Paleobathymetric Zonation of the Middle–Upper Jurassic Deposits in the Ulyanovsk–Saratov Trough (Russian Platform) Based on Benthic Foraminifers

Resumo

The environments, favorable for the development of benthic microfauna were predominant in the Jurassic Sea in the northeastern part of the Ulyanovsk–Saratov Trough (Russian Platform). Such parameters as the distribution and the taxonomic composition of the assemblage of Jurassic benthic foraminifers, their abundance, generic and species diversity, the occurrence of new species, a ratio of species with agglutinating and calcareous shells serve as a basis for developing the paleobathymetric zonation of the basin. The tracing of the variations in these parameters through the section enables us to construct a quantity paleobathymetric curve for the Middle-Late Jurassic and to distinguish the sequence–stratigraphic elements.