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    Defining the southern margin of Avalonia in the Pontides: Geochronological data from the Late Proterozoic and Ordovician granitoids from NW Turkey
    (Elsevier, 2008) Okay, Aral I.; Bozkurt, Erdin; Satir, Muharrem; Yiğitbaş, Erdinç; Crowley, Quentin G.; Shang, Cosmas K.
    We provide new isotopic data from the Pontides, which substantiate the presence of a Cadomian basement with latest Proterozoic granitoids but also show the existence of Ordovician intrusives. Before the opening of the Black Sea, the Pontides formed a Palaeozoic orogenic belt at the margin of the East European Platform (Baltica) in an analogous position to the Variscan terranes in the central Europe. The Pontides consist of three terranes: The Strandja terrane has a Variscan basement with Carboniferous and Permian granitoids and an epicontinental Triassic to Jurassic sedimentary cover. The Istanbul terrane has a Cadomian basement overlain by a sedimentary sequence of Ordovician to Carboniferous age. It underwent contractional deformation during the Late Carboniferous. The Sakarya terrane is characterized by Carboniferous high temperature metamorphism and plutonism. The boundary between the I.stanbul and Sakarya terranes forms a complex tectonic zone several tens of kilometres wide. The new age data come from this boundary zone in the Armutlu peninsula in northwest Turkey. Metagranitoids, which intrude amphibolites in the Armutlu peninsula, give latest Proterozoic and Ordovician U-Pb zircon laser ablation MC-ICP-MS and Pb-Pb evaporation ages. The latest Proterozoic (ca. 570 Ma) granitoids are similar in age to those reported previously from the basement of the Istanbul terrane; they all form part of the widespread Pan-African granitoid plutonism on the margins of Gondwana. The Mid to Late Ordovician granitoids (460 Ma), on the other hand, probably have formed during the rifting of the I.stanbul terrane away from Gondwana during the opening of the Rheic ocean. In terms of the tectonic position, stratigraphy and geological evolution, the I.stanbul and Sakarya terranes are comparable to the Avalonia and the Armorican terrane assemblage in central Europe, respectively. (C) 2008 Elsevier B.V. All rights reserved.
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    P-T-t evolution of eclogite/blueschist facies metamorphism in Alanya Massif: time and space relations with HP event in Bitlis Massif, Turkey
    (Springer, 2016) Cetinkaplan, Mete; Pourteau, Amaury; Candan, Osman; Koralay, O. Ersin; Oberhaensli, Roland; Okay, Aral I.; Chen, Fukun
    The Alanya Massif, which is located to the south of central Taurides in Turkey, presents a typical nappe pile consisting of thrust sheets with contrasting metamorphic histories. In two thrust sheets, Sugozu and GundogmuAY nappes, HP metamorphism under eclogite (550-567 A degrees C/14-18 kbar) and blueschist facies (435-480 A degrees C/11-13 kbar) conditions have been recognized, respectively. Whereas the rest of the Massif underwent MP metamorphism under greenschist to amphibolite facies (525-555 A degrees C/6.5-7.5 kbar) conditions. Eclogite facies metamorphism in Sugozu nappe, which consists of homogeneous garnet-glaucophane-phengite schists with eclogite lenses is dated at 84.8 +/- A 0.8, 84.7 +/- A 1.5 and 82 +/- A 3 Ma (Santonian-Campanian) by 40Ar/39Ar phengite, U/Pb zircon and rutile dating methods, respectively. Similarly, phengites in GundogmuAY nappe representing an accretionary complex yield 82-80 Ma (Campanian) ages for blueschist facies metamorphism. During the exhumation, the retrograde overprint of the HP units under greenschist-amphibolite facies conditions and tectonic juxtaposition with the Barrovian units occurred during Campanian (75-78 Ma). Petrological and geochronological data clearly indicate a similar Late Cretaceous tectonometamorphic evolution for both Alanya (84-75 Ma) and Bitlis (84-72 Ma) Massifs. They form part of a single continental sliver (Alanya-Bitlis microcontinent), which was rifted from the southern part of the Anatolide-Tauride platform. The P-T-t coherence between two Massifs suggests that both Massifs have been derived from the closure of the same ocean (Alanya-Bitlis Ocean) located to the south of the Anatolide-Tauride block by a northward subduction. The boundary separating the autochthonous Tauride platform to the north from both the Alanya and Bitlis Massifs to the south represents a suture zone, the Pamphylian-Alanya-Bitlis suture.