Carbon isotope stratigraphy of the Tournaisian (Lower Mississippian) successions of NE Europe

Abstract Biostratigraphically constrained δ13Ccarb variations in the Tournaisian successions of NE Europe (Komi Republic, Russia) are considered. Eight reference sections, characterizing platforms, slopes, and shelf depression facies, comprise the basis of this study. Of 412 studied samples of bulk carbonates, 268 samples passed all of the screening tests and were used to analyze the carbonate carbon isotope record. The established regional δ13Ccarb data allowed the recognition of the distinct, terminal Famennian and mid-Tournaisian carbon isotope events and two minor positive shifts in the sulcata Zone and Upper duplicata—lowermost quadruplicata interval. The age of the isotope shifts is underpinned by conodont biostratigraphy. These isotope events and shifts are traced through the facies gradient from the shallow-water carbonate platform to deep-water shelf depression. Because the regional δ13Ccarb variations match those known in different regions (Europe, South China, and North America), the recognized C-isotope shifts can be considered to be reliable isotope-stratigraphic markers for both regional and world-wide correlation.