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Koleksiyondaki öğeler
- MakaleYalnız künye2013Scopus SJRQ1The effect of composite patches on the failure of adhesively-bonded joints under bending moment
Akpinar, Salih
In this study, it was aimed to compare mechanical behavior of double-strap joints with aluminum (AA2024-T3) or 16-ply laminate of carbon/epoxy composite (T300/934) patches of different orientation angles at their overlap area subjected to bending moment. For this purpose, AA2024-T3 aluminum was used as adherend, while the adhesive was a two-part paste (DP 460). Six different types of joint samples were subjected to bending moment. The effect of patch material on failure load and stress distribution was examined experimentally and numerically. In the numerical analysis, the composite patches were assumed to behave linearly elastic, while adherend and adhesive layers were assumed to be nonlinear. It was found that the data obtained from 3-D finite element analysis were coherent with experimental results. Meanwhile, experiments showed that fiber orientation angles of the patches markedly affected the failure load of joints, failure mode and stress distributions appeared in adhesive and composite.
AtıfScopus38WoS38OpenAlex38
İncele - MakaleYalnız künye2015Scopus SJRQ3A new species of the harvestmen genus Rilaena (Opiliones: Phalangiidae) from Turkey
Kurt, Kemal
A new harvestman species, Rilaena artvinensis sp. n. (Opiliones: Phalangiidae), is described and illustrated based on males collected in north-eastern Anatolia, Turkey. The new species is similar to R. buresi (Šilhavý, 1965) and R. lenkoranica Snegovaya, 2007. The differences between these species are elaborated.
AtıfScopus6WoS3OpenAlex3İncele - MakaleYalnız künye2011Scopus SJRQ4New data on the harvestmen (Arachnida, Opiliones) fauna of Turkey
Kurt, Kemal; Snegovaya, Nataly Yu.; Demir, Hakan; Seyyar, Osman
A new collection of 8 species of harvestmen are reported from Turkey. Two of them: Zachaeus redikorzevi (Starega et Chevrizov, 1978) and Opilio coxipunctus (Sørensen, 1912), collected from the southern part of the country, represent new records for Turkish harvestmen fauna. These species are illustrated and their data regarding collecting sites and distribution all over the world are given.
AtıfScopus6WoS7İncele - MakaleYalnız künye2013Scopus SJRQ2Radical scavenging and antioxidant capacity of serotonin
Sarikaya, S. Beyza Öztürk; Gülçin, Ilhami
Serotonin is a monoamine neurotransmitter and biochemically derived from tryptophan. The present paper examines the in vitro antioxidant and radical scavenging capacity of serotonin using different in vitro methodologies. For the determination of antioxidant activity of serotonin, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2́-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by Fe3+-Fe2+ transformation method, superoxide anion radical scavenging by riboflavin-methionine-illuminate system, H2O2 scavenging and ferrous ions (Fe +) chelating activities of serotonin were performed. Also, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analog of α-tocopherol, were used as the reference antioxidant radical scavenger compounds. Serotonin completely inhibited lipid peroxidation of a linoleic acid emulsion at 15 μg/mL concentration. On the other hand, the above mentioned standard antioxidants displayed inhibition of 92.2, 99.6, 84.6 and 95.6% on peroxidation of linoleic acid emulsion, respectively at the 45 μg/mL concentration. In addition, serotonin was effective in DPPH· scavenging, ABTS•+ radical scavenging, superoxide anion radical scavenging, H2O2 scavenging, ferric ions (Fe3+) reducing power and metal chelating on ferrous ions (Fe+) activities. Also, those various antioxidant activities were compared to BHA, BHT α-tocopherol and trolox as references antioxidant compounds.
AtıfScopus31OpenAlex32İncele - MakaleYalnız künye2011Scopus SJRQ2A new Early Jurassic brachiopod fauna from the Eastern Pontides (Turkey)
Vörös, Attila; Kandemir, Raif
A newly collected Early Jurassic brachiopod fauna from the Kocamantaşi section (Gümüşhane region, Eastern Pontides, Turkey) yielded 160 specimens and 13 species (4 rhynchonellids, 3 spirifennids, 6 terebratulids). Apart from some long-ranging forms, five species prove the Late Pliensbachian age of the fauna. The paleoenvironmental setting of the Kocamantaşi fauna shows analogies to the Alpine Hierlatz limestones. On the basis of common lithological characters, bedding features and sedimentary associations, this lithofacies is interpreted as a complex of submarine, biodetrital talus associated with fault-related submarine rocky slopes. The numerical comparison of the Kocamantaşi brachiopod fauna to Pliensbachian brachiopod faunas of Europe revealed that the faunal similarity was the highest to Kotel (Balkans) and the Crimea. Very strong affinity was recorded to further NW-European faunas, whereas very low, or no similarity was recognized to the Mediterranean faunas. This paleobiogeographical result supports the hypothesis that in the Late Pliensbachian the Eastern Pontide segment of the Cimmerian microcontinent was far from the Gondwana and close to the Eurasian margin of the Tethys.
AtıfScopus18WoS17OpenAlex14İncele - MakaleYalnız künye2014Scopus SJRQ3The effect of different photoperiods and stocking densities on fattening performance, Carcass and some stress parameters in broilers
Das, H.; Lacin, E.
This study was carried out for the purpose of investigating the effects of different photoperiods and stocking densities on physiologic parameters such as body weight, feed consumption, feed efficiency, carcass traits and some stress parameters in broiler chickens. Throughout the experiment, 480 day-old male chickens obtained from a commercial hatchery were used. The chicks were placed in different partitions which had three different photoperiod (continuous lighting: 24 hour light, constant lighting: 16 hour light - 8 hour dark, intermittent lighting: 4 hour light – 2 hour dark) were applied. Each photoperiod group was formed with five replicates at two different stocking densities (normal stocking density: 12 broiler/m2, high stocking density: 20 broiler/m2). The experiment was carried for 42 days. At the end of the experiment, the effect of photoperiod and stocking density on live weight gain were significant (P<0.05) while photoperiod significantly affected the feed consumption only (P<0.05). The feed efficiency were insignificant (P>0.05) with respect to both factors. The photoperiod programs had significant effects on the relative weight of gizzard, blood, feather percentage values (P<0.05) and breast percentage values (P<0.01). The stocking density has a significant effect on relative heart weight (P<0.05) and entire thigh values (P<0.01). At the end of the experiment, it was ascertained that the photoperiod program and stocking density had no significant (P>0.05) difference on tonic immobility and tibial dyschondroplasia values. However, stocking density had a highly significant effect (P<0.01) on gait score values and on heterophil-lymphocyte rate values (P<0.01).
AtıfScopus22WoS21İncele - MakaleYalnız künye2011Scopus SJRQ3Mineralogy and whole rock geochemistry of lzate Cretaceous sandstones from the eastern Pontides (NE Turkey)
Eker, Cigdem Saydam; Korkmaz, Sadettin
This study focuses on Upper Cretaceous sandstones of the Eastern Pontides to identify the source area, subaerial weathering level, and tectonic environment. Thirty four sandstone samples from six stratigraphic sections were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MC) and by petrographic investigation. The late Cretaceous sandstones are defined as lithic arenites and feldspathic wackes, and lithic wackes depending on mineralogical and matrix content. The sandstones have low to moderate SiO2 contents (25-59%; on average -56%). There are high positive correlations between SiO2 Al2O3, and TiO2 and negative correlations between SiO2 and K2O. Geochemically, the sandstones are classified mainly as grey wackes and lithic arenites. Chemical index of alteration (CIA) and chemical index of weathering (CIW) values for Upper Cretaceous sandstones vary from 19 to 48 % and 20 to 49 % respectively. The combination of CIW/CIA values suggests little transportation until final deposition. The ratios of Th/Sc (on average -0.42), La/Sc (-1.81), Co/Th (-5.05) and Zr/Hf (-39.1) of sandstone samples in the study area indicate a mafic source. Furthermore, high light rare earth elements (LREE)/heavy rare earth elements (HREE) ratios (on average -19.72) and negative Eu anomalies (except in the Dagbasi section) suggest a contribution from a felsic source. The lower trace element contents of the Upper Cretaceous sandstones in relation to the Post-Archean Australian Shale (PAAS), which are considered to be representative of the upper continental crust, show that the recycling processes in their source areas were probably less intense than those of the PAAS. SiGyAlA (3.2-7.9) and K2O/Na20 (0.3-1) ratios, together with the Th (on average -3.3 ppm), Zr (on average -91.9 ppm), Co (on average -15 ppm), and Sc (on average -12.6 ppm) contents of the late Cretaceous sandstones of the eastern Pontides indicate a magmatic arc origin. Sandstones of the Trabzon region were probably deposited in fore-arc basins, and those from the Gumushane and Giresun regions in back-arc basins.
AtıfScopus39WoS42OpenAlex39İncele - MakaleAçık Erişim2014Scopus SJRQ3On some geometric properties of a new paranormed sequence space
Karakaya, Vatan; Altun, Fatma
We introduce a new sequence space which is defined by the operator W=(wnk) on the sequence space ℓ(p). We define a modular functional on this space and investigate structure of this space equipped with Luxemburg norm. Also we study some geometric properties which are called Kadec-Klee, k-NUC, and uniform Opial properties and prove that this new space possesses these properties.
AtıfScopus4WoS2OpenAlex5İncele - MakaleYalnız künye2011Scopus SJRQ2Radiological characterisation of Artvin and Ardahan provinces of Turkey
Kucukomeroglu, B.; Yesilbag, Y.O.; Kurnaz, A.; Celik, N.; Cevik, U.; Celebi, N.
Indoor radon concentration measurements were carried out and corresponding annual effective doses due to exposure to indoor radon were determined in Artvin and Ardahan provinces located in the eastern part of Turkey. The measurements were performed for four seasons in order to determine the seasonal fluctuations mostly observed in indoor environments. Indoor radon concentration values were observed to range from 21 to 321 Bq m-3 for the Artvin province and from 53 to 736 Bq m-3 for the Ardahan province. It was observed that minimum indoor radon concentration values were obtained in summer, while the highest ones were observed in winter. Indoor radon concentration values of the current study were compared with those of other provinces in Turkey. As elevated indoor radon concentrations are mostly correlated with high 238U activity concentrations in soil, a total of 57 and 33 soil samples were collected from the Artvin and Ardahan provinces, respectively, to determine 238U activity concentration as well as the concentration of 232TH and 40K-naturally occurring radionuclides. It was also observed that soil samples collected from the study areas contained 137Cs as an artificial radionuclide.
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İncele - MakaleYayıncıda açık erişim2015Scopus SJRQ2A study on the correlations between seismotectonic b-value and Dc-value, and seismic quiescence Z-value in the western anatolian region of Turkey
Öztürk, Serkan
The Western Anatolian region is one of the most seismically active sectors of Turkey where small-magnitude events with considerable clustering occur frequently. The spatial and temporal behaviors of seismic activity as quantified by the fractal dimension Dc-value, seismotectonic b-value and seismic quiescence Z-value are investigated for the Western Anatolian region. For this purpose, a statistical relationship is developed between b and Dc-values, and regional and temporal changes of these parameters are analyzed in order to reveal the potential of future earthquakes in the study region. By using standard deviate Z-value, current seismicity rate changes are estimated in the beginning of 2014. The Western Anatolian region is divided into 18 different seismogenic subregions. Orthogonal regression fit is preferred in order to estimate more up-to-date and reliable statistical correlation between two seismotectonic parameters. The relationship of Dc=2.74-0.29*b is computed with a significant negative correlation (r = -0.73) between b and Dc-values for the Western Anatolian earthquake distributions. There are clear fluctuations in the temporal changes of these two parameters and the same results are relatively obtained in previous studies in literature. Lower b-values smaller than 1.0 and also higher Dc-value are observed in the Burdur fault zone and Kütahya graben. In addition, the regions in which the lower b-values and the higher Z-values are estimated cover the Burdur fault zone, Aliağa-Dumlupınar faults and Bakırçay grabens. Consequently, the relationships between seismic bvalue, fractal dimension Dc-value and seismic quiescence Z-value may provide important evidences to put forth the next earthquake potential in Western Anatolia. In addition, monitoring of microseismic activity and behaviors of some other geophysical parameters should be analyzed in space and time and evaluated carefully.
AtıfScopus34WoS22OpenAlex28İncele - BildiriYalnız künye2014Determination of ground predominant period and H/V ratio by single station microtremor records in Trabzon (Arsin)
Akin, Ö.; Sayil, N.; Beker, Y.
Microtremor method used for engineering seismology is very important for determining of dynamic ground parameters and its variations. Method based on frequency of horizontal and vertical component microtremor records provides to quick and economical estimation of dynamic ground parameters. The most important advantage of Nakamura method defined as single station method does not require reference point and it can be applied easily in the area with low seismic density and without base rock. In this study, Nakamura (H/V) spectral ratio method has been applied to microtremor records taken with CMG-6TD three component broad band velocity seismometers at 116 points with the aim of determining ground predominant period and magnification parameters in the study area. Maps of predominant period and H/V ratio of the study area are created by derived values.
- MakaleAçık Erişim2015Scopus SJRQ2Optimization of electrical power transmission lines' routing using AHP, fuzzy AHP, and GIS
Eroʇlu, Hasan; Aydin, Musa
With the increase of people's need for energy, electrical energy transmission has become a very important issue as well as electrical power generation. One of the most important problems in energy transmission is finding the best route in a very complex study area. To date, many people from different disciplines have come together to find the best routes by manual methods like using paper maps and deciding which route is the least-cost path (LCP) to the destination point. Today it is known that, in engineering problems, and especially in path-finding or site-placing problems, the Geographic Information System (GIS) is the most powerful tool. On the other hand, as finding the best route is a very complicated problem and many criteria should be considered, including slope, landslide, road/railway/pipeline crossing, ice zones, distances to roads, national parks, archaeological areas, residential areas forests, and river crossings, multicriteria decision methods like the analytic hierarchy process (AHP) and fuzzy analytic hierarchy process (FAHP) should be used to make the most accurate decisions. In this study, the AHP and FAHP are used to weight criteria relevant to energy transmission line (ETL) routing. According to the criteria, digital maps of the sample study area are edited, weighted, converted to raster-based format, and gathered using the Environmental Systems Research Institute's ArcGIS Desktop 10 software. After generation of the weighted surface map, the LCP tool is used to find the best route. By selecting different start and end points in the sample study area, accuracy and performance of the best routes according to the LCP algorithm are assessed and some problems of the routes for ETL routing are presented. With this study, mistakes by manual methods will decrease in ETL routing and other routing problems.
AtıfScopus27WoS23OpenAlex40TR Dizin2
İncele - MakaleYalnız künye2010Scopus SJRQ2Numerical analysis of entropy generation in concentric curved annular ducts
Kucuk, Haydar
The entropy generation has been numerically investigated in concentric curved annular square ducts under constant wall temperature boundary condition. The problem has been assumed to be steady, hydrodynamically and thermally fully developed and incompressible laminar flow with constant physical properties. The solutions of discretized equations for continuity, momentum and energy have been obtained by using an elliptic Fortran Program based on the SIMPLE algorithm. Solutions have been achieved for i) Dean numbers ranging from 3.6 to 207.1, ii) Annulus dimension ratios of 5.5, 3.8, 2.9 and 2.36, and iii) Prandtl number of 0.7. In this regard, local entropy generation as well as overall entropy generation in the whole flow field has been analyzed in detail. Moreover, the effects of Dean number and annulus dimension ratio on entropy generation arising from the friction and heat transfer have been investigated. Accordingly, it is concluded that the effect of volumetric entropy generation that is a result of fluid frictional irreversibility can be neglected as compared with volumetric entropy generation due to heat transfer irreversibility. As Dean number increases, the distribution of volumetric entropy generation coming out from the heat transfer irreversibility is formed by the temperature field, which is depending on the curvature.
AtıfScopus19WoS17OpenAlex21İncele - MakaleAçık Erişim2013Scopus SJRQ3Solid phase extraction of Cd(ii) and pb(ii) ions by a new carbothioamide derivative
Ozdes, Duygu; Duran, Celal; Bayrak, Hacer; Serencam, Huseyin; Basri Senturk, Hasan
An effective, simple, low cost and accurate sorption-spectrophotometric platform for the extractions and subsequent quantifications of Cd(II) and Pb(II) ions in food and environmental samples has been described in this dissertation. The separation and preconcentration of the analyte ions were accomplished by solid phase extraction method based on the adsorption of their N-(4-methylphenyl)-2-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio] acetyl} hydrazinecarbothioamide (MFPTAHK) complex on Amberlite XAD-8 resin in a mini column. The developed method was systematically investigated in different set of experimental parameters that influence the separation and preconcentration of Cd(II) and Pb(II) ions. The precision of the method was determined by reproducibility studies and expressed as relative standard deviations (RSD %) which were less than 4% for both analyte ions. The limits of detections (LODs) for Cd(II) and Pb(II) ions based on the three times the standard deviation of the blanks (N:10) were found to be 0. 31 ?g L-1 and 0. 86 ?g L-1, respectively. The developed SPE procedure was utilized for the simultaneous extraction and determinations of Cd(II) and Pb(II) ions levels in rice, cracked wheat and red lentil as food samples and various water samples.
AtıfScopus5WoS4OpenAlex5İncele - MakaleYalnız künye2014Scopus SJRQ1The petrogenesis of Early Eocene non-adakitic volcanism in NE Turkey: Constraints on the geodynamic implications
Aydinçakir, Emre
Whole-rock geochemistry, mineral chemistry, the 40Ar-39Ar age, and Sr-Nd isotopic data are presented for the Early Eocene non-adakitic volcanic rocks on the eastern corner of the Eastern Pontides orogenic belt (NE Turkey). The tectonic setting of the Eastern Pontides during the Late Mesozoic to Early Cenozoic remains a topic of debate. Here, for the first time, we describe the Early Eocene non-adakitic volcanic rocks from the Eastern Pontides. These rocks contain plagioclase, hornblende phenocrysts, and magnetite/titanomagnetite and apatite microphenocrysts. Geochronology studies based on the 40Ar-39Ar ratio of the amphibole separates reveal that the non-adakitic porphyritic volcanic rocks have a crystallization age of 50.04±0.10 to 50.47±0.22Ma (Ypresian). The volcanic rocks show tholeiitic to calc-alkaline affinities and have low-to-medium K contents. They are also enriched in large-ion lithophile elements (LILE), light rare-earth elements (LREE), and depleted in high field strength elements (HFSE), with a no negative Eu anomaly (Eun/Eu*=1.03-1.08) in mantle-normalized trace element spidergrams. The samples (Lacn/Lucn=2.60-4.28) show low-to-medium enrichment in LREEs relative to HREEs, in chondrite-normalized REE patterns indicating similar sources for the rock suite. These rocks display a range of ISr (50Ma) values from 0.70451 to 0.70485, and E{open}Nd (50Ma) 2.9 and 3.7. The main solidification processes involved in the evolution of these volcanics consist of fractional crystallization, with minor amounts of crustal contamination. All of our evidence supports the conclusion that the parental magma of the rocks probably derived from an enriched mantle, previously metasomatized by fluids derived from the subducted slab, in a post-collisional, geodynamic setting.
AtıfScopus58WoS53OpenAlex55İncele - MakaleAçık Erişim2014Scopus SJRQ3On the problem of determining the parameter of an elliptic equation in a banach space
Ashyralyev, Allaberen; Ashyralyyev, Charyyar
The boundary value problem of determining the parameter of an elliptic equation -u(t) + Au(t) = f(t) + p (0 ≤ t ≤ T), u(0) = φ, u(T) = ψ u(λ) = ξ 0 < λ < T, with a positive operator A in an arbitrary Banach space E is studied. The exact estimates are obtained for the solution of this problem in Hölder norms. Coercive stability estimates for the solution of boundary value problems for multi-dimensional elliptic equations are established.
AtıfScopus67WoS58OpenAlex63İncele - MakaleYalnız künye2014Scopus SJRQ1Strength and ultrasonic properties of cemented paste backfill
Ercikdi, Bayram; Yilmaz, Tekin; Külekci, Gökhan
This paper presents the strength (UCS) and ultrasonic pulse velocity (UPV) properties of cemented paste backfill (CPB) produced from two different mill tailings (Tailings T1 and T2). A total of 240 CPB samples with diameter × height of 5 × 10 cm and 10 × 20 cm prepared at different binder dosages (5-7 wt.%) and water-to-cement ratios (3.97-5.10) were subjected to the UPV and UCS tests at 7, 14, 28 and 56-days of curing periods. UCS and UPV of CPB samples increased with increasing the binder dosage and reducing the w/c ratio irrespective of the sample size and tailings type. CPB samples with a diameter × height of 5 × 10 cm were observed to produce consistently higher (up to 1.69-fold) UCSs than those of 10 × 20 cm CPB samples at all binder dosages and w/c ratios. However, at the corresponding binder dosages and w/c ratios, the maximum variation of UPV between the CPB samples of 5 × 10 cm and 10 × 20 cm was only 7.45%. Using the method of least squares regression, the UCS values were correlated with the UPV values for CPB samples of 10 × 20 cm in size. A linear relation with a high correlation coefficient appeared to exist between the UCS and UPV for CPB samples. These findings suggest that the UPV is essentially independent of the sample size. In this regard, the UPV test can be suitably exploited for the rapid estimation of the strength and quality of CPB samples even using small samples with concomitant benefits of reducing sample size.
AtıfScopus126WoS108OpenAlex125İncele - MakaleAçık Erişim2015Scopus SJRQ3Outdoor efficiency analyses and comparison of on-grid CdTe and μc-Si/a-Si thin-film PV systems for three years in Ankara - Turkey
Ozden, Talat; Yardim, Ugur; Akinoglu, Bulent G.; Turan, Rasit
The present paper is mainly a comparison of the performances of two PV systems under outdoor conditions in Ankara. The systems are grid connected and consist of two PV arrays. The types of these PV arrays are CdTe thin film and amorphous silicon/micro-crystalline-based (μc-Si/a-Si) arrays. They are operated for 3 years; 2012-2014. Yearly averages of monthly efficiencies of these two systems working under the same ambient conditions are 6.88%, 6.65%, 6.80% and 6.64%, 5.86%, 5.25% for μc-Si/a-Si and CdTe, respectively. Using these values, simple calculation results for the degradation rates per year are about 0.39%/year and 6.98%/year, respectively for these two types of systems.
AtıfScopus5WoS4OpenAlex6İncele - MakaleYalnız künye2011Scopus SJRQ3Estimation of the carbon to nitrogen (C:N) ratio in compostable solid waste using artificial neural networks
Bayram, Adem; Kankal, Murat; Ozsahin, Talat Sukru; Saka, Fatih
Organic waste constitutes a majority of all municipal solid waste (MSW), a fact which yields some unfavorable results at open dumps, sanitary landfills, and incineration plants. As part of an integrated solid waste management strategy, composting could be applied to mixed collected MSWs or separately collected leaves, food, and yard wastes. The factor most crucial to successful composting is the carbon to nitrogen (C:N) ratio of the waste. This study employs two predictive models to estimate the C:N ratio of compostable MSW, an artificial neural network (ANN) and multiple linear regression (MLR). These models are based on 52 solid waste samples taken from the MSW open dumping area in Gümüşhane Province, Turkey. To estimate the C:N ratio, seven predictive variables were adopted. The proportions of food and yard (F&Y), and ash and scoria (A&S) waste; the moisture content (MC), the fixed carbon (FC) content, the total amount of organic matter (TOM), high calorific value (HCV), and pH. Fortytwo of the samples were used for training, and the remaining ten were used to test the models. The average relative error attained by the best ANN was 6.376%, while that attained by the MLR model was 11.002%. The effects of TOM content, F&Y percentage, and A&S percentage on the C:N ratio were investigated by running the ANN model for a range of input variables.
AtıfScopus7WoS6İncele - MakaleYalnız künye2011Scopus SJRQ1Crystal fractionation of adakitic magmas in the crust-mantle transition zone: Petrology, geochemistry and U-Pb zircon chronology of the Seme adakites, eastern Pontides, NE Turkey
Eyuboglu, Yener; Santosh, M.; Chung, Sun-Lin
Plutonic and porphyritic intrusions of adakitic rocks are widely distributed in the southern part of the eastern Pontides orogenic belt in Turkey. Ranging in age from late Paleocene to early Eocene, these intrusions provide critical information to evaluate the early Cenozoic geodynamic evolution of the eastern Mediterranean region. Here we report the results from our field, petrologic, geochemical and zircon U-Pb geochronological studies on adakitic intrusions in the Seme area from the southern part of eastern Pontides belt. The Seme granitoid, Daldibi dacite and Aslanca dacite porphyry from this region carry abundant plagioclcase, amphibole and biotite phenocrysts and have geochemical affinities typical of adakites including high SiO2 (58.48-75.6wt.%), Al2O3 (15.78-18.28wt.%), Na2O (3.94-5.08wt.%), Sr (506-1413ppm), and La (12.6-52.9ppm), moderate K2O (1.77-2.76wt.%), and low Y (4.7-14.2ppm) and Yb (0.28-1.29ppm). The early Eocene intrusions in the Seme area have compositional similarities with high-slica adakites, and their geochemical features suggest the involvement of slab-derived melts. The zircons separated from these rocks show euhedral crystal shapes with oscillatory cores typical of crystallization from magmas, as also confirmed by their high Th/U ratios (0.78 to 1.15). U-Pb analyses of zircons from the quartz diorite yielded a weighted mean 206Pb/238U age of 53.16±0.45Ma. Zircon grains from the Aslanca dacite porphyry occurring as a late phase within the Seme body show U-Pb isotopic ages of 53 and 52Ma concordant with U-Pb ages of zircons from quartz diorite. Based on major, trace and rare earth element data, we present a model suggesting crystal fractionation and/or differentation processes of subduction-related adakitic magmas stored in the crust-mantle transition zone, and their transfer into shallow depths of the overriding continental lithosphere.
AtıfScopus104WoS99OpenAlex100İncele
