Isotope Characteristics (δ13C, δ18O) of Continental Carbonates from Permian‒Triassic Rocks in the Northeastern Russian Plate: Paleoclimatic and Biotic Reasons and Chemostratigraphy

Abstract

Carbon and oxygen isotope compositions were determined in the pedogenic, sedimentary, and organogenic carbonates from Upper Permian (Vyatkian Stage) and Lower Triassic (Induan Stage) continental rocks in the northeastern Moscow Syneclise. Variations of δ¹⁸O (18.0 to 29.1‰ SMOW) and δ¹³C (‒8.8 to 0.7‰ PDB) in them could be provoked both by regional climatic fluctuations and by perturbation of the global carbon cycle at the Permian‒Triassic boundary. Decrease of δ¹⁸O in pedogenic carbonates at the top of the Vyatkian Stage was likely caused by cooling on the northeastern side of Pangea. The negative excursion of δ¹³C values at this stratigraphic level correlates with the analogous excursion recorded in marine carbonates of the Paleo- and Neotethys and corresponds to the end-Permian biotic event.