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Geochemical and isotopic (Sm–Nd and Sr) studies of deposits of the Baikal and Oselok Groups in the southern Siberian Craton and LA-ICP-MS U–Pb dating of detrital zircons show that they accumulated in passive continental-margin settings in the Vendian. The time limits of sedimentation were assessed on the basis of Sr chemostratigraphy of carbonate deposits of the Baikal Group and LA-ICP-MS U–Pb dating of detrital zircons in first-cycle terrigenous deposits of the Oselok Group. The main provenances for rocks of these groups were constant. These were rocks of the cover and basement of the Siberian Craton. Tuffite horizons in upper portions of the groups are the only sign of Late Vendian activation of this block, which is reflected in changes of geochemical indices of terrigenous rocks and their younger Sm–Nd model ages.

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The carbonate sediments from the Vendian–Cambrian shelf of the Tuva-Mongolian microcontinent were dated by Sr and C isotope chemostratigraphy. Analysis of the Sr-isotopic characteristics (0.70725–0.70873) and δ13C variations (+10.5 to –3.5‰), as well as their comparison with the data on the key sections of Siberia, Africa, Central Asia, Australia, South America, and Spitsbergen, showed that the carbonate sedimentary cover of the Tuva-Mongolian microcontinent accumulated at 600–520 Ma and the carbonate sediments of the Muren Formation and the basal beds of the Bokson Group near the Ukha-Gol River are the oldest. Their sedimentation followed the Marinoan global glaciation.

Felsic rocks of the Khamsara terrane in Tyva (southern Siberia) have been studied in terms of major- and trace-element compositions and U–Pb isotope geochronology. The Khamsara Formation rocks have compositions of A2-subtype within-plate anorogenic volcanics derived from molten continental crust and SIMS U–Pb zircon ages of 463.9 ± 2.8 and 461.7 ± 3.1 Ma of two rhyolite porphyry samples. The Khamsara volcanics are compared with subvolcanic granitoids of the Ognit complex in the Biryusa terrane (Sharyzhalgai basement inlier of the Siberian craton) adjacent to the Khamsara terrane. The volcanics and the granites are coeval and share compositional similarity. The Khamsara Formation is interpreted as a cap complex that marks the upper age bound of the accretionary-collisional events when amalgamated terranes in this part of the Central Asian orogen accreted to the Siberian craton.

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