Abstract: The Menderes Massif, which covers a large area in western Turkey, is made up of Pan-Afr... more Abstract: The Menderes Massif, which covers a large area in western Turkey, is made up of Pan-African basement rocks and a Palaeozoic to Early Tertiary cover sequence. The study area is located in the Dalama and Hallalar (AydÝn) area, in the northern and central parts of the ine submassif of the Menderes Massif. The oldest units of the Pan-African basement are metaclastics, consisting of paragneisses and mica schists that gradually and conformably overlay paragneisses. Macroscopic appearances and mineralogical and textural data indicate that paragneisses can be subdivided into four subgroups. These are: (1) black spotted, (2) white spotted, (3) massive, grey-coloured and (4) massive, purple-coloured paragneisses. Geochemical data show that the spotted and purple-coloured paragneisses are characterized by high alumina content that is consistent with high sillimanite content. Paragneisses exposed in the eastern part of the ine submassif were partly migmatized during the last stage of ...
nap yığını yapısı sunmaktadır. Masif kuzeyde Afyon Zonu, güneyde ise Likya napları tarafından tek... more nap yığını yapısı sunmaktadır. Masif kuzeyde Afyon Zonu, güneyde ise Likya napları tarafından tektonik olarak üzerlenmektedir. Öte yandan kuzeybatıda, Kikladik Kompleks ve onu üzerleyen Likya naplarından yapılı Alpin yaşlı yüksek basınç üniteleri ve İzmir – Ankara Zonu’na ait naplar Masif’i tektonik olarak sınırlamaktadır. Menderes Masifi’nin kaya istifi; 1-
Batı Anadolu’da yüzlek veren Menderes Masifi ana hatlarıyla Geç Alpin sıkışma tektoniği ile biçim... more Batı Anadolu’da yüzlek veren Menderes Masifi ana hatlarıyla Geç Alpin sıkışma tektoniği ile biçimlenmiş karmaşık bir nap yığını yapısı sunmaktadır. Bu kristalin kompleksin litostratigrafik istifi; 1-Pan-Afrikan temel (çekirdek serisi) ve 2-Paleozoyik – Erken Tersiyer yaşlı seri (örtü serisi) olmak üzere iki ana üniteye ayrılmaktadır. Kalınlığı sekiz kilometreye kadar ulaşan düzenli bir seri oluşturan paragnayslar ve onları uyumlu olarak üzerleyen mika şistler Menderes Masifi’nin Pan-Afrikan temeline ait en yaşlı birimleri oluşturmaktadır (Dora ve diğ., 2002). Heterojen karakterli kratonik bir kaynak alanından türeyen bu metaklastik serinin ilksel tortullarının çökelim yaş aralığı, içerdiği en genç kırıntı zirkon yaşı ve bunları kesen granitlerin sokulum yaşlarına dayanılarak 550 – 610 My (geç Proterozoyik) olarak belirlenmiştir. Anatektik granitlerin geliştiği, yaygın migmatizasyona uğramış yüksek dereceli bu metaklastikler çok evreli metamorfizmadan etkilenmiş Prekambriyen yaşlı ga...
The Menderes Massif (MM) forms a large metamorphic complex within the Alpine orogen in the wester... more The Menderes Massif (MM) forms a large metamorphic complex within the Alpine orogen in the western part of Turkey. Mainly, the MM can be divided into two units; 1Pan-African basement and 2Palaeozoic-Early Tertiary cover series (Şengör et al. 1984; Dora et al. 2001). Basement and cover series have experienced an intense phase of Alpine deformation and regional metamorphism in Tertiary time. The Pan-African basement comprises partly migmatized late Proterozoic clastic metasediments, (i.e. paragneisses and high-grade mica schists) which are intruded by the protoliths of syn-to post Pan-African orthogneisses, metagranites and metagabbros with eclogite relics (Candan et al. 2001; Dora et al. 2001). The cover series can be subdivided into two units consisting of Palaeozoic and Mesozoic-early Tertiary series (Dürr, 1975; Konak et al. 1987). Based on the geologic and geochronological evidence, three distinct acidic magmatic activities have been recognized in the MM: (i) Pan-African, (ii) Tr...
Investigated area is located in the Gordes submassif of the Menderes massif, the metamorphic base... more Investigated area is located in the Gordes submassif of the Menderes massif, the metamorphic basement consists of the fol- lowing lithologics in ascending order: Sillimanite-gamet gneiss. sillimanite-gamel-kyanitc schist. sillimanite-staurolite-gamet-kyanite schist, staurolite-garnet schist and garnet mica schist. Kyanite-andalusite pegmatoids which occur within the kyanite-bearing schists were formed in the course of the last major metamorphism giving the final stage to the Menderes massif. The metamorphic basement is overlain by the al- lochthonous units which are relicts of the Lycian nappes which caused the last major metamorphism during the Eocene-Oligocene time in Menderes massif. The age of the apatite crystals obtained from the pegmatoids arc determined by the fission-track method. The cooling age of the apatite crystals ranging from the Early Oligocene to Early Miocene are in good agreement with the field observations in the study area and geological evidences relating to t...
Eclogite and blueschist facies rocks occurring as a tectonic unit between the underlying Menderes... more Eclogite and blueschist facies rocks occurring as a tectonic unit between the underlying Menderes Massif and the overlying Afyon Zone / Lycian Nappes and the Bornova Flysch Zone in western Anatolia represent the eastward continuation of the Cycladic Blueschist Unit in Turkey. This high-P unit is attributed to the closure of the Pindos Ocean and consists of (i) a Triassic to Upper Cretaceous coherent series derived from passive continental margin sediments and (ii) the tectonically overlying Upper Cretaceous Selçuk mélange with eclogite blocks embedded in a pelitic epidote-blueschist matrix. The coherent series has experienced epidote-blueschist facies metamorphism (490 ± 25°C / 11.5 ± 1.5 kbar; 38 km depth). 40 Ar/ 39 Ar white mica and 206 Pb/ 238 U monazite dating of quartz metaconglomerate from coherent series yielded middle Eocene ages of 44 ± 0.3 and 40.1 ± 3.1 Ma for epidoteblueschist facies metamorphism, respectively. The epidote-blueschist facies metamorphism of the matrix of the Selçuk mélange culminates at 520 ± 15°C / 13 ± 1.5 kbar, 43 km depth, and is dated 57.5 ± 0.3-54.5 ± 0.1 Ma (40 Ar/ 39 Ar phengite). Eclogite facies metamorphism of the blocks (570 ± 30°C / 18 ± 2 kbar, 60 km depth) is early Eocene and dated at 56.2 ± 1.5 Ma by 206 Pb/ 238 U zircon. Eclogites experienced a nearly isothermal retrogression (490 ± 40°C / ~ 6-7 kbar) during their incorporation into the Selçuk mélange. The retrograde overprints of the coherent series (410 ± 15°C / 7 ± 1.5 kbar from Dilek Peninsula and 485 ± 33°C / ~ 6-7 kbar from Selçuk-Tire area) and the Selçuk mélange (510 ± 15°C / 6 ± 1 kbar) are dated at 35.8 ± 0.5-34.3 ± 0.1 Ma by 40 Ar/ 39 Ar white mica and 31.6 ± 6.6 Ma by 206 Pb/ 238 U allanite dating methods, respectively. Regional geological constrains reveal that the contact between the Menderes Massif and the Cycladic Blueschist Unit originally formed a lithosphere-scale transform fault zone. 40 Ar/ 39 Ar white mica age from the contact indicates that the Cycladic Blueschist Unit and the Menderes Massif were tectonically juxtaposed under greenschist facies conditions during late Eocene, 35.1 ± 0.3 Ma.
The Sakarya Zone (northern Turkey) is a Gondwana-derived continental block accreted to northern L... more The Sakarya Zone (northern Turkey) is a Gondwana-derived continental block accreted to northern Laurussia during the Carboniferous, and is regarded as the eastward extension of Armorica. Timing of its detachment from the northern margin of Gondwana, thus opening of the Paleo-Tethys, is poorly known. Here, we report on metagranite and amphibolite with Silurian igneous crystallization ages from the Early Carboniferous hightemperature/middle to low-pressure amphibolite-facies metamorphic rocks of the Sarıcakaya Massif within the Sakarya Zone (NW Turkey). The metagranite-amphibolite complex is exposed mainly along the southern margin of the Sarıcakaya Massif over an area of ca. 12 km by 1.5 km. The metagranite contains preserved domains of porphyric texture, indicative of derivation from a former granite porphyry. The amphibolite is devoid of any relict igneous texture. Both the metagranite and amphibolite are crosscut by late up to 50 cm thick felsic veins. Uranium-Pb dating on igneous zircons from both metagranite and amphibolite yielded Silurian ages of ca. 419 ± 6 to 434 ± 7 Ma (2σ), and on those from a felsic vein an age of 319 ± 5 Ma (2σ) (Late Carboniferous). Geochemically, amphibolite displays anorogenic transitional tholeiitic to alkaline signatures. Initial εHf values of the igneous zircons from both metagranite and amphibolite show a large variation with medial values of −16 to −9 and + 3 to +6, respectively. Thus, the protoliths of amphibolite were derived from melts of depleted mantle, and those of the metagranite, on the other hand, from melts of reworked crustal material. We suggest that the Silurian anorogenic magmatism is related to a rifting event at the northern margin of Gondwana leading to the detachment of the Sakarya Zone and hence placing an age on the initial opening of the Paleo-Tethys. This interpretation is based on (i) the presence of Late Silurian to Devonian deep-sea sedimentary blocks in the Paleo-Tethyan accretionary complexes, and (ii) the resemblance of the U\ \Pb age spectra of detrital zircons in the metaclastic sequence of the Sarıcakaya Massif to those of Cambro-Ordovician sandstones in Jordan (Gondwana), and (iii) the local occurrence of anorogenic A-type granites of Late Ordovician-Silurian age in the Anatolide-Tauride Block, a continental block which rifted from Gondwana during the Early Triassic. Wholly anorogenic nature of the Late Ordovician to Silurian igneous rocks in the Sarıcakaya Massif and reported in literature does not support the opening of the Paleo-Tethys as back-arc ocean, as suggested in most paleogeographic reconstructions.
The East Anatolian plateau (Turkey) is extensively covered by Neogene to Quaternary volcanic-sedi... more The East Anatolian plateau (Turkey) is extensively covered by Neogene to Quaternary volcanic-sedimentary rocks, and is characterized by an attenuated lithospheric mantle. Its pre-Neogene basement is commonly considered to consist entirely of Late Cretaceous to Oligocene oceanic accretionary complexes, formed at the junction of several continental blocks. Here we report on three main exposures of the pre-Neogene basement in this region. The exposed areas consist mainly of amphibolite-to granulite-facies metamorphic rocks, including marble, amphibolite, metapelite, metagranite, and metaquartzite. An upper amphibolite-to granulitefacies domain is equilibrated at similar to 0.7 GPa and similar to 800 degrees C at 83 +/- 2 Ma (2 sigma). U-Pb dating of magmatic zircons from the metagranite yielded a Late Ordovician-early Silurian protolith age (444 +/- 9 Ma, 2 sigma). The detrital zircons from one metaquartzite point to a Neoproterozoic-early Paleozoic provenance. Ophiolitic rocks tectonically sit on the metamorphic rocks. Both the metamorphic and ophiolitic rocks are in turn unconformably covered by lower Maastrichtian clastic rocks and reefal limestones, suggesting that the whole exhumation process and juxtaposition with the ophiolitic rocks had occurred by the early Maastrichtian. Several lines of evidence, such as (1) the absence of any indication of a former high-pressure metamorphism in the metamorphic rocks, (2) the allochthonous nature of the ophiolitic rocks, (3) the presence of metagranite with a Late Ordovician-early Silurian protolith age, and (4) the Neoproterozoic- early Paleozoic provenance of detrital zircons in the metaquartzite (in contrast to the dominance of late Paleozoic-Mesozoic crystalline rocks in the adjacent continental blocks) indicate a substantial component of continental basement beneath the Neogene to Quaternary cover. Thus, the loss of the lithospheric mantle probably resulted from lithospheric foundering processes beneath the plateau, rather than just slab steepening and break-off.
The recent discovery of HP-LT parageneses in the basal unit of the Lycian nappes and in the Mesoz... more The recent discovery of HP-LT parageneses in the basal unit of the Lycian nappes and in the Mesozoic cover of the Menderes massif leads us to reconsider and discuss the correlation of this region with the nearby collapsed Helle-nides in the Aegean domain. Although similarities have long been pointed out by various authors, a clear correlation has not yet been proposed and most authors insist more on differences than similarities. The Menderes massif is the eastern extension of the Aegean region but it has been less severely affected by the Aegean extension during the Oligo-Miocene. It would thus be useful to use the structure of the Menderes massif as an image of the Aegean region before a significant extension has considerably reduced its crustal thickness. But the lack of correlation between the two regions has so far hampered such comparisons. We describe the main tectonic units and metamorphic events in the two regions and propose a correlation. We then show possible sections of...
The Menderes massif consists of a Precambrian Core Series that preserves evidence for a polymetam... more The Menderes massif consists of a Precambrian Core Series that preserves evidence for a polymetamorphic history and a Paleozoic/Mesozoic Cover Series that experienced only the Alpine tectonometamorphic evolution. Structural, petrographic, and geochronologic investigations in the central Menderes massif demonstrate that (a) part of the metamorphic and structural evolution of the Precambrian basement is older than the undeformed 551±1.4-Maold Birgi metagranite, and (b) inferred Alpine fabrics overprinting the Cover Series largely have the same attitudes as the old structures in the much older Core Series. The inferred Alpine fabrics include both contractional and extensional structures. Contraction under greenschist to amphibolite facies conditions resulted in the imbrication of the Core and Cover Series and generated an inverted metamorphic sequence by north-directed thrusting. During Alpine extension, most of the south-dipping thrust faults were reactivated as extensional shear zones under decreasing greenschist facies conditions.
Carboniferous metagranites with U-Pb zircon crystallization ages of 331-315 Ma crop out in the Af... more Carboniferous metagranites with U-Pb zircon crystallization ages of 331-315 Ma crop out in the Afyon zone in the northern margin of the Anatolide-Tauride Block, which is commonly regarded as part of Gondwana during the Late Palaeozoic. They are peraluminous, calc-alkaline and are characterized by increase in Rb and Ba, decrease in Nb-Ta, and enrichment in Sr and high LILE/HFSE ratios compatible with a continental arc setting. The metagranites intrude a metasedimentary sequence of phyllite, metaquartzite and marble; both the Carboniferous metagranites and metasedimentary rocks are overlain unconformably by Lower Triassic metaconglomerates, metavolcanics and Upper Triassic to Cretaceous recrystallized limestones. The low-grade metamorphism and deformation occurred at the Cretaceous-Tertiary boundary. There is no evidence for Carboniferous deformation and metamorphism in the region. Carboniferous arc-type granites and previously described Carboniferous subduction-accretion complexes on the northern margin of the Anatolide-Tauride Block suggest southward subduction of Paleotethys under Gondwana during the Carboniferous. Considering the Variscan-related arc granites in Pelagonian and Sakarya zones on the active southern margin of Laurasia, a dual subduction of Paleotethys can be envisaged between Early Carboniferous and Late Permian. However, the southward subduction was shortlived and by the Late Permian the Gondwana margin became passive.
Southwest Turkey comprises two main complexes: the Lycian Nappes and the underly- ing autochthono... more Southwest Turkey comprises two main complexes: the Lycian Nappes and the underly- ing autochthonous Menderes Massif. On the Bodrum peninsula, south of the Menderes crystalline massif, a widespread distribution of fresh Fe-Mg-carpholite recently dis- covered in the metasediments from the base of the Lycian nappe complex attests for a high pressure-low temperature metamorphic event. Klippen of Lycian Nappes lo- cated
In Western and Central Turkey throughout Mesozoic and Tertiary times, the closure of the Tethys o... more In Western and Central Turkey throughout Mesozoic and Tertiary times, the closure of the Tethys oceanic realm took place through the consumption of oceanic basins and accretion of continental blocks. Regarding its Alpine (i.e. Cretaceous-Tertiary) history, the tectonic framework of W-Turkey is rather clear. The following blocks build up the Turkish microplate: a) Pontide Block, assembled during the Cimerian (late Triassic) closure of the Palaeo-Tethys; b) the Anatolide-Tauride Block, partly metamorphosed under HP-LT conditions in Late Cretaceous to Palaeocene times; c) the Central Anatolian Crystalline Complex, made of Late Cretaceous high grade metamorphics and intrusions; and d) the Alanya Nappes. The ways of imbrication of these tectonics units, however, are often matter of debate. Particularly, the number and position of former oceans is questioned. Recent studies int the Anatolide Tauride Block show that Alpine subduction-related HP-LT metamorphism is not restricted to the northernmost Tavsanli Zone, but is actually widespread in the tectonic slices of (Tavsanli Zone, Afyon Zone, Menderes Massif and Lycian Nappes). These new blueschist-facies metamorphism occurrences spark the debate on the Alpine evolution of this region. Fe,Mg-carpholite-bearing rocks occur not only in its central part of the Afyon Zone, but South of the Central Anatolian Crystalline Complex, all along from the Menderes Massif to East of Kayseri. Some of these occurrences are closely related to glaucophane- and/or lawsonite-bearing rocks already reported in the sixties by v. d. Kaaten. On top of the Mesozoic sequence of the Afyon Zone, consisting of a coherent marble sequence, an accretionary mélange, made of a serpentinized blueschists, marbles and mantellic rocks occurs. This mélange is typical of the Tavsanli Zone. We also observed it, croping out scarcely between the CACC and the Afyon Zone all the way to Kayseri. Therefore our field observations lead us to extend the Afyon and the Tavsanli Zones eastwards and to depict them as HP-LT tectonics slices, of more than 600-km long. P,T-conditions and ages from the Tavsanli lawsonite blueschists (24 kbar/450 °C; 85-80 Ma) contrast with the Afyon carpholite bearing metapelites and associated blueschists (8kb/350 °C; 65-60 Ma). The two HP-very LT metamorphic belts occurring in Central Anatolia are separated by an low grade flysch. This flysch and the age difference between HP belts open the question of the number of subduction zones during the late Cretaceous in Central Anatolia. If two subductions are assumed this area compares to the Alps, but an equivalent to the Briançonnais microcontinent is missing. The dynamic of a one subduction zone model could be similar to the the Aegean realm today. In this case, Tavsanli - Afyon can be compared to the situation between Rhodopes and Tinos. There, similarly significant differences in P,T conditions and ages are obvious, while direct observation of contacts are hampered by the seas. Contrarily the Tavsanli - Afyon realm allows insight into a dual metamorphic belt.
Abstract: The Menderes Massif, which covers a large area in western Turkey, is made up of Pan-Afr... more Abstract: The Menderes Massif, which covers a large area in western Turkey, is made up of Pan-African basement rocks and a Palaeozoic to Early Tertiary cover sequence. The study area is located in the Dalama and Hallalar (AydÝn) area, in the northern and central parts of the ine submassif of the Menderes Massif. The oldest units of the Pan-African basement are metaclastics, consisting of paragneisses and mica schists that gradually and conformably overlay paragneisses. Macroscopic appearances and mineralogical and textural data indicate that paragneisses can be subdivided into four subgroups. These are: (1) black spotted, (2) white spotted, (3) massive, grey-coloured and (4) massive, purple-coloured paragneisses. Geochemical data show that the spotted and purple-coloured paragneisses are characterized by high alumina content that is consistent with high sillimanite content. Paragneisses exposed in the eastern part of the ine submassif were partly migmatized during the last stage of ...
nap yığını yapısı sunmaktadır. Masif kuzeyde Afyon Zonu, güneyde ise Likya napları tarafından tek... more nap yığını yapısı sunmaktadır. Masif kuzeyde Afyon Zonu, güneyde ise Likya napları tarafından tektonik olarak üzerlenmektedir. Öte yandan kuzeybatıda, Kikladik Kompleks ve onu üzerleyen Likya naplarından yapılı Alpin yaşlı yüksek basınç üniteleri ve İzmir – Ankara Zonu’na ait naplar Masif’i tektonik olarak sınırlamaktadır. Menderes Masifi’nin kaya istifi; 1-
Batı Anadolu’da yüzlek veren Menderes Masifi ana hatlarıyla Geç Alpin sıkışma tektoniği ile biçim... more Batı Anadolu’da yüzlek veren Menderes Masifi ana hatlarıyla Geç Alpin sıkışma tektoniği ile biçimlenmiş karmaşık bir nap yığını yapısı sunmaktadır. Bu kristalin kompleksin litostratigrafik istifi; 1-Pan-Afrikan temel (çekirdek serisi) ve 2-Paleozoyik – Erken Tersiyer yaşlı seri (örtü serisi) olmak üzere iki ana üniteye ayrılmaktadır. Kalınlığı sekiz kilometreye kadar ulaşan düzenli bir seri oluşturan paragnayslar ve onları uyumlu olarak üzerleyen mika şistler Menderes Masifi’nin Pan-Afrikan temeline ait en yaşlı birimleri oluşturmaktadır (Dora ve diğ., 2002). Heterojen karakterli kratonik bir kaynak alanından türeyen bu metaklastik serinin ilksel tortullarının çökelim yaş aralığı, içerdiği en genç kırıntı zirkon yaşı ve bunları kesen granitlerin sokulum yaşlarına dayanılarak 550 – 610 My (geç Proterozoyik) olarak belirlenmiştir. Anatektik granitlerin geliştiği, yaygın migmatizasyona uğramış yüksek dereceli bu metaklastikler çok evreli metamorfizmadan etkilenmiş Prekambriyen yaşlı ga...
The Menderes Massif (MM) forms a large metamorphic complex within the Alpine orogen in the wester... more The Menderes Massif (MM) forms a large metamorphic complex within the Alpine orogen in the western part of Turkey. Mainly, the MM can be divided into two units; 1Pan-African basement and 2Palaeozoic-Early Tertiary cover series (Şengör et al. 1984; Dora et al. 2001). Basement and cover series have experienced an intense phase of Alpine deformation and regional metamorphism in Tertiary time. The Pan-African basement comprises partly migmatized late Proterozoic clastic metasediments, (i.e. paragneisses and high-grade mica schists) which are intruded by the protoliths of syn-to post Pan-African orthogneisses, metagranites and metagabbros with eclogite relics (Candan et al. 2001; Dora et al. 2001). The cover series can be subdivided into two units consisting of Palaeozoic and Mesozoic-early Tertiary series (Dürr, 1975; Konak et al. 1987). Based on the geologic and geochronological evidence, three distinct acidic magmatic activities have been recognized in the MM: (i) Pan-African, (ii) Tr...
Investigated area is located in the Gordes submassif of the Menderes massif, the metamorphic base... more Investigated area is located in the Gordes submassif of the Menderes massif, the metamorphic basement consists of the fol- lowing lithologics in ascending order: Sillimanite-gamet gneiss. sillimanite-gamel-kyanitc schist. sillimanite-staurolite-gamet-kyanite schist, staurolite-garnet schist and garnet mica schist. Kyanite-andalusite pegmatoids which occur within the kyanite-bearing schists were formed in the course of the last major metamorphism giving the final stage to the Menderes massif. The metamorphic basement is overlain by the al- lochthonous units which are relicts of the Lycian nappes which caused the last major metamorphism during the Eocene-Oligocene time in Menderes massif. The age of the apatite crystals obtained from the pegmatoids arc determined by the fission-track method. The cooling age of the apatite crystals ranging from the Early Oligocene to Early Miocene are in good agreement with the field observations in the study area and geological evidences relating to t...
Eclogite and blueschist facies rocks occurring as a tectonic unit between the underlying Menderes... more Eclogite and blueschist facies rocks occurring as a tectonic unit between the underlying Menderes Massif and the overlying Afyon Zone / Lycian Nappes and the Bornova Flysch Zone in western Anatolia represent the eastward continuation of the Cycladic Blueschist Unit in Turkey. This high-P unit is attributed to the closure of the Pindos Ocean and consists of (i) a Triassic to Upper Cretaceous coherent series derived from passive continental margin sediments and (ii) the tectonically overlying Upper Cretaceous Selçuk mélange with eclogite blocks embedded in a pelitic epidote-blueschist matrix. The coherent series has experienced epidote-blueschist facies metamorphism (490 ± 25°C / 11.5 ± 1.5 kbar; 38 km depth). 40 Ar/ 39 Ar white mica and 206 Pb/ 238 U monazite dating of quartz metaconglomerate from coherent series yielded middle Eocene ages of 44 ± 0.3 and 40.1 ± 3.1 Ma for epidoteblueschist facies metamorphism, respectively. The epidote-blueschist facies metamorphism of the matrix of the Selçuk mélange culminates at 520 ± 15°C / 13 ± 1.5 kbar, 43 km depth, and is dated 57.5 ± 0.3-54.5 ± 0.1 Ma (40 Ar/ 39 Ar phengite). Eclogite facies metamorphism of the blocks (570 ± 30°C / 18 ± 2 kbar, 60 km depth) is early Eocene and dated at 56.2 ± 1.5 Ma by 206 Pb/ 238 U zircon. Eclogites experienced a nearly isothermal retrogression (490 ± 40°C / ~ 6-7 kbar) during their incorporation into the Selçuk mélange. The retrograde overprints of the coherent series (410 ± 15°C / 7 ± 1.5 kbar from Dilek Peninsula and 485 ± 33°C / ~ 6-7 kbar from Selçuk-Tire area) and the Selçuk mélange (510 ± 15°C / 6 ± 1 kbar) are dated at 35.8 ± 0.5-34.3 ± 0.1 Ma by 40 Ar/ 39 Ar white mica and 31.6 ± 6.6 Ma by 206 Pb/ 238 U allanite dating methods, respectively. Regional geological constrains reveal that the contact between the Menderes Massif and the Cycladic Blueschist Unit originally formed a lithosphere-scale transform fault zone. 40 Ar/ 39 Ar white mica age from the contact indicates that the Cycladic Blueschist Unit and the Menderes Massif were tectonically juxtaposed under greenschist facies conditions during late Eocene, 35.1 ± 0.3 Ma.
The Sakarya Zone (northern Turkey) is a Gondwana-derived continental block accreted to northern L... more The Sakarya Zone (northern Turkey) is a Gondwana-derived continental block accreted to northern Laurussia during the Carboniferous, and is regarded as the eastward extension of Armorica. Timing of its detachment from the northern margin of Gondwana, thus opening of the Paleo-Tethys, is poorly known. Here, we report on metagranite and amphibolite with Silurian igneous crystallization ages from the Early Carboniferous hightemperature/middle to low-pressure amphibolite-facies metamorphic rocks of the Sarıcakaya Massif within the Sakarya Zone (NW Turkey). The metagranite-amphibolite complex is exposed mainly along the southern margin of the Sarıcakaya Massif over an area of ca. 12 km by 1.5 km. The metagranite contains preserved domains of porphyric texture, indicative of derivation from a former granite porphyry. The amphibolite is devoid of any relict igneous texture. Both the metagranite and amphibolite are crosscut by late up to 50 cm thick felsic veins. Uranium-Pb dating on igneous zircons from both metagranite and amphibolite yielded Silurian ages of ca. 419 ± 6 to 434 ± 7 Ma (2σ), and on those from a felsic vein an age of 319 ± 5 Ma (2σ) (Late Carboniferous). Geochemically, amphibolite displays anorogenic transitional tholeiitic to alkaline signatures. Initial εHf values of the igneous zircons from both metagranite and amphibolite show a large variation with medial values of −16 to −9 and + 3 to +6, respectively. Thus, the protoliths of amphibolite were derived from melts of depleted mantle, and those of the metagranite, on the other hand, from melts of reworked crustal material. We suggest that the Silurian anorogenic magmatism is related to a rifting event at the northern margin of Gondwana leading to the detachment of the Sakarya Zone and hence placing an age on the initial opening of the Paleo-Tethys. This interpretation is based on (i) the presence of Late Silurian to Devonian deep-sea sedimentary blocks in the Paleo-Tethyan accretionary complexes, and (ii) the resemblance of the U\ \Pb age spectra of detrital zircons in the metaclastic sequence of the Sarıcakaya Massif to those of Cambro-Ordovician sandstones in Jordan (Gondwana), and (iii) the local occurrence of anorogenic A-type granites of Late Ordovician-Silurian age in the Anatolide-Tauride Block, a continental block which rifted from Gondwana during the Early Triassic. Wholly anorogenic nature of the Late Ordovician to Silurian igneous rocks in the Sarıcakaya Massif and reported in literature does not support the opening of the Paleo-Tethys as back-arc ocean, as suggested in most paleogeographic reconstructions.
The East Anatolian plateau (Turkey) is extensively covered by Neogene to Quaternary volcanic-sedi... more The East Anatolian plateau (Turkey) is extensively covered by Neogene to Quaternary volcanic-sedimentary rocks, and is characterized by an attenuated lithospheric mantle. Its pre-Neogene basement is commonly considered to consist entirely of Late Cretaceous to Oligocene oceanic accretionary complexes, formed at the junction of several continental blocks. Here we report on three main exposures of the pre-Neogene basement in this region. The exposed areas consist mainly of amphibolite-to granulite-facies metamorphic rocks, including marble, amphibolite, metapelite, metagranite, and metaquartzite. An upper amphibolite-to granulitefacies domain is equilibrated at similar to 0.7 GPa and similar to 800 degrees C at 83 +/- 2 Ma (2 sigma). U-Pb dating of magmatic zircons from the metagranite yielded a Late Ordovician-early Silurian protolith age (444 +/- 9 Ma, 2 sigma). The detrital zircons from one metaquartzite point to a Neoproterozoic-early Paleozoic provenance. Ophiolitic rocks tectonically sit on the metamorphic rocks. Both the metamorphic and ophiolitic rocks are in turn unconformably covered by lower Maastrichtian clastic rocks and reefal limestones, suggesting that the whole exhumation process and juxtaposition with the ophiolitic rocks had occurred by the early Maastrichtian. Several lines of evidence, such as (1) the absence of any indication of a former high-pressure metamorphism in the metamorphic rocks, (2) the allochthonous nature of the ophiolitic rocks, (3) the presence of metagranite with a Late Ordovician-early Silurian protolith age, and (4) the Neoproterozoic- early Paleozoic provenance of detrital zircons in the metaquartzite (in contrast to the dominance of late Paleozoic-Mesozoic crystalline rocks in the adjacent continental blocks) indicate a substantial component of continental basement beneath the Neogene to Quaternary cover. Thus, the loss of the lithospheric mantle probably resulted from lithospheric foundering processes beneath the plateau, rather than just slab steepening and break-off.
The recent discovery of HP-LT parageneses in the basal unit of the Lycian nappes and in the Mesoz... more The recent discovery of HP-LT parageneses in the basal unit of the Lycian nappes and in the Mesozoic cover of the Menderes massif leads us to reconsider and discuss the correlation of this region with the nearby collapsed Helle-nides in the Aegean domain. Although similarities have long been pointed out by various authors, a clear correlation has not yet been proposed and most authors insist more on differences than similarities. The Menderes massif is the eastern extension of the Aegean region but it has been less severely affected by the Aegean extension during the Oligo-Miocene. It would thus be useful to use the structure of the Menderes massif as an image of the Aegean region before a significant extension has considerably reduced its crustal thickness. But the lack of correlation between the two regions has so far hampered such comparisons. We describe the main tectonic units and metamorphic events in the two regions and propose a correlation. We then show possible sections of...
The Menderes massif consists of a Precambrian Core Series that preserves evidence for a polymetam... more The Menderes massif consists of a Precambrian Core Series that preserves evidence for a polymetamorphic history and a Paleozoic/Mesozoic Cover Series that experienced only the Alpine tectonometamorphic evolution. Structural, petrographic, and geochronologic investigations in the central Menderes massif demonstrate that (a) part of the metamorphic and structural evolution of the Precambrian basement is older than the undeformed 551±1.4-Maold Birgi metagranite, and (b) inferred Alpine fabrics overprinting the Cover Series largely have the same attitudes as the old structures in the much older Core Series. The inferred Alpine fabrics include both contractional and extensional structures. Contraction under greenschist to amphibolite facies conditions resulted in the imbrication of the Core and Cover Series and generated an inverted metamorphic sequence by north-directed thrusting. During Alpine extension, most of the south-dipping thrust faults were reactivated as extensional shear zones under decreasing greenschist facies conditions.
Carboniferous metagranites with U-Pb zircon crystallization ages of 331-315 Ma crop out in the Af... more Carboniferous metagranites with U-Pb zircon crystallization ages of 331-315 Ma crop out in the Afyon zone in the northern margin of the Anatolide-Tauride Block, which is commonly regarded as part of Gondwana during the Late Palaeozoic. They are peraluminous, calc-alkaline and are characterized by increase in Rb and Ba, decrease in Nb-Ta, and enrichment in Sr and high LILE/HFSE ratios compatible with a continental arc setting. The metagranites intrude a metasedimentary sequence of phyllite, metaquartzite and marble; both the Carboniferous metagranites and metasedimentary rocks are overlain unconformably by Lower Triassic metaconglomerates, metavolcanics and Upper Triassic to Cretaceous recrystallized limestones. The low-grade metamorphism and deformation occurred at the Cretaceous-Tertiary boundary. There is no evidence for Carboniferous deformation and metamorphism in the region. Carboniferous arc-type granites and previously described Carboniferous subduction-accretion complexes on the northern margin of the Anatolide-Tauride Block suggest southward subduction of Paleotethys under Gondwana during the Carboniferous. Considering the Variscan-related arc granites in Pelagonian and Sakarya zones on the active southern margin of Laurasia, a dual subduction of Paleotethys can be envisaged between Early Carboniferous and Late Permian. However, the southward subduction was shortlived and by the Late Permian the Gondwana margin became passive.
Southwest Turkey comprises two main complexes: the Lycian Nappes and the underly- ing autochthono... more Southwest Turkey comprises two main complexes: the Lycian Nappes and the underly- ing autochthonous Menderes Massif. On the Bodrum peninsula, south of the Menderes crystalline massif, a widespread distribution of fresh Fe-Mg-carpholite recently dis- covered in the metasediments from the base of the Lycian nappe complex attests for a high pressure-low temperature metamorphic event. Klippen of Lycian Nappes lo- cated
In Western and Central Turkey throughout Mesozoic and Tertiary times, the closure of the Tethys o... more In Western and Central Turkey throughout Mesozoic and Tertiary times, the closure of the Tethys oceanic realm took place through the consumption of oceanic basins and accretion of continental blocks. Regarding its Alpine (i.e. Cretaceous-Tertiary) history, the tectonic framework of W-Turkey is rather clear. The following blocks build up the Turkish microplate: a) Pontide Block, assembled during the Cimerian (late Triassic) closure of the Palaeo-Tethys; b) the Anatolide-Tauride Block, partly metamorphosed under HP-LT conditions in Late Cretaceous to Palaeocene times; c) the Central Anatolian Crystalline Complex, made of Late Cretaceous high grade metamorphics and intrusions; and d) the Alanya Nappes. The ways of imbrication of these tectonics units, however, are often matter of debate. Particularly, the number and position of former oceans is questioned. Recent studies int the Anatolide Tauride Block show that Alpine subduction-related HP-LT metamorphism is not restricted to the northernmost Tavsanli Zone, but is actually widespread in the tectonic slices of (Tavsanli Zone, Afyon Zone, Menderes Massif and Lycian Nappes). These new blueschist-facies metamorphism occurrences spark the debate on the Alpine evolution of this region. Fe,Mg-carpholite-bearing rocks occur not only in its central part of the Afyon Zone, but South of the Central Anatolian Crystalline Complex, all along from the Menderes Massif to East of Kayseri. Some of these occurrences are closely related to glaucophane- and/or lawsonite-bearing rocks already reported in the sixties by v. d. Kaaten. On top of the Mesozoic sequence of the Afyon Zone, consisting of a coherent marble sequence, an accretionary mélange, made of a serpentinized blueschists, marbles and mantellic rocks occurs. This mélange is typical of the Tavsanli Zone. We also observed it, croping out scarcely between the CACC and the Afyon Zone all the way to Kayseri. Therefore our field observations lead us to extend the Afyon and the Tavsanli Zones eastwards and to depict them as HP-LT tectonics slices, of more than 600-km long. P,T-conditions and ages from the Tavsanli lawsonite blueschists (24 kbar/450 °C; 85-80 Ma) contrast with the Afyon carpholite bearing metapelites and associated blueschists (8kb/350 °C; 65-60 Ma). The two HP-very LT metamorphic belts occurring in Central Anatolia are separated by an low grade flysch. This flysch and the age difference between HP belts open the question of the number of subduction zones during the late Cretaceous in Central Anatolia. If two subductions are assumed this area compares to the Alps, but an equivalent to the Briançonnais microcontinent is missing. The dynamic of a one subduction zone model could be similar to the the Aegean realm today. In this case, Tavsanli - Afyon can be compared to the situation between Rhodopes and Tinos. There, similarly significant differences in P,T conditions and ages are obvious, while direct observation of contacts are hampered by the seas. Contrarily the Tavsanli - Afyon realm allows insight into a dual metamorphic belt.
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