Early-Middle Frasnian (Late Devonian) carbon isotope Event in the Timan-Pechora Basin (Chernyshev Swell, Pymvashor River section, North Cis-Urals, Russia)

Authors

  • Ivan S. Kotik Institute of Geology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences. Pervomaiskaya 54, Syktyvkar 167982, Russia
  • Andrey V. Zhuravlev Institute of Geology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences. Pervomaiskaya 54, Syktyvkar 167982, Russia
  • Tatyana V. Maydl Institute of Geology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences. Pervomaiskaya 54, Syktyvkar 167982, Russia
  • Dmitry A. Bushnev Institute of Geology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences. Pervomaiskaya 54, Syktyvkar 167982, Russia
  • Irina V. Smoleva Institute of Geology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences. Pervomaiskaya 54, Syktyvkar 167982, Russia

DOI:

https://doi.org/10.1344/GeologicaActa2021.19.3

Keywords:

Late Devonian, Punctata Event, Carbon isotopes, Biomarkers, Conodonts

Abstract

Details of the Early-Middle Frasnian boundary interval of the Pymvashor River section (Timan-Pechora Basin, Cis-Urals, in the far north of European Russia) are revealed by biostratigraphically constrained carbonate (δ13Ccarb) and organic carbon (δ13Corg) stable data. The studied interval corresponds to the lower part of the Domanik Formation, which consists of interbedded limestone and shale beds. Organic-rich black shale that lacks bioturbation and benthic organisms indicates an oxygen-depleted depositional environment. Detection of isorenieratene derivatives in organic matter indicates that anoxia was present in the photic zone during deposition. The Pymvashor River section contains δ13Ccarb and δ13Corg isotope records related to the Early-Middle Frasnian isotope Event. The similarity between the Cis-Uralian (this study) and the Chinese δ13Ccarb and δ13Corg oscillations, including the twostep pattern of the recorded major positive excursions, suggests a robust correlation of the Late Devonian Early- Middle Frasnian isotope Event and minor intra-event excursions. Magnitude of variations and values of δ13Corg and δ13Ccarb in the punctata Zone in the Pymvashor River section are minor than those observed in the North American, Polish, and Chinese successions. Such difference may reflect specific variation of the local environments.

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Published

2021-07-26

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