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Finding the Vendian-Ediacaran fossils in Oselok Group in the Sayan region of the Siberian Craton is the direct evidence for age of its stratigraphic analogous Taseeva, Baikal, Dal'nyaya Taiga and Zhuya Groups in peripheral foredeeps and Nepa Group at the base of Siberian Platform cover. The fossils were detected in the Uda and Biryusa rivers basin near the base of Oselok Group that is 2000-2500 m stratigraphicaly lower than the single instances in the Yenisei Mountain-Ridge and Baikal region. In the Marnya Formation of the Uda river basin two sequences separated by erosional boundary related to eustatic sea alterations were retraced. The lower sequence composed at the base by diamictite (Ulyakha tillite), faceted boulder breccia, glaciofluvial sandstone and cap dolostone with orthoquartzite strata in the upper part (Ozerki Member).
The upper sequence consist of shoreface arkose and orthoquartzite (ognit Member) and sandstone tempestites and tidelithes (Bol'shaya Aisa Member). Palaeontologic fossils are in two stratigraphic horizonts at middle part of Ozerki Member and lower-middle parts of Bol'shaya Aisa Member. Representative of ichnofacies Crusiana was found over laminated cap dolostone of Ozerki Member in quartzite , black pyrite bearing sandstone and aleurolite of underwater bar. Numerous ichnofossils Talassinoides and Planolites were the Metazoan have come first in shoreface environment. The moulds and prints of softbody animals from groups Radialia and Bilateria of COELENTERATA, PROARTICULATA, PETALONAMAE types are in Bol'shaya Aisa Member.
The idealy cycle medusoides printed on surface of tidal beds were the planctonic and belong to Cyclozoa and Inordozoa classes. The mass accumulation of fossils bentic nonsegmented volumetrical softbody organisms from Radialia and Bilateria groups was found in proximal storm sandstone. Redeposited by storm currents problematics cf. Dickinsonia Sprigg and organisms from PTERIDINIDAE family are more rare.
The marine deposits with Metazoa fossils in Marnya Formation and overlying Late Vendian continental molasse containing prints of problematics of Arumberia group on surface of levee beds extend broadly in south-western Siberian Platform. The continental molasse was accumulated in peripheral foreland basin followed in Early Cambrian (Nemakit-Daldynian Stage) to intracratonic evaporite sag basin. By chemostratigaphic correlation the first large sea transgression that bring in settling the Vendian-Ediacaran biota in the Siberian Platform took place after Marinoan glaciers melt out.
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