paleoecology

As a result of the complex analysis of petromagnetic, micro- and macrofaunistic data of deposits on the Kallovian – Oxfordian boundary of Dubki section (Saratov), which is one of candidates for a role of a Global Boundary Stratotype Section and Point of Oxfordian boundary (GSSP), it is established significant correlation between magnetic susceptibility variations and changes of an abundance, a specific variety of ostracodes, foraminiferes and ammonites.

The results of the paleoecological analysis on ostracods of the upper part of Sultanovskaya Formation (Boissieri zone) in the section near v. Alekseevka are presented. Five ostracod assemblages reflecting changing conditions in the paleobasin are defined. It was established that the sedimentation in the Late Berriasian time occurred under conditions of a warm normally salty with a calm hydrodynamic regime of the basin, mainly in oxygen waters.

The paper analyzes the taxonomic composition and the habitat of the representatives of the Middle – Late Cenomanian and the Middle Turonian marine biota. The examined fossils have been isolated from the bulk sample obtained from the phosphorite horizon lying in the bottom of the Middle Turonian carbonate rocks in the Senomanskaya Stenka section (Volgograd Region, Zhirnovsk district).