Microfossil assemblages as key to reconstruct sea-level fluctuations, cooling episodes and palaeogeography: The Albian to Maastrichtian of Boreal and Peri-Tethyan Russia

Abstract

AbstractThe main palaeogeographic features of the Late Cretaceous Eastern European Platform and its southern framework are reconstructed mainly based on micropalaeontological data. An integrated foraminiferal–radiolarian zonation for the Upper Albian–Maastrichtian serves as a basis for palaeogeographic reconstructions and as a framework for the interpretation of palaeoclimate and sea-level trends. The study focuses on time slices of late Albian–Cenomanian, Turonian–Coniacian and Santonian–Campanian intervals. The late Albian was characterized by the gradual disappearance of a meridional seaway and the opening of connections into the Tethys Ocean and parts of the Peri-Tethys seas during the Cenomanian. As a result, mainly carbonate sedimentation prevailed during middle Turonian–Santonian times, characterized by high global sea-level. A cold Boreal water influence can be discerned not only along the northern margin of the Eastern European Platform, but as far south as the Northern Caucasus during certain time intervals, particularly during the Campanian. The Western Siberia Boreal Basin also influenced the study area, giving evidence of cooler-water episodes through the Palaeo-Ural territory and the Turgai Seaway.