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The Ulyakha terrestrial tillite, the associated Nersa boulder conglomerate, Plity and Karachun faceted boulder breccia and outwash sandstone make up a four-cycle glacigenic succession of Marnya Formation in the base of Oselok Group in the north-west Sayan region of the Siberian Craton. The remains of Late Neoproterozoic glaciation was detected in addition in Yenisei Mountain-Ridge, south-east Sayan region, Baikal region, Patom Upland and central parts of the Siberian Craton. The erosive contact of the Ulyakha diamictite with grooves, gully and valley on the underlying sandstone, dolomite, chert and dolerite of the Middle Neoproterozoic Karagassy Group was mapped in the sides of the Uda river. The total erosion depth at this region approaches 1000 m. Two types of Ulyakha tillite were detected in the Sayan region. The dolomite tillite include predominant dolomite clasts and matrix from underlying Tagul Formation and argillaceous one with predominant arkose and orthoquartzite clasts from Ipsit Formation. The last contain the rare erratic granite, gneiss and schist boulders from basement of central part of the Siberian Craton. The granite clasts are prevailing in the stratigraphic analogy of Ulyakha tillite at the base of Baikal and Dal'nyaya Taiga Groups in Baikal region and Patom Upland. The main glacier by current marks in outwash alluvial fans and turbidites in deep sea fans and lodgement stones in terrestrial gullies has been located in the central part of the Siberian Craton and has sliped into ajacent seas.
The glacial event can be equated to the Marinoan glaciation for the following reasons: (1) obviously highed stratigraphic position of the Ulyakha tillite relative than the Kharlukhtah diamictite in the Patom Upland and Chivida diamictite (tillite) in the Yenisei Mountain-Ridge constrained by the coeval ca. 700 Ma volcanism; (2) occurrences of Vendian-Ediacaran Metazoan ichnofossils in cap dolostone; (3) postglacial regional transgression and correlation of related Bol'shaya Aisa terrigenous deposits containing Vendian-Ediacaran Metazoan moulds with the Nepa Group containing Pertatatak microfossils; (4) evidence that the Ulyakha tillite is stratigraphically lower that the Gackiers tillite provided by correlation of the Aisa syncollisional molasse in Greben regional stratigraphic horizont with sulphate-carbonate Oskoba Formation, the latter is marked by an intense δ13C low that correlates with the Zhuya (Siberian Craton) and Wonoka (Australian Craton) δ13C anomalies; (5) position of the δ13C positive anomaly in the Peschernaya Member (Uda Formation) below the Gaskiers glaciation confirmed by the 87Sr/86Sr ratios which are lower than those in the Wonoka Formation and in the correlated Shuram Formation: 0.70796-0.70848 against 0.7087-0.7085-0.7088, respectively; (6) late postglacial tectonothermal events in terranes in time of the accretion to the craton south-west at 600-550 Ma.
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