Mesozoic and Early Cenozoic Paleoecological Events in the Sedimentary Record of the NE Peri-Tethys and Adjacent Areas: An Overview

Resumo

Manifestations of short-term global and subglobal events have been recognized in the Mesozoic and Cenozoic sedimentary record of the North Caucasus: Paleocene/Eocene boundary PETM, late Cenomanian (OAE2), late Albian (OAE1c and OAE1d), terminal Aptian–early Albian (OAE1b), early Aptian (OAE1a), late Hauterivian (Faraoni), late Valanginian (Weissert), early Toarcian, late Pliensbachian, and others. The similarities and differences of their sedimentological, geochemical, and paleoecological characteristics were revealed during complex studies. Some events are characterized by both negative and positive carbon and oxygen isotopic anomalies. It was shown that most part of the paleoecological events occurred during the sharp sea-level fluctuations and was frequently accompanied by the accumulation of sediments variably enriched in organic matter (OM). The events were characterized by different-scale turnovers in the microbiota composition. Changes in microfossil assemblages allowed us to estimate the degree of perturbation of the trophic level of basins in response to the terrestrial influx of nutrients during marine transgression.