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    Micropaleontological (Ostracoda) content and mineralogical properties of the Neogene Ergene Formation (SW Thrace region): implications for the evolution of Thrace Basin
    (Springer, 2022) Şafak, Ümit; Güldürek, Manolya; Nurlu, Nusret; Güney, Ayşegül
    This study encompasses micropaleontological and mineralogical research conducted in the Neogene cover deposits of the Thrace Basin, within the celebi and Sinanli members of the Ergene Formation. The chronostratigraphic, paleoenvironmental, and paleobiogeographic features of the two members of this formation are studied in detail. Ostracod genera and species were found out, and those were also defined both in Tethys and Paratethys regions in silty clay and clayey levels of the Celebi Member of the Ergene Formation. Ostracod faunas, which have developed in brackish sedimentation and are specific to Central and East Paratethys basin, are firstly identified in the clayey limestone levels of the Sinanli Member. Micropaleontologically, the calcareous nannoplankton and ostracod assemblages of the units were investigated, but calcareous nannoplankton species were not identified in the samples from the Ergene Formation in the study area. The measured stratigraphic sections were taken from two locations where the Ergene Formation and its two members could be best observed throughout the study. As a result of the micropaleontological evaluation of the washing samples taken from these sections, three ostracod species and three species were reported in the celebi Member within the formation; eight ostracod genera and eight species were also defined in the Sinanli Member. Ostracod genera and species such as Cyprideis pannonica, Ilyocypris cf. bradyi, Heterocypris salina, and Heterocypris sp. were defined within the celebi Member. Micropaleontological findings based on ostracods were obtained for the first time in the Sinanli Member, the second member of the formation. Ostracod genera and species such as Euxinocythere (Maeotocythere) pseudodiafana, Caspiocypris aff. alta, Typhlocypris eremita, Typhlocypris sp., Caspiolla bacuana, Caspiolla fastigata, Caspiolla sp.1, Caspiolla sp. 2, Caspiolla sp.3, Pontoniella srebarnensis, Serbiella cf. bacevicae, Candona aff. elongata, and Stanchevia sp. were defined in the Sinanli Member. The described ostracod species were the same as the Paratethys species defined in Bulgaria, Hungary (Central Paratethys), Romania, Crimea, Black Sea, Turkmenistan, and Azerbaijan (Eastern Paratethys). These species were first described in this study, especially in the second member of the Ergene Formation in Thrace, during the Late Miocene-Pliocene. It was determined that the ostracod genera and species found are communities in the brackish water system, compatible with the oligo-mesohaline salinity criteria. In this study, where the petrography of the basement units under the sedimentary cover was investigated, the lithology and mineralogical characteristics of the Ergene Formation were evaluated in terms of the paleoenvironmental interpretation of the related unit. The presence of montmorillonite-type minerals in the clay lithology of the formation confirms its terrestrial origin.
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    Origin and geodynamic implications of basaltic rocks intercalated with Miocene turbidites around the Iskenderun Basin (Eastern Mediterranean / Turkey)
    (Pergamon-Elsevier Science Ltd., 2023) Akıncı, Ahmet C.; Nurlu, Nusret; Güney, Ayşegül
    We report a detailed investigation and the geodynamic implications of a basaltic lava flow that is intercalated with the early-middle Miocene turbiditic sedimentary rocks (Karatas, Formation) that are exposed near the Iskenderun Basin in southern Turkey. In order to reveal the age and origin of the basaltic rocks, we systematically sampled clastic samples from measured sedimentary sections, which include the basaltic lava flow, from around Ceyhan (east of Adana city). Forty different species belonging to 14 calcareous nannoplankton genera were identified in the samples, representing the Langhian-Tortonian (middle-late Miocene) time interval. Considering the stratigraphic distribution of the calcareous nannoplankton species in the section, the age of the basaltic lava flow is determined to be Serravallian (middle Miocene). The basaltic rocks experienced only minor magmatic evolution and have a restricted compositional range. Analysed in situ major element contents (from electron microprobe analysis, EMPA) for minerals (plagioclase, olivine and clinopyroxene) hosted by the late Miocene basaltic rocks show that they originated in an intraplate setting. Geochemical analysis indicates that olivine have Fo (forsterite) compositions between 57.81% and 83.83%. The EMPA contents (primarily based on pyroxenes) suggests that the late Miocene volcanism was related to the Pleistocene Delihalil-Turunclu basaltic volcanism. The studied late Miocene volcanism could have originated in two possible tectono-magmatic environments: 1) one involving collisional tectonics (e.g., folding) combined with a change from regional compression to strikeslip; or 2) an intraplate setting. We propose that the tectonic setting of the late Miocene basaltic lava flow was similar to that of the extensive Pleistocene Delihalil volcanism in the same region. This would extend the onset of the regional basaltic volcanism back to the middle-late Miocene, rather than being restricted to the Pleistocene-Quaternary.