23 results on '"Sevinç Özkan-Altiner"'
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2. CYCLIC SEDIMENTATION ACROSS THE PERMIAN – TRIASSIC BOUNDARY (CENTRAL TAURIDES, TURKEY)
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EMRE ÜNAL, DEMIR ALTINER, I. ÖMER YILMAZ, and SEVINÇ ÖZKAN-ALTINER
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Geology ,QE1-996.5 ,Paleontology ,QE701-760 - Abstract
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 sytems 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. Special issue International Conference on Paleozoic Foraminifera, Paleoforams 2001 Edited by Demir Altiner (Guest Editor)
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- 2003
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3. DESCRIPTION OF AN EARLY ONTOGENETIC EVOLUTIONARY STEP IN LEPIDORBITOIDES (LEPIDORBITOIDES) BISAMBERGENSIS ASYMMETRICA, EARLY MAASTRICHTIAN (CENTRAL TURKEY)
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ERCAN ÖZCAN and SEVINÇ ÖZKAN-ALTINER
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Geology ,QE1-996.5 ,Paleontology ,QE701-760 - Abstract
Lepidorbitoides bisambergensis is characterised by having a ‘quadriserial’ embryo without any chamberlet directly arising from the deuteroconch and is a very diagnostic and common species in Lower Maastrichtian flysch successions in Anatolia. Some populations of this species present an early ontogenetic morphologic feature which is characterised by distinctly asymmetric early chamber arrangement recognised in the horizontal sections. This asymmetry is mainly caused by the pronounced difference in the size of auxiliary chamberlets which rest on both, protoconch and deuteroconch and also enhanced by the development of unequal number of chamberlets in the series arising from these auxiliary chamberlets on the protoconchal side. These asymmetric specimens are commonly identified in stratigraphic horizons below the symmetric ones after the introduction of a new auxiliary chamberlet and progressively replaced by symmetric ones in the younger populations. Asymmetric "quadriserial" specimens representing the early phylogenetic stage of L. bisambergensis described in the stratigraphic horizons corresponding to G. havanensis and G. aegyptiaca (?) zones are thought to deserve a particular taxonomic status and are attributed to Lepidorbitoides bisambergensis asymmetrica Özcan & Özkan-Altiner, 1999a.
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- 2001
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4. First record of late Campanian paleoceanographic and paleoclimatic changes, Arabian Platform, Mazidag-Mardin area, SE Turkey
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Izzet Hoşgör, Sevinç Özkan-Altiner, Jiří Kvaček, Michael Wagreich, and Ismail Omer Yilmaz
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biology ,Stable isotope ratio ,paleoceanographic event ,Stratigraphy ,Arabian Platform ,Paleontology ,Geology ,SE Turkey ,biology.organism_classification ,Turbidite ,Foraminifera ,paleoclimate ,Paleoclimatology ,Stratigraphic section ,Marl ,plant fossil ,Siliciclastic ,upper Campanian ,Sedimentology - Abstract
The sedimentology, geochemistry and paleontology of the pelagic upper Campanian Maastrichtian Bozova Formation in the "Mazidag" (Mazıdağı) - Mardin area, SE Turkey, reveal paleoceanographic and paleoecological changes for the first time. A 119.25 m-thick composite stratigraphic section is characterized by alternating marls, clayey limestones, shales, and black shales; no coarse siliciclastic admixture or turbidite intercalations were recorded in the section. Biostratigraphic data indicate the presence of the Radotruncana calcarata Zone, and the UC15de/UC16 nannofossil zones. Stable isotope and elemental geochemical analyses have been carried out in the studied section. The isotope curves display similar patterns compared to reference curves from European and Chinese basins in the same interval. The prominent negative carbon isotope excursion determined in the upper interval can be correlated with the Late Campanian Event. Proxy elements display generally two relative rising trends in productivity from the lower part and the middle part of the succession. The lower part of the section records relatively more dysoxic/anoxic conditions and coincides with common black shale beds. The presence of both diverse planktonic foraminifera and calcareous nannofossils in the studied interval indicates a fully marine, warm-water, low-latitude Tethysian oceanic environment. In addition, the plant fossils derived from the nearby land mass indicate that a tropical humid climate was similar to that in northeast Australia. Therefore, warm water, tropical humid atmospheric conditions developed in the studied area causing the rise in productivity, precipitation and transportation of plant debris into offshore environments.
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- 2021
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5. Paynita PermotauricaN. Gen., N. SP., and the Other Dagmaritin Foraminifera from the Changhsingian (Permian) of Southern Turkey: Review of Dagmaritin Phylogeny
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Demir Altiner, Sevinç Özkan-Altiner, Serdar G. Atasoy, and Nazif Şahin
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Foraminifera ,010506 paleontology ,Paleontology ,biology ,Permian ,Phylogenetics ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Microbiology ,Geology ,0105 earth and related environmental sciences - Abstract
The name Paynita is proposed for a new dagmaritin genus from the upper Changhsingian (Permian) carbonates of the Southern Biofacies Belt in Turkey. Paynita permotaurica differs from its ancestor Paradagmarita monodi by a hook-shaped fold in the apertural flap terminating systematically against the inner surface of the septal wall to protect the opening from one chamber to the other. It is associated with several species of dagmaritins, belonging to Paradagmarita, Paradagmacrusta, Louisettita, Dagmarita, Danielita, and Bidagmarita. The overall analysis of dagmaritins reveals that the stratigraphic range of the group is from Wordian to Changhsingian. The revised chronostratigraphy in the type area of the genus Sengoerina indicates that this oldest dagmaritin was derived from Globivalvulina cyprica in the Wordian. The first occurrences of genera Dagmarita and Danielita postdate the first occurrence of Sengoerina in the Wordian. Paynita is the last evolutionary step of the Sengoerina-Dagmarita-Crescentia-Paradagmarita lineage characterized by a planar apertural flap whose structure practically remained unchanged during the process of evolution. Paynita is the first genus in this lineage displaying fold in the apertural flap similar to the evolution of Louisettita from Dagmarita.
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- 2021
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6. Triassic Foraminifera from the Great Bank of Guizhou, Nanpanjiang Basin, south China: taxonomic account, biostratigraphy, and implications for recovery from end-Permian mass extinction
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Demir Altiner, Mindi M. Summers, Meiyi Yu, Sevinç Özkan-Altiner, Brian M. Kelley, Daniel J. Lehrmann, Jonathan L. Payne, and OpenMETU
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010506 paleontology ,South china ,biology ,Paleontology ,Biostratigraphy ,Structural basin ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Foraminifera ,Geology ,Permian–Triassic extinction event ,0105 earth and related environmental sciences - Abstract
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 >100 Triassic species, including three that are newly described (Arenovidalina weiin. sp.,Meandrospira?enosin. sp., andSpinoendotebanella lehrmannin. 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.UUID:http://zoobank.org/2a6e9061-b163-402a-9098-8765a80576b3
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- 2021
7. Biostratigraphy and microfacies of the sedimentary sequences within volcano-sedimentary Maden Complex in Southeastern Turkey
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Ayse Atakul-Özdemir, Sesil Tancan, Nilgün Güleç, Sevinç Özkan-Altiner, Yavuz Özdemir, Çağrı Mercan, and Vural Oyan
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geography ,geography.geographical_feature_category ,Volcano ,Geochemistry ,Sedimentary rock ,Biostratigraphy ,Geology - Abstract
Maden Complex is a volcano-sedimantary unit, mainly composed of shallow and deep marine sedimentary rocks and associated volcanics. Deep marine units of Maden Complex, exposed between Çatak (Van) and Kozluk (Batman) regions have been studied with a combined sedimentological and paleontological approaches. The following species are recorded within the Melefan formation: Morozovella aragonensis, Acarinina collactea, Acarinina cf. esnehensis, Acarinina soldadoensis, Acarinina boudreauxi, Acarinina bullbrooki, Acarinina mckanni, Acarinina pentacamerata, Acarinina cf. pseudosubsphaerica, Acarinina topilensis, Acarinina esnehensis, Chiloguembelina sp., Globanomalina planoconica, Globanomalina australiformis, Globigerinatheka sp., Parasubbotina hagni, Pearsonites broedermanni, Pseudoglobigerinella bolivariana, Planoglobanomalina pseudoalgeriana, Pseudohastigerina wilcoxensis, Subbotina roesnaensis, Subbotina yeguaensis. Based on the defined planktonic foraminiferal species, the unit corresponds to the E7 zone and the depositional age of the formation is proposed as Early Eocene (Ypresian) to Middle Eocene (Lutetian). The deep marine sedimentary sequence mainly consists of pinkish to red colored micritic limestones including shale intercalations. The formation is represented by the pelloidal wackestone-packstone facies and comprises abundant planktonic foraminiferal assemblages.
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- 2021
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8. Petrolgy of the volcanic/subvolcanic members of the volcano-sedimentary Maden Complex in Eastern Turkey
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Nilgün Güleç, Ayse Atakul-Özdemir, Yavuz Özdemir, Sevinç Özkan-Altiner, Vural Oyan, and Çağrı Mercan
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geography ,geography.geographical_feature_category ,Volcano ,Geochemistry ,Sedimentary rock ,Geology - Abstract
Maden Complex exposed in Eastern Turkey, is a succession of volcano-sedimentary rocks and tectonically overlain by Bitlis Metamorphics and Cretaceous ophiolitic rocks. The succession includes shallow-water deposits and deep marine pelagic sediments intercalated with pillow lavas ranging from a few centimeters to ten meters in diameter. The planktonic foraminiferal assemblages from micritic limestones and zircon U-Pb ages from selected sedimentary rocks indicate the age of Late Ypresian - Early Lutetian. Plagioclase and clinopyroxenes are the main mineral phases, olivine rarely found as altered phenocrysts. Clinopyroxenes are augite and diopside, and their compositions are ranging between Wo44-51, En27-43, Fe10-21. The anorthite contents of plagioclases are between 32- 67 % in unaltered grains. The crystallization temperatures and pressures obtained from clinopyroxene chemistry are ranging from 1126 to 1250oC and 3 to 8 Kbar, respectively. The majority of the volcanic/subvolcanic rocks are subalkaline-tholeiitic basalts however; a few andesitic and rhyolitic derivatives are also present. The whole – rock and Sr-Nd-Pb isotope compositions reveal that the basaltic rocks are originated from E-MORB like asthenospheric mantle source without a subduction component.
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- 2021
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9. Planktonic foraminiferal and geochemical record across the Cretaceous-Paleogene boundary (K-Pg): evidence from the Neo-Tethys, Turkey
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Valentin Lorenzo, Jorge E. Spangenberg, Thierry Adatte, Demir Altiner, Ali Uygar Karabeyoglu, Sevinç Özkan-Altiner, and Sciencesconf.org, CCSD
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[SDU] Sciences of the Universe [physics] ,Paleontology ,Turkey ,Deccan Traps ,Mass Extinction ,Cretaceous–Paleogene boundary ,Pg boundary ,Planktonic Foraminifera ,Paleoecology ,Plankton ,Geology - Abstract
The end-Cretaceous mass extinction is a unique event such that it potentially coincides with both the Chicxulub bolide impact and the Deccan volcanism. Among these two drivers, the role of the Deccan volcanism is crucial to decipher if there is a causal relationship between volcanism and environmental stress, and if so, how stressed the environment was during the latest Maastrichtian. To assess the cause-and-effect relationship between Deccan volcanism and climate change and mass extinctions, high-resolution biostratigraphy, quantitative species analysis coupled with geochemical measurements have been performed on complete sections of Mudurnu-Göynük and Haymana basins (Turkey).Detailed quantitative study on planktonic foraminifera of the Haymana Basin revealed that planktonic foraminiferal community in the latest Maastrichtian is dominated by ecological generalists with small, simple morphologies (e.g., Heterohelix, Globigerinelloides, Guembelitria). Among them low oxygen tolerant Heterohelix globulosa is the most dominant taxa and their abundance changing with the presence of stress marker Guembelitria cretacea. In all sections, the K/Pg boundary itself is characterized by 2-3 mm thick reddish oxidized layer which corresponds to sudden annihilation of large, ornamented ecological specialists (e.g., Globotruncana, Rugoglobigerina, Racemiguembelina). Right after the boundary, there is an acme of calcareous dinoflagellate cysts (Thoracosphaera) and a surge of Guembelitria cretacea indicate ecosystem collapse in post-K/Pg environment.On the other hand, detailed quantitative analysis shows a systematic reduction in the species richness throughout the Plummerita hantkeninoides Zone corresponding to the final 150 kyr of the Cretaceous. Proliferations of the Guembelitria cretacea through late Maastrichtian is known as an indicator of high terrigenous influx; therefore, enhanced food resources. The high sedimentation rates observed in all the studied sections might be linked to increased greenhouse conditions due to Deccan volcanism leading to enhanced weathering. Overall, our multiproxy approach including quantitative biostratigraphy and geochemical analyses highlights the influence of the Deccan volcanism by releasing high amounts of atmospheric CO2 and SO2, leading to the climatic changes and associated biotic stress, which predisposed faunas to eventual extinction at the K/Pg boundary.
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- 2021
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10. THE ROLE OF DECCAN VOLCANISM ON FAUNAL AND ENVIRONMENTAL CHANGES ACROSS THE CRETACEOUS-PALEOGENE (K-PG) BOUNDARY: EXAMPLES FROM NEO-TETHYS, TURKEY
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Demir Altiner, Valentin Lorenzo, Sevinç Özkan-Altiner, Uygar Karabeyoglu, Thierry Adatte, and Jorge E. Spangenberg
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Paleontology ,Boundary (topology) ,Volcanism ,Paleogene ,Cretaceous ,Geology - Published
- 2021
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11. Timing of depositional regime changes during the Late Cretaceous evolution of the Southern Pontides (Ankara, Central Anatolia, Turkey)
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Demir Altiner, Sevinç Özkan-Altiner, and Nisan Sariaslan
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010506 paleontology ,biology ,Gansserina ,Paleontology ,Biozone ,Biostratigraphy ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Cretaceous ,Sedimentary depositional environment ,Foraminifera ,Stratigraphic section ,Siliciclastic ,Geology ,0105 earth and related environmental sciences - Abstract
During the Cretaceous, vast amounts of marine sediments were deposited along the south-facing active margin of the Eurasia. A stratigraphic section of 91 m was analyzed for planktonic foraminifera (75 samples), with the aim of establishing a refined biostratigraphy of Cenomanian–Campanian deposits in Central Anatolia. A biostratigraphic framework comprising nine biozones was established. In ascending order, the Rotalipora cushmani, Whiteinella archaeocretacea and Helvetoglobotruncana helvetica zones were defined in the uppermost Cenomanian–Turonian interval. The lack of Coniacian index markers suggests the existence of a hiatus for this interval. In the upper part of the section, the Dicarinella asymetrica, Globotruncanita elevata, Contusotruncana plummerae, Globotruncanella havanensis and Globotruncana aegyptiaca zones were identified for the Santonian and Campanian deposits. The presence of Gansserina gansseri, Globotruncanita angulata, G. conica and G. pettersi in the uppermost part of the section shows that the section ends at the base of the Gansserina gansseri Zone, indicating uppermost Campanian. The planktonic foraminifera biozonation framework provides strong evidence for the timing of the depositional history of the active continental margin that developed south of the Pontides. These phases are mainly the formation of olistostromes of pre-Santonian age, following condensed carbonate deposition during the Santonian and finally the switch from forearc deposition to the formation of a thick sequence of siliciclastic succession starting in the Campanian.
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- 2020
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12. Planktonic Foraminiferal Biostratigraphy, Microfacies Analysis, Sequence Stratigraphy, and Sea-Level Changes Across the Cretaceous-Paleogene Boundary In the Haymana Basin, Central Anatolia, Turkey
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Demir Altiner, Selen Esmeray-Senlet, Kenneth G. Miller, and Sevinç Özkan-Altiner
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biology ,Cretaceous–Paleogene boundary ,Geology ,Authigenic ,Biostratigraphy ,engineering.material ,biology.organism_classification ,Foraminifera ,Paleontology ,Marl ,engineering ,Sequence stratigraphy ,Progradation ,Glauconite - Abstract
The Cretaceous–Paleogene (K/Pg) boundary in the Haymana Basin, Central Anatolia, Turkey, was delineated using planktonic foraminiferal biostratigraphy, microfacies analysis, and sequence stratigraphy. An ∼ 29 m outcrop consisting of limestone and marl was measured, and four planktonic foraminiferal biozones were identified spanning the boundary. Planktonic foraminiferal extinction across the K/Pg boundary was catastrophic and abrupt. The extinction level is overlain by a unit (Zone P0) showing an increase in echinoid fecal pellets and authigenic clay minerals such as glauconite, suggesting low sedimentation rates in the early Danian. Ten microfacies types were identified indicating inner-ramp to basinal paleoenvironments based on the sedimentological characteristics and microfossil and macrofossil assemblages. Maastrichtian carbonates contain large benthic foraminifera, calcareous red algae, bryozoans, fragments of echinoderms and mollusks, and planktonic foraminifera. Overlying Maastrichtian–Danian silty marls and silty limestones have common planktonic and benthic foraminifera. Progradation of carbonates into the basin took place during the highstand systems tract, and deposition of a silty marl succession occurred during the transgressive systems tract. The K/Pg boundary is in the upper part of the transgressive systems tract, below a maximum flooding surface. Sequence stratigraphic analysis of a second section, Campo Pit, New Jersey, USA, showed that the K/Pg boundary occurs within a transgressive systems tract in New Jersey as well, suggesting a global sea-level rise across the K/Pg boundary.
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- 2015
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13. Quantitative analysis of planktonic foraminifera across the Cretaceous-Paleogene transition and observations on the extinction horizon, Haymana Basin, Turkey
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Sevinç Özkan-Altiner, A. Uygar Karabeyoğlu, and Demir Altiner
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010506 paleontology ,biology ,Paleontology ,Biozone ,Plankton ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Bathyal zone ,Cretaceous ,Foraminifera ,Marl ,Dominance (ecology) ,Paleogene ,Geology ,0105 earth and related environmental sciences - Abstract
The Haymana Basin, Turkey, hosts complete record of sedimentation across the Cretaceous-Paleogene (K-Pg) boundary. To examine the K-Pg boundary transition and delineate the bioevents, two consecutive sections (UH and UKHB) were measured and sampled at high resolution. Three biozones were established: Plummerita hantkeninoides, P0 and Pα. A detailed quantitative study on planktonic foraminifera was carried out for the P. hantkeninoides and the P0 zones for 63–150 μm and >150 μm size fractions. Results show dominance of ecological generalists with small, simple tests over ecological specialists with large, robust, ornamented morphologies. Heterohelicids are the most dominant group on both size fractions throughout the late Maastrichtian, however right after the K-Pg boundary Guembelitria cretacea blooms and dominates the planktonic foraminiferal assemblage in early Danian P0 Zone. The K-Pg boundary characterizes itself as 2–3 mm thick reddish oxidized layer and its transition reveals a series of events: A rapid change in sedimentation from Maastrichtian mudstones to Danian marls. A sudden annihilation of large, ornamented ecological specialists (e.g., Globotruncana, Rugoglobigerina, Planoglobulina) right at the reddish layer (even though quantitative study revealed that there is a systematic reduction in the foraminiferal species richness throughout the P. hantkeninoides Zone). Spikes of calcareous dinoflagellate Thoracosphaera and fecal pellets right after the K-Pg boundary in the Danian P0 Zone. Anomalous increase in CaO rich spherules and amorphous grains coupled with barite crystals right at the K-Pg boundary layer. Paleobathymetric calculations also revealed approximately 400 m paleodepth for the study area corresponding the upper bathyal zone.
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- 2019
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14. Lithofacies and Biofacies Characteristics of Lower Carboniferous Carbonates in Central Taurides, Turkey
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Sevinç Özkan-Altiner, Demir Altiner, and Ayse Atakul-Özdemir
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Carboniferous ,Geochemistry ,Geology - Abstract
The studied successions in the Central Taurides were mainly deposited in a shallow marine environment during the Early Carboniferous time. Conodonts are one of the most important microfossil groups for the Lower Carboniferous biostratigraphy. The measured sections are not rich in conodonts but important species including those of the Lower Carboniferous boundary conodonts. The conodont elements recorded in this study include Gnathodus cuneiformis, Gnathodus girtyi girtyi, Gnathodus girtyi simplex, Kladognathus sp., Lochriea commutata and Vogelgnathus campbelli. Based on the recovered conodont assemblages, Visean - Serpukhovian boundary has been recognized by the first occurrence of Gnathodus girtyi simplex. Conodont faunal variations in Paleozoic to Triassic marine deposits are generally environmentally controlled. Within the context of paleoenvironmental interpretations, different microfacies types could be determined by microfacies criteria reflecting patterns of the depositional environments. The types of microfacies and their environmental interpretations can provide a framework for conodont paleoecology. The defined facies types in BSE section are mainly crinoidal bioclastic packstone, bioclastic grainstone, sandy oolitic grainstone, quartz-peloidal grainstone and quartz arenitic sandstone facies. Crinoidal bioclastic packstones and bioclastic grainstones are suitable facies for conodonts owing to environmental conditions. Bioclasts associated with the conodonts are mainly crinoids, fusulinids, algae, echinoids, brachiopods and ostracods. Conodont elements could not be recorded from sandy oolitic grainstone and quartz arenitic sandstone facies due to the deposition in high energy environments under unstable conditions.
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- 2019
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15. NECDETINA, A NEW FUSULINOIDEAN FORAMINIFERA WITH A RECRYSTALLIZED OR REPLACED WALL FROM THE MIDDLE PERMIAN OF THE CENTRAL TAURIDE BELT, TURKEY
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Ayşe Atakul, I. Ömer Yilmaz, John R. Groves, Demir Altiner, and Sevinç Özkan-Altiner
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Calcite ,biology ,Permian ,Aragonite ,Shell (structure) ,Paleontology ,Anatomy ,engineering.material ,biology.organism_classification ,Microbiology ,Foraminifera ,Type species ,chemistry.chemical_compound ,chemistry ,Genus ,engineering ,Geology - Abstract
Necdetina (type species N. taurica n. sp.) is described here as a new fusulinoidean genus with a replaced or recrystallized wall from the Middle Permian (Capitanian) of Turkey. In addition to its distinctive wall structure, which was probably originally keriothecal and composed of aragonite or high-Mg calcite, the genus is characterized by an ovate shell with rounded to acute poles and axially elongated, biserially enrolled chambers. Chomata are absent, but inconsistently developed parachomata-like structures are present in the test where biserially enrolled chambers overlap. Circular foramina alternate in two rows at the bases of the apertural face and septa. Phylogenetic analysis indicates that Necdetina belongs in the clade of staffellid fusulinoideans, a group whose walls are invariably altered. Among the staffellids, Necdetina is allied with other genera in which the coiling axis is elongated to produce a spherical, oval or fusiform test. In this subclade, Necdetina is further united with Thailandina and Neothailandina in possessing parachomata and having well-organized foramina along the antetheca and septa. Necdetina is the only known staffellid, indeed the only known fusulinoidean, with biserial chambers.
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- 2007
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16. Cretaceous and Triassic subduction-accretion, high-pressure-low-temperature metamorphism, and continental growth in the Central Pontides, Turkey
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Demir Altiner, Recep Hayri Eren, Sarah C. Sherlock, Sevinç Özkan-Altiner, Okan Tüysüz, Aral I. Okay, and Muharrem Satir
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Continental collision ,Greenschist ,Continental crust ,Geochemistry ,Metamorphism ,Geology ,Thrust fault ,Shear zone ,Petrology ,Foreland basin ,Nappe - Abstract
Biostratigraphic, isotopic, and petrologic data from the Central Pontides document major southward growth of the Eurasian continental crust by subduction-accretion during the Cretaceous and Triassic Periods. A major part of the accreted material is represented by a crustal slice, 75 km long and up to 11 km thick, consisting of metabasite, metaophiolite, and mica schist that represent underplated Tethyan oceanic crustal and mantle rocks. They were metamorphosed at 490 degrees C and 17 kbar in mid-Cretaceous time (ca. 105 Ma). The syn-subduction exhumation occurred in a thrust sheet bounded by a greenschist facies shear zone with a normal sense of movement at the top and a thrust fault at the base. A flexural Foreland basin developed in front of the south-vergent high-pressure-low-temperature (HP-LT) metamorphic thrust sheet; the biostratigraphy of the foreland basin constrains the exhumation of the HP-LT rocks to the lbronian-Coniacian, similar to 20 m.y. after the HP-LT metamorphism, and similar to 25 m.y. before the terminal Paleocene continental collision. The Cretaceous subduction-accretion complex is tectonically overlain in the north by oceanic crustal rocks accreted to the southern margin of Eurasia during the latest Triassic-earliest Jurassic. The Triassic subduction-accretion complex is made up of metavolcanic rocks of ensimatic arc origin and has undergone a high pressure, greenschist facies metamorphism with growth of sodic amphibole. Most of the Central Pontides consists of accreted Phanerozoic oceanic crustal material, and hence is comparable to regions such as the Klamath Mountains in the northwestern United States or to the Altaids in Central Asia.
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- 2006
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17. CHARLIELLA ROSSAE N. GEN., N. SP., FROM THE TETHYAN REALM: REMARKS ON THE EVOLUTION OF LATE PERMIAN BISERIAMMINIDS
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Demir Altiner and Sevinç Özkan-Altiner
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Paleontology ,Lineage (genetic) ,Permian ,Genus ,Biology ,Microbiology - Abstract
The name Charliella is proposed for a new biseriamminid genus characterized by a four-layered wall that thickens along the anterior side of the septa and partially occludes the chamber cavity. Charliella rossae was derived from the Globivalvulina graeca-Globivalvulina vonderschmitti lineage which also constituted the root stock of true Paraglobivalvulina ( P. mira ) in Late Permian time. The Globivalvulina decrouezae-Septoglobivalvulina gracilis-Paraglobivalvulinoides septulifer lineage is another trend in the evolution of biseriamminids. The recognition of such a lineage in the Late Permian necessitates taxonomic revision of the biseriamminids to attribute globular and involute forms with thin and undifferentiated walls to Septoglobivalvulina, a genus which was synonymized under Paraglobivalvulina in previous work.
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- 2001
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18. Late Permian Foraminiferal Biofacies Belts in Turkey: Palaeogeographic and Tectonic Implications
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Sevinç Özkan-Altiner, Demir Altiner, and Ali Koçyiğit
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Paleontology ,Tectonics ,Permian ,Geology ,Ocean Engineering ,Water Science and Technology - Published
- 2000
- Full Text
- View/download PDF
19. The generaLepidorbitoides andOrbitoides: evolution and stratigraphic significance in some Anatolian basins
- Author
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Sevinç Özkan-Altiner and Ercan Özcan
- Subjects
education.field_of_study ,Paleontology ,Flysch ,Taxon ,Phylogenetic tree ,Stage (stratigraphy) ,Ontogeny ,Population ,Geology ,Morphology (biology) ,Biostratigraphy ,Biology ,education - Abstract
Early ontogenetic morphologic features previously recognized as evolutionary parameters in Lepidorbitoides and Orbitoides have been tested in several flysch successions of Anatolia. Increase in embryo size (Li+li), number of epi-embryonic chambers (E) and organization of embryonal chamber arrangement from ‘quadrilocular’ to ‘bilocular’ and multilocular in Orbitoides, increase in deuteroconch size (D), in deuteroconch–protoconch ratio (D/P) and in number of adauxiliary chambers (Ad) in Lepidorbitoides have been recognized as the main evolutionary trends, thus allowing the correlation of these features with time. The different developmental stages in Lepidorbitoides, i.e. L. pembergeri, L. campaniensis, L. bisambergensis, L. minor, L. socialis, and in Orbitoides, i.e. O. media, O. megaloformis, O. gruenbachensis, O. apiculata and O. gensacicus, have been described and illustrated based on the biometry of the populations. The values observed in some horizons, however, may not reflect the true phylogenetic stage of the orbitoidal taxa, especially in the species of Orbitoides, which usually show a wide variation of evolutionary parameters in the same population. A correlation scheme of phylogenetic development in Lepidorbitoides and Orbitoides with the planktonic foraminiferal zones is proposed. Lepidorbitoides populations with highly asymmetric ‘quadriserial’ nepionts occurring stratigraphically below the symmetric ones in Early Maastrichtian are thought to deserve a particular taxonomic status. In Orbitoides, a new embryonal chamber morphology previously undescribed from horizontal sections has been discovered. Copyright © 1999 John Wiley & Sons, Ltd.
- Published
- 1999
- Full Text
- View/download PDF
20. An Olistostrome-Melange Belt Formed Along A Suture: Bornova Flysch Zone, Western Turkey
- Author
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Nilgün Okay, Ismail Isintek, Aral I. Okay, Demir Altiner, and Sevinç Özkan-Altiner
- Subjects
geography ,Flysch ,geography.geographical_feature_category ,Metamorphism ,Olistostrome ,Massif ,Ophiolite ,Cretaceous ,Paleontology ,Geophysics ,Passive margin ,Suture (geology) ,Geology ,Earth-Surface Processes - Abstract
The Bornova Flysch Zone (BFZ) in western Turkey is a regional olistostrome-melange belt located between the Izmir-Ankara Tethyan suture in northwest and the Menderes Massif in the southeast. The BFZ consists mostly of tectonized gravity mass flows. The blocks are Mesozoic limestone and ophiolite, which are enclosed in Cretaceous-Paleocene sheared sandstone and shale. The limestone blocks are of two types. The first type consists of Late Triassic to Cretaceous shallow marine carbonates. The second type has an Upper Triassic shallow marine section overlain by Jurassic to Cretaceous pelagic limestones. A semi-intact part of the platform occurs in the Karaburun peninsula and on the island of Chios. The ophiolitic blocks in the BFZ include ultramafic rock, gabbro, basalt and radiolarian chert of Middle Triassic to Cretaceous in age. The formation of the BFZ overlaps with the Cretaceous subduction and HP/LT metamorphism of the northern passive continental margin of the Anatolide-Tauride Block. This subduction zone was bounded in the west by a strike-slip tear fault. The BFZ formed in a narrow basin between this tear fault and the Tethyan ocean. The mass flows came from the southeast from the overriding ophiolite and accretionary complex, and from the northwest from the uplifted segments of the platform margin. This model provides an explanation as why the BFZ is unmetamorphosed, whereas the equivalent strata in the Menderes Massif were metamorphosed at depths of over 20 km. It also explains the prominence of gravity flows and the southward younging in the BFZ, and for the apparently anomalous observation that, although the Tethyan ocean lay to the northwest, the ophiolitic blocks are more common on the southeastern part of the BFZ. Regions away from the tear fault, such as the Karaburun peninsula, were least affected by subsidence and deformation during the Cretaceous and Paleocene. (C) 2012 Elsevier B.V. All rights reserved.
- Published
- 2012
21. The genus Lepidorbitoides: Evolution and stratigraphic significance in some Anatolian basins (Turkey)
- Author
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Sevinç Özkan-Altiner, Erean Ozcan, Özcan, E., Department of Geological Engineering, Nigde University, 51000 Nigde, Turkey -- Özkan-Altiner, S., Mar. Micropaleontology Research Unit, Department of Geological Engineering, Middle East Technical University, 06531 Ankara, Turkey, and 0-Belirlenecek
- Subjects
Nepionic arrangement ,Paleontology ,Flysch ,Phylogenetic tree ,Turkey ,Genus ,Evolution ,Ontogeny ,Biology ,Lepidorbitoides ,Campanian-Maastrichtian - Abstract
Evolution of Lepidorbitoides in some flysch basins of Anatolia has been investigated considering the early ontogenesis in horizontal sections. Different developmental states of L. permbergeri, L. campaniensis, L. bisambergensis, L. minor and L. socialis have been described and illustrated with their morphometric features based on the earliest chamber arrangement. A correlation scheme of phylogenetic developmental states of Lepidorbitoides to the planktonic foraminiferal zones is also proposed. Populations with highly asymmetric quadriserial nepionts identified stratigraphically below the symmetric ones in Early Maastrichtian are thought to deserve a new status and attributed to L. bisambergensis asymmetrica n. spp. Orbitoides in common association with Lepidorbitoides has also been studied for the evolution of embryo-related parameters such as embryo size (Li + Ii), number of epi-embryonic chambers (E) and other embryonal features to correlate the phylogenetic developmental state of both genera., The authors would like to acknowledge the Scientific and Technical Council of Turkey for funding the project (T1JBiTAK, YDAB~AG-69) "Microfacies variations around Cretaceous-Tertiary boundary: An integrated zonation of calcareous nannofossil, planktonic foraminifera and benthic foraminifera" related to the subject of this paper.
- Published
- 1999
22. Upper Cretaceous planktonic foraminiferal biostratigraphy from NW Turkey: calibration of the stratigraphic ranges of larger benthonic foraminifera
- Author
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Sevinç Özkan-Altiner, Ercan Özcan, 0-Belirlenecek, and Middle E Tech Univ, Marine Micropalaeontol Res Unit, Dept Geol Engn, TR-06531 Ankara, Turkey -- Nigde Univ, Dept Geol Engn, TR-51100 Nigde, Turkey
- Subjects
Gansserina ,biology ,Turkey ,Lithology ,benthonic foraminifera ,Geology ,Plankton ,Biostratigraphy ,biology.organism_classification ,calibration ,Cretaceous ,Foraminifera ,Paleontology ,Sequence (geology) ,planktonic foraminifera ,Stratigraphy ,Late Cretaceous ,biostratigraphy ,NW Anatolia - Abstract
WOS: 000085050300006, Planktonic and larger benthonic foraminifers of the Upper Cretaceous (Santonian-Maastrichtian)-Lower Tertiary (Danian) rock units from north, northwest and central Anatolian fore-are basins have been investigated in order to improve the biostratigraphic resolution of this time interval. Total abundance and diversity of planktonic foraminifers vary from rare (the sequence from the Haymana region) to high (the sequences from the Cide, Caycuma, Hanonu and Yenikonak regions) and preservation is poor to moderate due to lithologic variation. First and last appearances of the planktonic foraminifera evaluated as major bio-events have been used to establish the biostratigraphic framework. Planktonic foraminiferal zonation from bottom to top of the succession consists of zones defined by Dicarinella concavata, Dicarinella asymetrica, Globotruncanita elevata, Globotruncana, ventricosa, Radotruncana calcarata, Globotruncanella havanensis, Globotruncana aegyptiaca, Gansserina gansseri, Abathomphalus mayaroensis and Morozovella pseudobulloides. Ten Orbitoides and Lepidorbitoides species have been identified. The different phylogenetic development stages of Orbitoides and Lepidorbitoides populations and other larger benthonic foraminifers, Pseudosiderolites vidali, Siderolites calcitrapoides, Siderolites denticulatus, Omphalocylus macroporus, Cideina sozerii, Hellenocyclina beotica, and Clypeorbis mamillata have been calibrated with the planktonic foraminiferal zonation established in the same successions. Hence, an integrated zonational scheme composed of planktonic foraminifers and larger benthonic foraminifers has allowed a detailed stratigraphy of these successions to be erected. Copyright (C) 1999 John Wiley & Sons, Ltd.
- Published
- 1999
23. CONODONT DISTRIBUTION ACROSS THE MID-CARBONIFEROUS BOUNDARY IN THECENTRAL TAURIDES, TURKEY
- Author
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AYSE ATAKUL-ÖZDEMIR, DEMIR ALTINER, and SEVINC ÖZKAN-ALTINER
- Subjects
Conodont biostratigraphy ,Mid-Carboniferous boundary ,Declinognathodus ,Central Taurides ,Geology ,QE1-996.5 ,Paleontology ,QE701-760 - Abstract
The Mid-Carboniferous boundary in the Aladað Unit of the Central Taurides, previously delineated on the basis of foraminifers, is now further recognizable on the basis of conodonts. Latest Serpukhovian conodonts are assigned to the Rhachistognathus muricatus Zone, whereas the early Bashkirian forms correspond to the Declinognathodus inaequalis - Declinognathodus noduliferus Zone. Conodont assemblages discovered in the Taurides are comparable to those described from Mid-Carboniferous boundary sections in North America, Japan, southern Urals, southern China, Ukraine and Uzbekistan. The Mid-Carboniferous boundary is located at a horizon marked by the first appearance of Declinognathodus inaequalis, just above the last appearance of the conodont Gnathodus girtyi simplex. This horizon coincides with the boundary indicated by foraminiferal data.
- Published
- 2012
- Full Text
- View/download PDF
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