İzmir‐Ankara suture as a Triassic to Cretaceous plate boundary – data from central Anatolia

The İzmir‐Ankara suture represents part of the boundary between Laurasia and Gondwana along which a wide Tethyan ocean was subducted. In northwest Turkey, it is associated with distinct oceanic subduction‐accretion complexes of Late Triassic, Jurassic and Late Cretaceous ages. The Late Triassic and Jurassic accretion complexes consist predominantly of basalt with lesser amounts of shale, limestone, chert, Permian (274 Ma zircon U‐Pb age) metagabbro and serpentinite, which have undergone greenschist facies metamorphism. Ar‐Ar muscovite ages from the phyllites range from 210 Ma down to 145 Ma with a broad southward younging. The Late Cretaceous subduction‐accretion complex, the ophiolitic mélange, consists of basalt, radiolarian chert, shale and minor amounts of recrystallized limestone, serpentinite and greywacke, showing various degrees of blueschist facies metamorphism and penetrative deformation. Ar‐Ar phengite ages from two blueschist metabasites are ca. 80 Ma (Campanian). The ophiolitic mélange includes large Jurassic peridotite‐gabbro bodies with plagiogranites with ca. 180 Ma U‐Pb zircon ages. Geochronological and geological data show that Permian to Cretaceous oceanic lithosphere was subducted north under the Pontides from the Late Triassic to the Late Cretaceous. This period was characterized generally by subduction‐accretion, except in the Early Cretaceous, when subduction‐erosion took place. In the Sakarya segment all the subduction accretion complexes, as well as the adjacent continental sequences, are unconformably overlain by Lower Eocene red beds. This, along with the stratigraphy of the Sakarya Zone indicate that the hard collision between the Sakarya Zone and the Anatolide‐Tauride Block took place in Paleocene

Geologische Entwicklung des Strandja-Massivs (Thrakien, Türkei)

The Strandja Massif is located in the NW part of Turkey. The massif is bounded by the Thrace basin to the south, the Istanbul Zone to the east and the Black Sea to the north. It is roughly a NW-SE trending mountain belt, ca. 200 km long and 90 km wide. The tectonic position of the massif is interpreted as a western part of the Pontide belt. The main aim of this study focuses on the formation history of metamorphic rocks of the Strandja Massif using structural, petrological, geochemical, and radiogenic dating methods. The Strandja Massif mainly consist of two assemblages (the basement and the cover), which can be distinguished to each other with their rock association, age, and pre-metamorphic unconformity defined between them. The basement constitutes Paleozoic metasediments (bioitite and garnet-biotite schists) and orthogneisses (hornblende-biotite, biotite-muscovite, and muscovite orthogneisses) whereas the cover association compound of Mesozoic metaclastic rocks. Metamorphic grade decreases from the epidote-amphibolite facies in the south to the albite-epidote amphibolite/greenschist-facies transition in the north. Estimated P-T conditions reach 485-530 °C and 0.60-0.80 GPa in the south and ~450-500 °C in the northern part. Rb-Sr muscovite ages decrease systematically northwards from 162 to 142 Ma. The Rb-Sr biotite ages also decrease systematically from 153 Ma in the south to 134 in the north. These ages point out diachronous metamorphism and cooling. Structural features such as (i) consistent south-dipping foliation, (ii) southwest to southeast-plunging stretching lineation, (iii) top to north shear sense, and ductile shear zones suggest compressional deformation coupled with exhumation. Various types of orthogneisses constitute a significant part of the metamorphic basement. Their modal compositions correspond to quartz diorite, tonalite, granodiorite and trondhjemite. Geochemical data suggest a calc-alkaline trend of differentiation. Isotopic dating using the single zircon Pb-Pb evaporation method has shown that there are two magmatic events; one occurred within a short time interval between 312±2 and 315 ±5 Ma and another one is dated as 257±6 Ma, which shows extensive magmatic activity in the study area during the late Carboniferous and Permian intervals. These magmatic activities indicate existence of a mature magmatic arc. For the deposition age of the basement metasediments, evaporation Pb-Pb ages of detrital zircons are used. According to that protholite age of garnet-biotite schists of the metamorphic basement were deposited later than 430 Ma and prior to 315 Ma whereas biotite schists exposed along the southern boundary of the basement were restricted between 300 and 271 Ma. Pb-Pb detrital zircon ages have been used for revealing tectonic history and initial position of the Strandja massif. Age data derived from detrital zircons vary between 430 and 2700 Ma, which reveal to heterogeneous source areas. Detrital zircon ages of the Strandja Massif are correlative with both the Avalonian and the Armorican tectonic units of Western Europe. The presence of Mesoproterozoic zircon ages in the metasediments of the Strandja massif indicates that the proximity of the Strandja massif to Avalonian (or Baltica) derived units occured during the late Silurian-Carboniferous interval.Das Strandja-Massiv liegt im Nordwesten der Türkei und wird vom Thrakien-Becken im Süden, von der Istanbul-Zone im Osten und vom Schwarzen Meer im Norden abgegrenzt. Es bildet eine NW-SO streichenden Gebirgsgürtel, ca. 200 km lang und 90 km breit. Tektonisch betrachtet wird das Massiv als westlicher Ausläufer des Pontischen Gebirgsgürtels angesehen. Diese Arbeit befasst sich mit der Entwicklungsgeschichte der metamorphen Gesteine des Strandja Massivs. Seine Gesteine wurden mit Hilfe von strukturgeologischen, petrographischen, geochemischen und radiometrischen Methoden untersucht. Das Massiv besteht hauptsächlich aus zwei Einheiten (Basement und Decke), die sich bezüglich ihrer Gesteinsvergesellschaftung, des Alters und einer pre-metamorphen Diskordanz voneinander unterscheiden. Die Basement-Einheit besteht im Wesentlichen aus Paläozoischen Metasedimenten (Biotit- und Granat-Biotit-Schiefer) und Orthogneissen (Hornblende-Biotit-, Biotit-Muskovit- und Muskovit-Orthogneissen), während sich die Deckeneinheit aus Mesozoischen, metaklastischen Gesteinen, wie etwa Metakonglomeraten und Metasandsteinen, zusammensetzt. Der Metamorphosegrad nimmt von einer Epidot-Amphibolit-Fazies im Süden zu einer Albit-Epidot-Amphibolit/Grünschiefer-Fazies im Norden ab. Geschätzte P-T Bedingungen reichen von 485-530 °C / 0.60-0.80 GPa in Süden bis zu ~ 450-500 °C im Norden. Rb-Sr Muskovit Alter zeigen eine systematische Abnahme von 162 Ma auf 142 Ma nach Norden hin. Die Rb-Sr Biotit Alter nehmen ebenfalls systematisch von 153 Ma im Süden auf 134 Ma im Norden ab. Diese Alterdaten deuten auf eine diakrone Metamorphose und Abkühlung hin. Mehrere strukturelle Merkmale, wie z.B. (i) einstimming nach Süden einfallende Foliation, (ii) S-SE streichende Lineation und (iii) nordvergente Verscherung und duktilen Scherzonen deuten auf Kompression während der Exhumierung hin. Die Orthogneisse, die den wesentlichen Bestandteil der Basement-Einheit ausmachen, weisen Modalbestände auf, die einem Quarz-Diorit, Tonalit, Granodiorit und Trondhjemite entsprechen. Geochemisch lässt sich eine kalk-alkalischer Differenziationstrend erkennen. Pb-Pb Evaporationsdatierungen an magmatischen Zirkonen erbrachten Alterswerte, die auf zwei getrennte magmatischen Aktivitäten hin deuten. Die erste erfolgte von 312±2 Ma bis zu 315±5 Ma, und die zweite ca. bei 257±6 Ma. Diese deutet auf einen weit verbreiteten Magmatismus während des Spätkarbons und Frühperms hin. Dieser Magmatismus lässt sich auf eine Bildung in einem reifen magmatischen Bogen zurückführen. Die Sedimentationsalter der Metasedimente im Basement wurden anhand von Pb-Pb Evaporationsaltern von detritischen Zirkonen eingegrenzt, demnach erfolgte die Ablagerung der Protolithe der Granat-Biotit-Schiefer zwischen 430 und 315 Ma, während die Sedimentation der Protolithe der Biotit-Schiefer im südlichen Teil des Arbeitsgebietes zwischen 300 Ma und 271 Ma eingegrenzt werden konnte. Pb-Pb Alterswerte detritischer Zirkone wurden zur Ermittlung der ursprünglichen geotektonischen Stellung des Strandja-Massivs verwendet. Ihre Alterswerte variieren zwischen 430 Ma und 2700 Ma, was auf sehr heterogene Einzugsgebiete zurückschliessen lässt. Vergleichbare Alterswerte sind aus den sogenanten tektonischen Einheiten Avalonia und Armorika in West-Europa bekannt. Die Anwesenheit von mesoproterozoischen Zirkonen in den Metasedimenten deutet darauf hin, dass sich das Strandja-Massiv der tektonischen Einheit Avalonia während des Spätsilur-Karbon-Intervalls annäherte

Gürsel Sunal's Quick Files

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The Geology Around Cide And Kurucaşble

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1998Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1998İnceleme alanı Batı Karadeniz bölgesinde Cide (Kastamonu)- Kurucaşile (Bartın) arasında kıyıya paralel ince bir şerit halinde yer almaktadır. Bölge Batı Pontid temeli, İstanbul Zonu üzerinde bulunur. Çalışma alanında çeşitli jeolojik olay ve ortamlarda oluşmuş, Karbonifer-Tersiyer aralığında gelişmiş birimler yayılır. Çalışma alanı Karboniferde karasal koşulların hüküm sürdüğü bir dönemdir. Bu dönemde bölgede, kömür ara seviyeleri de içeren akarsu fasiyesinde gelişmiş birimler çökelmiştir. Yine karasal koşullarda gelişmiş birimlerin bulunduğu Triyas dönemi akarsu ve rüzgar çökelleriyle temsil edilir. İstanbul bölgesi ve Pontidlerin diğer kesimlerinin aksine bu iki dönemde de bölge kara halindadir. Dogerde bölgede kısa süreli bir deniz ilerlemesi görülür. Malm döneminde ise bu denizel istifle uyumsuz olarak gelişmiş, daha uzun süreli bir deniz transgresyonu ile platform karbonatları çökelmiştir. Bu çökeller Neo-Tetis'in pasif kıta kenarında gelişmiş birimlerdir. Albiyen döneminde tekrar alttaki birimlerle uyumsuz olarak gelişmiş denizel çökeller görülür. Bu birimler Ulus havzasının açılımını temsil etmektedir. Troniyen-Santoniyen devrinde bölgede ilk defa volkanik birimler ve normal fay önünde gelişmiş derin denizel birimler görülür. Ulus havzasında gelişmiş birimlerin üzerinde uyumsuz olarak gelişmiş bu çökeller, Ulus havzasının kenarını oluşturan çalışma alanının, artık açılmakta olan Karadenizin kıta kenarı haline geldiğini göstermektedir. Bu birimlerin hemen üzerinde ise Troniyen-Koniasiyen döneminde, bölgesel ölçekte açısal uyumsuz olarak duran ve ana kopma uyumsuzluğunu temsil eden derin denizel birimler gelişmiştir. Kampaniyen dönemi bölgede yay özelliği gösteren volkanik kayaçların gelişimi ile temsil edilir. Bu dönem ve sonrasında gelişmiş birimler Karadeniz'in pasif kıta kenarını temsil eden çökeller niteliğindedir. Çalışma alanında kuvaterner çökelleri haricinde, Eosenden günümüze kadar çökel gelişimi gözlenmez. Bölge Eosende sıkışmalı bir rejimden etkileniş ve kuzey verjanslı, ekaylı bir yapı kazanmıştır. Bu rejim altında bir çok ters fay ve kıvrım gelişmiştir. Bu sıkışma rejimi olasılıkla bir taban kopma fayından hareketle bölgenin bugün de görülebilen ekaylı yapısının gelişmesine neden olmuştur. Bu rejim bölgede daha önceden gelişmiş jeolojik olayları tahrip etmiştir.The study area is situated Cide (Kastamonu) and Kurucaşile towns (Bartın) in Western Black Sea, toward seaside. The investigation area covers approximately 250 km2. The area is located on Western Pontites (Ketin, 1966; Şengör and Yılmaz, 1981) (Fig.l). Western Pontites was named as İstanbul Zone by Okay et al, (1994). At the base of the İstanbul Zone, there are a group of rocks Paleozoic in age and Triassic terrestrial units. Formers represent passive continental margin sequence (Apdülselamoğlu, 1977). There are different units over the basement ranging in age from Dogger to Eocene. The area was effected different tectonic events. After the Triassic, there are three main tectonic events; the opening of the Neo-Tethian ocean in Malm (Şengör and Yılmaz, 1981), the opening of the Black Sea in Lower Cretaceous (Görür, 1989) and the closing of the Neo-Tethian ocean (Şengör and Yılmaz, 1981). The interest of the investigation is the Tertiary structures developed depending on the closure of the Neo-Tethian ocean (Şengör and Yılmaz, 1981; (Şengör, 1995). As a result of that closure, the area won an imbricated structure that has known since Grancy (1938). Fig.2 shows the general theoretical structural model for Pontides preferred by Şengör (1995). According to such model Pontides have two against imbricated vergents which are in the sought to sought and in the north to north. The aim of the study is to find out the effects of such events and development of the imbricated structure. In addition to, the geological evaluation of the area was tired to explain. The study area comprises twelve distinct units, which of two are basement units and the others are cover units. The Zonguldak formation is in the İstanbul-Zonguldak Paleozoic succession (Yılmaz et al., 1981). In the Zonguldak area, Zonguldak formation is represented by fluvial, deltaic and lacustrine sediments consist of the coal layers. Moreover in the study area, the Zonguldak formation represented by only the fluvial sediments consist of conglomerates, sandstones and mudstone intercalated with coal layers. The Çakraz formation of Triassic is represented by red coloured fluvial and aeolian sediments deposited in terrestrial processes. Base of the Çakraz unit comprise trough bedded, channel-structured conglomerates and sandstones and, laminated, planer cross-bedded, thin mudstone. In the upper part of the formation is represented by big scaled planer cross-bedded sandstones and thin bedded mudstone layers. Near of the western part of the study area, over of the Çakraz unit there is Çakrazboz formation that developed in lacustrine environment. The Çakraz formation pass the Çakrozboz formation gradually. The paleontological data derived from Çakrazboz formation gives Upper Triassic age (Alişan and Derman 1995). According to that data, the age of the Çakraz formation is accepted as Lower-Middle Triassic. The Himmetpaşa formation that belong the cover unites is the first marine unit placed in the study area. The unit begins at the base transgressively and than finishes regressively. The Himmetpaşa formation overlies the older basement unites unconformably and over of it, İnaltı formation stands unconformably. The Himmetpaşa formation indicates short-term sea exceeding the area. It is thought that the Himmetpaşa formation is the remnant of the Paleo-Tethyan ocean (Aydın et. al., 1986). The İnaltı formation of Malm is generally massive, thick bedded platform carbonates that is a transgressive series indicating of opening of the Neo-Tethian ocean (Şengör and Yılmaz, 1981). At the base of the unit, there are mudstone and sandstone alternations. Over the İnaltı formation, Ulus formation of Lower Cretaceous stands unconformably. The study area is located on the Ulus basin that opened in that time. The Ulus basin was interpreted as opening of the Black Sea (Görür, 1988; Görür et al., 1993). Yenice and Dereköy formations are the time equivalent unites, developed in Tronian-Coniacian time interval. Although their lower contact can not be seen, it is thought that, the unites overlie the Ulus formation with an unconformity. The Dreköy formation is the first unit consisting of volcanic rocks. The Yenice formation indicates olistolites that accumulated in front of the fault scarps. Both unite developed under the deep marine sea environment. The Unaz formation Tronian in age consists mainly of red coloured, thin-bedded micritic limestone and marl alternation. The formation overlies the Dereköy formation in some place with an ungular unconformity. East of the Cide town, that contact is parallel unconformity. That unite indicates general subsiding of the whole area. Such subsiding was interpreted as the major break unconformity developed during the opening of the Black Sea (Görür et. al., 1993). The Unaz formation is overlain by the Cambu formation conformably. The Cambu formation consists of mainly volcanic rocks in part with sedimentary interbeds. The formation is overlain by Akveren formation conformably. The unit consists of calc-turbidites, marls and olistolites developed in deep-sea environment. Over the Akveren formation, there is the Akveren formation stood conformably. The Atbaşı formation is represented by deep-sea red coloured and thin-bedded marls. The last unit can be observed in the field is the Kusuri formation except Quaternary unites. The formation is represented by volcano-clastic turbidites. The unites that developed after the Ulus formation are the marginal deposits of the Black Sea. Such unites are feed by the south. The area was effected by compressional regime in Eocene time. According to that regime, the area has won an imbricated structure (Fig.2). The result of the imbricating, high angle reverse faults and overturned folds developed in the area. The angles of the reverse faults in the sought are higher than the north. And the angles of the limbs of the folds in the south are less than the north. It is visible that there are two different stile deformations developed in the area in the same regime. In the south area is seen less deformed and the deformation style represented by big scale structures: open folds, steep angled faults etc. In most places the stratigraphy of the units does not disrupted. They can clearly be traced in wide areas. The reason of that structural character is the deformation exerted on more competence unites that are of older than Lower Cretaceous. Especially, depending on the carbonate content and thick bedding of İnaltı formation deformation can not be seen as penetrative.Yüksek LisansM.Sc

Reconstructing the deformation of the North Anatolian Fault Zone through restoring the Oligo–Miocene exhumation pattern of the Almacık Block (northwestern Turkey) based on the apatite (U–Th)/He ages

The Almacık Block is a ~73 km long and ~21 km wide tectonic sliver formed by the North Anatolian Fault (NAF) in north western Turkey. Morphologically, it is one of the most pronounced structures along the North Anatolian Fault Zone (NAFZ). All of the segments bounding the Almacık Block are ruptured during the second half of the 20th century. Fifty-four apatite (U-Th)/He ages we obtained show that the region including the Almacık Block has exhumed during the Oligo-Miocene interval and then original exhumation pattern was distorted by the NAFZ during the Miocene to recent. To interpret this distortion and to reconstruct it to the original state, we modelled an “Λ” shaped mountain fronts in most probable deformation scenarios. The block has been tilted southward about an approximately E-W trending, horizontal (slightly dipping to the east) axis. As a result of this rotation northern part of the block has been uplifted ~2800 m whereas southern part has subsided ~430 m probably during last 2.5 Ma.The exhumation in the region studied started at around 34 Ma ago and lasted until 16 Ma with a mean exhumation rate of ~60 m/Myr.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Quaternary evolution of the Suluova Basin: implications on tectonics and palaeonvironments of the Central North Anatolian Shear Zone

The Suluova Basin is a prominent member of the wide transtensional Amasya Shear Zone located at the central part of the North Anatolian Shear Zone. This basin is crucial and provides well-resolved data to understand the evolution of transtensional tectonic zones as well as the morphological and paleoenvironmental changes of North Anatolia during the Quaternary. Analysis of detailed stratigraphical sections, faulting data, and mammal paleontology reveals that the Suluova Basin has started to evolve as a closed half-graben along the NW–SE-trending, SW-dipping basin bounding fault zone with normal slip in the early Quaternary. Initial sedimentation mode of the basin was dominated by alluvial fan facies associations. Progressive basin subsidence resulted in an expansion of a freshwater lake at the basin depocenter as faults propagated westwards. Further extensions in the basin were caused to initiate the E–W-trending southern tectonic boundary. Newly created accommodation space hosted a vast freshwater lake during the Calabrian (∼1.8–0.78 Ma) acting as a refugia for a rich faunal assemblage of large and small land mammals. The conditions prior to the onset of Middle Pleistocene (MIS19, ∼0.79 Ma) is marked with increasing regional erosion where paleo-Lake Suluova was captured by the regional river system. Synchronously, the next phase of the shear zone formation was introduced with E–W-trending dextral and NE–SW-trending sinistral strike-slip faults, cross-cutting the former basin structure, forming new depocenters. These faults are still active with noticeable seismic activity and comprise future risks for the major cities of the region.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Orta Karadeniz dağlarında Sakarya ile İstanbul zonları arasındaki pontid-içi sınırın niteliği ve jeolojik evrimi

TÜBİTAK ÇAYDAG31.12.201

Precambrian to Early Cretaceous rocks of the Strandja Massif (NW Turkey); evolution of a long lasting magmatic arc

The Strandja Massif, Turkey, forms a link between the Balkan Zone of Bulgaria, which is correlated with Variscan orogen in Europe, and the Pontides, where Cimmerian structures are prominent. Five fault-bounded tectonic units form the massif structure; 1) The Kırklareli Unit consist of the Paleozoic basement intruded by the Carboniferous to Triassic Kırklareli metagranites. It is unconformably overlain by Permian and Triassic metasediments. 2) The Vize Unite is made of the Neoproterozoic metasediments, Cambrian metagranites, and pre-Ordovician molasse. Unconformable Ordovician quartzites pass upward into quartz schists and then to marble and chert. Rocks of the Vize Unit are intruded by the late Carboniferous metagranites. 3) The Mahya accretionary complex and 4) the paired Yavuzdere magmatic arc were formed in the Carboniferous. 5) A nappe consisting of the Jurassic dolomites and marbles thrust to the north in late Jurassic – early cretaceous time. This thrusting affects all above-mentioned tectonic units. Tectonic subdivision of the Strandja Massive is supported by 19 newly obtained age determinations of magmatic and detrital zircons. The LA ICPMS and SHRIMP U–Pb methods of isotopic dating have been used in this study. The long duration of magmatism in the reign and its continuity in the Triassic contradicts to the widely accepted ideas about the dominance of the passive continental margin settings in the tectonic evolution. The Strandja Massif is interpreted as a fragment of the long-lived, Cambrian to Triassic Silk Road magmatic arc. At least since the late Paleozoic this arc evolved on the northern side of Paleo-Tethys.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author