Ostracoda assemblage of pliensbachian aged "Ammonitico rosso Facies" around of kösrelikkızığı (Bağlum/Ankara)

The subject of this work is the research of ostracod assemblage of Ammonitico Rosso facies, which is represented by red, nodular and pelagic limestones and choronostratigaphic, paleoenvironmental, paleogeographic characteristics of this facies. This work intended to do chronostratigraphic and paleoenvironmental analysis of Ammonitico Rosso facies in Kösrelik and Kösrelikkızığı by using ostracods taken from the Ammonitico Rosso facies which is represented by Kösrelik Member of Bayırköy Formation. In this research, field studies were made, two mesured stratigraphic sections were drawn and laboratory work was done on the samples and at the end, after the samples were examined under the binocular microscope; their taxonomic, chronostratigraphic, biostratigraphic, paleoenvironmental and paleogeographic definitions were made. Finally, 13 ostracod genera namely Polycope, Cytherella, Ledahia, Ogmoconcha, Ogmoconchella, Bairdia, Lobobairdia, Isobythocypris, Ptychobairdia, Schuleridea, Liasina, Paracypris, and Tanycythere and 24 taxa was defined. With the help of 11 determined taxa, it is concluded that the age of Kösrelik Member to be Pliensbachien and that Ammonitico Rosso facies was situated in the shallow parts of Neotethys in Early Jurassic. Key Words: Ammonitico Rosso, Bayırköy Formation, Early Jurassic, Kösrelikkızığı, Kösrelik Member, Neotethys, ostracod, Pliensbachien