Geologicheskii Vestnik

The Asselian Stage of the Cisuralian Series of the Permian System, established in the Southern Urals (section in the Uskalyk River basin), is divided into two horizons and combines three fusulinid zones. The horizons are distinguished based on biostratigraphic features and comparison with the fusulinid zonal scale. In the Ural Regional Stratigraphic Scheme, the lower (Kholodnolozhian) horizon is correlated with the two lower zones. The upper – Shikhan Horizon of the Asselian Stage of the Lower Permian is correlated with the upper Schwagerina (= Sphaeroschwagerina) sphaerica – Pseudofusulina (= Globifusulina) firma Zone of the fusulinid scale. The stratotype of the Shikhan Horizon is the Tra-Tau (Toratau) shikhan near Sterlitamak. However, in the stratotype section, the zonal assemblage of fusulinids is of little information. Zonal complex is represented by rare, scattered finds of a limited quantity of fusulinid species. A richer and more diverse assemblage has been studied at Kushtau shikhan. The extent of the Shikhan horizon has been substantiated based on a number of boreholes at Kushtau, in accordance with the boundaries of the upper fusulinid zone. The article provides images and brief descriptions of 14 taxa of fusulinids from the Shikhan Horizon, belonging to the genera Globifusulina, Grozdilovia, Rugosofusulinoides, Pseudochusenella, Schubertella, Schwagerina.

Asselian stage, Shikhanian Horizon, fusulinid zonation, shikhan Kushtau

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