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    Dose estimation, kinetics and dating of fossil marine mollusc shells from northwestern part of Turkey
    (Pergamon-Elsevier Science Ltd, 2015) Aydas, Canan; Engin, Birol; Kapan, Sevinc; Komut, Tolga; Aydin, Talat; Paksu, Ufuk
    Electron spin resonance (ESR) spectroscopy was used to determine the geological formation age of fossil mollusc shells taken from marine terrace deposits (Ikizlerceme-Canakkale) in northwestern part of Turkey. This work reports the first results obtained by the ESR technique on shells collected from this region. In the ESR spectra of the natural and gamma-irradiated shell samples, two different signals attributed to orthorombic (g(xx)=2.0030, g(zz)=2.0015, g(yy)=1.9980) and isotropic (g=2.0006) CO2- ion radicals were overlaped (Signal C). Annealing and kinetic experiments suggest the possibility of using the ESR signal at g=2.0015 (C signal) for the estimation of accumulated geological doses. The ESR signal growth curve on additional gamma irradiation has been best fitted by a combination of two single exponential saturation functions. This may support the existence of at least two components of the g=2.0015 ESR dating signal. Based on this model, the accumulated dose of the samples was determined as 110 +/- 11 Gy. Also the isothermal decay curves of the ESR dating signal could be best described by the combination of two first order decay functions. Activation energy and meanlifetime values at 15 C of the two components were calculated as E-1 = 1.4 +/- 0.1 eV, E-2 = 1.1 +/- 0.1 eV, tau(1) = 7.2 x 10(6) years and tau(2)=33 x 10(3) years, respectively. Uranium content of the studied shells was found to be high according to their chemical analysis. This may point out that the marine shell has received uranium from outside particularly in carbonate sediment. Therefore, the ESR age of the samples was also calculated using Early Uptake (EU), Linear Uptake (LU) and Combined Uptake (CU) models and results were discussed. (C) 2015 Elsevier Ltd. All rights reserved.
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    Geochemical Evidences of Paleoenvironmental Changes in Late Quaternary Lacustrine Sediments of the Konya Closed Basin (Konya, Turkey)
    (Springer International Publishing Ag, 2019) Orhan, Hukmu; Delikan, Arif; Demir, Ahmet; Kapan, Sevinc; Olgun, Kemal; Ozmen, Ayhan; Sayin, Ulku
    Important geochemical evidence reflecting Quaternary climatic changes was obtained by evaluating geochemical data from 51 samples and datings from 3 samples by ESR method from sediments of a 7-m-deep trench in Great Konya lake area at the southwest of Adakale village (Konya, Turkey). The geochemical data indicate that the study area was influenced, four times, by a climate having strong precipitation, which caused strong erosion and high detrital input between 25,276 +/- 1732-year BP and approximately 50,000-year BP. These periods correspond to climatic changes during the last glacial periods, the warm climate of D-O-2, D-O-5, D-O-6 and D-O-14 events and the cold climate of H2, H3, H4 or H5 and H6 events.
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    PALEOGENE STRATIGRAPHY AND MOLLUSCA FAUNA OF NORTHERN PART OF THE BIGA PENINSULA: FICITEPE FORMATION BETWEEN LAPSEKI-SEVKETIYE, CANAKKALE
    (Stef92 Technology Ltd, 2016) Gursoy, Birben; Kapan, Sevinc
    In this work, it is planned that to rearrange the Paleogene stratigraphy of the study area and interpret paleogeographic and paleoecological properties of the Paleogene sediments are exposed northeastern part of the Biga Peninsula (Ficitepe Formation and Danismen Formation) by using the data obtained from gastropoda-bivalvia fauna. Eleven measured stratigraphic sections were taken from sedimentary rocks which are outcroped in the study field. According to lithostratigraphic and biostratigraphic correlation of these sections, it was determined the stratigraphic positon of the investigation area. Systematic sampling was also carried out during the stratigraphic section measurement. It is identified that; 11 genus, 10 species from the samples are belonging to Fcitepe Formation. According to the stratigraphic level and paleogeographic distribution of the fauna, Fcitepe Formation's age is found as Late Eocene. Identified fauna represent that the shallow marine brackish water envorinment during the Late Eocene. At the same time, 36 genera, 34 species have been identified belonging to Danismen Formation which unconformably overlying on Ficitepe Formation. In the light of these fauna, the age of Danismen Formation is found as Late Oligocene and interpreted that warm, shallow, sublitoral and brackish water conditions were dominant.
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    The Importance of Pre-Annealing Treatment for ESR Dating of Mollusc Shells: A Key Study for Ismil in Konya Closed Basin/Turkey
    (Amer Inst Physics, 2018) Ekici, Gamze; Sayin, Ulku; Aydin, Hulya; Isik, Mesut; Kapan, Sevinc; Demir, Ahmet; Engin, Birol
    In this study, Electron Spin Resonance (ESR) spectroscopy is used to determine the geological ages of fossil mollusc shells systematically collected from two different geological splitting at Ismil Location (37.72769 degrees N, 33.17781 degrees E) in eastern part of Konya. According to the assessment of obtained ESR ages, the importance of pre-annealing treatment emphasize in the case of g=2.0007 dating signal is overlapped with the other signals arisen from short lived radicals that cause the wrong age calculation. To overcome this problem, the samples are pre-annealed at 180 degrees C for 16 minutes and, in this case ESR ages are recalculated for g=1.9973 dating signal. Dose response curves are obtained using 1.9973 signals after pre-annealing treatments for each samples. ESR ages of samples are obtained in the range of 138 +/- 38 ka and 132 +/- 30 ka (Upper Pleistocene) according to the Early Uranium Uptake model and the results are in good agreement with the estimated ages from stratigraphic and paleontological correlation by geologists. Thus, it is suggested that especially in the case of g=2.0007 dating signal cannot been used due to superimposition case, the signal with 1.9973 g value can be used for dating after pre-annealing treatment. The results reports the first ESR ages on shells collected from Ismil Location and highlight the importance of pre-annealing treatment. This study is supported by TUBITAK 114Y237 research project.
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    The Quaternary fluvial-lacustrine system in the Akarçay Basin (SW Anatolia): depositional environments and paleoclimatic interpretation
    (Tubitak Scientific & Technological Research Council Turkey, 2025) Akturk, Koray; Kapan, Sevinc
    The Akar & ccedil;ay Closed Basin, located in southwest Anatolia, contains deformed formations and the drying Ak & scedil;ehir and Eber lakes. This study aimed to interpret the paleoenvironmental and paleoclimatic conditions of the Ak & scedil;ehir and Eber lakes, which are reported to have been connected during the Pleistocene. Based on sedimentological and mineralogical data, three different depositional subenvironments were defined, corresponding to the formation and development stages of the lake. Sedimentary facies analysis of the Pleistocene deposits in the basin revealed the following facies associations, listed from bottom to top: 1) an alluvial fan and fluvial facies association, representing the formation stage of the lake, which developed due to tectonic activity and a humid/wet climate; 2) a lakeshore facies association, corresponding to the expansion stage when the lake spread shallowly, and 3) a lake center facies association, corresponding to the closing stage when the lake began to dry, characterized by limited levels of clastic deposition under very shallow lake conditions. In the lakeshore and lake center facies association, Valvata piscinalis, Dreissena iconica and D. polymorpha species living in shallow waters and streams, as well as Laevicaspia caspia species living in mesohaline environments were identified. X-ray diffraction analysis was performed on the levels that best represented the facies associations in the basin, revealing that the dominant clay minerals in the sequence were illite and kaolinite. Combined evaluation of the sedimentological, mineralogical, and paleontological data suggests that the abundance of Valvata piscinalis and Dreissena iconica-both stream-dwelling species-at levels with increased kaolinite content indicates rainy and humid climatic periods when stream-fed conditions prevailed in the basin. Conversely, the dominance of Laevicaspia caspia and the intervals marked by illite deposition indicate cold and arid climatic periods.
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    The superiority of using the ESR dating method in mollusc shells compared to 14C and 230Th/234U: A case study at the eastern part of Konya closed basin, central Turkiye
    (Pergamon-Elsevier Science Ltd, 2025) Ekici, Gamze; Sayin, Ulku Akpinar; Delikan, Arif; Kapan, Sevinc; Biyik, Recep; Demir, Ahmet; Isik, Mesut
    The Konya Closed Basin in central Anatolia preserves Quaternary lacustrine sediments, providing critical evidence for regional paleoclimatic reconstructions. Accurate dating of these is essential for understanding Quaternary climate evolution in the area. In this study, fossil mollusc shells systematically collected from the eastern part of the basin were dated for the first time using ESR spectroscopy. Prior to dating analyses, comprehensive geological investigations and paleontological classifications were conducted. ESR spectra recorded at room temperature on both natural and gamma-irradiated samples revealed freely rotated CO2- radical signals at g = 2.0007. Kinetic studies confirmed the long-term stability of the CO2- radical, with high activation energies (similar to 1.3 eV) and thermal lifetimes exceeding similar to 10(6) years, reconfirming its reliability as a dating signal throughout the Quaternary period. Most ESR ages were derived from the 2.0007 signal, while the signal of the orthorhombic CO2- radical at g = 1.9973 was utilized for a few samples. Dose-response curves were best fitted to a single exponential saturation function and equivalent doses were calculated accordingly. ESR ages ranged from 138 to 6 ka, showing stratigraphic consistency with the sedimentary record. Comparative dating using C-14 AMS and Th-230/U-234 techniques demonstrated general agreement with ESR ages, although minor discrepancies were observed due to the open-system behavior of mollusc shells. Overall, the results support the chronological reconstruction of Holocene to Middle Pleistocene paleoenvironmental events in the Konya Closed Basin.