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

Morphological variation in Hemigordius harltoni Cushman & Waters, 1928: Remarks on the taxonomy of Carboniferous and Permian hemigordiopsids

Nine morphotypes recognized within its population suggest that Hemigordius harltoni is a polytypic species. Narrowly discoidal to discoidal morphotypes are dominant in the population whereas lenticular ones are rare and sporadic. The degree of morphological variation in H. harltoni prompts us to question the validity of several previously named Carboniferous and Permian taxa. The definition of these taxa, generally based on few specimens, is far from being satisfactory to describe the intraspecific variability. Some named species are actually morphotypes belonging to highly variable species

The effect of major element oxide and moisture loss on grindability of Afsin–Elbistan low-grade coal

In this paper, the influences of major element oxides and moisture loss in coal on its grindability were examined using the Hardgrove equipment. The major element oxides in the coal could be a predictor of HGI. If CaO content in the coal was high, the grindability of coal could be easier. The moisture loss in the coal had a strong effect on the grindability property. The pH could be a good indicator to predict and classify HGI. If the pH is lower than 9.5, HGI is also lower than 53 and those type of coal was classified as heavily grindable. © 2017 Taylor & Francis Group, LLC

Cyclic sedimentation across the Permian-Triassic boundary (Central Taurides, Turkey)

The best preserved Permian - Triassic boundary beds in Turkey are found in the Hadim region of the central Taurides. The succession is exposed in one of the allochthonous units of the Tauride Belt, the Aladag Unit, whose stratigraphy includes beds ranging from the Devonian to the Cretaceous systems. In the Aladag Unit, the Permian - Triassic boundary beds are entirely composed of carbonates. The Permian portion of these beds belongs to the Paradagmarita Zone, whereas the lowermost Triassic contains the Lower Griesbachian marker Rectocornuspira kalhori. The uppermost Permian carbonates, composed of meter-scale upward shallowing subtidal cycles, are characterized by oolitic limestones of regressive character at the top and are overlain sharply by Lower Triassic stromatolites. Cyclic Upper Permian carbonates are interpreted as highstand systems tract deposits of the last third-order sequence of the Permian System. The Permian - Triassic boundary is an unconformity corresponding to both erosional and non-depositional hiatuses. The gap at the Permian - Triassic boundary partially corresponds to the shelf-margin systems tract and partly to the transgressive systems tract of the overlying third-order sequence. Stromatolites are interpreted as transgressive systems tract deposits

Prediction of Hardgrove Grindability Index of Afsin-Elbistan (Turkey) Low-grade Coals Based on Proximate Analysis and Ash Chemical Composition by Neural Networks

The aim of the study is to provide insights about the Hardgrove grindability index (HGI) value of Piocene aged Afsin-Elbistan low-grade coal determination without human or experimental errors, timely and low cost. For this reason, the HGI for Afsin-Elbistan low-grade coal based on twelve coal parameters was predicted through linear regression (LR), feed forward neural network (ANN), generalized regression neural network (GRNN) and elman network (EN) approaches in this study.. The obtained results show that LR and EN approaches were unsatisfactory because of high differences determined between actual and predicted HGI. However, ANN and GRNN approaches make quite reliable predictions on HGI with a high accuracy. The R-value of the models was 0.93 for ANN and 0.98 for GRNN approaches. The percentage of predicted HGI within ±3 deviation through ANN and GRNN approaches was found to be 89.53 and 94.19, respectively. The sensitivity of approaches to predictors was evaluated by an enterremove selection method to determine the individual effect of each parameter on the prediction of HGI. The best prediction approach for the Afsin-Elbistan Pliocene aged coal was GRNN that can be applied to predict HGI for the similar aged coals. © 2017 Taylor & Franci

Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin

Western Anatolia is a complex assemblage of terranes, including the Sakarya Terrane and the Tauride-Anatolide Platform that collided during the late Cretaceous and Palaeogene (80–25 Ma) after the closure of the Izmir-Ankara Ocean. Determining the precise timing at which this ocean closed is particularly important to test kinematic reconstructions and geodynamic models of the Mediterranean region, and the chronology of suturing and its mechanisms remain controversial. Here, we document the Cretaceous-Eocene sedimentary history of the Central Sakarya Basin, along the northern margin of the Neotethys Ocean, via various approaches including biostratigraphy, geochronology, and sedimentology. Two high-resolution sections from the Central Sakarya Basin show that pelagic carbonate sedimentation shifted to rapid siliciclastic deposition in the early Campanian (~ 79.6 Ma), interpreted to be a result of the build-up of the accretionary prism at the southern margin of the Sakarya Terrane. Rapid onset of deltaic progradation and an increase in accumulation rates in the late Danian (~ 61 Ma), as well as a local angular unconformity are attributed to the onset of collision between the Sakarya Terrane and the Tauride-Anatolide Platform. Thus, our results indicate that though deformation of the subduction margin in Western Anatolia started as early as the Campanian, the closure of the İzmir-Ankara Ocean was only achieved by the early Palaeocene. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.National Science Foundation: EAR-1543684 104Y153 Türkiye Bilimsel ve Teknolojik Araştirma KurumuThis work was supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK) under Grant 104Y153; National Science Foundation (NSF) under Grant EAR-1543684

Triassic Foraminifera From the Great Bank of Guizhou, Nanpanjiang Basin, South China: Taxonomic Account, Biostratigraphy, and Implications for Recovery From End-Permian Mass Extinction

Foraminifera are important components of tropical marine benthic ecosystems and their recovery pattern from the end-Permian mass extinction can yield insights into the Mesozoic history of this group. Here we report the calcareous and agglutinated foraminifera recovered from five measured stratigraphic sections on the Great Bank of Guizhou, an uppermost Permian to Upper Triassic isolated carbonate platform in the Nanpanjiang Basin, south China. The material contains \u3e100 Triassic species, including three that are newly described (Arenovidalina weii n. sp., Meandrospira? enosi n. sp., and Spinoendotebanella lehrmanni n. gen., n. sp.), ranging from Griesbachian (Induan) to Cordevolian (Carnian) age. The species belong to the classes Miliolata, Textulariata, Fusulinata, Nodosariata, and to an unknown class housing all aragonitic forms of the orders Involutinida and Robertinida. Based on previously established conodont zones and carbon isotope chemostratigraphy, the Griesbachian (early Induan) through Illyrian (late Anisian) interval has been subdivided into 12 foraminiferal zones and two unnamed intervals devoid of foraminifera. Following the extinction at the Permian-Triassic boundary, habitable ecological niches of Griesbachian age were invaded by disaster taxa that subsequently became extinct during the Dienerian (late Induan) and left no younger descendants. The disaster taxa were replaced by Lazarus taxa with Permian origins, which were then decimated by the Smithian-Spathian (mid-Olenekian) boundary crisis. The tempo of recovery appears to have been modulated by environmental changes during the Griesbachian through Smithian that involved both climate change and expansion of anoxic ocean bottom waters. Uninterrupted and lasting recovery of benthic foraminifera did not begin until the Spathian

Stratigraphy and tectonic evolution of the Kazdağı Massif (NW Anatolia) based on field studies and radiometric ages

The Kazda Massif was previously considered as the metamorphic basement of the Sakarya Zone, a microcontinental fragment in NW Anatolia. Our new field mapping, geochemical investigations, and radiometric dating lead to a re-evaluation of previous suggested models of the massif. The Kazda metamorphic succession is subdivided into two major units separated by a pronounced unconformity. The lower unit (the Tozlu metaophiolite) is a typical oceanic crust assemblage consisting of ultramafic rocks and cumulate gabbros. It is unconformably overlain by a thick platform sequence of the upper group (the Sarkz unit). The basement ophiolites and overlying platform strata were subjected to a single stage of high-temperature metamorphism under progressive compression during the Alpine orogeny, accompanied by migmatitic metagranite emplacement. Radiometric age data obtained from the Kazda metamorphic succession reveal a wide range of ages. Metagranites of the Kazda metamorphic succession define a U-Pb discordia upper intercept age of ca. 230Ma and a lower intercept age of 24.8 +/- 4.6Ma. This younger age agrees with Pb-207/Pb-206 single-zircon evaporation ages of 28.2 +/- 4.1 to 26 +/- 5.6Ma. Moreover, a lower intercept age of 28 +/- 10Ma from a leucocratic metagranite supports the Alpine ages of the massif within error limits. Reconnaissance detrital zircon ages constrain a wide range of possible transport and deposition ages of the metasediments in the Sarkz unit from ca. 120 to 420Ma. Following high-temperature metamorphism and metagranite emplacement, the Kazda sequence was internally imbricated by Alpine compression, and the lowermost Tozlu ophiolite thrust southward onto the Sarkz unit. Field mapping, internal stratigraphy, and new radiometric age data show that the Sarkz unit is the metamorphic equivalent of the Mesozoic platform succession of the Sakarya Zone. The underlying metaophiolites are remnants of the Palaeo tethys Ocean, which closed during the early Alpine orogeny. After strong deformation attending nappe emplacement, the unmetamorphosed Miocene Evciler and Kavlaklar granites intruded the tectonic packages of the Kazda Massif. During Pleistocene time, the Kazda Massif was elevated by EW trending high-angle normal faults dipping to Edremit Gulf, and attained its present structural and topographic position. Tectonic imbrication, erosion and younger E-W-trending faulting were the main cause of the exhumation of the massif