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The basement of the Central Pontides, and by implication that of Crimea, consists of pre-Permian low-grade metaclastic rocks intruded by latest Permian – Early Carboniferous (305–290 Ma) granitoids. Further up in the stratigraphic sequence are Triassic limestones, which are now preserved as olistoliths in the deformed Upper Triassic turbidites. New conodont and foraminifera data indicate an Anisian to Carnian (Middle to Late Triassic) age for these hemi-pelagic Hallstatt-type limestones. The siliciclastic turbidites surrounding the Triassic limestone contain the Norian (Late Triassic) bivalve Monotis salinaria; the same species is also found in the Tauric series in Crimea. The Upper Triassic flysch in the Central Pontides is locally underlain by basaltic pillow lavas and includes kilometre-size tectonic slices of serpentinite. Both the flysch and the serpentinite are cut by an undeformed acidic intrusion with an Ar–Ar biotite age of 162 ± 4 Ma (Callovian–Oxfordian). This indicates that the serpentinite was emplaced into the turbidites before Middle Jurassic time, most probably during latest Triassic or Early Jurassic time, and that the deformation of the Triassic sequence pre-dates the Middle Jurassic. Regional geological data from the circum-Black Sea region, including widespread Upper Triassic flysch, Upper Triassic eclogites and blueschists of oceanic crustal affinity, and apparent absence of a ‘Cimmerian continent’ between the Cretaceous and Triassic accretionary complexes indicate that the latest Triassic Cimmeride orogeny was accretionary rather than collisional and is probably related to the collision and accretion of an oceanic plateau to the southern active margin of Laurasia. [ABSTRACT FROM AUTHOR]

The Lower Carboniferous flysch of the Istanbul Zone in Turkey is an over 1500 m thick turbiditic sandstone–shale sequence marking the onset of the Variscan deformation in the Pontides. It overlies Lower Carboniferous black cherts and is unconformably overlain by Lower Triassic continental sandstones and conglomerates. The petrography of the Carboniferous sandstones and the geochronology and geochemistry of the detrital zircons and rutiles were studied to establish the provenance of the clastic rocks. The sandstones are feldspathic to lithic greywackes and subgreywackes with approximately equal amounts of quartz, feldspar and lithic clasts. The amount of quartz and lithic fragments decreases upwards in the sequence at the expense of feldspar. The lithic fragments are dominated by intermediate volcanic rocks, followed by metamorphic and sedimentary rock fragments. Coarse lithic fragments are generally granitoidic. In the discrimination diagrams, sandstone samples lie mainly in the field of dissected arc. A total of 218 detrital zircons and 35 detrital rutiles from four sandstone samples were analysed with laser ablation ICP-MS. The detrital zircons show a predominantly bimodal age distribution with Late Devonian to Early Carboniferous (390 to 335 Ma) and Cambrian–Neoproterozoic (640 to 520 Ma) ages. The remaining 9 % of the analysed zircons are in the 1700–2750 Ma range; zircons of the 700–1700 Ma age range are absent. The REE patterns and Th/U ratios of the zircons are consistent with a magmatic origin. With one exception (Neoproterozoic), the rutile ages are Late Devonian–Early Carboniferous and their geochemistry indicates that they were derived from amphibolite-facies metamorphic rocks. Sandstone petrography and detrital zircon–rutile ages suggest one dominant source for the Lower Carboniferous sandstones: a Late Devonian to Early Carboniferous magmatic and metamorphic province with overprinted Neoproterozoic basement. Late Devonian–Early Carboniferous magmatic and metamorphic rocks are unknown from the Eastern Mediterranean region. They are, however, widespread in central Europe. The Istanbul Zone is commonly correlated with the Avalonian terrranes in central Europe, which collided with the Armorican terranes during Carboniferous times, resulting in the Variscan orogeny. The Carboniferous flysch of the Istanbul Zone must have been derived from a colliding Armorican terrane, as indicated by the absence of 700–1700 Ma zircons and by Late Devonian–Early Carboniferous magmatism, typical features of the Armorican terranes. This suggests that during Carboniferous times the Istanbul terrane was located close to the Bohemian Massif and has been translated by strike-slip along the Trans-European Suture Zone to its Cretaceous position north of the Black Sea. [ABSTRACT FROM PUBLISHER]

Six individual tectonostratigraphic units are identified within the İzmir--Ankara--Erzincan Suture Zone in the critical Erzincan area of the Eastern Pontides. The Ayıkayası Formation of Campanian--Maastrichtian age is composed of bedded pelagic limestones intercalated with polymict, massive conglomerates. The Ayikayasi Formation conformably overlies the Tauride passive margin sequence in the Munzur Mountains to the south and is interpreted as an underfilled foredeep basin. The Refahiye Complex, of possible Late Cretaceous age, is a partial ophiolite composed of ~75 % (by volume) serpentinized peridotite (mainly harzburgite), ~20 % diabase and minor amounts of gabbro and plagiogranite. The complex is interpreted as oceanic lithosphere that formed by spreading above a subduction zone. Unusual screens of metamorphic rocks (e.g. marble and schist) locally occur between sheeted diabase dykes. The Upper Cretaceous Karayaprak Mélange exhibits two lithological associations: (1) the basalt + radiolarite + serpentinite association, including depleted arc-type basalts; (2) the massive neritic limestone + lava + volcaniclastic association that includes fractionated, intermediate-composition lavas, and is interpreted as accreted Neotethyan seamount(s). The several-kilometre-thick Karadağ Formation, of Campanian--Maastrichtian age, is composed of greenschist-facies volcanogenic rocks of mainly basaltic to andesitic composition, and is interpreted as an emplaced Upper Cretaceous volcanic arc. The Campanian--Early Eocene Sütpınar Formation (~1500 m thick) is a coarsening-upward succession of turbiditic calcarenite, sandstone, laminated mudrock, volcaniclastic sedimentary rocks that includes rare andesitic lava, and is interpreted as a regressive forearc basin. The Late Paleocene-Eocene Sipikör Formation is a laterally varied succession of shallow-marine carbonate and siliciclastic lithofacies that overlies deformed Upper Cretaceous units with an angular unconformity. Structural study indicates that the assembled accretionary prism, suprasubduction zone-type oceanic lithosphere and volcanic arc units were emplaced northwards onto the Eurasian margin and also southwards onto the Tauride (Gondwana-related) margin during Campanian-Maastrichtian time. Further, mainly southward thrusting took place during the Eocene in this area, related to final closure of Tethys. Our preferred tectonic model involves northward subduction, suprasubduction zone ophiolite genesis and arc magmatism near the northerly, Eurasian margin of the Mesozoic Tethys. [ABSTRACT FROM AUTHOR]