloponnese and in Crete, the rocks of the Gavrovo–Tripolitza Block and the Pindos Unit are only weakly metamorphosed. The Ionian block comprises late Carboniferous to possibly Triassic rocks overlain by limestone and late Eocene to Miocene turbidites (Jacobshagen, 1986). Rocks of both the Gavrovo–Tripolitza and Ionian blocks do not crop out in western Turkey. Tectonic units in the footwall of the Pelagonian Unit lack any Cretaceous orogenic history, and were metamorphosed to high pressures at least 20 Ma later than the Pelagonian Unit and the Vardar– İzmir–Ankara Oceanic Units (Ring et al., 2010). The most outboard tectonic domain of the Hellenides is the Mediterranean Ridge Accretionary Complex (Fig. 2) (Kopf et al., 2003). Along the central Mediterranean Ridge, East Mediterranean oceanic crust has been subducted and the leading edge of the African passive continental margin is currently entering the subduction zone. The subduction of the Vardar–İzmir–Ankara Ocean that fringed Adria and Anatolia on its northern sides caused high-pressure metamorphism in these oceanic units in the Late Cretaceous (Sherlock et al., 1999). Beginning in the Early Tertiary, the northern edge of the Pindos Unit was underthrust causing high-pressure metamorphism in large parts of the Cycladic Blueschist Unit in the central Aegean Sea region (Cyclades islands) and westernmost Anatolia. Well-constrained ages for high-pressure metamorphism range from ca. 53 Ma to 30 Ma (Ring and Layer, 2003; Tomaschek et al., 2003; Putlitz et al., 2005; Ring et al., 2007b). High-pressure metamorphism took place in the External Hellenides in Crete and the Peloponnesus in the latest Oligocene to Miocene, at ca. 25–20 Ma (Seidel et al., 1982; Jolivet et al., 1996). Recent reviews (Jolivet and Brun, 2010; Ring et al., 2010; Jolivet et al., in press) demonstrated the progression of high-pressure that metamorphism gets younger towards the south. Major along-strike variations in the Hellenide–Anatolide orogen therefore should be related to the arrival of Anatolia in the eastern Mediterranean subduction systems in the Eocene (Gessner et al., 2001c). During incipient underthrusting of the leading edge of Anatolia the high-pressure metamorphosed Cycladic Blueschist Unit was thrust onto the Menderes nappes between 42 Ma and 32 Ma (Ring et al., 2007a). 2.2. Structure of the Anatolides in western Turkey In the Anatolide belt of western Turkey the Pindos Unit (represented by the Cycladic Blueschist unit) overlies the Menderes nappes (Figs. 3, 4, and 5) — which are part of Anatolia — whereas in the Aegean region the Pindos Unit overlies the Basal Unit — which is part of the External Hellenides (Gavrovo–Tripolitza) (Dürr, 1975; Robertson et al., 1991; van Hinsbergen et al., 2005). The Vardar–İzmir–Ankara Oceanic units contain Triassic to Eocene remnants of Neothethys which were subducted below Sakarya since the Cretaceous (Okay and Tüysüz, 1999; Okay, 2011). In western Turkey, Cretaceous to Palaeogene subduction–accretion complexes constitute the footwall of the Vardar–İzmir– Ankara suture, including the Tavşanlı zone, and the Bornova Flysch zone (Okay and Tüysüz, 1999; Okay, 2011). The Ören/Afyon zone and the Lycian nappes (Okay and Tüysüz, 1999; Pourteau et al., 2010) occur structurally below the ophiolitic parts of the Vardar–İzmir–Ankara Oceanic units, parts of which may constitute remains of a separate, continuous Anatolian ophiolite nappe (Okay, 2010). The Tavşanlı zone, and the Afyon/Ören units were metamorphosed under blueschist-facies conditions in the Late Cretaceous and Palaeocene (Sherlock et al., 1999; Rimmelé et al., 2003; Pourteau et al., 2010), and overlie the Pindos unit, represented by the Cycladic Blueschist Unit. In western Turkey, the Cycladic Blueschist occurs above the Menderes Nappes, separated by the Cyclades–Menderes Thrust (Fig. 4) (Gessner et al., 2001c). We follow the tectonic division of the Menderes Massif as an Alpine nappe stack (Gessner et al., 1998; Partzsch et al., 1998; Ring et al., 1999a; Gessner et al., 2001c; Regnier et al., 2003) consisting of, from top to bottom (1) the Selimiye Nappe, (2) the Cine Nappe, (3) the Bozdağ Nappe, and (4) the Bayındır Nappe (Fig. 4). The Çine and Bozdağ nappes have a polyorogenic history, which extends back into the Neoproterozoic/Cambrian (Kröner and Sengör, 1990; Hetzel and Reischmann, 1996; Candan et al., 2001; Gessner et al., 2001a; Gessner et al., 2004; Ring et al., 2004; Catlos and Çemen, 2005; Ring and Collins, 2005; Oberhänsli et al., 2010; Candan et al., 2011; Zlatkin et al., 2012). K. Gessner et al. / Gondwana Research 24 (2013) 243–274 247 Fig. 3. Schematic architecture of tectonic units in the Aegean Sea region and western Anatolia. According to this subdivision the structurally lowest unit of the Menderes nappes, the Bayındır nappe, has only been affected by one major Alpine tectonometamorphic event, whereas in the overlying Bozdağ, Çine and Selimiye nappes pre-Alpine and Alpine events are documented. The Cyclades–Menderes thrust cuts through several nappes of the underlying Menderes nappe stack. Deformation/metamorphism relations across the Cyclades–Menderes thrust indicate that the breakdown of garnet and biotite to chlorite in the Bozdağ nappe at temperatures below ca. 400 °C occurred during mylonitization. Accordingly, the Cyclades–Menderes thrust has been interpreted as a late Alpine out-of-sequence thrust (Gessner et al., 2001c). The structurally highest tectonic unit, the Selimiye Nappe, contains Palaeozoic metapelite, metabasite and marble (Schuiling, 1962; Çaglayan et al., 1980; Loos and Reischmann, 1999; Regnier et al., 2003; Gessner et al., 2004). The Eocene Selimiye Shear Zone separates the Selimiye Nappe from the underlying Çine Nappe (Fig. 4) (Bozkurt and Park, 1994; Bozkurt and Park, 1997; Gessner et al., 2004). Most of the Çine nappe consists of deformed orthogneiss, largely undeformed metagranite and minor pelitic gneiss, eclogite and amphibolite. Protoliths of much of the orthogneiss/metagranite intruded at ca. 560–530 Ma (Hetzel and Reischmann, 1996; Hetzel et al., 1998; Loos and Reischmann, 1999; Gessner et al., 2001a, 2004; Zlatkin et al., 2012). The underlying Bozdağ Nappe is made up of metapelite containing amphibolite, eclogite and marble lenses. Protolith ages of the Bozdağ Nappe metamorphics are unknown, but geological constraints (Candan et al., 2001; Gessner et al., 2001a, 2004) suggest a Precambrian age. Like the Çine Nappe, the Bozdağ Nappe was intruded by granitoids at ca. 240– 230 Ma (Dannat and Reischmann, 1999; Koralay et al., 2001). The Bayındır Nappe contains phyllite, quartzite, marble and greenschist of inferred Permo-Carboniferous to Mesozoic age (Özer and Sozbilir, 2003) that were affected by a single Eocene greenschist-facies metamorphism (Lips et al., 2001; Catlos and Çemen, 2005; Cemen et al., 2006). The Bayındır nappe was deformed by the first common deformation event recorded in the Menderes Massif and the Cycladic blueschist unit (Gessner et al., 2001c). The corresponding foliation is associated with a fine-grained N-trending stretching lineation associated with ductile shear bands and sigma-type objects indicating a top-to-the-S shear sense (Gessner et al., 2001c). Fig. 4. Interpretative thrust sequence during formation of Anatolide belt. Notice that the Cyclades–Menders Thrust emplaces units with a high-pressure accretion history on top of the Menderes nappes. After Gessner et al. (2011). Age data refer to Lips (1998)†, Loos and Reischmann (1999)††, and Gessner et al. (2001c)†††. 248 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Fig. 5. Exposed below the Vardar–İzmir–Ankara Ocean suture and overlying high-pressure metamorphic units, the Menderes Massif is the structurally lowest part of the Tethyan orogen in western Anatolia. Early Miocene extensional detachments at the massif's northern boundary constitute Stage 1 of northeast stretching and tectonic denudation. During Stage 2, the Central Menderes Metamorphic Core Complex (CMCC) has formed within already exhumed Stage 1 basement. The analysis of regional structures and metamorphism shows that the tectonic units below the Cycladic Blueschist Unit are different from the Aegean area from those in western Turkey. The oldest known basement rocks in the Phyllite–Quartzite Unit in Crete are about 510 Ma old (Romano et al., 2004), whereas there is widespread evidence for a Pan-African orogenic cycle in parts of the Menderes Nappes. The late Triassic to Eocene platform sequence of the Gavrovo–Tripolitza Block has no equivalent in the Menderes Nappes. The orogenic history of both tectonic units was also different: the Gavrovo–Tripolitza Block did not enter the subduction zone until about 35–30 Ma, whereas the Menderes Nappes were already underthrust by that time. In contrast to the Aegean Sea region, high-pressure metamorphism in the Anatolide belt is absent in the structural deeper units. Quantitative data from the Menderes Nappes so far have produced no evidence for Tertiary high-pressure metamorphism (Candan et al., 2001; Ring et al., 2001b; Whitney and Bozkurt, 2002; Regnier et al., 2003; Ring et al., 2004; Catlos and Çemen, 2005; Baker et al., 2008; Oberhänsli et al., 2010). Tertiary metamorphism in the Bayındır Nappe, which is the structurally deepest nappe in the pile (Gessner et al., 1998; Ring et al., 1999a; Gessner et al., 2001c, 2010), reached 4–6 kbar at a maximum of 400–450 °C (Ring et al., 2007b). Available age data indicate ages of 42–37 Ma for greenschist-facies metamorphism in the Menderes Nappes (Hetzel and Reischmann, 1996; Catlos and Çemen, 2005; Baker et al., 2008). The Menderes Nappes, together with the overlying Cycladic Blueschist Unit, the Afyon– Ören Unit and the Lycian nappes formed a southward propagating thrust stack in the Late Eocene and Oligocene (Fig. 4) (Collins and Robertson, 1997, 1998; Gessner et al., 2001c; Rimmelé et al., 2003; Pourteau et al., 2010). While the underthrusting of Anatolia caused a greenschist-facies metamorphic belt in western Turkey, ongoing deep subduction in the Aegean caused an orogenic wedge characterised by sustained high-pressure metamorphism (Ring et al., 2007b). The structural data constrain two important aspects: firstly, there is no evidence for Alpine high-pressure metamorphism in the Menderes nappes, and secondly, the available data are consistent with the proposal that maximum temperature and age of metamorphism associated with Alpine shortening decrease structurally downward. Temperatures in the Selimiye nappe were >450 °C and occurred before 43–37 Ma K. Gessner et al. / Gondwana Research 24 (2013) 243–274 (Hetzel and Reischmann, 1996), whereas in the Bayındır nappe temperatures barely reached 400 °C and occurred later at ca. 37 Ma (Lips et al., 2001). 2.3. Controversies on Alpine tectonics of the Menderes Massif The Menderes Massif is a complex geological terrain that still yields unresolved issues regarding its tectonic and metamorphic history. 2.3.1. Alpine crustal shortening and the age of deformation fabrics Alpine shortening of the Menderes Massif has been interpreted in terms of large-scale recumbent fold (Okay, 2001; Gessner et al., 2002), a series of nappes stacked during south directed thrusting (Ring et al., 1999a; Gessner et al., 2001c), and a series of north-directed thrusts that collapsed either in a bivergent fashion (Hetzel et al., 1995a) or through top-to-south extension (Bozkurt and Park, 1994; Bozkurt, 2007). The key controversies are focused on which structures are related to the kinematics of early Tertiary Alpine crustal shortening, which ones are related to late Tertiary crustal extension, and how this fits with the observed large scale architecture of the Massif. While the role of Miocene to Pliocene normal fault systems bounding the Gediz and Büyük Menderes grabens (see section ‘Miocene to recent extension’) is less controversial, the age of kinematic indicators in the metamorphic rocks of the Massif, and in some cases the age of the protoliths are controversial. Top-N–N/NE shear sense indicators are common in amphibolite facies metamorphic rocks in the Menderes Massif. Outside the contact aureoles of Miocene intrusions, these fabrics predate Miocene extension, and have also been interpreted as Alpine nappe stacking (Bozkurt and Park, 1994; Bozkurt, 1995; Hetzel et al., 1995a; Hetzel et al., 1998; Lips et al., 2001; Bozkurt, 2007). Based on detailed regional fabric mapping and cross-cutting relationships, a number of studies have shown that the Menderes nappe stack was assembled by south-directed shearing under greenschist facies conditions and that north-directed fabrics often are relics of earlier deformation events in individual tectonic units (Gessner et al., 2001a, 2001c, 2004). Regionally significant north-directed kinematics also would be difficult to reconcile with regional tectonic models that have shown that Tertiary convergence encompasses south directed shearing and thrusting (e.g. Sengör and Yilmaz, 1981; Sengör et al., 1984; Collins and Robertson, 1998; Gessner et al., 2001c; van Hinsbergen et al., 2010b; Gessner et al., 2011; van Hinsbergen and Schmid, 2012). High-grade metamorphism in the Çine and Bozdağ nappes (Candan et al., 2001; Ring et al., 2001b; Ring et al., 2004; Oberhänsli et al., 2010) occurred before the intrusion of Neoproterozoic to Cambrian granites, and reliable P–T estimates for the Tertiary tectonometamorphic evolution only exist for the uppermost nappe of the Menderes nappe pile, the Selimiye Nappe (Fig. 4) (Whitney and Bozkurt, 2002; Regnier et al., 2003). Metasediments in the Selimiye Nappe reached pressures of ca. 6 kbar and temperatures of ca. 500 °C near the base of the nappe, decreasing up section (Regnier et al., 2003). The mineral isograds in the Selimiye Nappe run parallel to the regional foliation and parallel to the Selimiye Shear Zone and suggest that the Selimiye Shear Zone formed during this prograde greenschist to lower amphibolite-facies metamorphic event. No reliable P–T estimates exist for chlorite-stable mylonitic rocks within the Cyclades–Menderes Thrust. However, biotite is destroyed in the mylonite, and pressures of 4–6 kbar in the rocks of the Selimiye Nappe below the thrust suggest P–T conditions of b4–6 kbar and b400 °C in the mylonite. These P–T estimates are largely similar to those from mylonitic metagabbros within the Cycladic Blueschist unit (Ring et al., 2007b). 2.3.2. Significance of the Selimiye shear zone The tectonic significance of the greenschist facies deformation fabrics in the Selimiye shear zone (Fig. 4 and 6) remains controversial. Interpretations include (i) Alpine shortening (Gessner et al., 2001c; Gessner et al., 2004), (ii) Precambrian and Alpine polymetamorphic 249 deformation (Regnier et al., 2003), (iii) post-Precambrian, pre-Alpine monometamorphic deformation (Regnier et al., 2006), (iv) folding during Alpine shortening (Erdogan and Güngör, 2004), and (v) late Alpine extension (Bozkurt and Park, 1994; Bozkurt, 2007). While the current down-dip, south-directed sense of shear suggests an apparent extensional deformation, the orientation of the Selimiye Shear Zone relative to Earth's surface may well have been different when the deformation fabrics formed. Also there is inconsistent evidence for a telescoped metamorphic field gradient, or for a change in cooling history across the Selimiye Shear Zone (Gessner et al., 2001c, 2004). Another contentious issue is that a number of authors claim that the granitic rocks intrude lithologies that can be correlated with Mesozoic sediments and are therefore ‘Alpine’ in age (Sengör et al., 1984; Bozkurt et al., 1993; Bozkurt and Oberhänsli, 2001; Bozkurt et al., 2001; Erdogan and Güngör, 2004). Radiometric ages of the intrusions, however, consistently have given Late Proterozoic to Cambrian ages (Reischmann et al., 1991; Hetzel and Reischmann, 1996; Gessner et al., 2001c, 2004), and we regard stratigraphy based on lithological correlations in the highly deformed metasediments of the Selimiye Nappe as problematic. A further problem is that the Selimiye shear zone appears to be wrapped around the granites and orthogneisses towards the western outcrop limit of these lithologies, which has lead to contradicting interpretations (Gessner et al., 2001a; Regnier et al., 2003; Gessner et al., 2004; Regnier et al., 2006). Based on lithological and metamorphic similarities the schists and marbles overlying the Selimiye nappe can be correlated with Cycladic blueschists, and that these, as well as the Afyon– Ören Unit preserve high pressure metamorphic relics for which there is no evidence in the Menderes nappes (Oberhänsli et al., 1998a, 1998b; Ring et al., 1999b; Oberhänsli et al., 2001; Rimmelé et al., 2003; Pourteau et al., 2010). 2.3.3. Stratigraphic position of low grade metasediments One of the most contentious geological issues of the Menderes Massif has been the tectonic position of Carboniferous to Mesozoic metasedimentary rocks. Along the southern margin of the Çine submassif fossilferous Palaeozoic metasediments in what we classify as the Selimiye nappe, have been known as the Göktepe Formation (Kaaden and Metz, 1954; Schuiling, 1962; Dürr, 1975). These metasediments — our Selimiye nappe — overlie amphibolite facies metamorphic rocks that occur above orthogneisses and granitoids that we would classify as Çine nappe. In the Aydın Mountains and the Bozdağ range in the central massif greenschist facies metasedimentary units that have been correlated with the Göktepe Formation occur below the amphibolite facies metapelites (our Bozdağ nappe), which, in turn are overlain by what we would consider Çine nappe orthogneisses (Dora et al., 1995; Hetzel et al., 1998; Candan et al., 2001; Gessner et al., 2007). This situation has been explained in two different ways: as a recumbent fold, or as a south-directed thrust stack. The recumbent fold hypothesis (Okay, 2001) is based on the assumption that the contact between orthogneisses above and below the Palaeozoic to Mesozoic metasediments represents an equivalent tectonostratographic position. The thrust hypothesis is based on the analysis of deformation fabric elements (Hetzel et al., 1995a, 1995b, 1998; Gessner et al., 2001a, 2001b, 2001c, 2002). These studies suggest that tectonic contacts in the Aydın Mountains and the Bozdağ range have formed in tectonic events that include Neoproterozoic to Cambrian shortening, Eocene contraction, and Miocene to recent extension of the crust. According to this hypothesis the juxtaposition of amphibolite facies rocks with Paleozoic to Mesozoic schists has occurred by south-directed thrusting during Alpine contraction and by bivergent tectonic denudation during Neogene extension (Gessner et al., 2001b). While we consider the case for recumbent folding on the 100 km scale unlikely for the Menderes Massif (Gessner et al., 2002), reports of non-cylindrical folding, particularly at the southern, and the lateral margins of the Çine submassif (Rimmelé et al., 2003; Erdogan and Güngör, 2004; Regnier et al., 2006; Candan et al., 2011) present a challenge to existing tectonic models of the Menderes Massif. 250 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Fig. 6. Map showing tectonic units of the Alpine nappe stack and the key structures within the Menderes Massif. Due to their unresolved stratigraphic position, the Karaburun peninsula rocks have been left separate. For order of stacking refer to Fig. 3. The thrust hypothesis implies that the Palaeozoic to Mesozoic metasediments in the Aydın Mountains and the Bozdağ range represents the lowest tectonic unit of the Menderes Massif, and could thus be a parautochtonous unit that correlates with the Bey Dağları unit (Figs. 4, 5 and 6) (Gessner et al., 2001c; van Hinsbergen et al., 2010b). 2.4. Miocene to recent extension After earlier extension in the northern Aegean — e.g. Eocene in the Rhodope (Dinter, 1998; Burg, 2011) — the onset of north–south extension in the central Aegean Sea region and in the Anatolide Belt of western Turkey has been placed around the Oligocene–Miocene boundary (Schermer et al., 1990; Hetzel et al., 1995b; Seyitoglu and Scott, 1996; Dinter, 1998; Gessner et al., 2001b; Keay et al., 2001; Ring et al., 2003a; Kumerics et al., 2005; Ring and Collins, 2005; Cemen et al., 2006; Thomson and Ring, 2006; Glodny and Hetzel, 2007; Thomson et al., 2009; Öner and Dilek, 2011; Catlos et al., 2012), but the overall magnitude of extension differs significantly in both regions. Extension in the Aegean has been estimated at ca. 350 km (Gautier et al., 1999), and at ca. 150 km across the Menderes Massif (van Hinsbergen, 2011). The difference in the amount of extension is also apparent in the topography of both regions. The Aegean is largely submerged with the Cycladic archipelago representing a horst structure between the more highly extended northern Aegean Sea and the Cretan Sea (Tirel et al., 2004). Western Turkey is characterised by thicker crust than the Aegean (Makris and Stobbe, 1984; Saunders et al., 1998; Tirel et al., 2004; Zhu et al., 2006b; Özeren and Holt, 2010; Mutlu and Karabulut, 2011) and this also reflected in peak elevation exceeding 2 km. The E–W-oriented grabens in western Turkey bend to the south and curve into a NE orientation in the vicinity of the Aegean Sea (Fig. 7). An early Miocene or older boundary between the Aegean and Anatolian domains has been proposed by a number of studies, based on the differences in extension geometry and metamorphic history between Samos and western Anatolia (e.g. Ring et al., 1999b, 2010; Gessner et al., 2011), the tectonic controls on the formation of the Late Cretaceous to Palaeocene Bornova Flysch Zone (Okay, 2011), and also on the occurrence of NNE-trending active fault systems and Cenozoic to recent basins in western Anatolia (Sözbilir et al., 2003; Özkaymak and Sozbilir, 2008; Uzel and Sozbilir, 2008, and references therein; Erkül, 2010). Uzel and Sozbilir (2008) and Sözbilir et al. (2011) have proposed that this seismically active NNE-trending corridor of crustal deformation represents the transfer zone between the Aegean and Anatolia and named it the İzmir–Balıkesir Transfer Zone (Fig. 7). 2.4.1. Extension of the Anatolide belt Since the early Miocene the Anatolide belt underwent extensional deformation (Dewey and Sengör, 1979). Miocene extension is expressed by normal-fault systems of Miocene to recent age (Hancock and Barka, 1987; Cohen et al., 1995; Hetzel et al., 1995a, 1995b; Gessner et al., K. Gessner et al. / Gondwana Research 24 (2013) 243–274 2001b; Isik and Tekeli, 2001; Ring and Collins, 2005; Emre and Sözbilir, 2007; Glodny and Hetzel, 2007; Erkül, 2010). The Menderes Massif has experienced a two-stage cooling history (Table 1). Three crustal segments differing in structure and cooling history are identified. The Central Menderes Metamorphic Core Complex (CMCC) represents an ‘inner’ axial segment of the Anatolide Belt and exposes its lowest structural levels, whereas the two ‘outer’ submassifs, the Gördes submassif to the north and the Çine submassif to the south, represent higher levels of the nappe stack (Figs. 6 and 7). Rocks in Çine submassif and the Gördes submassif, as well as in the upper structural levels of the CMCC recorded significant cooling during the latest Oligocene and early Miocene (Fig. 8). In the northern part of the Gördes submassif, cooling most likely occurred as a consequence of rapid tectonic denudation during N to NNE-directed movement on the Simav and Alacamdağ detachment systems (Isik and Tekeli, 2001; Ring and Collins, 2005; Erkül, 2010; Bozkurt et al., 2011; Catlos et al., 2012). In this area, apatite-fission-track ages show a northward younging trend in the direction of hanging wall movement of the detachments (Fig. 8) (Thomson and Ring, 2006). This view, however has been questioned by some recent studies (Akay, 2009; Hasozbek et al., 2010; Hasozbek et al., 2011; Hasozbek et al., 2012) and we refer to Section 2.5.2, where we discuss this controversy in more detail. There is also strong evidence for relatively rapid cooling in the late Oligocene and early Miocene in the Çine submassif. However, field evidence for a well-developed extensional detachment system is lacking (Ring et al., 2003a). The apatite fission track data in Fig. 8 show a gradient towards older ages across the boundary between 251 the Cycladic Blueschist Unit and the Ören unit. This pattern could be explained by either a top-S extensional reactivation of the basal thrust of the Ören unit, the tilting of the crustal section (Fitzgerald et al., 1991; Foster and John, 1999) in the footwall of a — now eroded — detachment system, or a combination of both. The second phase of cooling in the Anatolide belt is related to the formation of the CMCC. Since the late Miocene/Pliocene, two opposite-facing contemporaneous normal-fault systems, the Kuzey detachment in the north (also known as the Karadut fault, the Alaşehir detachment, or the Gediz detachment) and the Güney detachment (also known as the Büyük Menderes detachment) in the south (Hetzel et al., 1995b; Emre and Sözbilir, 1997; Gessner et al., 2001b) have caused symmetrical footwall uplift, thus forcing a synform structure on the relatively flat lying Alpine age structures (Gessner et al., 2001b; van Hinsbergen et al., 2010a) (Fig. 8). Within the CMCC Eocene foliation and the boundaries of the tectonic units define an east-trending synform with a wavelength of ca. 45 km and an amplitude of ca. 10 km. Across this synform fission-track cooling ages become younger in the hanging wall displacement direction (Fig. 8) (Gessner et al., 2001b; Ring and Layer, 2003; Thomson and Ring, 2006). Miocene sediments only occur in fault-bounded blocks in the hanging wall of the detachment faults (Seyitoglu and Scott, 1996; Emre and Sözbilir, 1997; Çiftçi and Bozkurt, 2009a; Çiftçi and Bozkurt, 2010; Öner and Dilek, 2011). Defined by structure and cooling history, the CMCC extends ca. 100 km east–west and 50 km north–south in the central part of the Anatolide belt. The detachment systems cut the upper levels of the Alpine nappe stack for a lateral distance of ca. 80 km, displacing the hanging wall regions to the north above the Kuzey Fig. 7. Map highlighting the extent of the Menderes Nappes and of Tertiary sediments and magmatic rocks. Notice that overall the outcrop of the Menderes nappes is elliptical with a NE oriented long axis. Tectonic units overlying the Menderes nappes (Fig. 5) are shown in grey. 252 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Table 1 Apatite fission-track data. Track density (×106 tr cm-2) rs ri rd (Ns) (Ni) (Nd) Age dispersion (Pc2) Central age (Ma) (± 2s) Apatite mean track length (µm ± 1 s.e.) (no. of tracks) Standard deviation (µm) 1.240 (8561) <0.01% (99.8%) 20.5 ± 2.7 14.36 ± 0.11 (100) 1.06 0.2394 (159) 1.234 (8519) 0.70% (91.4%) 18.1 ± 10.5 − − 0.0453 (35) 0.3595 (278) 1.228 (8477) <0.01% (95.0%) 27.7 ± 10.1 − − 20 0.644 (44) 0.5544 (379) 1.221 (8434) <0.02% (89.1%) 25.4 ± 8.3 14.96 ± 0.16 (37) 0.94 Çine 14 0.1247 (62) 1.024 (509) 1.215 (8392) <0.01% (93.8%) 26.5 ± 7.4 14.93 ± 0.17 (27) 0.87 37°23.36’N; 27°45.04’E Selimiye 20 0.0797 (78) 0.6199 (607) 1.209 (8350) <0.01% (91.2%) 27.8 ± 7.0 13.81 ± 0.29 (7) 0.71 THT37 37°28.35’N; 27°35.05’E Selimiye 20 0.0924 (90) 0.8350 (813) 1.203 (8307) 0.01% (97.2%) 23.9 ± 5.6 − − G1 37°12.87’N; 27°34.87’E 13 0.1557 (34) 1.099 (240) 1.301 (4060) <0.01% (95%) 31.5 ± 5.8† − − G2 37°12.92’N; 27°34.93’E 20 0.1785 (41) 0.9361 (215) 1.292 (4031) 0.13% (96%) 42.1 ± 7.2† − − G4 37°12.66’N; 27°34.89’E 10 0.0931 (29) 0.5555 (173) 1.283 (4003) 0.01% (82%) 36.7 ± 7.4† − − Sample no. Location (in degrees and decimal minutes) Unit/nappe No. of crystals THT28 37°38.28’N; 28°18.50’E Çine 20 0.8569 (355) 9.305 (3855) THT29 37°31.01’N; 28°21.02’E Çine 20 0.0196 (13) THT31 37°23.31’N; 27°48.01’E Çine 20 THT33 37°26.53’N; 27°42.24’E Selimiye THT34 37°27.11’N; 27°43.04’E THT35 Notes: (i). Analyses by external detector method using 0.5 for the 4p/2p geometry correction factor (ii). Ages calculated using dosimeter glass: CN5 with zCN5 = 358.8 ± 12.7; CN2 with zCN2 = 130.7 ± 2.8 (†) CN5 with ζCN5 = 342.5±3.8 (iii). Pc2 is the probability of obtaining a 2 value for v degrees of freedom where v = no. of crystals - 1 detachment, and to the south in the Güney detachment. The Kuzey detachment dips 15°–20°N and its hanging wall consists of south-dipping Miocene continental basin sequences, locally underlain by small volumes of amphibolite-grade orthogneiss. The footwall exposes a greenschist facies mylonitic shear zone of middle Miocene age (Hetzel et al., 1995a, 1995b; Emre and Sözbilir, 1997; Glodny and Hetzel, 2007). The Güney detachment is exposed along the northern shoulder of the Büyük Menderes graben as a 0°–15°S dipping ductile to cataclastic shear zone that constitutes the basal cut-off to Neogene basins (Fig. 7) (Gessner et al., 2011). While the Küçük Menderes graben in the centre of the CMCC also dates back to the Miocene, it mainly developed in the Plio-Quaternary and has not experienced nearly as much extension as the Gediz and Büyük Menderes graben systems (Rojay et al., 2005, and references therein). Detailed work on the Gediz–Alaşehir graben system at the northern margin of the CMCC (Çiftçi and Bozkurt, 2009a, 2009b; Çiftçi and Bozkurt, 2010) has confirmed the hypothesis of Gessner et al. (2001b) that displacement originated along a high-angle normal fault system and became shallower in orientation due to footwall uplift. It was also shown that the Gediz–Alaşehir graben system has grown from a series of smaller normal fault segments that controlled the subsidence in early Miocene sub-basins, to a larger structure during its later activity (Çiftçi and Bozkurt, 2009a, 2009b; Çiftçi and Bozkurt, 2010). An alternative hypothesis, where the Miocene to Pliocene basinal strata in Gediz– Alaşehir graben system are interpreted as having formed in a supradetachment basin above an initially shallow-dipping detachment (Öner and Dilek, 2011) is difficult to reconcile with the observed footwall uplift (Gessner et al., 2001b) and with seismic reflection data that suggest that sediments accumulated much closer to its southern than its northern margin (Çiftçi and Bozkurt, 2009a, 2009b; Çiftçi and Bozkurt, 2010). A distinct garnet-bearing orthogneiss, that occurs in the internal part of the Central Menderes Metamorphic Core Complex as well as in the hanging wall of the Kuzey detachment suggests a minimum down-dip displacement of ca. 12 km (Gessner et al., 2001b); this order of magnitude of displacement has been supported by numerical models of core complex formation (Wijns et al., 2005). Assuming that the overall structural symmetry between the two detachment systems also applies to displacement-to-length relationships, displacements along Güney detachment are likely to mirror those of the Kuzey detachment. The Kuzey and the Güney detachments root in the Miocene to recent Gediz graben and the Büyük Menderes graben, which continue to be active (Schaffer, 1900; Eyidogan and Jackson, 1985). The Gediz and Büyük Menderes grabens are associated with a number of geothermal fields (Simsek, 1985; Gökgöz, 1998; Faulds et al., 2009; Gessner et al., 2010), and Miocene to recent volcanic activity north of the Gediz graben has been associated with ongoing lithospheric extension (Seyitoglu et al., 1997; Ersoy et al., 2008; Prelevic et al., 2010a). The Gediz graben and the Büyük Menderes graben separate the Central Menderes Metamorphic Core Complex from adjacent plateau-like areas: the Gördes massif to the north and the Çine massif to the south (Figs. 6 and 7). In both the Gördes and Çine massifs flat-lying Miocene sediments overlie rocks of the Menderes nappe stack. When viewed parallel to the Miocene extension direction the Eocene foliation, the bedding of the Miocene sediments and the remnants of a late Miocene erosion surface are flat-lying and parallel to each other, although there are pronounced changes along strike, that will be addressed in more detail in a subsequent section on dynamic topography. 2.4.2. Magmatic record of crustal extension Magmatic activity related to Alpine convergence in western Turkey ranges from Eocene to Holocene in age with the largest volumes of igneous rocks produced during the Miocene (e.g. Ersoy et al., 2008). In general there is a trend from older, subduction-related sub-alkaline K. Gessner et al. / Gondwana Research 24 (2013) 243–274 253 Fig. 8. Map of apatite fission-track age locations. White data points with white numbers represent new data (Table 1); others are taken from published sources (Gessner et al., 2001b; Ring et al., 2003b; Thomson and Ring, 2006). Colours generated by spline interpolation in ESRI ARCGIS10.2, using faults and tectonic regions (grey. purple) as barriers. Notice the pronounced age gap between the Tavşanlı zone and northern Menderes Massif, compared to a smaller jump in ages between the Menderes and the Ören Unit in the south. The decrease of cooling ages towards fault zones in the centre outline the second denudation stage (Central Menderes Metamorphic Core Complex, CMCC). magmatic compositions that intruded into the Izmir–Ankara zone in the north, to younger, alkaline compositions in the south (Seyitoglu et al. 1996; Dilek and Altunkaynak, 2009; Ersoy et al. 2010). Although the source regions and geodynamic setting of the magmatic rocks have been discussed controversially, the emerging consensus appears to be that the Oligocene–Miocene igneous activity took place in a postcollisional crustal extension setting, and documents thermal melting of a previously metasomatized subcontinental lithospheric mantle (SCLM). Ersoy et al. (2010) have pointed out that Miocene high-Mg volcanics along the NNE-trending Izmir–Balıkesir Transfer Zone — which coincides with the edge of the Aegean slab (cf. Section 4 ‘Upper mantle structure and active deformation’) — tend to be K-rich, whereas ultrapotassic and shoshonotic suites are common the eastern parts on the volcanic province. Dilek and Altunkaynak (2009) have proposed that volcanic centres along the eastern margin of the magmatic province in the Afyon–Isparta region are related to the western edge of the Cyprus slab. While Miocene to recent magmatic activity has recorded increasing temperatures and shallower depths of melting that are consistent with removal of large portions of the lithospheric mantle below the Menderes Massif, it is unclear whether the removed lithospheric mantle has been autochthonous or not. A related question is if the metasomatic event that produced the subduction signature within the Oligocene to Miocene igneous compositions relates to Alpine convergence or records an older event. Based on the composition of Oligocene to Miocene igneous rocks Dilek and Altunkaynak (2009) and Altunkaynak et al. (2012a, 2012b) argue that the subcontinental lithospheric mantle of the Menderes Massif was metasomatised in the Miocene by flat subduction of a continuous African slab that comprised the now separated Cyprus and Aegean slabs. A further argument for a flat slab has been made based on ultra-depleted harzburgitic xenoliths within Miocene lamproitic rocks in western Turkey. Prelevic et al. (2010b) argued that these xenoliths originated from an intraoceanic subduction system within a flat slab, because they considered the other possible source, Archaean lithosphere, unlikely. There is, however, increasing evidence for Archaean model ages of crust formation, documented in detritic and magmatic zircons within metamorphic units of the Menderes Massif (Kröner and Sengör, 1990; Ring and Collins, 2005; Candan et al., 2011; Zlatkin et al., 2012). In contrast to a Cenozoic metasomatism, Pe-Piper and Piper (2007) consider a large component of mantle metasomatism to be of Neoproterozoic age. As will be discussed in our section on geophysical imaging of upper mantle structure, the proposition that a continuous slab of oceanic lithosphere has replaced autochthonous lithosphere beneath the Menderes Massif during Alpine convergence cannot be easily reconciled with the existing geophysical data. 254 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 2.5. Controversies on crustal extension 2.5.1. Fabric overprinting — extension or contraction? The discovery that down-dip greenschist facies deformation fabrics overprint north-directed shearing at higher metamorphic grades in the southern Çine submassif and in the area between Aydın Mountains and Bozdağ range led to the proposal that this overprinting relation represents crustal extension (Bozkurt and Park, 1994; Hetzel et al., 1995b; Bozkurt and Park, 1997; Hetzel et al., 1998). In the case of the Aydın Mountains and Bozdağ range, the greenschist facies fabrics, however, were folded into the large scale synform that was forced by the symmetric uplift of the detachment footwall areas. For both areas it is also questionable whether or not there are sufficiently ‘telescoped’ metamorphic field gradients that would support a crustal thinning scenario (Gessner et al., 2001a, 2001c). In the case of the Selimiye shear zone, new apatite fission track data presented as part of our data compilation (Fig. 8) show near uniform ages of between 25 and 30 Ma on both sides of the structure, requiring that it was sealed by late Oligocene times. This shear zone therefore could did not undergo any Miocene extension — at least not at temperatures above ca. 120 °C. 2.5.2. Exhumation of the Gördes submassif and the role of the Simav detachment Most studies agree that the Gördes submassif was exhumed in the Miocene as a consequence of tectonic denudation. An intriguing mapscale feature of the Gördes submassif is the corrugation-like alternation between northeast trending Miocene sedimentary basins, and basement highs that typically expose Çine nappe orthogneisses (Fig. 7). A number of hypotheses were put forward to explain this pattern, including the formation of an array of cross-faults that accommodated differential stretching of the Kuzey detachment hanging wall (Sengör, 1987), a component of ESE–WNW shortening that accompanied Miocene north– south extension (Yilmaz, 1981; Bozkurt and Park, 1997; Bozkurt, 2003; Cemen et al., 2006), oblique slip faulting in N–S extension (Yilmaz et al., 2000), early strike-slip movement of NE–SW trending faults that were later reactivated as normal faults (Özkaymak and Sozbilir, 2008; Özkaymak and Sözbilir, 2012), and the existence of spoon-shaped detachment faults at the base of Miocene basins (Purvis and Robertson, 2004; Purvis and Robertson, 2005). Recent three-dimensional models of Miocene to Pliocene basins in the Alaşehir–Gediz graben system (Çiftçi and Bozkurt, 2009a, 2009b; Çiftçi and Bozkurt, 2010) have shown that the corrugation pattern in the Gördes massif exists as basement topography in an axial direction of the Alaşehir–Gediz graben system, i.e. along strike of the Kuzey detachment. This may support the hypothesis that ESE–WNW shortening was involved in controlling basin topography, which is also consistent with the observation that Miocene sediments often show onlap relations towards folded orthogneiss (Purvis and Robertson, 2005; Cemen et al., 2006). Folding parallel to extension has been described from other extensional provinces, such as the Basin and Range province in North America (e.g. Yin, 1991; Fletcher and Bartley, 1994; Fletcher et al., 1995) and the Aegean Sea region (Avigad et al., 2001; Jolivet et al., 2004). Scaled physical experiments suggest that folding parallel to extension is an unstable deformation mode, where elastic folding of the upper crust gets imposed on viscous mid- to lower crustal layers (Venkat-Ramani and Tikoff, 2002; Lévy and Jaupart, 2011). Lévy and Jaupart (2011) point out that in their model shortening induced by these folds takes place as an elastic response perpendicular to extension without the need of externally imposed far-field shortening, and suggest that this process may be common in extensional provinces. While the relationship between this folding pattern and the Simav and Alacamdağ detachment systems has not been investigated, the Kuzey detachment appears to postdate the 255 ESE–WNW shortening. Temporal overlap of folding and normal faulting is, however, very likely. Zhu et al. (2006a, 2006b) present moment tensor determinations that provide evidence for ongoing NNE–SSW extension contemporaneous with ESE–WNW shortening in the central Menderes area. A recent study also reviews and synthesises reports of N–S and NE–SW shortening in Miocene basin rocks of the Alaşehir graben, and interprets these in the context of progressive simple shear in an overall extensional situation rather than as episodes of Cenozoic shortening that were suggested by earlier workers (cf. Şengör and Bozkurt, 2013; and references therein). The tectonic denudation of the Gördes submassif in the footwall of north-directed detachments has been questioned by studies that favour Miocene cooling of the Menderes massif due to uplift related lithosphere scale cooling after a change from steep to flat slab subduction below the Menderes Massif (Westaway, 2006; Prelevic et al., 2010b). Furthermore, recent studies on the Simav, Koyunoba and Alaçam plutons (Akay, 2009; Hasozbek et al., 2010; Hasozbek et al., 2011; Hasozbek et al., 2012) have suggested that these magmatic complexes stitch tectonic units related to Alpine crustal shortening, and questioned whether they were emplaced in the footwall of a synchronously operating Miocene extensional detachment system. While we acknowledge that the intrusion–deformation relationships in the area may be more complex than previously suggested, we are very sceptical about these hypotheses. A strong argument for tectonic denudation of the Gördes submassif is the existence of ophiolitic klippen that directly overlie Çine nappe orthogneiss across the Gördes submassif (Fig. 6). Together with the large jump in apatite fission track ages across the contact between the Menderes Massif and the overlying Tavşanlı zone (Fig. 8), this suggests to us that large parts of the Alpine nappe stack have been cut out by an early Miocene Simav–Alaçamdağ detachment system (Isik and Tekeli, 2001; Ring and Collins, 2005; Thomson and Ring, 2006; Erkül, 2010), which can be traced to ophiolitic klippen that occur as far south as the southern Gördes massif (e.g. Fig. 6). The age of normal faulting across the Menderes Massif has been constrained by K–Ar dating of brittle fault rocks from the high-angle Simav fault, and the low-angle Kuzey and Güney detachment systems (Hetzel et al., 2013). Hetzel et al. (2013) suggest that the onset of brittle faulting in the CMCC was diachronous, with cataclasite formation in the hanging wall units dating back to ca. 22 Ma in the Güney detachment and to ca, 9 Ma in the Kuzey detachment. Both faults, however recorded gouge formation as late as 4–3 Ma. According to Hetzel et al. (2013) brittle faulting in the Simav fault dates back to ca. 17–16 Ma. Bozkurt et al. (2011) produced Rb–Sr ages as young as 12–10 Ma from grains of a late biotite generation in a mylonitic detachment near Gördes, but the synkinematic growth of the dated grains is questionable (Hetzel et al., 2013). Overall we favour a two-stage denudation model that is consistent with the symmetric structure of the CMCC, and with the age gap between the exhumation of the Simav detachment footwalls between ca. 23 Ma (Isik and Tekeli, 2001; Ring and Collins, 2005; Erkül, 2010) and 16–17 Ma (Hetzel et al., 2013), and the onset of major denudation of the CMCC as constrained by the cooling below the Kuzey detachment in the Late Miocene–Pliocene (Ring et al., 2003a). We note that while these two stages are based on structures that can be detected and mapped across the northern part of the Menderes Massif, it is also plausible that the sequence of detachments, folds and faults reflects the changing style of strain localisation in a progressively exhuming metamorphic terrain. 2.5.3. Block rotation versus diffuse extension The normal fault systems bordering the Gediz and Büyük Menderes grabens are prominent geological and topographical features with a prolonged normal faulting history that have played an important role Fig. 9. Movement of western Turkey relative to Eurasia based on published GPS measurements (Aktug et al., 2009; McClusky et al., 2000). Stations are located at end of arrow; values are in millimetre per year; (a) shows all components (black), (b) westward component (blue), and (c) southward component (red); outline of Menderes Massif is given for reference. Notice the pronounced increase in southward component and the decrease in westward component towards the southwest. 256 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 in the tectonic denudation of the CMCC. There are, however, conflicting interpretations as to what extent crustal extension across western Turkey has been localised by these graben systems. Based on palaeomagnetic studies, it has been proposed that the Gediz graben represents a ‘breakaway’ structure, with fragmented blocks to its south and southwest — including the CMCC having rotated around a pole near Denizli in a counter-clockwise direction since the Early Miocene, while crust to the north has not experienced such rotation (van Hinsbergen et al., 2010a). While consistent with topographic features across southwest Turkey, block rotation on the proposed scale is not supported by the strain field calculated from geodetic GPS measurements (Aktug et al., 2009; Özeren and Holt, 2010; Pérouse et al., 2012). Instead, these studies have shown that the area to the west and southwest of the Anatolian plateau is currently deforming in a relatively homogeneous displacement field that does neither show distinct block rotations, nor sharp strain gradients across structures like the NNE-trending İzmir– Balıkesir Transfer Zone (Erkül, 2010); or the West Anatolian Shear Zone proposed by Papanikolaou and Royden (2007). The apparent discrepancy between the fragmented blocks and the distributed strain could be that the rotation is a component of the westward increasing sinistral shearing of western Turkey. Pérouse et al. (2012) have shown that in an absolute plate motion frame the velocity pattern is toroidal relative to the edges of the Hellenic subduction zone, with displacement directions defining rotation poles in northwest Greece and some 200 km west of Cyprus in the Eastern Mediterranean Sea. Hence, geodetic displacement measurements (Fig. 9) would capture the quasi instantaneous strain component, while the palaeomagnetic data have recorded the finite rotational strain after many million years of this shearing. The block rotation scenario is also incompatible with the observation by Çiftçi and Bozkurt (2010) that the oldest sub-basins in Gediz graben occur in the east, and the graben system propagated from east to west.). In a block rotation scenario one would expect propagation of the graben from west to east, i.e. in the direction of decreasing tangential displacement towards the proposed rotation pole near Denizli. Both the Gediz and Büyük Menderes grabens, however, are narrow and deep in the east, and become wider and shallower towards the west. Maximum depths to basement are on the order of 4 km in the eastern Büyük Menderes graben and 2 km in the eastern Gediz graben (Sari and Şalk, 2006; Çiftçi and Bozkurt, 2009a; Isik and Senel, 2009). The eastern (Alaşehir) segment of the Gediz graben also contains the oldest Miocene sedimentary infill (Çiftçi and Bozkurt, 2009a; Gürer et al., 2009; Çiftçi and Bozkurt, 2010; Öner and Dilek, 2011). To us this suggests an east–west propagation of the grabens, and we speculate that they may have originated from the area near Denizli. estimated ca. 400 m of regional surface uplift since the Middle Pleistocene. We have produced a digital terrane model to generate topographic swath models, and to model drainage channels across the Menderes Massif. The surface models we present here highlight the short wavelength effect of faulting on the topography of the central Menderes region as well as the long wavelength effect, which we tentatively link to lower crustal flow. 3.1. Methods and materials We have used SRTM data (Farr et al., 2007) to generate a terrain model from which we have extracted two east–west and two north– south oriented topography swaths, modelled the catchments in the Menderes region, and extracted a representative selection of drainage channel profiles. The area that defines the swaths is shown in Fig. 10. Swath 1 extends from 27.32°E to 27.53°E, and from 37.02°N to 39.39°N (ca. 19 km×236 km) and swath 2 from 28.12°E to 28.38°E, and from 37.02°N to 39.39°N (ca. 23 km×263 km). Swath 3 extends from 26.5°E to 29.43°E, and from 38.12°N to 38.23°N (256 km×12 km) and swath 4 from 26.5°E to 29.43°E, and from 38.7°N to 39°N (253 km×33 km). The data have a spatial resolution of approximately 92 m in N–S, and range between 72 m and 74 m in E–W direction. To calculate the profiles shown in Fig. 11, we determined the minima, maxima and mean values perpendicular to the orientation of the profiles. No smoothing has been applied parallel to the orientation of the profiles. 3.2. Topographic profiles The higher amplitude and shorter wavelength topography of the north–south profiles reflect the dominant E–W orientation of the graben systems (Fig. 11). Profiles 3 and 4 show a long wavelength negative elevation gradient from their eastern end to around 27.5°E. West of this latitude, roughly corresponding to the western limit of the Menderes Massif and the location of the İzmir–Balıkesir Transfer Zone (Uzel and Sozbilir, 2008) (Fig. 7), the character of elevation changes, with the ranges closer the coast showing no systematic long wavelength elevation trend. This observation is corroborated by Profile 1, which runs along the western margin of the Menderes Massif (Figs. 10 and 11) and also lacks a long wavelength trend. Profile 2 runs across the Menderes Massif at a high angle to the graben systems and thus highlights the difference between the more plateau-like character of the Gördes and Çine submassifs, and the much higher Bozdağ and Aydın Mountains that were uplifted in the footwall of the detachment systems of the CMCC (Fig. 10). The drainage elevation of both the Çine submassif and the Gördes submassifs shows a negative gradient towards the CMCC, where the base level is higher. 3. Topographic response to crustal extension 3.3. Drainage channels Miocene crustal extension in western Turkey has been accompanied by surface uplift that has exposed and eroded the Menderes Massif around the time of the first stage of tectonic denudation. Thermochronological (Gessner et al., 2001a, 2001b, 2001c; Ring et al., 2003a, 2003b; Thomson and Ring, 2006) and sedimentological studies (Yilmaz et al., 2000, and references therein) suggest that erosion to near base level produced an extensive and relatively flat land surface covered by shallow continental basins from the Gördes submassif in the north across what is now the CMCC and including most of the Çine submassif. Currently, the central west coast of the Anatolian peninsula is characterised by the transition from the Anatolian plateau to the Aegean Sea. The landforms of the area are mainly controlled by a series of E–W and ESE–WNW oriented horsts and grabens that bound mountain ranges and highlands. This basin and range type topography, which is particularly conspicuous in the central Menderes Massif, is a consequence of Neogene to recent normal and strike-slip faulting combined with uplift and erosion. Constraints on the ‘background uplift’ of the area exist for the Gediz submassif, for which Westaway et al. (2004) We discuss general forms of the channel data using concavity data for inferring zones where uplift rates change along profiles and to test if there are major differences between the CMCC and adjacent plateaux. The stream channel profiles from the CMCC and the adjacent plateaux are distinctly different. The Gördes submassif is drained to the southwest by a number of shallow gradient channels (Fig. 12); the Çine submassif by similarly shallow channels towards the northwest. Most of the channels originating on the plateaux north and south of the CMCC feed in to the axial drainages of the Gediz and Büyük Menderes rivers (channels 28 and 5), in general, the plateau channels get steeper towards the west. Most of the drainage channels originating on the plateaux (Fig. 12) have smooth concave profiles with knick points separating upstream and downstream channel segments with different slopes. In general, profiles located on the eastern plateau regions (profiles 4–7) are less concave. However, some of these profiles (especially 7 but also 5 and 6) have steep segments in their downstream parts of the profile before they enter the valleys around the CMCC uplift area. The outward K. Gessner et al. / Gondwana Research 24 (2013) 243–274 257 Fig. 10. Map showing location of swath profiles shown in the figure, and topographic features such as relevant river valleys, mountain ranges, and coastal embayments. draining channels of the CMCC are distinctly more concave than the plateaux channels (Fig. 13). Most of the profiles resemble well-developed river channel profiles (Wobus et al., 2006) with minor knick points; however, concavity is particularly prominent in profile 30, which transects a well-exposed portion of the Kuzey detachment, and in profiles 22 and 23. The inward draining channels of the CMCC (Fig. 14) also represent well-developed river channel profiles, but they are steeper, smoother, and lack major knick points. The N–S oriented channels, which run close to perpendicular to the Kuzey and Güney detachments and drain the slopes of the Küçük Menderes valley, are the steepest channels in the study area and have nearly identical profiles. The axial drainage channel, the Küçük Menders river (channel 13 in Fig. 14), has a much shallower gradient than the N–S oriented channels, but nevertheless is much steeper than axial channels in the Büyük Menderes and Gediz graben systems (channels 28 and 5 in Fig. 12). 3.4. Interpretation of topography and river channel data The pronounced mountain ranges and steep drainage channels in the CMCC (Figs. 13 and 14) are consequences of high uplift rates in the footwall areas of the Kuzey and Güney detachments. The distinct knick point in profile 30 in the footwall of the Kuzey detachment coincides spatially with the youngest apatite fission track data (Fig. 8) (Gessner et al., 2001b; Ring et al., 2003a) and is therefore likely to reflect an active uplift pulse. Other than the distinct knick point near the Kuzey detachment footwall, the inward and outward draining channel profiles on either side of the CMCC are similar, suggesting similar uplift rates in the footwalls of the opposite facing normal fault systems. The topographic profiles and the drainage models support the hypothesis that the CMCC is a symmetrical uplift that was superimposed on a Miocene peneplain (Yilmaz et al., 2000; Gessner et al., 2001b; Ring et al., 2003a; Thomson and Ring, 2006). The area of this Miocene peneplain is nearly identical with the outcrop area of the Menderes Massif (Figs. 6 and 8). The channel profiles for the plateaux reflect relatively slow uplift, which is likely to be consistent with regional scale long wavelength uplift, as proposed by Westaway et al. (2004). We note that these authors considered the role of footwall uplift and E–W graben formation in the central Menderes to be insignificant for a lower crustal flow system. Based on our data we find this interpretation difficult to support. While data from Miocene fluviatile deposits in the Gördes submassif indicate mostly north or east directed flow directions (Yilmaz, 1979; Purvis and Robertson, 2005) the channels now are reversed, and presently drain to the southwest. Comparable data for the Çine massif are not known, but we note that the northward slope of the drainage level is consistent with a symmetric surface tilting of both plateaux towards the CMCC (Fig. 11). To accommodate the drastic footwall uplift associated with the Kuzey and the Güney detachments, and the formation of the Miocene to Holocene basins in the Büyük Menderes and Gediz grabens, redistribution of mid- to lower crustal material may have played a major role in the central Menderes area. Flow of the lower crust as a response to metamorphic core complex formation (Wdowinski and Axen, 1992; Wijns et al., 2005; Gessner et al., 2007; Rey et al., 2009; Schenker et al., in press) occurs when lateral pressure gradients drive low viscosity lower crust from regions of high overburden into the thinned crustal ‘gap’ generated by tectonic denudation. We would argue that the 258 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 259 Fig. 12. Profiles of channels draining the plateau areas to the north, east and south of the Central Menderes Metamorphic Core Complex. Notice that overall channel slopes are relatively small, and increase towards the west. overall higher values in the maximum, mean and minimum elevation profiles, as well as the steeper drainage channels in the CMCC are consistent with a lower crustal flow system driven by the Kuzey and Güney detachment systems. Estimates for the viscosity of the lower crust are similar to values suggested for the Basin and Range province in North America. For the Menderes, values are likely to be on the order of between 1019 and 1020 Pa s (Westaway et al., 2004; Sodoudi et al., 2006). We would argue that in the central Menderes region the weak lower crust has been driven toward the Gediz and Büyük Menderes grabens from below the southern Gördes and the northern Çine submassifs, and from below the CMCC. The oldest cooling ages in the CMCC are similar in age to those found near the Miocene peneplain on the plateaux to the north and the south, but the rocks occur in core of the synform at much lower elevations. Even though the CMCC supports high mountain ranges in the footwall of the opposite-facing detachment systems — probably by elastic flexure — its overall loss of lower crustal thickness may have caused the central CMCC to ‘sink’ to a lower elevation relative to the neighbouring plateaux (Fig. 11). 4. Upper mantle structure and active deformation Studies based on P-wave and S-wave tomography have shown that parts of the upper mantle below Anatolia are asthenospheric rather than lithospheric (Spakman et al., 1988; Spakman et al., Fig. 11. Topography profiles across the Menderes Massif calculated from swaths across a terrain model. Red is the maximum elevation, black the lateral mean elevation, and blue the minimum elevation, which also corresponds to local drainage elevation. Locations of geomorphological features are also shown in Fig. 9. Notice difference between Profile 1 (mostly west of the MM), and Profile 2 (within MM), expressed in Profile 2's higher amplitudes, and an overall trend of decreasing drainage elevation towards the Gediz and Büyük Menderes valleys (Profile 2); a feature not present in Profile 1. Profiles 3 and 4 show a long wavelength decrease in elevation form E to W, which is less clear in Profile 3, because it captures parts of the eastern Aydın Mountains and Bozdağ range area. 260 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Fig. 13. Profiles of channels draining the Central Menderes Metamorphic Core Complex ‘outward’ into the Gediz and Büyük Menderes systems. Notice that slopes are much steeper compared to plateau draining channels (Fig. 11). 1993; Spakman, 1999; Wortel and Spakman, 2000; Şengör et al., 2003; Faccenna et al., 2006; Berk Biryol et al., 2011; Mutlu and Karabulut, 2011; Paul et al., 2011; Zhu et al., 2012; Jolivet et al., in press). Due to the inherently low resolution of mantle tomography compared to geological data, and the variety of the methods used (e.g. body wave tomography in older studies versus adjoint tomography in Zhu et al., 2012) the shape of the anomaly is not consistent across the models, and cannot always be related to crustal structure with confidence. In general a slow wavespeed region of variable shape below western Turkey is a common and robust feature in the topography models, with the Berk Biryol et al. (2011) model probably being the most detailed. A number of studies have proposed that the asthenospheric window below western Turkey (Fig. 15) originated from a tear in the highvelocity material that separates the oceanic lithosphere domains of the African plate into an Aegean section and a Cyprus section (Dilek and Sandvol, 2009; van Hinsbergen et al., 2010b; Berk Biryol et al., 2011; Mutlu and Karabulut, 2011). This scenario would imply that prior to the rupture, the current Aegean slab extended across all of western Anatolia, including across the Hellenide–Anatolide transition, and was connected to the Cyprus slab (Fig. 15). Dilek and Altunkaynak (2009) on the basis of geochemical arguments, proposed that the Miocene to Pliocene trend of southward younging alkaline volcanics between Eskişehir and Isparta record the formation of a tear, which they interpret to have separated the Cyprus slab and the Aegean slab, that prior to tearing would have constituted a continuous slab from central Anatolia to the Ionian Sea. While the alkaline volcanic trend is likely to record a significant lithospheric feature, this model does not account for the eastern termination of the Aegean slab below western Turkey as imaged by most tomography models. An alternative to tearing a continuous slab could be that the window reflects a primary lithospheric feature, for example thick buoyant sub-lithospheric mantle domains within the Anatolides, for which Proterozoic and Archaean ages are known (Kröner and Sengör, 1990; Ring and Collins, 2005; Candan et al., 2011; Zlatkin et al., 2012). To better understand the upper mantle architecture, and to assess how a mantle-scale discontinuity across the Aegean K. Gessner et al. / Gondwana Research 24 (2013) 243–274 261 Fig. 14. Profiles of channels draining the Central Menderes Metamorphic Core Complex ‘inward’ into the Küçük Menderes river. Notice that slopes are much steeper compared to plateau draining channels (Fig. 11). coastline of Anatolia relates to crustal structure, we have produced gravity anomaly and crustal thickness models across this area, and have produced a three-dimensional representation of earthquake hypocentres and the MIT-P08 seismic tomography model (Li et al., 2008). 4.1. Geophysical evidence 4.1.1. Gravity anomaly and Moho depth We analysed Sandwell and Smith's 1′×1′ free gravity anomaly grid (Sandwell and Smith, 2009) and transformed it into a conventional Bouguer anomaly (Fig. 16a) using bathymetry and topography data from Smith and Sandwell (1997). We concentrated our modelling efforts on Bouguer anomalies with wavelengths longer than 10 km, since shorter wavelength anomalies are masked by the lateral resolution of the original data and do not capture the gravity signatures of mantledepth heterogeneities. We used these Bouguer anomaly data to estimate Moho depths assuming lateral continuity of the interface and initial average depths of 30 km as reported from teleseismic receiver functions (Saunders et al., 1998; Zhu et al., 2006b; Özeren and Holt, 2010; Mutlu and Karabulut, 2011). We inverted the gravity data for the relief of the Moho interface using a layered inversion algorithm (Gallardo et al., 2005) assuming a density contrast of 400 kg m−3 (Tirel et al., 2004) and a tension factor for layer continuity of 1×10−4 km−1 for a regular mesh of 5 km-wide cells. These parameters provided a model of depths that range between 18.6 and 40.5 km. The gravity response of this interface shows regional gravity anomaly (Fig. 16) and fits the data at a standard deviation of 15.26 mGal, which is well above the reported precision of the satellite gravity data ranging 1.8 to 3.6 mGal (Sandwell and Smith, 2009). Residual gravity anomalies not justified by our model (Fig. 16c) are likely to be caused by crustal-depth heterogeneities. 4.1.2. Earthquake hypocentres Earthquake data include magnitude and hypocentre location of 13,935 events listed in the USGS PDE catalogue (USGS, 2011) between 262 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Fig. 15. Location and depth of the upper limit of the fast p-wave speed anomaly of the Hellenic and Cyprus slab fragments, as interpreted by Berk Biryol et al. (2011). The Menderes Massif is located above the western margin of a ca. 300 km wide ‘asthenospheric window’; a slow wave speed anomaly that is commonly interpreted as a tear in the African plate (see text for details). 19 April 1973 and 14 June 2011, and also including data from events that occurred before 1973 but were not systematically recorded. Data that lacked either magnitude or depth information were not considered. We subdivided the earthquake locations into different domains, according to the spatial distribution within the study area. 4.1.3. 3D model of seismic tomography and earthquake hypocenters For the three-dimensional model, we projected earthquake data and seismic velocity anomalies in Cartesian coordinates in UTM Zone 35 N using PARADIGM™ SKUA© v.2009.3. Seismic tomography data are subsampled from MIT global depth-corrected p-wave velocity anomaly Fig. 16. Bouguer gravity anomaly of western Anatolia (a) modelled from satellite gravity and topography data (Sandwell and Smith, 2009); (b) filtered for low frequencies; and (c) high frequency residual. The data show a long wavelength positive anomaly (b) in the southern Aegean Sea region that becomes weaker to the north. A pronounced negative gradient can be seen towards central Anatolia, where a slight ridge below the Central Menderes Metamorphic Core Complex separates negative anomalies. Short wavelength data (c) show north to northeast oriented linear trends broken up by negative anomalies in the graben systems surrounding the Stage 2 core complex and along the northern margin of the Stage 1 core complex. K. Gessner et al. / Gondwana Research 24 (2013) 243–274 263 Fig. 17. Locations and magnitudes (M) of 11,995 earthquakes (a subset within the region of interest of the total 13,935 shown in Fig. 17 and in the supplementary material) recorded in western Anatolia from 19 April 1973 to 22 April 2011 displayed with (a) active faults and p-wave anomaly data (dVp) at 22.6 km depth and (b) depth of Moho modelled after satellite gravity data (cf. Fig. 15). Data show relative few earthquakes in the Stage 1 core complex (outlined), except along its northern boundary, and along the grabens defining the Stage 2 core complex (Fig. 7), especially at an intersection of two graben systems in the east. Earthquake locations data are also presented in 3D PDF format (cf. Supplementary material 1). dataset MIT-P08 (Li et al., 2008) and interpolated with SKUA's Discrete Smooth Interpolator algorithm from 1568 data points in UTM zone 35 at a resolution of ca. 78 km in N–S (seven rows per depth layer), ca. 61 km in E–W (eight columns per depth layer); and 45.2 km depth resolution (28 layers). Earthquake data include all events listed in the previous section. 4.2. Results A long wavelength, gravity low is located in the Aegean Sea region; it has a steep gradient parallel to the Aegean coastline, and a much shallower gradient across strike to the north. Crustal thickness increases from below 20 km in the Aegean to ca. 40 km at the eastern margin of the Menderes Massif (Figs. 17 and 18). Short wavelength gravity anomalies reveal linear corrugation trends that are consistent with folded basement ridges and elongate Miocene basins covering the Stage 1 core complex footwall, particularly in the northern part of the Menderes Massif. These linear trends are offset by negative anomalies of the grabens that formed above the Stage 2 detachment faults that eventually fragmented the Stage 1 core complex. Bouguer gravity (Fig. 17), seismic velocities and crustal thickness (Fig. 18) are consistent with published data (Tirel et al., 2004; Sodoudi et al., 2006; Zhu et al., 2006b) and show how extensional tectonics caused exhumation of denser and faster material to shallower crustal levels, predominantly in the eastern Aegean but also in western Turkey. The pattern of earthquake distribution can be used to define distinct domains of seismic activity (i) in the north around Simav and (ii) within the Menderes Massif south of Simav, west of the Menderes Massif, and in the southern part of the study area (Figs. 17, 18, 19, Table 2). Within the Menderes Massif as well as to its north and west, earthquakes occur in the shallow crust, with the mean depth being shallower in the Simav domain (9.7 km) compared to the western domain (11.9 km) and the Menderes (11.2 km) domain. Our data show the Menderes Massif as a distinct, seismically relatively quiet area with a crustal thickness of about 30 km (Fig. 17). Relatively few seismic events have occurred across the Menderes Massif, except for activity along east to southeast trending graben systems (Figs. 17, 18, and 19). Overall, seismic activity shows strong spatial correlation with the western and northern margin of the Stage 1 core complex and with Anatolia's western and southern coastline. The spatial distribution changes markedly across a NE-trend along the western margin of the Menderes Massif (Figs. 17 and 18). There are also a number of shallow and deep crustal earthquake clusters. In a significant deviation from the overall depth pattern earthquakes occur at great depths below the Gulf of Gökova separated by a gap from an even deeper cluster below the Dodekanes (down to 176 km), in a pronounced, sheet-like cluster that gets deeper towards the west (Fig. 19, and supplementary material). Surface rendering of the MIT-P08 tomography model (Fig. 20) shows the outline of the north-dipping Aegean slab. In the Aegean, a low velocity layer in the upper mantle defines a hot mantle wedge that below the Menderes Massif connects to asthenospheric mantle in the southeast of the model (Fig. 20). The shape of the slab is a robust feature that has been consistently imaged by virtually all tomography studies and has been interpreted by van Hinsbergen et al. (2005) to record continuous subduction of the African plate since the Mesozoic. The location and depth of subducting African lithosphere is also consistent with seismic receiver function imaging (Sodoudi et al., 2006). The slab has a marked edge in the upper 264 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Fig. 18. Map of earthquakes in the Simav (yellow), the Menderes Massif (blue), the Western (green) and Southern (orange) earthquake domains. The Menderes Massif is outlined in red; subdivision is based on the overall geographic earthquake distribution pattern. Notice the change of event density in the central and northern areas of the map, where domains are defined by a NE-trend at the western margin of the Menderes Massif, and continuing north from there. See Fig. 18 for cross section views; coordinates refer to WGS1984 UTM zone 35 N (in thousands of metres). mantle below western Turkey but continues eastward for 0.5%, 0.6%, and 0.7% p-wave velocity anomaly contours. The surface representation of the slab edge as based on the MIT-P08 model, differs somewhat from Berk Biryol et al. (2011), who see the slab continuing slightly further to the east (Fig. 15). Previous studies have suggested that the Benioff zone of the Aegean subduction zone may extend to the Turkish coastline (Papazachos et al., 2000; Sodoudi et al., 2006). While this may be the case for the Dodekanes area, the deep earthquake cluster below the Gulf of Gökova does not correlate with any positive seismic velocity anomaly in the MIT-P08 model that would indicate the presence of a slab (Fig. 18), and the deeper earthquakes occur in a region for which most other seismic tomography models do not show a steep E–W oriented slab that could be interpreted as a Benioff zone. A possible exception is the Zhu et al. (2012) model where anomalies in the vertically polarised component of the shear wave speed outline a gradient parallel to the Gulf of Gökova in the 275 km depth slice. The Gökova deep earthquake cluster bears strong resemblance in shape, size and depth extent, to a cluster in the south-eastern Carpathians, which has been interpreted as a strain pattern of continental delamination (Fillerup et al., 2010), or of a Rayleigh–Taylor type instability within continental lithosphere (Lorinczi and Houseman, 2009). We would argue that the location and shape of the Gökova earthquake cluster suggests a similar scenario where deep earthquakes occur in a steep sheet of delaminated or otherwise detached continental crust. 5. Tectonic synthesis We have reviewed the structure of the Menderes Massif in the light of new and published geological and geophysical data. The picture that is emerging is a snapshot of an extending orogenic system, situated in a laterally inhomogeneous convergent geodynamic setting. The challenge in understanding the tectonic evolution of southwest Turkey lies in constraining how closely the dynamics inferred from mantle structure can be related to the evolution of geological structure. The datasets we have produced in this study provide new detail on western Anatolia's lithospheric structure, highlight pronounced differences to the Aegean, and support our claim of the existence of the West Anatolia Transfer Zone (WATZ), a transtensional structure that has originated from a wide lithosphere scale transtension zone that denuded the Menderes Massif in the Miocene. We argue that the İzmir–Balıkesir Transfer Zone, the structural corridor that limits the western exposure of the Menderes Massif, is the current upper crustal expression of the lithospheric mantle-driven transtension across the Western Anatolia Transfer zone. K. Gessner et al. / Gondwana Research 24 (2013) 243–274 265 Fig. 19. Cross-sections and summary statistics of earthquake depth data shown in Figs. 16 and 17. The features that stand out are the deep earthquakes in the southern domain that range from ca. 60 km in the east to 176 km in the west with a notable gap between ca. 520,000 and 550,000 mE, and vertical clusters in the crust at a northing of ca. 41,000 in the southern domain along the Gulf of Gökova (see Fig. 17 for location), and a second cluster southeast of Izmir at a northing of ca. 42,220. There is also an increase in mean depth from north to south, and a much greater depth range in the southern domain. Clusters to the northwest and north of the Menderes Massif have different depths, with the Simav domain having the shallowest mean depth and also a lower mean magnitude than the Western domain (also see Figs. 16 and 17). Table 2 Summary statistics of earthquake depth and magnitude. 5.1. Lateral differences in lithospheric structure Depth Domain n Min [m] Max [m] Mean [m] Median [m] Standard deviation Simav South Menderes (MM) West 2581 2086 670 1000 2000 1000 60,000 170,000 58,000 9747 28,044 11,176 10,000 13,000 10,000 3894 35,342 6957 6656 1000 176,000 11,912 10,000 7734 Domain n Min Max Mean Median Standard deviation Simav South Menderes (MM) West 2581 2086 670 1.70 2.40 2.50 7.30 7.10 6.50 2.86 3.55 3.40 2.70 3.40 3.20 0.44 0.50 0.56 6656 1.90 7.50 3.11 3.00 0.48 Magnitude Below the Aegean Sea, the north-subducting slab is imaged by both the gravity data (Fig. 16) and by the P-wave velocity model of the mantle (Figs. 17 and 20). We envisage that in the late Oligocene/early Miocene the Hellenide–Anatolide boundary was expressed as the lateral transition from dense oceanic lithosphere in the Aegean to the thickened continental root below the Anatolide belt. It is difficult to assess the tectonic record of this transition, but it is likely that it represents a former domain boundary (e.g. a passive margin) between the Adriatic and Anatolian domains, and was already tectonically active during late Mesozoic convergence, when the NNE-trending Bornova Flysch Zone (Fig. 5) formed in a transtensional setting (Okay, 2011). We argue that the continuing southwest-ward rollback of the Aegean slab by the late Oligocene/early Miocene initiated the West Anatolia Transfer Zone (WATZ) either by localization across a lithosphere scale material boundary, or by reactivation of an earlier feature. We would argue that rollback turned the north– south oriented trailing edge of the Aegean slab into a rigid transtensional 266 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 boundary relative to western Anatolia's sub-continental lithosphere. This kinematic framework caused tearing at the western and eastern boundaries of the continental lithosphere and delamination of large parts of the subcontinental lithospheric mantle accompanied by uplift, crustal extension, and alkaline magmatism (Figs. 20, 21, and 22). There is no evidence for a presently subducting slab below the Menderes Massif in the MIT-P08 tomography model. Tomographic data presented in other studies are variable in orientation, shape, and size of the slow wave speed anomaly (de Boorder et al., 1998; Govers and Wortel, 2005; van Hinsbergen et al., 2010b; Berk Biryol et al., 2011; Paul et al., 2011; Zhu et al., 2012; Jolivet et al., in press). Following the STEP fault concept (Govers and Wortel, 2005), most studies have proposed that asthenospheric material was emplaced along a tear fault that ruptured a previously continuous slab to accommodate the difference between the fast rollback of the Aegean slab section versus the slow rollback of the Cyprus slab section (Govers and Wortel, 2005; Dilek and Altunkaynak, 2009). This would require that the lithospheric mantle below the Menderes Massif would have been either no different from the Aegean one, or — if it was different — would have been sheared off during convergence, as suggested by proponents of flat slab hypotheses (Westaway, 2006; Prelevic et al., 2010b; van Hinsbergen et al., 2010b). In the latter case it is unclear where the sheared-off autochthonous continental mantle material would be now, and how it could be imaged. If the ca. 300 km wide asthenospheric window formed within a previously continuous flat slab in the Miocene (van Hinsbergen et al., 2010b), the western and eastern edges of the slab (Fig. 15), now separated by ca. 250 km, would have needed to experience an E–W component of separation at rates between ca. 7 mm/a (in case of onset in Eocene) and ca. 17 mm/a (onset in the Miocene). Not only is there a lack of evidence for an E–W difference within this range in geodetic measurements (Fig. 9), but there is also no record of any crustal deformation that could relate to these kinematics. Furthermore, a gradually widening tear in a continuous slab should have produced a pattern of symmetrically outward migrating alkalic magmatic rocks in the Miocene, rather than the observed southward progression focused along the eastern and western edges of the asthenospheric window (Fig. 15). There are considerable differences between the Aegean Sea region and the Menderes Massif, particularly regarding lithospheric evolution. In the light of Archaean zircon ages produced from magmatic and metamorphic rocks (Kröner and Sengör, 1990; Candan et al., 2011; Zlatkin et al., 2012), we regard it possible that the lithosphere below the Menderes Massif may have been considerably older, and thicker than Aegean lithosphere prior to its Miocene delamination. We propose a scenario where the Menderes arrived into the convergence zone containing thick buoyant continental lithosphere with a passive margin sequence towards the north, and possibly to the west. Upon the collision, the continental lithosphere thickened, and at some stage the leading, oceanic lithospheric domain to the north decoupled (van Hinsbergen et al., 2010b). The thick lithosphere below the Menderes then became mechanically unstable either by an increase in temperatures (Houseman et al., 1981; England and Houseman, 1989; Molnar et al., 1993; Platt and England, 1993; Houseman and Molnar, 1997; Stern et al., 2006), due to advection of asthenospheric mantle where the Aegean slab decoupled, or as a result of heterogeneity in plastic strength (Gorczyk et al., 2012) causing the thick lithosphere below the Menderes to delaminate (Fig. 22). Such a model would be similar to scenarios proposed for the Carpathians (Lorinczi and Houseman, 2009), the North American Great Basin (West et al., 2009), New Zealand's North Island (Stern et al., 2006), Eastern Anatolia (Gögüs and Pysklywec, 2008), and intraplate orogenic systems in general (Gorczyk et al., 2013). As many studies have pointed out before, southward progressing removal of lithospheric mantle below western Turkey is consistent with the change in age and composition of Miocene to recent volcanic rocks (Seyitoglu et al., 1997; Pe-Piper and Piper, 2007; Ersoy et al., 2008; Dilek and Altunkaynak, 2009; Ersoy et al. 2010; Prelevic et al., 2010a; Altunkaynak and Dilek, 2009). We would argue that the Miocene southward progression of alkaline volcanic rocks both along the Anatolian west coast and along the Afyon–Isparta line track the edges of the delaminated Anatolian crustal domain. 5.2. Sinistral transtension across West Anatolian Transfer Zone as a driver for Menderes extension The current strain field shows a clear westward gradient to higher velocities, both in overall movement, and in the southward component (Fig. 9) (Reilinger et al., 2006; Aktug et al., 2009; Pérouse et al., 2012), but it is difficult to assess how fast the two driving processes, slab rollback and removal of the lithospheric mantle, could have operated through time. In general the geodetic measurements of the Hellenic subduction zone suggest a movement of ca. 33 mm/a (Reilinger et al., 2006), which is at the lower range of what Stegman et al. (2006) and Schellart et Fig. 20. Three-dimensional model of P-wave velocity (dVp) anomaly contours and hypocentres in the eastern Aegean and western Anatolia from the surface to a depth of ca. 1250 km. Land surface (white, transparent) is shown for reference. The north-dipping slab (a) is discontinuous in the upper mantle (b), but continues eastward for 0.5%, 0.6%, and 0.7% dVp contours (white arrows). Slow, hot mantle above the slab is represented as a negative dVp anomaly in the Aegean (a) that is connected to a vertical anomaly southeast. In the south, a westward deepening cluster of earthquake hypocentres in normal velocity lithosphere reaches depths of 176 km. These data are also presented in 3D PDF format (cf. supplementary materials 2 and 3). K. Gessner et al. / Gondwana Research 24 (2013) 243–274 267 Fig. 21. Summary figure showing the two denudation stages of the Menderes Massif in the context of regional structures, including the area approximate area currently affected by the West Anatolian Transfer Zone (hatched). Elevations of more than 1000 m are shown with white transparent overlay. Box indicates extent of model shown in Fig. 21. al. (2007) consider characteristic for narrow oceanic slabs, but very close to the ca. 30 mm/a for decoupled continental collision systems in Faccenda et al. (2009). In the Aegean, fast displacement rates have been proposed for individual normal fault systems: ca. 20 mm/a along the Cretan detachment (Ring and Reischmann, 2002) and 6.5 mm/a along the Vari detachment on Syros and Tinos. Gessner et al. (2001a, 2001b, 2001c) and Wijns et al. (2005) estimated displacement along the Kuzey detachment at 2 mm/a. The Aegean displacement rates are typical for fast displacement rates in metamorphic core complexes, the Kuzey detachment would be typical for slower displacement rates (Gessner et al., 2007). The velocity of southward delamination of lithospheric mantle below western Turkey is difficult to constrain directly, but can be approximated by the progression of alkaline magmatism in western Anatolia. Data compiled by Dilek and Altunkaynak (2009) and Ersoy et al. (2010) imply that Miocene volcanic activity is limited by both the eastern edge of the Aegean slab and the western edge of the Cyprus slab, and that this activity progressed southward at a rate of ca. 10–15 mm/a. Even though these are only rough estimates, these rates suggest that the southward retreat of the Hellenic subduction zone took place at least twice as fast as delamination progressed in western Anatolia. Therefore, we would argue that the formation of the West Anatolian Transfer Zone caused very different Miocene developments on either side: rapid rollback of the dense lithosphere of the Adriatic plate in the Aegean Sea region triggered a surge of lithospheric extension in the mid Miocene. In western Anatolia at the same time a plateau with associated (Yilmaz et al., 2000), and increasingly alkaline volcanic activity formed in the northern Menderes (Seyitoglu et al., 1997; Pe-Piper and Piper, 2007; Ersoy et al., 2008; Dilek and Altunkaynak, 2009; Prelevic et al., 2010a; Altunkaynak et al., 2012a, 2012b), while the Lycian nappes were thrust onto the Bey Dağları foreland (Fig. 5) to the south (Collins and Robertson, 1998). Such close proximity of crustal shortening and extension in conjunction with alkali magmatism is also known from eastern Anatolia (Şengör et al., 2003; Gögüs and Pysklywec, 2008), and the North Island of New Zealand (Stern et al., 2006); areas in convergent settings for which removal of lithosphere has been proposed. Transtensional kinematics could provide an explanation for folding about NE–SW to NNE–SSW axes that is most prominent in the northern Menderes (Bozkurt, 2003; Cemen et al., 2006), but has also been described from other parts of the Menderes (Schuiling, 1962; Rimmelé et al., 2003; Regnier et al., 2006) and may be the reason for the sinusoidal basement topography in the Alaşehir–Gediz graben system (Çiftçi and Bozkurt, 2009a, 2010). Folding parallel to extension at the observed NNE–SSW fold axis orientations and wavelengths of ca. 20–40 km may have recorded the initial elastic response during Stage 1 crustal extension. Thinning of the crust parallel to stretching could therefore partially have been countered by shortening in a perpendicular direction, hence crustal thickness in this case would be no adequate measure of crustal stretching, as for example implied by Zhu et al. (2006b). Folding caused uplift of basement in the anticlines, while providing accommodation space for the Miocene basins in the synclines. The relation between basement topography and fault segment length in the Alaşehir–Gediz graben system suggests that transtensional folding may have overlapped with the early stages of tectonic denudation of the CMCC. This means that the Menderes Massif has experienced northeast–southwest stretching before 268 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Fig. 22. Conceptual model of the present slab dynamics in southwest Turkey, where the southwest retreat of the Aegean slab with its vertical edge maintains a transtensional situation that controls diffuse brittle deformation along the coast and inboard of the Aegean. The two stages of Menderes denudation exposed one of Earth's largest metamorphic core complexes displaying frozen in mid-crustal levels of transtensional deformation. north–south fragmentation by the Kuzey and Güney detachment systems, and that overall extension in western Anatolia may be greater than estimated by the displacement of rigid blocks. The previous estimate of 150 km extension (van Hinsbergen, 2011) is mainly based on the assumption that the Simav detachment footwall experienced little or no internal deformation, before being fragmented by the Kuzey and Güney detachments. While earthquake distribution patterns support the fragmentation of western Anatolia into different domains (Figs. 18 and 19) geodetic measurement shows that the overall strain is very homogeneous (Aktug et al., 2009; Özeren and Holt, 2010). This discrepancy may be explained to some extent by the variation of rock composition in the study area, where heterogeneous rock units such as the tectonic melanges of the Bornova Flysch and the Tavşanlı Zone may respond to ductile flow of the lower crust by fracturing more often and in a more distributed manner than the metamorphic rocks of the Menderes Massif. It is also clear that, compared to the current situation, transtension across the WATZ would have played a much larger role during the Miocene, when transtension affected the entire area of the thermally weakened Menderes Massif lithosphere. Structures like the İzmir–Balıkesir Transfer Zone (Uzel and Sozbilir, 2008) — which we argue would be the present day upper crustal expression of the West Anatolia Transfer Zone — may at present only constitute a rheological boundary in a wide zone of bottom-driven crustal deformation between the North Anatolian Fault Zone and the Hellenic Trench. That the WATZ does not cut the surface as one distinct fault zone is likely to be the consequence of the overall rheological stratification of the continental lithosphere in the Aegean and western Turkey. The weak lower crust constitutes a thick viscous layer that mechanically decouples the brittle-elastic upper crust from the bottom-driven kinematics, such that the only thing the upper crust ‘feels’ is a westward increase in crustal extension (Fig. 9) resulting in a thinner crust and shallower Moho in the Aegean relative to the Menderes area. 5.3. Continuous versus punctuated crustal extension The geological evidence points to a two-stage denudation of the Menderes Massif, with movement on the Simav detachment slowing down or stopping around ca. 19–16 Ma (Ring and Collins, 2005; Thomson and Ring, 2006; Hetzel et al., 2013). Synkinematic granites that were exhumed in the footwall of the Simav detachment were probably intruded in conjunction with asthenospheric flow caused by decoupling of the leading part of the African slab (van Hinsbergen et al, 2010b). We envisage a scenario where footwall up-doming at the scale of the Menderes Massif caused secondary late-stage top-S extension at the base of the Afyon/Ören Unit at the southern margin of the dome, explaining the break in fission-track ages across the base of this unit (Fig. 8). There is also strong evidence for relatively rapid cooling in the late Oligocene and early Miocene in the Çine submassif. However, field evidence for a well-developed extensional detachment system is lacking (Ring et al., 2003a). The steep gradient in apatite fission track ages between the Cycladic Blueschist Unit and the Afyon/Ören unit in Fig. 8 could be explained by either a top-S extensional reactivation of the basal thrust of the Afyon/Ören unit, but also by footwall uplift below the original Simav–Alaçam detachment system (Fig. 23), if indeed it extended this far south. We propose that the development of a wide, distributed West Anatolia Transfer Zone caused the lithospheric extension in the Menderes Massif and the dome-shape of the evolving core complex (Fig. 23). Extension waned by 19–16 Ma in the northern part of the massif. In the central Menderes Massif granites intruded at 16– 15 Ma (Glodny and Hetzel, 2007) and the basin fill suggests ongoing extension in the mid Miocene (Çiftçi and Bozkurt, 2010). Modest footwall cooling by this time (Ring et al., 2003a, 2003b) suggests limited extensional activity by this time. Continuing uplift of the evolving Stage 1 Menderes core complex led to the formation of a plateau with K. Gessner et al. / Gondwana Research 24 (2013) 243–274 269 Fig. 23. Conceptual model of the two stage tectonic denudation of the Menderes Massif from the Early Miocene to the present. According to our model the monocline in the southern Menderes formed as a footwall uplift after Miocene detachment faulting. Miocene crustal melts get exhumed either soon after intrusion in the north, of by the Kuzey detachment in the Late Miocene. Corrugation occurring due to E–W shortening of the basement in the footwall of the Early Miocene detachments still shape the drainage of the Çine and Gördes submassifs (Fig. 9); the CMCC footwall ‘inherited’ corrugations as topographic features that control the orientation of drainage in the Aydın and Bozdağ mountains (Figs. 12 and 13). an associated peneplain (Yilmaz et al., 2000). Our surface topography analysis supports the hypothesis that this peneplain has been significantly modified by the movement along the Kuzey and Güney detachments and the high-angle normal fault systems in the Gediz and Büyük Menderes grabens since the Pliocene (Gessner et al., 2001b). Whether or not the early Miocene extensional pulse was clearly separated in time from the distinct Pliocene to Recent extensional activity is difficult to assess. It is conceivable that the two events represent a continuum of lithospheric extension that commenced in the early Miocene and then slowed down. As a result of the denudation and cooling of the Menderes Massif, transtension across the WATZ changed character from the wide transtensional deformation of thermally weakened crust to a more focussed structural corridor at the western margin of the massif. 5.4. Open questions We propose that sinistral movement along the boundary of the Aegean and Anatolian domains played a much larger role in the tectonic evolution of the Anatolian peninsula than previously proposed, particularly with regard to the extensional deformation in the Menderes Massif, but also with respect to the distribution of seismic hazard, and the structural control on hydrothermal metallic resources and geothermal reservoirs (Yigit, 2006; Faulds et al., 2009; Yigit, 2009; Gessner et al., 2010). The West Anatolia Transfer Zone is a wide and diffuse lithospheric deformation zone that has localised at the western margin of one of its earlier products, the Menderes Massif, and constrained the shape and location of Anatolia's Aegean coastline. Despite large advances in understanding this rapidly deforming region, there is still a considerable lack of detailed knowledge, for example on how deformation has partitioned across the WATZ over time, how extensional strain has been accommodated at the flanks of the Menderes Massif, and how the crustal structure changes toward the east. There is a need to better resolve crustal and mantle structure below western Turkey to increase our knowledge of three-dimensional architecture and to further constrain the processes that have lead to the low velocity anomaly below the Menderes Massif. Our review shows the significance and benefit of integrating geological and geophysical data in three dimensions to arrive at a better understanding of lithospheric structure and tectonic evolution. 6. Summary points • The Hellenide and Anatolide domains of the Tethyan orogen can be defined on the grounds of their geological history that encompasses differences in the age of pre-Alpine basement rocks, as well as in structure, metamorphic and magmatic history related to continental subduction and crustal extension. • The lithospheric mantle across the Hellenide and Anatolide domains is heterogeneous. Seismic velocity anomalies show a sharp vertical boundary between the fast, cold and dense slab below the Aegean and a slow, hot and buoyant asthenospheric region below western Turkey. Gravity data show a north–south oriented boundary between a high in the Aegean and lower gravity values below the Menderes Massif, and towards the Anatolian plateau to the east. • We propose that geological differences between the Hellenide and the Anatolide domains are closely related to the discontinuity in the lithospheric mantle. We interpret this discontinuity as a lithosphere 270 • • • • • • K. Gessner et al. / Gondwana Research 24 (2013) 243–274 scale shear zone, the West Anatolia Transfer Zone (WATZ), which has accommodated the difference between fast roll back of the slab in the Aegean and slow delamination of the Anatolian continental lithosphere since the Miocene, and links the North Anatolian Fault zone to the Hellenic trench. The lack of oceanic lithosphere below western Anatolia's upper mantle together with the lack of high-pressure metamorphism supports the hypothesis that thick buoyant continental lithosphere of the Anatolian microplate brought about an end to continental subduction in western Turkey in the Eocene. We link the Late Oligocene/Early Miocene to recent crustal extension in the Anatolide belt in western Turkey to sinistral transtension across the WATZ. Within this kinematic framework the Menderes Massif, of one of Earth's largest metamorphic core complexes, has experienced NNE–SSW extension, including extensional detachment faulting, folding parallel to extension, doming, and footwall uplift. The Menderes Massif appears to be coincident with a Miocene peneplain, but since the Late Miocene has been fragmented by E–W and WNW–ESE trending graben systems. We propose that fragmentation of the plateau has driven flow in the weak lower crust towards the Central Menderes area, causing a dynamic topographic response across the fracture system in the plateau and in the footwall of Miocene to Pliocene graben bounding detachment faults. Earthquake locations in western Anatolia strongly correlate with the spatial distribution of tectonic units. Seismic activity in the Menderes Massif is lower than in adjacent regions, but it strongly localises along graben systems. Most earthquakes occur at shallow to mid-crustal depths, with the notable exception of a narrow E–W oriented zone of very deep earthquakes below the Gulf of Gökova. We tentatively link this steep seismic zone to delamination of continental lithosphere. Our findings highlight the significance of lateral variations in evolving continental arcs for the structure of orogenic belts, particularly with respect to the formation of metamorphic core complexes. Acknowledgements K. Gessner wishes to acknowledge funding by a 2010 University of Western Australia Professional Development Award, the Australian Research Council (LP100200785), and support by Ariana Resources Pty. Ltd. and the ARC Centre of Excellence for Core to Crust Fluid Systems (Publication 279). We thank J.-P. Burg, P.A. Cawood, B. Çiftçi, M. Fiorentini, T. Güngör, R. Hetzel, A.I.S. Kemp, E. Koralay, Y. Lu, D.J.J. van Hinsbergen, F. Wedin, G. Duclaux, and K.-H. Wyrwoll for discussions and comments on previous versions. Y. Dilek and an anonymous reviewer are thanked for formal reviews that helped to improve the manuscript; M. Santosh and T. Horscroft are thanked for outstanding editorial support, and patience. Appendix A. Supplementary data The supplementary material consists of three 3D PDF pages in one file. Notice that the 3D PDF models, which contain earthquake locations and p-wave anomaly contours — similar to the content shown in Fig. 20 — allow a range of interactions, including the selection of objects in the model tree. Explicit instructions are given in Supplementary Fig. 1. Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.gr.2013.01.005. References Akay, E., 2009. Geology and petrology of the Simav Magmatic Complex (NW Anatolia) and its comparison with the Oligo-Miocene granitoids in NW Anatolia: implications on Tertiary tectonic evolution of the region. International Journal of Earth Sciences 98, 1655–1675. Aktug, B., Nocquet, J.M., Cingöz, A., Parsons, B., Erkan, Y., England, P., Lenk, O., Gürdal, M.A., Kilicoglu, A., Akdeniz, H., Tekgül, A., 2009. Deformation of western Turkey from a combination of permanent and campaign GPS data: limits to block-like behavior. Journal of Geophysical Research 114, B10404. Allmendinger, R.W., Jordan, T.E., Kay, S.M., Isacks, B.L., 1997. The evolution of the Altiplano–Puna Plateau of the central Andes. Annual Review of Earth and Planetary Sciences 25, 139–174. Altherr, R., Kreuzer, H., Wendt, I., Lenz, H., Wagner, G.H., Keller, J., Harre, W., Höhndorf, A., 1982. A late Oligocene/early Miocene high temperature belt in the Attic-Cycladic crystalline complex (SE Pelagonian, Greece). Geologisches Jahrbuch E23, 97–164. Altunkaynak, Ş., Dilek, Y., 2009. Timing and nature of postcollisional volcanism in western Anatolia and geodynamic implications. In: Dilek, Y., Pavlides, S. (Eds.), Postcollisional Tectonics and Magmatism in the Mediterranean Region and Asia: Geological Society of America Special Paper, 409, pp. 321–352 (Boulder, CO). Altunkaynak, Ş., Dilek, Y., Genç, C.Ş., Sunal, G., Gertisser, R., Furnes, H., Foland, K.A., Yang, J., 2012a. Spatial, temporal and geochemical evolution of Oligo-Miocene granitoid magmatism in western Anatolia, Turkey. Gondwana Research 21, 961–986. Altunkaynak, Ş., Sunal, G., Aldanmaz, E., Genç, C.Ş., Dilek, Y., Furnes, H., Foland, K.A., Yang, J., Yıldız, M., 2012b. Eocene granitic magmatism in NW Anatolia (Turkey) revisited: new implications from comparative zircon SHRIMP U–Pb and 40Ar–39Ar geochronology and isotope geochemistry on magma genesis and emplacement. Lithos 155, 289–309. An, Y., 2006. Cenozoic tectonic evolution of the Himalayan orogen as constrained by along-strike variation of structural geometry, exhumation history, and foreland sedimentation. Earth-Science Reviews 76, 1–131. Aubouin, J., 1959. Contribution a l'étude de la Grèce septrionale; les confins de l'Epire et de la Thessalie. Annales Géologiques des Pays Hellèniques 10, 1–483. Avigad, D., Ziv, A., Garfunkel, Z., 2001. Ductile and brittle shortening, extension-parallel folds and maintenance of crustal thickness in the central Aegean. Tectonics 20, 277–287. Baker, C.B., Catlos, E.J., Sorensen, S., Çemen, I., Hancer, M., 2008. Evidence for polymetamorphic garnet growth in the Çine (southern Menderes) Massif, Western Turkey. 2008 IOP Conference Series: Earth Environmental Science, p. 012020. Berk Biryol, C., Beck, S.L., Zandt, G., Özacar, A.A., 2011. Segmented African lithosphere beneath the Anatolian region inferred from teleseismic P-wave tomography. Geophysical Journal International 184, 1037–1057. Bozkurt, E., Park, G.R., Winchester, J.A., 1993. Evidence against the core/cover interpretation of the southern sector of the Menderes massif, west Turkey. Terra Nova 5, 445–451. Bozkurt, E., Park, G.R., 1994. Southern Menderes massif: an incipient metamorphic core complex in western Anatolia, Turkey. Journal of the Geological Society of London 151, 213–216. Bozkurt, E., 1995. Metamorphism of Palaeozoic schists in the southern Menderes Massif: filed, petrographic, textural and microstructural evidence. Turkish Journal of Earth Sciences 5, 105–121. Bozkurt, E., Park, R.G., 1997. Evolution of a mid-Tertiary extensional shear zone in the southern Menderes Massif, western Turkey. Bulletin de la Societe Geologique de France 168, 3–14. Bozkurt, E., Oberhänsli, R., 2001. Menderes Massif (Western Turkey): structural, metamorphic and magmatic evolution — a synthesis. International Journal of Earth Sciences (Geologische Rundschau) 89, 679–708. Bozkurt, E., Park, G., Loos, S., Reischmann, T., 2001. Discussion on the evolution of the Southern Menderes Massif in SW Turkey as revealed by zircon dating. Journal of the Geological Society of London 158, 393–395. Bozkurt, E., 2003. Origin of NE-trending basins in western Turkey. Geodinamica Acta 16, 61–81. Bozkurt, E., 2007. Extensional v. contractional origin for the southern Menderes shear zone, SW Turkey: tectonic and metamorphic implications. Geological Magazine 144, 191–210. Bozkurt, E., Satır, M., Buğdaycıoğlu, Ç., 2011. Surprisingly young Rb/Sr ages from the Simav extensional detachment fault zone, northern Menderes Massif, Turkey. Journal of Geodynamics 52, 406–431. Brinkmann, R., 1971. Das kristalline Grundgebirge von Anatolien. Geologische Rundschau 60, 886–899. Burg, J.P., 2011. Rhodope: from Mesozoic convergence to Cenozoic extension. Review of petro-structural data in the geochronological frame. Journal of the Virtual Explorer 42. Çaglayan, M.A., Öztürk, Z., Sav, H., Akat, U., 1980. Menderes Masifi güneyine ait bulgular va yaptisal yorum. Jeoloji Mühendisligi 10, 9–19. Candan, O., Dora, O.Ö., Oberhänsli, R., Çetinkaplan, M., Partzsch, J.H., Warkus, F.C., Dürr, S., 2001. Pan-African high-pressure metamorphism in the Precambrian basement of the Menderes Massif, western Anatolia, Turkey. International Journal of Earth Sciences (Geologische Rundschau) 89, 793–811. Candan, O., Koralay, O.E., Akal, C., Kaya, O., Oberhänsli, R., Dora, O.Ö., Konak, N., Chen, F., 2011. Supra-Pan-African unconformity between core and cover series of the Menderes Massif/Turkey and its geological implications. Precambrian Research 184, 1–23. Catlos, E.J., Çemen, I., 2005. Monazite ages and the evolution of the Menderes Massif. International Journal of Earth Sciences 94, 204–217. Catlos, E.J., Jacobs, L., Oyman, T., S, S., 2012. Long-term exhuation of Aegean metamorphic core complex granitoidsin the northern Menderes Massif, western Turkey. American Journal of Science 312, 534–571. Cemen, I., Catlos, E.J., Gögüs, O., Özerdem, C., 2006. Postcollisional extensional tectonics and exhumation of the Menderes massif in the Western Anatolia extended terrane, Turkey. In: Dilek, Y., Pavlides, S. (Eds.), Postcollisional Tectonics and Magmatism in the Mediterranean Region and Asia: Geological Society of America Special Paper, 409, pp. 353–379. Çiftçi, N.B., Bozkurt, E., 2009a. Pattern of normal faulting in the Gediz Graben, SW Turkey. Tectonophysics 473, 234–260. Çiftçi, N.B., Bozkurt, E., 2009b. Evolution of the Miocene sedimentary fill of the Gediz Graben, SW Turkey. Sedimentary Geology 216, 49–79. K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Çiftçi, N.B., Bozkurt, E., 2010. Structural evolution of the Gediz Graben, SW Turkey: temporal and spatial variation of the graben basin. Basin Research 22, 846–873. Cohen, H.A., Dart, C.J., Akyüz, H.S., Barka, A., 1995. Syn-rift sedimentation and structural development of the Gediz and Büyük Menderes graben, western Turkey. Journal of the Geological Society of London 152, 629–638. Collins, A.S., Robertson, A.H.F., 1997. Lycian mélange, southwest Turkey: an emplaced Cretaceous accretionary complex. Geology 25, 255–258. Collins, A.S., Robertson, A.H.F., 1998. Process of Late Cretaceous to Late Miocene episodic thrust-sheet translation in the Lycian Taurides. Journal of the Geological Society of London 155, 759–772. Collins, W.J., 2002. Nature of extensional accretionary orogens. Tectonics 21, 1024. http://dx.doi.org/10.1029/2000TC001272. Dannat, C., 1997. Geochemie, Geochronologie und Nd–Sr-Isotopie der granitoiden Kerngneise des Menderes Massivs, SW-Türkei (in German). Unpublished PhD thesis. Johannes Gutenberg University, Mainz, p. 120. Dannat, C., Reischmann, T., 1999. Single zircon ages of migmatites from the Menderes Massif, SW Turkey. EUG Journal of Conference Abstracts 4, 805. de Boorder, H., Spakman, W., White, S.H., Wortel, M.J.R., 1998. Late Cenozoic mineralization, orogenic collapse and slab detachment in the European Alpine Belt. Earth and Planetary Science Letters 164, 569–575. Dewey, J.F., Sengör, A.M.C., 1979. Aegean and surrounding regions: complex and multiplate continuum tectonics in a convergent zone. Geological Society of America Bulletin 102, 812–829. Dilek, Y., Altunkaynak, Ş., 2009. Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt. In: Van Hinsbergen, D.J.J., Edwards, M.A., Govers, R. (Eds.), Collision and Collapse at the Africa–Arabia–Eurasia Subduction Zone: The Geological Society, London, Special Publication, 311 (London). Dilek, Y., Sandvol, E., 2009. Seismic structure, crustal architecture and tectonic evolution of the Anatolian–African Plate Boundary and the Cenozoic Orogenic Belts in the Eastern Mediterranean Region. Geological Society, London, Special Publications 327, 127–160. Dinter, D.A., 1998. Late Cenozoic extension of the Alpine collisional orogen, northeastern Greece: origin of the north Aegean basin. Geoligical Society of America Bulletin 110, 1208–1230. Dora, O.Ö., Candan, O., Kaya, O., Dürr, S., Oberhänsli, R., 1995. New evidence concerning the geotectonic evolution of the Menderes Massiv. Proceedings International Earth Science Colloqium on the Aegean Region, Izmir, Turkey 1, 53–72. Dürr, S.H., 1975. Über Alter und geotektonische Stellung des Menderes-Kristallins/SWAnatolien und seine Äquivalente in der mittleren Ägäis. Habilitation thesis. Philipps-University Marburg, Germany. Dürr, S.H., Altherr, R., Keller, J., Okrusch, M., Seidel, E., 1978. The Median Aegean Crystalline Belt: stratigraphy, structure, metamorphism, magmatism. In: Cloos, H., Roeder, D., Schmidt, K. (Eds.), Alps, Appenines, Hellenides. Schweitzerbart, Stuttgart, pp. 455–477. Emre, T., Sözbilir, H., 1997. Field evidence for metamorphic core complex, detachment faulting and accommodation faults in the Gediz and Büyük Menderes Grabens, Western Anatolia. Proceedings IESCA 1995 (1), 73–94. Emre, T., Sözbilir, H., 2007. Tectonic evolution of the Kiraz Basin, Küçük Menderes Graben: evidence for compression/uplift-related basin formation overprinted by extensional tectonics in West Anatolia. Turkish Journal of Earth Science 16, 441–470. Engel, M., Reischmann, T., 1998. Single zircon geochronology of orthogneisses from Paros, Greece. Bulletin of the Geological Society of Greece 32, 91–99. England, P., Houseman, G.A., 1989. Extension during continental convergence, with application to the Tibetan Plateau. Journal of Geophysical Research 94 (17,561– 517,579). Erdogan, B., Güngör, T., 1992. Stratigraphy and tectonic evolution of the northern margin of the Menderes Massif. TAPG Bulletin 4, 9–34. Erdogan, B., Güngör, T., 2004. The problem of the core–cover boundary of the Menderes Massif and an emplacement mechanism for regionally extensive gneissic granites, western Anatolia (Turkey). Turkish Journal of Earth Sciences 13, 15–36. Erkül, F., 2010. Tectonic significance of synextensional ductile shear zones within the Early Miocene Alaçamdag granites, northwestern Turkey. Geological Magazine 147, 611–637. Ersoy, Y., Helvaci, C., Sozbilir, H., Erkul, F., Bozkurt, E., 2008. A geochemical approach to Neogene–Quaternary volcanic activity of western Anatolia: an example of episodic bimodal volcanism within the Selendi Basin, Turkey. Chemical Geology 255, 265–282. Ersoy, E.Y., Helvacı, C., Palmer, M.R., 2010. Mantle source characteristics and melting models for the early-middle Miocene mafic volcanism in Western Anatolia: Implications for enrichment processes of mantle lithosphere and origin of K-rich volcanism in post-collisional settings. Journal of Volcanology and Geothermal Research 198, 112–128. Eyidogan, H., Jackson, J., 1985. A seismological study of normal faulting in the Demirci, Alasehir and Gediz earthquakes of 1969–70 in western Turkey: implications for the nature and geometry of deformation in the continental crust. Geophysical Journal of the Royal Astronomical Society 81, 569–607. Faccenda, M., G., M., Gerya, T.V., 2009. Coupled and decoupled regimes of continental collision: numerical modeling. Earth and Planetary Science Letters 278, 337–349. Faccenna, C., Bellier, O., Martinod, J., Piromallo, C., Regard, V., 2006. Slab detachment beneath eastern Anatolia: a possible cause for the formation of the North Anatolian fault. Earth and Planetary Science Letters 242, 85–97. Farr, T.G., Rosen, P.A., Caro, E., Crippen, R., Duren, R., Hensley, S., Kobrick, M., Paller, M., Rodriguez, E., Roth, L., Seal, D., Shaffer, S., Shimada, J., Umland, J., Werner, M., Oskin, M., Burbank, D., Alsdorf, D., 2007. The Shuttle Radar Topography Mission. Reviews of Geophysics 45, RG2004. 271 Faulds, J.E., Bouchot, V., Moeck, I., Oguz, K., 2009. Structural controls on geothermal systems in western Turkey: a preliminary report. Geothermal Resources Council Transactions 33, 375–381. Fillerup, M.A., Knapp, J.H., Knapp, C.C., Raileanu, V., 2010. Mantle earthquakes in the absence of subduction? Continental delamination in the Romanian Carpathians. Lithosphere 2, 333–340. Fitzgerald, P.G., Fryxell, J.E., Wernicke, B.P., 1991. Miocene crustal extension and uplift in southeastern Nevada — constraints from fission-track analysis. Geology 19, 1013–1016. Fletcher, J.M., Bartley, J.M., 1994. Constrictional strain in a non-coaxial shear zone: implications for fold and rock fabric development, central Mojave metamorphic core complex, California. Journal of Structural Geology 16, 555–570. Fletcher, J.M., Bartley, J.M., Martin, M.W., Glazner, A., Walker, J.D., 1995. Large-magnitude continental extension: an example from the central Mojave metamorphic core complex. GSA Bulletin 107, 1468–1483. Foster, D.A., John, B.E., 1999. Quantifying tectonic exhumation in an extensional orogen with thermochronology; examples from the southern Basin and Range Province. In: Ring, U., Brandon, M.T., Lister, G.S., Willett, S. (Eds.), Exhumation Processes: Normal Faulting, Ductile Flow and Erosion. Geological Society, London, pp. 343–364. Gallardo, L.A., Perez-Flores, M.A., Gomez-Trevino, E., 2005. Refinement of threedimensional multilayer models of basins and crustal environments by inversion of gravity and magnetic data. Tectonophysics 397, 37–54. Gautier, P., Brun, J.-P., Moriceau, R., Sokoutis, D., Martinod, J., L., J., 1999. Timing, kinematics and cause of Aegean extension: a scenario based on a comparison with simple analogue experiments. Tectonophysics 315, 31–72. Gessner, K., Ring, U., Lackmann, W., Passchier, C.W., Gungor, T., Anonymous, 1998. Structure and crustal thickening of the Menderes Massif, southwest Turkey, and consequences for large-scale correlations between Greece and Turkey. Deltio tes Ellenikes Geologikes Etaireias — Bulletin of the Geological Society of Greece 32, 145–152. Gessner, K., Piazolo, S., Gungor, T., Ring, U., Kroener, A., Passchier, C.W., 2001a. Tectonic significance of deformation patterns in granitoid rocks of the Menderes nappes, Anatolide Belt, Southwest Turkey. International Journal of Earth Sciences 89, 766–780. Gessner, K., Ring, U., Johnson, C., Hetzel, R., Passchier, C.W., Gungor, T., 2001b. An active bivergent rolling-hinge detachment system: Central Menderes metamorphic core complex in western Turkey. Geology 29, 611–614. Gessner, K., Ring, U., Passchier, C.W., Gungor, T., 2001c. How to resist subduction: evidence for large-scale out-of-sequence thrusting during Eocene collision in western Turkey. Journal of the Geological Society 158, 769–784. Gessner, K., Ring, U., Passchier, C.N., Hetzel, R., 2002. Discussion on “Stratigraphic and metamorphic inversions in the central Menderes Massif: a new structural model”, by Aral I. Okay. International Journal of Earth Sciences 91, 168–172. Gessner, K., Collins, A.S., Ring, U., Gungor, T., 2004. Structural and thermal history of poly-orogenic basement: U–Pb geochronology of granitoid rocks in the southern Menderes Massif, Western Turkey. Journal of the Geological Society 161, 93–101. Gessner, K., Wijns, C., Moresi, L., 2007. Significance of strain localization in the lower crust for structural evolution and thermal history of metamorphic core complexes. Tectonics 26, TC001768. Gessner, K., Porwal, A., Markwitz, V., Wedin, F., 2010. Tectonic framework of hydrothermal and geothermal systems in the Menderes Massif, western Turkey. Geophysical Research Abstracts 12 (EGU2010-5118-2012). Gessner, K., Ring, U., Güngör, T., 2011. Field guide to Samos and the Menderes Massif; along-strike variations in the Mediterranean Tethyan Orogen. Glodny, J., Hetzel, R., 2007. Precise U–Pb ages of syn-extensional Miocene intrusions in the central Menderes Massif, western Turkey. Geological Magazine 144, 235–246. Godfriaux, I., 1968. Etude géologique de la région de l'Olympe (Gréce. Annales Géologiques des Pays Hellèniques 19, 1–271. Gögüs, O., Pysklywec, R.N., 2008. Mantle lithosphere delamination driving plateau uplift and synconvergent extension in eastern Anatolia. Geology 36, 723–726. Gökgöz, A., 1998. Geochemistry of the Kizildere–Tekkehamam–Buldan–Pamukkale geothermal fields, Turkey. The United Nation University Report 199B, Reykjavik. Gorczyk, W., Hobbs, B., Gerya, T., 2012. Initiation of Rayleigh–Taylor instabilities in intra-cratonic settings. Tectonophysics 514–517, 146–155. Gorczyk, W., Hobbs, B., Gerya, T., Gessner, K., 2013. Intracratonic geodynamics. Gondwana Research. http://dx.doi.org/10.1016/j.gr.2013.01.006. Govers, R., Wortel, M.J.R., 2005. Lithosphere tearing at STEP faults: response to edges of subduction zones. Earth and Planetary Science Letters 236, 505–523. Gürer, F., Sarica-Filoreau, N., Özburan, M., Sangu, E., Dogan, B., 2009. Progressive development of the Büyük Menderes Graben based on new data, western Turkey. Geological Magazine 146, 652–673. Hasozbek, A., Satir, M., Erdogan, B., Akay, E., Siebel, W., 2011. Early Miocene postcollisional magmatism in NW Turkey: geochemical and geochronological constraints. International Geology Review 53, 1098–1119. Hasozbek, A., Erdogan, B., Satir, M., Siebel, W., Akay, E., Dogan, G.D., Taubald, H., 2012. Al-in-hornblende thermobarometry and Sr–Nd–O–Pb isotopic compositions of the Early Miocene Alacam granite in NW Anatolia (Turkey). Turkish Journal of Earth Sciences 21, 37–52. Hasozbek, A., Akay, E., Erdogan, B., Satir, M., Siebel, W., 2010. Early Miocene granite formation by detachment tectonics or not? A case study from the northern Menderes Massif (Western Turkey). Journal of Geodynamics 50, 67–80. Hancock, P.L., Barka, A.A., 1987. Kinematic indicators on active normal faults in western Turkey. Journal of Structural Geology 9, 573–584. Hetzel, R., Passchier, C.W., Ring, U., Dora, O.Ö., 1995a. Bivergent extension in orogenic belts: the Menderes massif, southwestern Turkey. Geology 23, 455–458. 272 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Hetzel, R., Ring, U., Akal, C., Troesch, M., 1995b. Miocene NNE-directed extensional unroofing in the Menderes massif, southwestern Turkey. Journal of the Geological Society of London 152, 639–654. Hetzel, R., Reischmann, T., 1996. Intrusion age of Pan-African augen gneisses in the southern Menderes massif and the age of cooling after Alpine ductile extensional deformation. Geological Magazine 133, 565–572. Hetzel, R., Romer, R.L., Candan, O., Passchier, C.W., 1998. Geology of the Bozdag area, central Menderes massif, SW-Turkey: Pan African basement and Alpine deformation. Geologische Rundschau 87, 394–406. Hetzel, R., Zwingmann, H., Mulch, A., Gessner, K., Akal, C., Hampel, A., Güngör, T., Petschick, R., Mikes, T., Wedin, F., 2013. Spatio-temporal evolution of brittle normal faulting and fluid infiltration in detachment fault systems — a case study from the Menderes Massif, western Turkey. Tectonics. http://dx.doi.org/10.1002/tect.20031. Houseman, G.A., McKenzie, D.P., Molnar, P., 1981. Convective instability of a thickened boundary layer and its relevance for the thermal evolution of continental convergent belts. Journal of Geophysical Research 86, 6115–6132. Houseman, G.A., Molnar, P., 1997. Gravitational (Rayleigh–Taylor) instability of a layer with non-linear viscosity and convective thinning of continental lithosphere. Geophysical Journal International 128, 125–150. Hyndman, R.D., Currie, C.A., Mazzotti, S.P., 2005. Subduction zone backarcs, mobile belts, and orogenic heat. GSA Today 15, 4–10. Isik, M., Senel, H., 2009. 3D gravity modeling of Büyük Menderes basin in Western Anatolia using parabolic density function. Journal of Asian Earth Sciences 34, 317–325. Isik, V., Tekeli, O., 2001. Structure of lower plate rocks in metamorphic core complex: Northern Menderes Massif, Western Turkey. International Journal of Earth Sciences (Geologische Rundschau) 89, 757–765. Jacobshagen, V., 1986. Geologie von Griechenland.Borntraeger, Berlin. Jolivet, L., Goffé, B., Monié, P., Truffert-Luxey, C., Patriat, M., Bonneau, M., 1996. Miocene detachment in Crete and exhumation P–T–t paths of high-pressure metamorphic rocks. Tectonics 15, 1129–1153. Jolivet, L., Brun, J.P., 2010. Cenozoic geodynamic evolution of the Aegean. International Journal of Earth Sciences 99, 109–138. Jolivet, L., Famin, V., Mehl, C., Parra, T., Aubourg, C., Hebert, R., Philippot, P., 2004. Strain localization during crustal-scale boudinage to form extensional metamorphic domes in the Aegean Sea. In: Whitney, D.L., Teyssier, C., Siddoway, C.S. (Eds.), Gneiss Domes in Orogeny: GSA Special Paper, 380, pp. 185–210 (Boulder, CO). Jolivet, L., Faccenna, C., Huet, B., Labrousse, L., Le Pourhiet, L., Lacombe, O., Lecomte, E., Burov, E., Denele, Y., Brun, J.P., Philippon, M., Paul, A., Salaün, G., Karabulut, H., Piromallo, C., Monie, P., Gueydan, F., Okay, A.I., Oberhänsli, R., Pourteau, A., Augier, R., Gadenne, L., Driussi, O., 2012. Aegean tectonics: strain localisation, slab tearing and trench retreat. Tectonophysics. http://dx.doi.org/10.1016/j.tecto.2012.06.011. Kaaden, G.V.D., Metz, K., 1954. Beiträge zur Geologie des Raumes zwischen Datça– Mugla–Dalaman Çay (SW Anatolien). Bulletin of the Geological Society of Turkey 5, 1–71. Katzir, Y., Avigad, D., Matthews, A., Garfunkel, Z., Evans, B.W., 2000. Origin, HP/LT metamorphism and cooling of ophiolitic mélanges in southern Evia (NW Cyclades), Greece. Journal of Metamorphic Geology 18, 699–718. Keay, S., G.S., L., Buick, I., 2001. The timing of partial melting, Barrovian metamorphism and granite intrusion in the Naxos metamorphic core complex, Cyclades, Aegean Sea, Greece. Tectonophysics 342, 275–312. Kopf, A., Mascle, J., Klaeschen, D., 2003. The Mediterranean Ridge: a mass balance across the fastest growing accretionary complex on Earth. Journal of Geophysical Research 108, 2372. Koralay, O.E., Satir, M., Dora, O.Ö., 2001. Geochemical and geochronological evidence for Early Triassic calc-alkaline magmatism in the Menderes Massif, western Turkey. International Journal of Earth Sciences (Geologische Rundschau) 822–835. Kröner, A., Sengör, A.M.C., 1990. Archean and Proterozoic ancestry in late Precambrian to early Proterozoic crustal elements of southern Turkey as revealed by singlezircon dating. Geology 18, 1186–1190. Kumerics, C., Ring, U., Brichau, S., Glodny, J., Monie, P., 2005. The extensional Messaria shear zone and associated brittle detachment faults, Aegean Sea, Greece. Journal of the Geological Society 162, 701–721. Lévy, F., Jaupart, C., 2011. Folding in regions of extension. Geophysical Journal International 185, 1120–1134. Li, C., van der Hilst, R.D., Engdahl, E.R., Burdick, S., 2008. A new global model for P wave speed variations in Earth's mantle. Geochemistry, Geophysics, Geosystems 9, Q05018. Lips, A.L.W., 1998. Temporal constraints on the kinematics of the destabilization of an orogen; syn- to post-orogenic collapse of the Northern Aegean region. Geologia Ultraiectinae 166, 223. Lips, A.L.W., Cassard, D., Sözbilir, H., Yilmaz, H., Wijbrans, J.R., 2001. Multistage exhumation of the Menderes Massif, western Anatolia (Turkey). International Journal of Earth Sciences (Geologische Rundschau) 89, 781–792. Loos, S., Reischmann, T., 1999. The evolution of the southern Menderes Massif in SW Turkey as revealed by zircon dating. Journal of the Geological Society of London 156, 1021–1030. Lorinczi, P., Houseman, G.A., 2009. Lithospheric gravitational instability beneath the Southeast Carpathians. Tectonophysics 474, 322–336. Makris, J., Stobbe, C., 1984. Physical properties and state of the crust and upper mantle of the Eastern Mediterranean Sea deduced from geophysical data. Marine Geology 55, 347–363. McClusky, S., Balassanian, S., Barka, A., Demir, C., Ergintav, S., Georgiev, I., Gurkan, O., Hamburger, M., Hurst, K., Kahle, H., Kastens, K., Kekelidze, G., King, R., Kotzev, V., Lenk, O., Mahmoud, S., Mishin, A., Nadariya, M., Ouzounis, A., Paradissis, D., Peter, Y., Prilepin, M., Reilinger, R., Sanli, I., Seeger, H., Tealeb, A., Toksöz, N.M., Veis, G., 2000. Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. Journal of Geophysical Research 105, 5695–5719. Molnar, P., England, P., Martinod, J., 1993. Mantle dynamics, uplift of the Tibetan Plateau, and the Indian Monsoon. Reviews of Geophysics 31, 357–396. Mutlu, A.K., Karabulut, H., 2011. Anisotropic Pn tomography of Turkey and adjacent regions. Geophysical Journal International 187, 1743–1758. Oberhänsli, R., Monié, P., Candan, O., Warkus, F.C., Partzsch, J., Dora, O.Ö., 1998a. The age of blueschist metamorphism in the Mesozoic cover series of the Menderes Massif. Schweiz. Mineralogische und Petrographische Mitteilungen 78, 309–316. Oberhänsli, R., Partzsch, J., Çetinkaplan, M., Candan, O., 1998b. HP record in the Lycian Nappes (western Turkey). Third International Turkish Geology Symposium, Ankara, p. 274. Oberhänsli, R., Partzsch, J.H., Candan, O., Çetinkaplan, M., 2001. First occurrence of Fe–Mgcarpholite documenting a high pressure metamorphism in metasediments of the Lycian Nappes, SW Turkey. International Journal of Earth Sciences (Geologische Rundschau) 89, 867–873. Oberhänsli, R., Candan, O., Wilke, F., 2010. Geochronological evidence of Pan-African eclogites from the central Menderes Massif, Turkey. Turkish Journal of Earth Sciences 19, 431–447. Okay, A.I., Tüysüz, O., 1999. Tethyan sutures of northern Turkey. In: Durand, B., Jolivet, L., Horvath, E., Seranne, M. (Eds.), The Mediterranean Basins: Tertiary Extension Within the Alpine Orogen, London, pp. 475–515. Okay, A.I., 2001. Stratigraphic and metamorphic inversions in the central Menderes Massif: a new structural model. International Journal of Earth Sciences 89, 709–727. Okay, A.I., 2010. Deep subduction of a passive continental margin: comparison of the Tavsanli zone and Oman. Tectonic Crossroads: Evolving Orogens of Eurasia–Africa– Arabia, Ankara, p. 36. Okay, A.I., 2011. A regional olistostrome–mélange belt formed along a major strike-slip tear fault: Bornova Flysch Zone, western Turkey. Geophysical Research Abstracts 13, EGU2011–EGU4689. Okrusch, M., Bröcker, M., 1990. Eclogite facies rocks in the Cycladic blueschist belt, Greece: a review. European Journal of Mineralogy 2, 451–478. Öner, Z., Dilek, Y., 2011. Supradetachment basin evolution during continental extension: the Aegean province of western Anatolia, Turkey. Geological Society of America Bulletin 123, 2115–2141. Özer, S., Sozbilir, H., 2003. Presence and tectonic significance of Cretaceous rudist species in the so-called Permo-Carboniferous Goktepe Formation, central Menderes metamorphic massif, western Turkey. International Journal of Earth Sciences 92, 397–404. Özeren, M.S., Holt, W.E., 2010. The dynamics of the eastern Mediterranean and eastern Turkey. Geophysical Journal International 183, 1165–1184. Özkaymak, C., Sozbilir, H., 2008. Stratigraphic and structural evidence for fault reactivation: the active Manisa fault zone, western Anatolia. Turkish Journal of Earth Sciences 17, 615–635. Özkaymak, C., Sözbilir, H., 2012. Tectonic geomorphology of the Spildagi High Ranges, western Anatolia. Geomorphology 173, 128–140. Papanikolaou, D.J., Royden, L.H., 2007. Disruption of the Hellenic arc: Late Miocene extensional detachment faults and steep Pliocene–Quaternary normal faults—or what happened at Corinth? Tectonics 26, TC5003. Papazachos, B.C., Karakostas, V.G., Papazachos, C.B., Scordilis, E.M., 2000. The geometry of the Wadati–Benioff zone and lithospheric kinematics in the Hellenic arc. Tectonophysics 319, 275–300. Paréjas, E., 1940. La tectonique transversale de la Turquie. Review of the Faculty of Science, University of Istanbul Series B 5, 133–244. Partzsch, J., Oberhänsli, R., Candan, O., Warkus, F.C., 1998. The evolution of the central Menderes Massif, west Turkey: a complex nappe pile recording 1.0 Ga of geological history. Freiberger Forschungshefte C471, 166–168. Paul, A., Salaun, G., Pedersen, H., 2011. New s-wave velocity model and anisotropy measurements or the upper mantle beneath the Aegean and Anatolia: images of a very complex subduction system. Fragile Earth: Geological Processes From Global to Local Scales. Associated Hazards & Resources, Munich, p. A25. Pe-Piper, G., Piper, D.J.W., 1984. Tectonic setting of the Mesozoic Pindos basin of the Peloponnese, Greece. In: Dixon, J.E., Robertson, A.H.F. (Eds.), The Geological Evolution of the Eastern Mediterranean: Geologcal Society Special Publication, 17 (London). Pe-Piper, G., Piper, D.J.W., 2007. Neogene backarc volcanism of the Aegean: new insights into the relationship between magmatism and tectonics. In: Beccaluva, L., Bianchini, G., Wilson, M. (Eds.), Cenozoic Volcanism in the Mediterranean Area: Geological Society of America Special Paper, 418, pp. 17–31. Pérouse, E., Chamot-Rooke, N., Rabaute, A., Briole, P., Jouanne, F., Georgiev, I., Dimitrov, D., 2012. Bridging onshore and offshore present-day kinematics of central and eastern Mediterranean: implications for crustal dynamics and mantle flow. Geochemistry, Geophysics, Geosystems 13, Q09013. Platt, J.P., England, P.C., 1993. Convective removal of the lithosphere beneath mountain belts: thermal and mechanical consequences. American Journal of Science 293, 307–336. Pourteau, A., Candan, O., Oberhänsli, R., 2010. High-pressure metasediments in central Turkey: constraints on the Neotethyan closure history. Tectonics 29, TC5004. Prelevic, D., Akal, C., Foley, S.F., Romer, R.L., Stracke, A., van den Bogaard, P., 2010b. Postcollisionsl mantle dynamics of an orogenic lithosphere: lamproitic mafic rocks from SW Anatolia, Turkey. Tectonic Crossroads: Evolving Orogens of Eurasia–Africa–Arabia, Ankara, p. 42. Prelevic, D., Akal, C., Romer, R.L., Foley, S.F., 2010a. Lamproites as indicators of accretion and⁄or shallow subduction in the assembly of south-western Anatolia, Turkey. Terra Nova 22, 443–452. Purvis, M., Robertson, A., 2004. A pulsed extension model for the Neogene–Recent E– W-trending Alasehir Graben and the NE–SW-trending Selendi and Gordes Basins, western Turkey. Tectonophysics 391, 171–201. Purvis, M., Robertson, A., 2005. Miocene sedimentary evolution of the NE–SW-trending Selendi and Gordes basins, W Turkey: implications for extensional processes. Sedimentary Geology 174, 31–62. K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Putlitz, B., Cosca, M.A., Schumacher, J.C., 2005. Prograde mica 40Ar/39Ar growth ages recorded in high pressure rocks (Syros, Cyclades, Greece). Chemical Geology 214, 79–98. Regnier, J.L., Ring, U., Passchier, C.W., Gessner, K., Gungor, T., 2003. Contrasting metamorphic evolution of metasedimentary rocks from the Cine and Selimiye nappes in the Anatolide belt, western Turkey. Journal of Metamorphic Geology 21, 699–721. Regnier, J.L., Metzger, J.E., Passchier, C.W., 2006. Metamorphism of Precambrian– Palaeozoic schists of the Menderes core series and contact relationships with Proterozoic orthogneisses of the western Çine Massif, Anatolide belt, western Turkey. Geological Magazine 144, 67–104. Reilinger, R., McClusky, S., Vernant, P., Lawrence, S., Ergintav, S., Cakmak, R., Ozener, H., Kadirov, F., Guliev, I., Stepanyan, R., Nadariya, M., Hahubia, G., Mahmoud, S., Sakr, K., ArRajehi, A., Paradissis, D., Al-Aydrus, A., Prilepin, M., Guseva, T., Evren, E., Dmitrotsa, A., Filikov, S.V., Gomez, F., Al-Ghazzi, R., Karam, G., 2006. GPS constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications for the dynamics of plate interactions. Journal of Geophysical Research 111, B05411. Reischmann, T., Kröner, A., Todt, W., Dürr, S., Sengör, A.M.C., 1991. Episodes of crustal growth in the Menderes Massif, W Turkey, inferred from Zircon dating. Terra Abstracts 3, 34. Reischmann, T., 1997. Single zircon Pb/Pb dating of tectonic units from the Metamorphic Complex of Naxos, Greece. Terra Nova 9, 496. Reischmann, T., Loos, S., 2001. Discussion on the evolution of the Southern Menderes Massif in SW Turkey as revealed by zircon dating. Reply. Journal of the Geological Society of London 158, 393–395. Rey, P.F., Teyssier, C., Whitney, D.L., 2009. Extension rates, crustal melting, and core complex dynamics. Geology 37, 391–394. Rimmelé, G., Oberhänsli, R., Goffé, B., Jolivet, L., Candan, O., Cetinkaplan, M., 2003. Deformation history of the high-pressure Lycian Nappes and implications for tectonic evolution of SW Turkey. Tectonics 22, 1007. Ring, U., Gessner, K., Gungor, T., Passchier, C.W., 1999a. The Menderes Massif of western Turkey and the Cycladic Massif in the Aegean — do they really correlate? Journal of the Geological Society 156, 3–6. Ring, U., Laws, S., Bernet, M., 1999b. Structural analysis of a complex nappe sequence and late-orogenic basins from the Aegean Island of Samos, Greece. Journal of Structural Geology 21, 1575–1601. Ring, U., Layer, P.W., Reischmann, T., 2001a. Miocene high-pressure metamorphism in the Cyclades and Crete, Aegean Sea, Greece: evidence for large-magnitude displacement on the Cretan detachment. Geology 29, 395–398. Ring, U., Willner, A.P., Lackmann, W., 2001b. Stacking of nappes with unrelated pressure–temperature paths: an example from the Menderes nappes of western Turkey. American Journal of Science 301, 912–944. Ring, U., Reischmann, T., 2002. The weak and superfast Cretan detachment, Greece: exhumation at subduction rates in extrusion wedges. Journal of the Geological Society 159, 225–228. Ring, U., Johnson, C., Hetzel, R., Gessner, K., 2003a. 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. Geological Magazine 140, 421–441. Ring, U., Layer, P.W., 2003. High-pressure metamorphism in the Aegean, eastern Mediterranean: underplating and exhumation from the Late Cretaceous until the Miocene to Recent above the retreating Hellenic subduction zone. Tectonics 22, TC001350. Ring, U., Thomson, S.N., Bröcker, M., 2003b. Fast extension but little exhumation: the Vari detachment in the Cyclades, Greece. Geological Magazine 140, 245–252. Ring, U., Buchwaldt, R., Gessner, K., 2004. Pb/Pb dating of garnet from the Anatolide Belt in western Turkey; regional implications and speculations on the role Anatolia played during the amalgamation of Gondwana. Zeitschrift der Deutschen Geologischen Gesellschaft 154, 537–555. Ring, U., Collins, A.S., 2005. U–Pb SIMS dating of synkinematic granites: timing of core– complex formation in the northern Anatolide belt of western Turkey. Journal of the Geological Society 162, 289–298. Ring, U., Glodny, J., Will, T., Thomson, S.N., 2007a. An Oligocene extrusion wedge of blueschist-facies nappes on Evia Island, Aegean Sea, Greece: implications for the early exhumation of high-pressure rocks. Journal of the Geological Society 164, 637–657. Ring, U., Will, T., Glodny, J., Kumerics, C., Gessner, K., Thomson, S., Gungor, T., Monie, P., Okrusch, M., Druppel, K., 2007b. Early exhumation of high-pressure rocks in extrusion wedges: cycladic blueschist unit in the eastern Aegean, Greece, and Turkey. Tectonics 26, TC001872. Ring, U., Glodny, J., Will, T., Thomson, S.N., 2010. The Hellenic subduction system: highpressure metamorphism, exhumation, normal faulting and large-scale extension. Annual Review of Earth and Planetary Sciences 38, 45–76. Robertson, A.H.F., Dixon, J.E., 1984. Introduction: aspects of the geological evolution of the eastern Mediterranean. In: Dixon, J.E., Robertson, A.H.F. (Eds.), The Geological Evolution of the Eastern Mediterranean. Geological Society, London, pp. 1–74. Robertson, A.H.F., Clift, P.D., Degnan, P.J., Jones, G., 1991. Palaeogeographic and palaeotectonic evolution of the Eastern Mediterranean Neotethys. Palaeogeography, Palaeoclimatology, Palaeoecology 87, 289–343. Robertson, A.H.F., Dixon, J.E., Brown, S., Collins, A.S., Morris, A., Pickett, E., Sharp, I., Ustaömer, T., 1996. Alternative tectonic models for the Late-Palaeozoic–Early Tertiary development of Tethys in the Eastern Mediterranean region. In: Morris, A., Tarling, D.H. (Eds.), Palaeomagnetism and Tectonics of the Mediterranean Region. Geological Society, London, pp. 239–263. Rojay, B., Toprak, V., Demirci, C., Süzen, L., 2005. Plio-Quaternary evolution of the Küçük Menderes Graben (Southwestern Anatolia, Turkey). Geodinamica Acta 241–255. Romano, S.S., Dörr, W., Zulauf, G., 2004. Cambrian granitoids in pre-Alpine basement of Crete (Greece): evidence from U–Pb dating of zircon. International Journal of Earth Sciences 93, 844–859. 273 Royden, L.H., 1993. Evolution of retreating subduction boundaries formed during continental collision. Tectonics 12, 629–638. Rudnick, R.L., 1995. Making continental crust. Nature 378, 571–578. Sandwell, D.T., Smith, W.H.F., 2009. Global marine gravity from retracked Geosat and ERS-1 altimetry: ridge segmentation versus spreading rate. Journal of Geophysical Research 114, B01411. Sari, C., Şalk, M., 2006. Sediment thicknesses of the western Anatolia graben structures determined by 2D and 3D analysis using gravity data. Journal of Asian Earth Sciences 26, 39–48. Saunders, P., Priestley, K., Taymaz, T., 1998. Variations in the crustal structure beneath western Turkey. Geophysical Journal International 134, 373–389. Schaffer, F., 1900. Das Maeanderthalbeben vom 20. September 1899. Mitteilungen der kaiserlichen und königlichen geographischen Gesellschaft Wien 43, 221–230. Schellart, W.P., Freeman, J., Stegman, D.R., Moresi, L., May, D., 2007. Evolution and diversity of subduction zones controlled by slab width. Nature 446, 308–311. Schenker, F.L., Gerya, T., Burg, J.P., in press. Bimodal behavior of extended continental lithosphere: Modeling insight and application to thermal history of migmatitic core complexes. Tectonophysics 579, 88–103. Schermer, E.R., Lux, D.R., Burchfiel, B.C., 1990. Temperature–time history of subducted continental crust, Mount Olympos Region, Greece. Tectonics 9, 1165–1196. Schmid, S.M., Fügenschuh, B., Kissling, E., Schuster, R., 2004. Tectonic map and overall architecture of the Alpine orogen. Eclogae Geologicae Helvetiae 97, 93–117. Schuiling, R.D., 1962. On petrology, age and structure of the Menderes Migmatite complex (SW-Turkey). Bulletin. Mineral Research and Exploration Institute (Turkey) 58, 71–83. Seidel, E., Kreuzer, H., Harre, W., 1982. A late Oligocene/early Miocene high pressure belt in the External Hellenides. Geologisches Jahrbuch E23, 165–206. Sengör, A.M.C., Yilmaz, Y., 1981. Tethyan evolution of Turkey: a plate tectonic approach. Tectonophys 75, 181–241. Sengör, A.M.C., Satir, M., Akkök, R., 1984. Timing of the tectonic events in the Menderes massif, western Turkey: implications for tectonic evolution and evidence for PanAfrican basement in Turkey. Tectonics 3, 693–707. Sengör, A.M.C., 1987. Cross faults and differential stretching of hangingwalls in regions of low-angle normal faulting: examples from Western Turkey. In: Coward, M.P., Dewey, J.F., Hancock, P.L. (Eds.), Continental Extensional Tectonics, pp. 575–589. Şengör, A.M.C., Özeren, S., Genç, T., Zor, E., 2003. East Anatolian high plateau as a mantle-supported, north–south shortened domal structure. Geophysical Research Letters 30, 8045. Şengör, A.M.C., Bozkurt, E., 2013. Layer-parallel shortening and related structures in zones undergoing active regional horizontal extension. International Journal of Earth Sciences 102, 101–119. Seyitoglu, G., Scott, B.C., 1996. The cause of N–S extensional tectonics in western Turkey: tectonic escape vs back-arc spreading vs orogenic collapse. Journal of Geodynamics 22, 145–153. Seyitoglu, G., Anderson, D., Nowell, G., Scott, B., 1997. The evolution from Miocene potassic to Quaternary sodic magmatism in western Turkey: implications for enrichment processes in the lithospheric mantle. Journal of Volcanology and Geothermal Research 96, 127–147. Shaked, Y., Avigad, D., Garfunkel, Z., 2000. Alpine high-pressure metamorphism at the Almyropotamos window (southern Evia, Greece). Geological Magazine 137, 367–380. Sherlock, S., Kelley, S., Inger, S., Harris, N., Okay, A., 1999. 40Ar–39Ar and Rb–Sr geochronology of high-pressure metamorphism and exhumation history of the Tavsanli Zone, NW Turkey. Contributions to Mineralogy and Petrology 137, 46–58. Simsek, S., 1985. Geothermal model of Denizli, Sarayköy–Buldan area. Geothermics 14, 393–417. Smith, W.H.F., Sandwell, D.T., 1997. Global seafloor topography from satellite altimetry and ship depth soundings. Science 277, 1957–1962. Sodoudi, F., Kind, R., Hatzfeld, D., Priestley, K.F., Hanka, W., Wylegalla, K., Stavrakakis, G., Vafidis, A., Harjes, H.-P., Bohnhoff, M., 2006. Lithospheric structure of the Aegean obtained from P and S receiver functions. Journal of Geophysical Research 111, B12307. Sotiropoulos, S., Kamberis, E., 2003. Thrust sequences at the central part of the External Hellenides. Geological Magazine 140, 661–668. Sözbilir, H., Sarı, B., Uzel, B., Sümer, Ö., Akkiraz, S., 2011. Tectonic implications of transtensional supradetachment basin development in an extension-parallel transfer zone: the Kocacay Basin, western Anatolia, Turkey. Basin Research 23, 423–448. Sözbilir, H., Inci, U., Erkül, F., Sümer, Ö., 2003. An active intermittent transform zone accommodating N–S extension in western Anatolia and its relation to the North Anatolian Fault System. International Workshop on the North Anatolian, East Anatolian and Dead Sea Fault Systems Abstracts, p. 87. Spakman, W., Wortel, R., Vlaar, N.J., 1988. The Hellenic subduction zone: a tomographic image and its geodynamic implications. Geophysical Research Letters 15, 60–63. Spakman, W., van der Lee, S., van der Hilst, R.D., 1993. Travel-time tomography of the European–Mediterranean mantle down to 1400 km. Physics of the Earth and Planetary Interiors 79, 3–74. Spakman, W., 1999. Tomographic images of the upper mantle below central Europe and the Mediterranean. Terra Nova 2, 542–553. Spakman, W., Hall, R., 2010. Surface deformation and slab–mantle interaction during Banda arc subduction rollback. Nature Geoscience 3, 562–566. Stegman, D.R., Freeman, J., Schellart, W.P., Moresi, L., May, D., 2006. Influence of trench width on subduction hinge retreat rates in 3-D models of slab rollback. Geochemistry, Geophysics, Geosystems 7, Q03012. Stern, T.A., Stratford, W.R., Salmon, M.L., 2006. Subduction evolution and mantle dynamics at a continental margin: Central North Island, New Zealand. Reviews of Geophysics 44. Thomson, S.N., Stöckhert, B., Rauche, H., Brix, M.R., 1998. Apatite fission-track thermochronology of the uppermost tectonic unit of Crete, Greece: implications for the post-Eocene tectonic evolution of the Hellenic Subduction System. 274 K. Gessner et al. / Gondwana Research 24 (2013) 243–274 Advances in Fission-Track Geochronology. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 187–205. Thomson, S.N., Ring, U., 2006. Thermochronologic evaluation of post-collision extension in the Anatolide Orogen, western Turkey. Tectonics 25, TC3005. Thomson, S.N., Ring, U., Brichau, S., Glodny, J., Will, T., 2009. Timing and nature of formation of the Ios metamorphic core complex, southern Cyclades, Greece. In: Ring, U., Wernicke, B. (Eds.), Extending a Continent: Architecture, Rheology and Heat Budget, pp. 269–274. Tirel, C., Gueydan, F., Tiberi, C., Brun, J.-P., 2004. Aegean crustal thickness inferred from gravity inversion. Geodynamical implications. Earth and Planetary Science Letters 228, 267–280. Tomaschek, F., Kennedy, A., Villa, I., Lagos, M., Ballhaus, C., 2003. Zircons from Syros, Cyclades, Greece — recrystallization and mobilization during high pressure metamorphism. Journal of Petrology 44, 1977–2002. USGS, 2011. USGS PDE catalogue. http://earthquake.usgs.gov/earthquakes/eqarchives/ epic/epic_rect.php. Uzel, B., Sozbilir, H., 2008. A first record of a strike-slip basin in western Anatolia and its tectonic implication: the Cumaovasi basin. Turkish Journal of Earth Sciences 17, 559–591. van Hinsbergen, D.J.J., Hafkenscheid, E., Spakman, W., Meulenkamp, J.E., Wortel, R., 2005. Nappe stacking resulting from continental lithosphere below subduction of oceanic and Greece. Geology 33, 325–328. van Hinsbergen, D.J.J., Dekkers, M.J., Bozkurt, E., Koopman, M., 2010a. Exhumation with a twist: paleomagnetic constraints on the evolution of the Menderes metamorphic core complex, western Turkey. Tectonics 29. van Hinsbergen, D.J.J., Kaymakci, N., Spakman, W., Torsvik, T.H., 2010b. Reconciling the geological history of western Turkey with plate circuits and mantle tomography. Earth and Planetary Science Letters 297, 674–686. van Hinsbergen, D.J.J., 2011. A key extensional metamorphic complex reviewed and restored: the Menderes Massif of western Turkey. Earth-Science Reviews 102, 60–76. van Hinsbergen, D.J.J., Schmid, S.M., 2012. Map view restoration of Aegean–West Anatolian accretion and extension since the Eocene. Tectonics 31 (n/a-n/a). Venkat-Ramani, M., Tikoff, B., 2002. Physical models of transtensional folding. Geology 30, 523–526. Wdowinski, S., Axen, G.J., 1992. Isostatic rebound due to tectonic denudation: a viscous flow model of a layered lithosphere. Tectonics 11, 303–315. West, J.D., Fouch, M.J., Roth, J.B., Elkins-Tanton, L.T., 2009. Vertical mantle flow associated with a lithospheric drip beneath the Great Basin. Nature Geoscience 2, 439–444. Westaway, R., Pringle, M., Yurtmenc, S., Demir, T., Bridgland, D., Rowbotham, G., Maddy, D., 2004. Pliocene and Quaternary regional uplift in western Turkey: the Gediz River terrace staircase and the volcanism at Kula. Tectonophysics 391, 121–169. Westaway, R., 2006. Cenozoic cooling histories in the Menderes Massif, western Turkey, may be caused by erosion and flat subduction, not low-angle normal faulting. Tectonophysics 412, 1–25. Whitney, D.L., Bozkurt, E., 2002. Metamorphic history of the southern Menderes Massif, Western Turkey. Geolocial Society of America Bulletin 114, 829–838. Wijns, C., Weinberg, R., Gessner, K., Moresi, L., 2005. Mode of crustal extension determined by rheological layering. Earth and Planetary Science Letters 236, 120–134. Wobus, C., Whipple, K.X., Kirby, E., Snyder, N., Johnson, J., Spyropolou, K., Crosby, B., Sheehan, D., 2006. Tectonics from topography: procedures, promise, and pitfalls. In: Willett, S., Hovius, N., Brandon, M.T., Fisher, D.M. (Eds.), Tectonics, Climate ad Landscape Evolution: Geological Society of America Special Paper, 398, pp. 55–74 (Penrose Conference Series). Wortel, R., Spakman, W., 2000. Subduction and slab detachment in the Mediterranean– Carpathian region. Science 290, 1910–1917. Yigit, O., 2006. Gold in Turkey—a missing link in Tethyan metallogeny. Ore Geology Reviews 28, 147–179. Yigit, O., 2009. Mineral deposits of Turkey in relation to Tethyan metallogeny: implications for future mineral exploration. Economic Geology 104, 19–51. Yilmaz, H., 1979. Genesis of uranium deposits in Neogene sedimetary rocks, Menderes metamorphic massif, Turkey. Faculty of Graduate Studies. The University of Western Ontario, London, Ontario, p. 197. Yilmaz, H., 1981. Genesis of uranium deposits in Neogene sedimetary rocks overlying the Menderes metamorphic massif, Turkey. Chemical Geology 31, 185–210. Yilmaz, Y., Genç, S.C., Gürer, F., Bozcu, M., Yilmaz, K., Karacik, Z., Altunkayak, S., Elmas, A., 2000. When did the western Anatolian grabens begin to develop? In: Bozkurt, E., Winchester, J.A., Piper, J.D.A. (Eds.), Tectonics and Magmatism in Turkey and the Surrounding Area, pp. 353–384. Yin, A., 1991. Mechanisms for the formation of domal and basinal detachment faults: a three-dimensional analysis. Journal of Geophysical Research 96, 14577–14594. Zhu, H., Bozdag, E., Peter, D., Tromp, J., 2012. Structure of the European upper mantle revealed by adjoint tomography. Nature Geoscience 5, 493–498. Zhu, L., Akyol, N., Mitchell, B.J., Sozbilir, H., 2006a. Seismotectonics of western Turkey from high resolution earthquake relocations and moment tensor determinations. Geophysical Research Letters 33, L07316. Zhu, L., Mitchell, B.J., Akyol, N., Cemen, I., Kekovali, K., 2006b. Crustal thickness variations in the Aegean region and implications for the extension of continental crust. Journal of Geophysical Research 111, B01301. Zlatkin, O., Avigad, D., Gerdes, A., 2012. Evolution and provenance of Neoproterozoic basement and Lower Paleozoic siliciclastic cover of the Menderes Massif (Western Taurides): coupled U–Pb–Hf zircon isotope geochemistry. Gondwana Research. http://dx.doi.org/10.1016/j.gr.2012.05.006. Klaus Gessner is the 3D Geoscience Manager at the Geological Survey of Western Australia, and Adjunct Research Fellow at The University of Western Australia. He received a ‘Diplom’ in Geology–Palaeontology from Johann Wolfgang Goethe University in Frankfurt, Germany (1996), and a PhD from Johannes Gutenberg University in Mainz, Germany (2000). Klaus has worked as a structural geologist at CSIRO Exploration and Mining, and has taught at The University of Western Australia. His research focus is on the structural evolution of Phanerozoic, Proterozoic and Archaean orogenic belts in Turkey, Australia, and New Zealand, and on the processes involved in hydrothermal mineral deposits and geothermal systems. Luis A. Gallardo is a titular researcher in the Department of Applied Geophysics at CICESE, Mexico; a National Scientist from the National Council of Science and Technology in Mexico; and an Adjunct Scientist of the Centre for Exploration Targeting at the University of Western Australia. He obtained an MSc in Applied Geophysics from CICESE (1997), a PhD in Environmental Science from Lancaster University, UK (2005) and held the Goodeve Lectureship at The University of Western Australia from 2009 to 2011. Luis' research focuses on geophysical inverse theory and the joint inversion of gravity, electromagnetic and seismic data. He has worked on geophysical imaging for mineral and petroleum exploration in Western Australia, Western Turkey, Southeast Brazil as well as East and West Africa. He has also worked on near surface imaging projects around the world for environmental and geotechnical applications. Vanessa Markwitz is a Research Fellow at the Centre for Exploration Targeting at The University of Western Australia in Perth. She graduated from Johann Wolfgang Goethe University in Frankfurt, Germany with a ‘Diplom’ in Geology– Palaeontology (1996). Vanessa has carried out structural research on the Rhenish Massif in Germany as a contract geologist for the Geological Survey of Rhineland Palatinate in Mainz, Germany. Vanessa is a GIS specialist at the Centre for Exploration Targeting and has worked on uranium, nickel and gold prospectivity in Australia, Zimbabwe, West Africa, and Turkey. Uwe Ring is a Professor in the Department of Geological Sciences at Stockholm University in Sweden. He obtained a ‘Diplom’ in Geology from the Technische Hochschule Darmstadt, Germany (1985), and a PhD in Geology from Eberhard-Karls-Universität in Tübingen, Germany (1988). Uwe was a Humboldt Fellow at Yale University in the USA, has taught Geology at Johannes Gutenberg University in Mainz, Germany, and at the University of Canterbury in Christchurch, New Zealand. His research interests include continental extensional tectonics in Greece, Turkey, and the East African Rift. Uwe also has worked on the exhumation of metamorphic rocks from great depths and on the interactions between climate and tectonics. Stuart N. Thomson is a Research Scientist at the University of Arizona. He obtained a BSc in Geology from Durham University, UK (1988) and a PhD in Geology from University College London (1993). His research focuses primarily on the application of geochronology and low temperature thermochronology to problems in geology, tectonics, structural geology, and tectonic geomorphology. He has worked on projects around the world including on Cenozoic glacial–tectonic interactions in the South American Andes, various projects on Mediterranean tectonics in Italy, Greece, and Turkey, to methodological work on apatite U–Pb dating.
© Copyright 2026 Paperzz