Strontium Isotopic, Ostracod fauna, and Paleoenvironmental Features of the Late Miocene Sequence in Mut/Dağpazarı Region (Southern Turkey)

Abstract

The primary focus of this study was the Dağpazarı village in the Mut region of Mersin, southern Turkey. In this research area, two stratigraphic sections were meticulously measured. The study conducted a comprehensive examination of the Middle-Late Miocene period in the Dağpazarı, Ballı, and Mut Formations by analyzing the ostracod fauna and utilizing strontium isotope chemostratigraphic dating. This research determined that the upper levels of the Mut/Köselerli formations, specifically from the Burdigalian to Serravallian, signify the commencement of the Miocene succession in the study area.The Dağpazarı Formation, characterized by abundant silty-clay, Ostrea fossils, and lignite layers, is deposited unconformably just above these levels.This formation contains the following ostracod taxa; Bairdia subdeltoidea, C. glypta, Cytheridea acuminata acuminata, Acanthocythereis hystrix, Krithe monosteracensis, Neomonoceratina mouliana, Hemicyprideis sp., Cistacythereis caelatura, Cyherella terguemi, T. prava, K. langhiana, A. ulicznyi, Pokornyella deformis minor, Loxoconcha alata, Tenedocythere salebrosa. Furthermore, the planktonic foraminifera species are; O. universa, Globigerinoides trilobus, Glb. ruber, Orbulina bilobata, Glb. sacculifer, O. suturalis, and the formation includes abundant bryozoa, echinoid spines, gastropods such as Terebralia at distinct levels, and fish otolith. The formation, dating from the late Serravallian to the early Tortonian, exhibits the shallow reef characteristics that continued to develop in the late Miocene.The formation consists of dark green, bulbous weathered claystone, Bairdia subdeltoidea and Ostrea which are reduced in size at the levels that pass into hard clayey sandstone, abundant benthic foraminifera with abundant echinoid spines. The formation consists of benthic foraminifera, hard clayey sandstone, and weathered dark green claystone, which contains numerous echinoid spines.Ostrea and Bairdia subdeltoidea are also present. The upper section of the analyzed succession concludes with silty, compact, clayey limestone layers and light-colored limestone bands. The Tırtar Ballı Formation, which conformably overlays the Dağpazarı Formation, signifies the culmination of a relatively recent reef formation during the Tortonian period.Ostracod species such as Aurila pigadiana, Thalmannia hodgii, Buntonia sublatissima dertonensis, Bairdia subdeltoidea, Aurila sp. Bassiouni have been defined. The limestones also contain abundant benthic foraminifera and echinoid spines. The 87Sr/86Sr ratio analyzed from the carbonate sample obtained from the Dağpazarı formation is 0.708920. Based on these isotope data, the age of the Dağpazarı formation was calculated to be 8.7 million years (Ma).