A strontium isotopic, petrographic, and Ostracoda biostratigraphic study of Middle-Late Miocene sequences: implications of record in the Silifke-Erdemli/Mersin, southern Turkey


Şafak Ü. , Nurlu N.

ARABIAN JOURNAL OF GEOSCIENCES, cilt.11, 2018 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

In this paper, we present new data on Ostracoda micropaleontology, strontium isotopic ages, and petrology of the Miocene sequences in the Silifke-Erdemli area (Mersin/S. Turkey). Ostracods were investigated in the Middle and Late Miocene units, which are composed of clayey limestone and marl levels, reef limestones, and clay. Fifty-six ostracod species were identified, and a total of two initial levels were defined, one beginning in the Langhian stage, and the second at the end of the Serravallian and beginning of the Tortonian stage. The initial level of the Langhian stage is represented by the Carinocythereis, and the end of the Serravallian-beginning of the Tortonian stage is characterized by the initial level of Cyprideis. These levels have also been compared with other regions in the same stratigraphic levels in Turkey (Adana, Antakya, Mut, Denizli, and Antalya regions) and in areas around Turkey (Egypt, Italy, Greece, Croatia, and other Tethys-Paratethys regions). In addition, the levels identified in this study were also correlated to the planktonic foraminiferal zones identified for this region. The ostracod species identified are Carinocythereis at the initial level and subsequently, Cytherella postdenticulata Oertli, Grinioneis haidingeri minor (Ruggieri), Pokornyella deformis minor (Moyes), Carinocythereis antiquata (Baird), and Paracypris polita Sars; also, the other ostracod species are an initial level of Cyprideis followed by Cyprideis seminulum (Reuss), C. torosa (Jones), Cytheridea acuminata acuminata Bosquet, Miocyprideis sarmatica (Zalanyi), Neomonoceratina interiecta Bonaduce, Ruggieri, Russo and Bismuth, Schneidrella dromas (Schneider), and Krithe monosteracensis (Sequenza). Detailed petrographic analyses were carried out on the studied units. This analysis revealed that the reef limestones are composed of sandy intraclast-biomicrites, intra-packed biosparite, intra-packed biomicrite, microintra-packed micrite, and bioclastic-intramicrites; clayey limestones were rare clayey biomicrites and clayey intraclast-biomicrites. The main purpose of the study was to evaluate micropaleontological samples from the Miocene sequence based on ostracods and strontium dating to determine the precise age ranges. The Sr-87/Sr-86 ratios obtained from three samples of the limestones range between 0.708849 and 0.708902 and between 0.708868 and 0.708902, respectively. The Miocene sequences have been calibrated to range in age from 9.7 to 11.4 Ma via the strontium isotope ratio.