Early Frasnian (Upper Devonian) Genundewa Event in the Bolshaya Nadota River section of the Subpolar Urals (Russia)

Evidence of the Frasnian Genundewa Event at the FZ 2 – FZ 3 boundary interval has been detected in the facies of the isolated carbonate platform in Subpolar Urals. The preserved traces of the Genundewa Event represent micritic microlaminated carbonates, which manifests a short-term deepening episode in an extremely shallow water background. From the onset of this deep-water deposition there is a dominance of Polygnathus, Ancyrodella, and Mesotaxis whereas in the underlying shallow water deposits, the genus Polygnathus clearly predominated. No specific features of the Genundewa Event were observed in the C-isotope record. The mean δ13Ccarb value is approximately 2‰ in the event interval. The onset of the Genundewa Еvent corresponds to the beginning of Euro-American IIb-2 cycle and is correlated with the base of the Sargaevian regional substage of the Urals and Russian Platform, as well as the base of Poland IC cycle. This correlation confirms the global character of this event.