New data on Volgian foraminifera (eastern part of Russian platform)

In this paper, results of a comprehensive study of the elemental composition, carbon (d13С) and oxygen (d18О) isotopes, and of the Mg/Ca ratio in tests of foraminifera of families Lagenidae and Ceratobuliminidae with the aim to find out their ecological specialization are presented. It has been shown that the probable habitat of Ceratobuliminidae was the surface of soft sediment but Lagenidae preferred to settle in the sediment.