Ostracodes from the devonian-carboniferous boundary deposits on the reference section Yjid-Kamenka river (Pechora uplift)

This article presents new data on ostracodes and their stratigraphic distribution in the boundary deposits of the Devonian and Carboniferous (D3-C1) in the reference section Kamenka River (Pechora Uplift). The positions of the Kamenka River section and stratotypic sections of the southern Urals relative to the transgressive-regressive sequence are considered. The ostracode assemblage of the Ps. venulosa - Cor. alba - Cr. primaris zone, which occurs in the section on the Kamenka River and appears in sections of the southern Urals from the base of this zone, is represented by the following taxa: Pseudoleperditia venulosa (Kummerov), Coryellina alba Kotschetkova, Bairdia zaninae Posner, Blessites feluyensis Tschigova, Shishaella alekseevae Tschigova, Knoxiella complanata (Kummerov), Cavellina subeichwaldi Buschmina. The taxonomic characteristics of the upper part of the Pseudoleperditia venulosa - Coryellina alba - Cribroconcha primaris ostracode zone (Gumerovian Regional Substage (Horizon)) are supplemented Acratia subordinaria Buschmina, Healdianella ex gr. alba Lethiers, Phlyctiscapha ? pusilla Gurevitsсh, Pustulobairdia ex gr. confragosa (S. et Sm.), Acanthoscapha pechorica Sobolev, Acratina romboiformis Sobolev, and Rectobairdia eleganta Sobolev first appear at this level A gradual and insignificant change in the ostracode association is observed during the transition from the Gumerovian Horizon to the Malevkian Horizon, which precludes drawing the boundary between them. It is suggested that it would have been more appropriate to draw the boundary at the base of the global Hangenberg transgressive event near the base of the Ps. venulosa - Cor. alba - Cr. primaris ostracode zone (South Urals), which coincides with the initial phase of this transgression.