The Ostracod Fauna And Environmental Characteristics Of The Volcanosedimentary Yolüstü Formation In The Hınıs Region, Erzurum (Eastern Anatolia), Turkey

The volcanosedimentary Yolüstü formation which outcrops in the vicinity of Hınıs Town, the southeast of Erzurum City, consists of conglomerate, marl, agglomerate, claystone,tuffite, fragmented travertine limestone with fragments of sand ? pebble - plant, lacustrine limestone and tuffaceous ? clayey limestone. In this formation, carefully selected 3 measured stratigraphic sections were taken at levels in which the lithology of hard travertine limestones with plant fragments and soft tuffaceous ? clayey limestone are present. Washed samples which had been taken from these sections were studied and assessed, and then ostracods reflecting freshwater and brackish water environments were detected. In the unit, 5 genera and 12 species of ostracod and their taxonomies, which are generally peculiar to Ponto ? Caspian basin, were defined. Besides; few micro mollusks, and 2 genera and 1 species of gastropod and 1 species of pelecypod (non well preserved) were found from the recrystallized looking tuffaceous, clayey, consolidated, hard limestone levels. In sequence,genera and species types of osracod such as; Leptocythere (Amnicythere) cf. litiva Livental, Tyrrhenocythere bailovi (Suzin), Loxoconcha granulata Sars, L. cf. diligena Kulieva, L.agilis Ruggieri, Candona (Caspiocypris) araxica Freels, C. (Caspiocypris) erzurumensis Freels, C. (Caspiocypris) aff. alta (Zalanyi), C. (Typhlocypris) amblygonica Freels, C. (Candona) parallela pannonica Zalanyi, C. (Candona) burdurensis Freels, C. (Candona) candida (O.F.Müller), C. (Candona) sp. 1 Freels, gastropods like Valvata piscinalis (O.F.Müller), Viviparus sp. and genus and species types of pelecypod like Dreissena polymorpha (Palas) were defined. For the main fossil envrionmtents; Leptocythere and Tyrrhenocythere indicate the brackish water environment, Loxoconcha mesohaline, Candona (Caspiocypris), C. (Typhlocypris) oligohaline, Candona (Candona), Valvata,Viviparus and Dreissena indicate the freshwater environment.