Microfossil assemblages as key to reconstruct sea-level fluctuations, cooling episodes and palaeogeography: The Albian to Maastrichtian of Boreal and Peri-Tethyan Russia
Published:April 14, 2020
Valentina S. Vishnevskaya, Ludmila F. Kopaevich, 2020. "Microfossil assemblages as key to reconstruct sea-level fluctuations, cooling episodes and palaeogeography: The Albian to Maastrichtian of Boreal and Peri-Tethyan Russia", Cretaceous Climate Events and Short-Term Sea-Level Changes, M. Wagreich, M. Hart, B. Sames, I. O. Yilmaz
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The 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.
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Cretaceous Climate Events and Short-Term Sea-Level Changes
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Sea-level constitutes a critical planetary boundary for both geological processes and human life. Sea-level fluctuations during major greenhouse phases are still enigmatic and widely discussed in terms of changing climate systems. The geological record of the Cretaceous greenhouse period provides a deep-time view on greenhouse-phase Earth system processes that facilitates a much better understanding of the causes and consequences of global, geologically short-term, sea-level changes. In particular, Cretaceous hothouse periods can serve as a laboratory to better understand a near-future greenhouse Earth. This volume presents high-resolution sea-level records from globally distributed sedimentary archives of the Cretaceous involving a large group of scientists from the International Geoscience Programme IGCP 609. Marine to non-marine sedimentary successions were analysed for revised age constraints, the correlation of global palaeoclimate shifts and sea-level changes, tested for climate-driven cyclicities, and correlated within a high-resolution stratigraphic framework of the Geological Timescale. For hothouse periods, the hypothesis of significant global groundwater-related sea-level change, i.e. aquifer-eustasy as a major process, is reviewed and substantiated.