Constraints on Variscan and Cimmerian magmatism and metamorphism in the Pontides (Yusufeli–Artvin area), NE Turkey from U–Pb dating and granite geochemistry
Timur Ustaömer, Alastair H. F. Robertson, P. Ayda Ustaömer, Axel Gerdes, Irena Peytcheva, 2013. "Constraints on Variscan and Cimmerian magmatism and metamorphism in the Pontides (Yusufeli–Artvin area), NE Turkey from U–Pb dating and granite geochemistry", Geological Development of Anatolia and the Easternmost Mediterranean Region, A. H. F. Robertson, O. Parlak, U. C. Ünlügenç
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Metamorphic and igneous rocks exposed in NW-vergent thrust sheets and their autocthonous basement in the NE Pontides were dated by the U–Pb method using zircons, supported by geochemical data for granitic rocks. Two meta-sedimentary units (Narlık schist and Karadağ paragneiss) yielded detrital zircon populations of 0.50–0.65 and 0.9–1.1 Ga, suggesting an affinity with NE Africa (part of Gondwana). The youngest concordant zircon age is Ediacaran for the schist but Devonian for the paragneiss, bracketing the paragneiss depositional age as Mid-Devonian to Early Carboniferous. Metamorphic rims of zircon cores in the paragneiss gave Carboniferous ages (345–310 Ma). The zircon rim data indicate two Variscan metamorphic events (334 and 314 Ma) separated by a hiatus (320–325 Ma). Granite emplacement took place during early Carboniferous, Early Jurassic and Late Jurassic phases. The crystallization age of the early Carboniferous granites (c. 325 Ma) corresponds to a hiatus in the zircon age data that could reflect subduction slab break-off. The Variscan granitic rocks intruded a Gondwana-derived continental terrane that was loosely accreted to Eurasia during early–late Carboniferous time but remained isolated from Eurasian-derived terrigenous sediment. In contrast, the Jurassic granitic magmatism relates to later back-arc extension along the southern margin of Eurasia.
Full isotope data (8 tables) are available at http://www.geolsoc.org.uk/SUP18558
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Geological Development of Anatolia and the Easternmost Mediterranean Region
Anatolia and the easternmost Mediterranean region, especially Turkey, Cyprus and northern Syria, represent an excellent natural laboratory for the study of fundamental geological processes (e.g. rifting, seafloor spreading, ophiolite genesis and emplacement, subduction, exhumation and collision). Their interaction has created an intriguing array of deep-sea basins, microcontinents and suture zones.
The volume’s 22 papers include a large amount of new field-based information (much of it multidisciplinary and the product of teamwork). After an overview, the volume is divided into four sections: Late Palaeozoic–Early Cenozoic of the Pontides (northern Turkey); Late Palaeozoic–Early Cenozoic of the Taurides–Anatolides (central and southern Turkey); Late Cretaceous–Pliocene sedimentary basins and structural development (central Anatolia to the Mediterranean); Late Miocene–Recent Neotectonics (southern Turkey, Cyprus and northern Syria).
The volume will interest numerous academic researchers, those concerned with resources (e.g. hydrocarbons; mineral deposits) and also hazards (e.g. earthquakes), as well as advanced undergraduate and postgraduate students.