TREPOSTOME BRYOZOANS FROM THE LOWER CARBONIFEROUS DEPOSITS IN THE SOUTHWESTERN WEST SIBERIAN PLAIN

Z. A. Tolokonnikova

Diverse trepostome bryozoans are found in the Upper Tournaisian-Lower Viséan (Lower Carboniferous) deposits uncovered by the Kurgan-Uspenskaya 1 well. It is located within the Uvat structure-facies region (southwestern part of the West Siberian Plain). During the Early Carboniferous the investigated territory was represented by a shelf of the Kazakhstan continent. The bryozoan assemblage includes seven known species such as Triznotrypa tenuilignata (Trizna, 1958), T. ramosa (Balakin, 1975), Crustopora aff. lubrica (Trizna, 1958), Tabulipora corticosa Nekhoroschev, 1956, Dyscritella aff. tenuata Dunaeva, 1964, Leptotrypa crista Troizkaya, 1975, Tabuliporella cf. mosjuchensis Trizna, 1958 and three new species: Triznotrypa uvatica sp. n., Crustopora elegans sp. n., Eostenopora carbonica sp. n. The trepostome species such as Tabulipora corticosa Nekhoroschev, 1956 and Triznotrypa ramosa (Balakin, 1975) are specifi c markers for the Late Tournaisian-Early Visean ages. The most similarity of the Early Carboniferous trepostome bryozoans in the southwestern part of Western Siberia is determined with coeval complex of the Kuznetsk Basin. Faunal similarity between these regions coincides also with data on foraminifers and brachiopods.

Key words: bryozoans, Early Carboniferous, Western Siberia.

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