Cosmopolitan foraminiferal assemblages from Jurassic deposits of Central Turkey

Foraminiferal assemblages from the Jurassic Alacaatli section of Central Tu rkey are studied. The section of the reference type for the Ankara region r epresents a transgressive rock succession spanning the time range from the Upper Jurassic to the Valanginian. The Jurassic carbonate-siliceous rocks o f the section are characterized by diverse foraminiferal assemblages that i nclude both benthic and planktonic species. The occurrence of characteristi c benthic foraminiferal genera and species, together with the zonal plankto nic species Globuligerina oxfordiana (Grigelis) allows these deposits to be correlated within the Oxfordian in general and to distinguish separate sub stages and foraminiferal zones. The peculiar feature of the considered asse mblages is their composition represented by cosmopolitan forms without any endemic Tethyan species. Paleoecological peculiarities of these biocoenoses indicate that foraminiferal communities lived in deep open-marine environm ents. This is also confirmed by the composition of radiolarian assemblages coexisting with foraminifers.