Late Mississippian (early Serpukhovian) carbon isotope record of northern Laurussia: A proposal for the Viséan/ Serpukhovian boundary

The fauna provincialism in the interval led to the appearance of some problems with the tracing of this boundary with biostratigraphic methods. Therefore, it is important to determine auxiliary non-biostratigraphic markers of the boundary. The article is focused on the evaluation of the correlation potential of carbon isotope excursions near the Viséan/Serpukhovian boundary, with special attention to the northern Laurussia region. The biostratigraphically constrained carbon isotope record is revealed from the terminal Viséan ‑ lower Serpukhovian (Mississippian) shelf successions of the northern Laurussia (six key sections located in the north of Urals and Cis-Urals, NE Europe). Onset of a negative excursion in the middle part of the Lochriea ziegleri conodont Zone (lower Serpukhovian) shows amplitude of 1–2‰ and high spatial stability, and can be used as a stratigraphic marker in regional and global correlations.