Cretaceous palaeogeography of the North-Eastern Peri-Tethys

The Cretaceous stratigraphy and main palaeogeographic features of the North-Eastern Peri-Tethys are briefly summarised on the base of new data. The study is mainly focused on the time-slices that were chosen for the recently published Peri-Tethys Atlas: Early Hauterivian, Early Aptian, Late Cenomanian, Early Campanian and Late Maastrichtian. Two main epochs in the development of this area are recognised. The Early Cretaceous is characterised by the prevalence of the terrigenous sedimentation and the existence of a large longitudinal strait through the Russian Platform, which controlled the Boreal/Tethyan connection. The southward Boreal water movement prevailed during the Neocomian. The strongest Boreal transgression took place in the Late Hauterivian, when cool water reached the Crimea basin. The Aptian–Albian time was characterised by a northward Tethyan water movement, interrupted by the Early Albian Boreal transgression. Tectonic rebuilding of the region took place in the Albian–Cenomanian. It resulted in the disappearance of the sea-strait through the Russian Platform and in the opening of another sea-strait in the Turgai area in the Turonian. This strait connected the Peri-Tethyan seas, the Western Siberia Boreal basin and joined with the Western Interior Seaway in the other side of the Hemisphere. The Northern Hemisphere Megastrait appeared. During this time mainly carbonate sedimentation prevailed, but the existence of a new longitudinal strait determined a two-way water and faunal exchange. Tethyan water moved up to the south and the south-east parts of the Western Siberian basin, while the cold Boreal water influence can be recognised along the northern margin of the Russian Platform basin.