Palaeontological, diagenetic and facies characteristics of Cretaceous/Paleogene boundary sediments in the Ordu, Yavuzlu and Uzunisa areas, Eastern Pontides, NE Turkey (original) (raw)
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Turkish Journal of Earth Sciences
Th e Late Cretaceous-Eocene geological evolution of northwest Turkey between the Black Sea and Bursa was studied through detailed biostratigraphic characterization of eleven stratigraphic sections. Th e Upper Cretaceous sequence in the region starts with a major marine transgression and lies unconformably on a basement of Palaeozoic and Triassic rocks in the north (İstanbul-type basement) and on metamorphic rocks and Jurassic sedimentary rocks in the south (Sakarya-type basement). Four megasequences have been diff erentiated in the Late Cretaceous-Eocene interval. Th e fi rst one, of Turonian to Late Campanian age, is represented by volcanic and volcanoclastic rocks in the north along the Black Sea coast, and by siliciclastic turbidites and intercalated calcarenites in the south, corresponding to magmatic arc basin and fore-arc basin, respectively. A major ridge along the present southern margin of the Kocaeli Peninsula separated these two realms. In the Late Campanian, volcanism and clastic sedimentation gave way to the widespread deposition of the pelagic limestone and marl of the Akveren Formation; only in the extreme south near Bursa are the pelagic micrites of the Akveren Formation replaced by calciturbidites and siliciclastic turbidites. Th e age of the Akveren Formation ranges from Late Campanian to Late Palaeocene. Th e third megasequence is a thick fl ysch wedge of Early Eocene age, which extends from north of Bursa to the Black Sea coast. Th e base of the Lower Eocene fl ysch is marked by a major unconformity. Th e fl ysch wedge marks the collision between the Pontides and the Anatolide-Tauride Block. Th e fourth megasequence is a thick volcanic and volcaniclastic series of late Early to Middle Eocene age, which extends from north of Bursa to the northern margin of the Armutlu Peninsula. Th e coherent Upper Cretaceous-Eocene stratigraphy, the laterally traceable facies belts, absence of ophiolitic slices and high pressure metamorphic rocks in the Upper Cretaceous-Tertiary series in the region between the Black Sea and Bursa indicate pre-Santonian juxtaposition of the İstanbul and Sakarya zones.
1985
The study area is situated on the northern extention of the Tuzgolu basin, (Central Anatolia) and contains Upper Cretaceous-Tertiary volcanic, clastic, and carbonate rocks with evaporites deposited on an ophiolitic melange basement, the Ankara Melange. The present structure of the area is the result of tectonism during late Alpine movements. The movements controlled the timing and conditions of sediment accumulation. The Bala basin evolved on the northern continental margin of the Kirsehir block. A brief period of south dipping subduction, which originated a continental island arc, was followed by oblique subduction, transform fault and continent to continent collision stages. These determined the shape and depositional characteristics of the basin. This is sup ported by independent magnetic evidence which suggests a 90° anti-clock wise rotation of the Kirsehir block during the Upper Cretaceous-Eocene period. Deposition of sediments occured in two phases. The Upper Cretaceous-Middle Eocene phase contains seven forma tions, Four are believed to have been deposited in a deep marine environment by mass movements and turdidity currents sometimes forming submarine fans, and two are shallow marine to continental deposits. The seventh is composed mainly of Andean type calc-alkaline volcanic rocks and their pyroclastics and was formed by subaerial lava flows. The formations reflect conditions of deposition in different parts of the basin and therefore some are the time equivalent of others. The Middle Eocene to probably Oligocene phase consists of two interfingering formations deposited in continental and marine environments of deposition. Palaeocurrent and pétrographie data suggest that during the first phase, the source area was to the southeast and formed by volcanic rocks of Sarikaya formation and Ankara Melange, while in the second phase sediments were derived from multiple marginal sources, including the sedimentary rocks of the first phase. ACKNOWLEDGEMENT The author is indebted to the Mineral Research and Exploration Institute for providing the grant as well as for the use of the Institute's facilities during the field work. The author gratefully acknowledges the unfailing support, encouragement and guidance of his supervisor Professor A.J. Smith, in every stage of the present research. This thesis would not have been completed without his constant interest and critical reading. Special thanks are extended to the academic and technical staff of the Geology Department of the Bedford College. Amongst the academic staff Dr. A. Saunders for stimulating discussions and suggestions on orogenic volcanic rock and their plate tectonic interpretation. Dr. G. Mariner for her help during the minerological and chemical analyses of rocks. Dr. D. Powell and Dr. P. Banham for fruitfull dis cussion on structural geology and magmatic rocks. Dr. T. Rose for his help and suggestions for the identification of fossils will be remembered. Miss R. Fricher and Mrs S. Bishop for their kind help and assistance. Mr. S Houlding, Mr. N. Sinclair, Mr. J. Mock and Mr. J. Keith for their technical assistance and help deserve special thanks. The author also wishes to thank Dr. A.G. Adams of the Natural History Museum and S. Tekler of M.T.A. for iden tification of microfossils, professor D.J. Shearman for use ful discussion in aspects of limestone diagenesis, Dr. 0. Varol of Robertson Research Institute for indentification of Nannofossils and Professor T.N. Norman of Middle East Technical University and Dr. F.Y. Oktay of Istanbul Technical University for useful discussions on the geology of the Central Anatolia.
Ofioliti, 2015
In the Central Pontides (Northern Turkey), south of Tosya, a tectonic unit consisting of non-metamorphic volcanic rocks and overlying sedimentary succession is exposed inside a fault-bounded elongated block. It is restrained within a wide shear zone, where the Intra-Pontide Suture zone, the Sakarya Terrane and the Izmir-Ankara-Erzincan Suture zone are juxtaposed as result of strike-slip activity of the North Anatolian Shear Zone. The volcanic rocks are mainly basalts and basaltic andesites (with their pyroclastic equivalents) associated with a volcaniclastic formation made up of breccias and sandstones that are stratigraphically overlain by a marly-calcareous turbidite formation. The calcareous nannofossil biostratigraphy points to a late Santonian-middle Campanian age (CC17-CC21 Zones) for the sedimentary succession. The geochemistry of the volcanic rocks reveals an active continental margin setting as evidenced by the enrichment in Th and LREE over HFSE, and the Nb-enriched nature...
2009
Keywords: Intra-Pontide suture, Ä°stanbul Zone, Sakarya Zone, U-Pb zircon ages, Rb-Sr mica ages We provide new isotopic data from the Intra-Pontide Suture Zone, which indicate Early Cretaceous collision between the Sakarya and Ä°stanbul terranes following the consumption of the Intra-Pontide Ocean. The study area is located south of Sapanca Lake between the Ä°stanbul and Sakarya terranes in northwest Turkey. These two terranes show different geological histories, as reflected in their stratigraphic record, and are juxtaposed along the Intra-Pontide suture. The new U/Pb zircon and Rb/Sr mica ages come from south of the Sapanca Lake, south of the North Anatolian Fault in northwest Turkey. The Ä°stanbul terrane has a late Proterozoic basement (Chen et al., 2002; 570 Ma) overlain by a sedimentary sequence of Ordovician to Carboniferous age. The Sakarya terrane is characterized by Carboniferous (330-310 Ma) high temperature metamorphism (Okay et al., 2006), Paleozoic granitic plutonism (Topuz et al., 2007) and by the presence of Palaeo-Tethyan subduction-accretion units. South of the Sapanca Lake, three main tectonostratigraphic units have been differentiated forming a northeastward dipping thrust stack. At the top of the thrust stack is an amphibolite-facies metamorphic unit consisting of an intercalation of amphibolite, metaperidotite, metapyroxenite and gneiss representing a Proterozoic metaophiolite in the basement of the Istanbul Zone. This old metaophiolite is underlain by a Cretaceous accretionary complex of metabasite, metachert, slate and serpentinite. The lowermost tectonic unit in the thrust stack is a metasandstone, slate, phyllite and marble unit metamorphosed in greenschist facies. Our U/Pb geochronological data comes from the basement gneisses and the metasedimentary unit. The age of deposition and metamorphism of this metasedimentary unit were not constrained. The U/Pb ages of the clastic zircons from metasandstones are between 500-317 Ma. These new clastic zircon ages from the metasedimentary unit show that deposition of the sandstones must be later than Carboniferous (316±2,4 Ma). The Rb-Sr muscovite and biotite ages from metasedimentary unit and the basement gneisses give Early Cretaceous (138-111 Ma) ages. The muscovite ages of metasandstones are 138±1,5 Ma represents the metamorphic age of metasedimentary unit and the biotite Cretaceous cooling age of 111,3±1,1 Ma from the reheating of the Proterozoic basement. The new Rb/Sr ages indicate that the collision between the Istanbul and Sakarya terranes occurred during the Early Cretaceous. REFERENCES Chen, F., Siebel, W., Sati r, M., TerzioÄlu, N., Saka, K., 2002. Geochronology of the Karadere basement (NW Turkey) and implications for the geological evolution of the Ä°stanbul Zone. Int. J. Earth Sci., 91, 469-481. Okay, A.I., Sati r, M. & Siebel, W., 2006, Pre-Alpide orogenic events in the Eastern Mediterranean region. In: European Lithosphere Dynamics (eds. Gee, D. G., and Stephenson, R. A.), Geological Society, London, Memoirs 32, 389-405. Topuz, G., Altherr, R., Schwartz,W.H., Dokuz, A.,Meyer, H.-P., 2007. Variscan amphibolites-facies rocks from the KurtoÄlu metamorphic complex (Gümüşhane area, Eastern Pontides, Turkey). Int. J. Earth Sci. 96, 861-873. Please fill in your abstract text.
Geological Magazine, 2009
Six individual tectonostratigraphic units are identified within theİzmir-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 Ayıkayası 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 Karadag 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.
Geological Magazine, 2002
Fingerprints of the opening of the Western Black Sea Basin and collision of Pontides and Sakarya Continent along the Intra-Pontide suture can be traced in the area between Cide (Kastamonu) and Kurucaşile (Bartin) in northern Turkey, along the southern coast of the Black Sea. The Western Black Sea Basin is an oceanic basin opened as a back-arc basin of the northward-subducting Intra-Pontide Ocean. Basement units related to this opening are represented by Lower Cretaceous and older units. The first arc magmatism related to this subduction began during Turonian times. Coeval with this magmatism, back-arc extension affected the region and caused development of horst-graben topography. This extensional period resulted in the break-up of continental crust and the oceanic spreading in the Western Black Sea Basin during Late Santonian times. During the Late Campanian–Early Maastrichtian period, the Sakarya Continent and Pontides collided and arc magmatism on the Pontides ended. After this c...
The Upper Cretaceous Korkuteli (Antalya) carbonate sequence of the Bey Dağları Autochthonous unit (western Taurides) comprises two formations. The Cenomanian-Santonian Bey Dağları formation lies at the base of this sequence and can be divided into two parts. Neritic part is characterized by platform-type, peritidal limestones and comprises an approximately 600-m-thick sequence that contains two main rudistid horizons corresponding to Cenomanian and early Santonian. The neritic limestones pass gradually upward into the 15-m thick, middle-upper Santonian massive hemipelagic limestones that form the upper part. The upper Campanian middle Maastrichtian Akdağ formation consists totally of pelagic limestones that indicate basinal conditions and disconformably overlies different stratigraphic levels of the Bey Dağları formation. Palaeogene pelagic marls form the base of the Tertiary sequence and disconformably overlie different stratigraphic levels of the Upper Cretaceous sequence. The presence of two erosional phases in the Upper Cretaceous sequence is obvious. The autochthonous unit was subaerially exposed after post-Santonian and middle Maastrichtian regressions.
Geological Magazine, 2001
Late Cretaceous–Early Eocene Tethyan evolution of western Turkey is characterized by ophiolite obduction, high-pressure/low-temperature metamorphism, subduction, arc magmatism and continent–continent collision. The imprints of these events in the Upper Cretaceous–Lower Eocene sedimentary record of western Anatolia are studied in thirty-eight well-described stratigraphic sections. During the Late Cretaceous period, western Turkey consisted of two continents, the Pontides in the north and the Anatolide-Taurides in the south. These continental masses were separated by the İzmir-Ankara Neo-Tethyan ocean. During the convergence the Pontides formed the upper plate, the Anatolide-Taurides the lower plate. The arc magmatism in the Pontides along the Black Sea coast is biostratigraphically tightly constrained in time between the late Turonian and latest Campanian. Ophiolite obduction over the passive margin of the Anatolide-Tauride Block started in the Santonian soon after the inception of s...
Early Cretaceous closure of the Intra-Pontide Ocean in western Pontides (northwestern Turkey)
The Intra-Pontide suture is the boundary between theİstanbul and Sakarya terranes in northwest Turkey. We provide new isotopic and stratigraphical data from the Intra-Pontide suture zone, which indicate Early Cretaceous collision between the Sakarya andİstanbul terranes. These two terranes along with the Strandja Massif make up the Pontides. Metamorphic units of the Intra-Pontide suture zone are best exposed in the Armutlu Peninsula. In the eastern part of the Armutlu Peninsula, three metamorphic units crop out forming an eastward dipping thrust stack. At the base of the thrust stack there is a metaclasticmarble sequence, which is tectonically overlain by a Cretaceous subduction-accretion complex, farther up in the thrust stack there is a high-grade metamorphic unit, which represents the Proterozoic basement of theİstanbul Zone. New clastic zircon ages from the metaclastic-marble sequence indicate that deposition of the sandstones must be later than Permian (∼264 Ma) possibly during Triassic. Similar Triassic metasediments are also reported in Strandja Massif. We interpret that these metasediments were deposited during Triassic along the rift flanks leading to the opening of the Intra-Pontide Ocean, which suggest a possible Early Triassic opening for the Intra-Pontide Ocean. Our new Rb-Sr mica and Sm-Nd garnet ages dates the regional metamorphism between Late Jurassic-Early Cretaceous (158-111 Ma) along the Intra-Pontide suture zone, similar ages are also reported in the Strandja Massif. The metamorphic rocks of the Intra-Pontide suture are unconformably overlain by Campanian-Ypresian clastics. The collision between theİstanbul and Sakarya-Strandja terranes has occurred during Early Cretaceous and the Proterozoic basement ofİstanbul terrane was reheated during this collision.