Frasnian age (upper devonian) key section biostratigraphic characteristic of Voronezh anteclise middle part (well 16, Schigry, Nizhnekrasnoe village, Kursky region)

Conodonts, scolecodonts, and foraminifers were studied from Frasnian age deposits of Well 16 Schigry (Nizhnekrasnoe village, Voronezh anteclise). Six conodont complexes are identified: I in Timan regional stage, II and III in Sargaevo regional stage, and IV and VI in Semiluky regional stage. Correlation by local zonal units and Standard Conodont Zonation is performed. Shallow environment is confirmed for Timan regional stage, the deepest environment settings is confirmed for Semiluky regional stage. Five scolecodont complexes are identified: complexes 1 and 2 for Sargaevo regional stage, complexes 3 and 4 for Semiluky regional stage, and complex 5 for the upper part of Semiluky regional stage and Voronezh regional stage. Foraminifers are presented by two complexes: first for Sargaevo regional stage and the second for the Semiluky regional stage. The characteristic microfossils species are given in plates.

Conodonts and ostracodes from the late Tournaisian bathyal sequence of the Polar Urals

Early Carboniferous (late Tournaisian) conodonts, recovered from siliceous shales and silicites of the Nyan- Vorga Formation within the Lemva tectonic belt of the Polar Urals (Russia), include the biostratigraphically important taxa Siphonodella lanei, Gnathodus typicus, Dollymae hassi, and Scaliognathus anchoralis, marking the following conodont zones of the upper Tournaisian: crenulata, typicus, and anchoralis. Associated species include representatives of genera Siphonodella, Polygnathus, Pseudopolygnathus, Dollymae, Gnathodus, Kladognathus, and Idioprioniodus. These conodont faunas provide the first biostratigraphically constrained correlations between bathyal deposits of the Lemva Allochthone in the Polar Urals and the “standard” conodont zonation. Ostracodes found in the silicite of the typicus Zone are represented by Sagittibythere ? sp. and Tricornina (Bohemia) sp. The ostracodes are reported from the bathyal deposits of Urals for a first time. The traces of the global Mid-Aikuanian Event are recognized in the upper part of the Tournaisian bathyal succession. This event led to turnover in conodont associations and is followed by increasing in conodont diversity.