Kimmeridgian

A detailed description of the Upper Jurassic formations of the south of the European part of Russia, mainly restricted by the Kimmeridgian and Volgian stages, is given. The characteristic of the reference section is provided for the Vechkusy Formation, and the neostratotype is proposed for the Novikovka Formation. The criteria for drawing the boundaries of local stratigraphic units (formations) and the features of strata distribution are considered in detail.

The analysis of the distribution of the Kimmeridgian–Volgian ostracods in the section near the village Valy made it possible to establish a sequence of eight communities, the change of which reflects changes in the ecological conditions in the basin. Changes in sea level fluctuations, the main physical and chemical parameters of the ostracod habitat – temperature, salinity of water, oxygen content in it, eutrophy and concentration of organic matter in sediment – are reconstructed. Information on the magnetic susceptibility and its increase after heating was obtained.