Isotope features (δ13С, δ18О) of continental carbonates from Permian and Triassic boundary deposits Northeast of Russian plate: paleoclimatic and biotic causes, chemostratigraphy

The carbon and oxygen isotopic composition were determined in pedogenic, sedimentary and organogenic carbonates of continental deposits of the Upper Permian (Vyatkian stage) and lower Triassic (Induan stage) of the northeastern part of the Moscow Syneclise. It is assumed that variations in 18О (18.0 29.1 SMOW) and 13С (-8.8 0.7 PDB) values in them could be associated with both regional climate fluctuations and perturbation of the global carbon cycle at the Permian and Triassic boundary. The decrease in 18О values in the pedogenic carbonates of the roof sequence of the Vyatkian stage, apparently, was due to the cooling in the northeast of the Pangea supercontinent. The negative excursion of 13С values at this stratigraphic level is correlated with a similar excursion found in the Paleo-and Neotetis marine carbonates and corresponds to the Late Permian biotic event.