The paper presents new data on the composition of Late Paleozoic terrigenous and volcanogenic-terrigenous rocks of the Upper Devonian-Lower Carboniferous Tocher formation of the Bagdarin synform (Western Transbaikalia). The authors consider petrographic and lithogeochemical features of the rocks, and clarify the conditions of depositional environment, source area, and tectonic settings that controlled sedimentogenesis. It has been established that terrigenous rocks of the Tocher formation were formed from decomposing igneous and volcanogenic rocks. The petrographic and lithogeochemical characteristics of the Late Paleozoic sedimentary rocks of the Tocher formation make it possible to classify them as greywacke, arkose, tuffaceous and silt sandstones. The distribution of petrogenic oxides, as well as rare and rare-earth elements, together with the results of petrographic studies of thin sections indicate that mixed (felsic, intermediate, mafic) magmatic rocks were decomposed in the source area. The sediments in the first member of the Tocher formation, were predominantly derived from felsic source rocks, and those in the second and third members – from mafic and intermediate source rocks. The Riphean island-arc volcanics of the Usoy and Burom formations, as well as gabbro-diorites and diorites composing the Shaman basement protrusion of the Bagdarin synform, are presumed to be the main source of clastic material. Another source area at that time could be a magmatic arc, as evidenced by the volcanomictic composition of terrigenous clastic rocks and the presence of pyroclastic rocks. The sedimentary complexes of the Tocher formation were formed in a deepening basin adjacent to the volcanic zone. Sedimentation took place in conditions of the continental slope and its foot, against the background of the growth of paleobasin-border uplifts. These conclusions are in agreement with the previous ideas that the Tocher formation accumulated in the geodynamic environment of an active Andean-type continental margin, concurrently to the formation of the Kydzhimite supra-subduction volcanic zone and the Tocher rear trough-fill graywacke turbidite system at the end of the Late Devonian-beginning of the Early Carboniferous between the Siberian Continent and the Mongol-Okhotsk Ocean.

We present new data on the composition and U-Pb (LA-ICP-MS) age of detrital zircons from the Carboniferous sedimentary rocks of the Siberian Platform cover, in which diamonds and accessory minerals were found, namely, the Baeronovka Formation in the southwest and the Tushama and Kata formations at the center of the Siberian Platform. The geochemical characteristics and results of analysis of minerals of the heavy fraction from the Baeronovka Formation indicate a predominantly felsic composition of the provenance rocks. The latter are, most likely, the rocks of the Cis-Sayan uplift of the Siberian Platform basement, including mostly Paleoproterozoic granitoids and volcanic rocks of the South Siberian postcollisional magmatic belt. Smaller amounts of detrital material got into the sedimentation basin of the Baeronovka Formation through the destruction of early Paleozoic rocks at the northern segment of the Central Asian Orogenic Belt. The geochemical characteristics of the terrigenous rocks of the Carboniferous Tushama and Kata formations testify to a felsic composition of the provenance rocks, but the mineral compositions of the heavy fractions indicate different compositions of these rocks. These data and the age of detrital zircons suggest that the Neoproterozoic sedimentary rocks and middle Paleozoic igneous rocks of the Baikal-Patom zone on the southern margin of the Siberian Platform and the Middle Paleozoic igneous rocks of the Vilyui rift and the Yakut diamondiferous province are the main provenances for the Tushama and Kata formations. The established differences in the composition and age of provenance rocks for the Carboniferous sandstones of different areas of the Siberian Platform confirm the earlier conclusions about the existence of several local sedimentary basins within it in the Devonian-Carboniferous. These basins formed after the middle Paleozoic tectonomagmatic activity accompanied by diamondiferous lamproite and kimberlite magmatism.

The paper presents the results of the integrated study of the features of geological structure of the southeastern Kamo arch of the Baikit anticlise. Use has been made of both already published and unpublished geological-geophysical data obtained through seismic survey using the common depth point (CDP 2D) and the side view seismic location (SVSL) methods. The conducted research made it possible to improve understanding of the geological structure and formation conditions of the terrigenous-carbonate rocks of the Lower Riphean (Madrа, Yurubchen and Dolgokit formations) and Vendian (Vanavara and Oskoba formations) Kamo Group in the southern Kamo arch of the Baykit anticlese in terms of the prospects for the discovery of hydrocarbon (HC) deposits therein. The interpretation of seismic data (CDP and SVSL) provided the possibility to specify the thickness of the Lower Riphean terrigenous-carbonate rocks, most promising for hydrocarbons, to generate the predictive geology map of the pre-Vendian erosion surface, and to map the HC-promising Early Riphean and Vendian deposit thickness. Along with the previously explored large HC deposits in the central Kamo arch of the Baykit anticlise, the new data presented here testify in favor of the structural-and tectonic conditions for the development of the Lower Riphean and Vendian rocks on the southeastern slope of the Kamo arch of the Baykit anticlise and imply their high potential.

Data on petrography, chemistry, and U-Pb ages of detrital zircons have been obtained for clastic sedimentary rocks within the Sayan regional stratigraphic stage from different parts of the southern Siberia craton, namely for the Ust'-Tagul (Biryusa zone, Sayan area), Shamanka (Irkut zone, Sayan area), Ushakovka and Kurtun (Baikal area) formations. The sedimentary strata share much similarity in lithofacial patterns, with gradual transition from continental to shallow -marine facies. The analyzed lithic sandstones have poorly to moderately sorted clastic grains, with large percentages of lithic fragments (16-37 %). The lithic sandstones from different formations were deposited in continental and deltaic settings as a result of clastic transport from different provenance lithologies. The clastic material for the Ust'-Tagul Fm. deposition came from the Precambrian rocks of the Siberian craton and the Neoproterozoic (870-940 Ma) units: either the Yenisei Ridge of the craton or the Arzybey terrane of the Central Asian Orogenic Belt (CAOB). For the Shamanka Fm., it was Ediacaran and Early Cambrian material from blocks and terranes of the northern CAOB. The clastic inputs for the Ushakovka and Kurtun Fms. deposition were from the Precambrian basement of the Siberian craton and the Neoproterozoic (550-920 Ma) North Transbaikalian group of CAOB terranes. The youngest detrital zircons have the earliest Cambrian ages (530-540 Ma). The clastic sedimentary rocks of the Sayan regional stratigraphic stage dispersed over the southern Siberian craton were deposited in the earliest Cambrian in separate disconnected sedimentary basins which resulted from Ediacaran accretionary-collisional events in southern Siberia.

—We present new data on the chemical composition of the late Precambrian rocks in the upper part of the regional Balaganakh stratigraphic horizon (the Nugan Formation at the Baikal segment of the Sayan–Baikal–Patom belt (SBPB) and the Bugarikhta Formation of the Balaganakh Group at the Patom segment of the SBPB) and the U–Pb (LA-ICP-MS) age of detrital zircons from the Bugarikhta Formation. It has been established that the rocks of the Nugan and Bugarikhta formations resulted from the destruction of igneous and metamorphic rocks. The contents and ratios of trace and rare-earth elements in the rocks of the Nugan and Bugarikhta formations indicate a predominance of felsic igneous rocks in the provenance and the presence of rocks of mafic and intermediate compositions at the source of the terrigenous rocks of the Nugan Formation. The U–Pb age of detrital zircons from all rocks of the upper part of the regional Balaganakh Horizon is close to the age of the rocks in the basement of the southern margin of the Siberian Platform, which suggests that this basement was the main source of clastic material in the sedimentation basins. It is argued that the “pre-glacial” (pre-Marinoan) terrigenous deposits of the Nugan and Bugarikhta formations, as well as the deposits of the Ipsit Formation at the Sayan segment of the SBPB, accumulated in the Late Riphean (ca. 720–640 Ma), probably in postrift basins that formed immediately after the separation of Siberia from Laurentia at the early stages of the opening of the Paleoasian Ocean.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070048

Petrographic, geochemical and U-Pb geochronological research studies are done into cataclastic granitoids of the southeastern part of the Irkutsk block of the Sharyzhalgay basement uplift of the Siberian craton – the uplift which is considered southern part of the Tungus superterrane according to most of tectonic schemes. The representative sample of these granitoids corresponds to granodiorite in its geochemical properties and is characterized by high contents of Al 2 O 3 , Th, Sr, Ba, low concentrations of K 2 O, Nb, Y, Yb, a highly fractionated rare earth elements pattern (La n /Yb n =284), and the absence of europium anomaly. U-Pb geochronological studies of zircon from cataclastic granodiorite were carried out independently by two methods: SIMS and LA-ICP-MS, which showed good consistency of the results. The U-Pb age of the cores of zircon grains with magmatic zoning corresponds to 2893±19 Ma (SIMS method) and 2889±16 Ma (LA-ICP-MS method). These results can be interpreted as the age of the Archean granodiorite protolith. The rims of zircon crystals with the Archean cores, as well as the individual zircon crystals with parallel zoning, yielded ages of 1855±6 Ma (SIMS method) and 1864±5 Ma (LA-ICP-MS method), which record the time of granodiorite transformations. The age of about 1.86 Ga corresponds to the main Early Proterozoic stage of metamorphism, migmatization and magmatism, which show their widespread occurrence in the Sharyzhalgay basement uplift. This age estimate together with the previously published ages for metamorphic and their synchronous magmatic events in the Sharyzhalgay uplift allowed concluding that the Tungus superterrane joined the earlier formed core of the Siberian craton in the time interval 1.85–1.88 Ga. The final stage in the Siberian craton formation is the development of the South Siberian post-collisional magmatic belt, intersecting all large Early Precambrian blocks of the southern part of the Siberian craton, already united into a single structure.

—We present results of petrographic, geochemical, and isotope-geochemical (Sm–Nd) studies of the Paleoproterozoic terrigenous rocks of the Urik–Iya graben, which formed during three successive stages of extension. We have established that these rocks are both petrogenic (Ingashi and Daldarma formations) and lithogenic (Ermosokha Formation) sediments. It is concluded that the rocks in the lower and, partly, middle parts of the Urik–Iya graben section (Ingashi Formation and Lower Daldarma Subformation) resulted mostly from the disintegration of felsic igneous rocks. The terrigenous rocks in the middle part of the section (Upper Daldarma Subformation) might have formed through the disintegration of both felsic and mafic igneous rocks. The rocks in the upper part of the section (Ermosokha Formation) probably formed from the underlying terrigenous rocks of the Ingashi and Daldarma formations. The Nd model age (2.3–2.5 Ga) estimated for the rocks of the three studied sections points to a predominance of rocks of the Neoarchean and Paleoproterozoic upper continental crust in the provenance.

This paper presents the results of petrographic, lithogeochemical, and U-Pb geochronological studies of detrital zircons in deep core sediments from the Vendian terrigenous sequences of the Nepa and Tira formations in the interior of the Siberian Platform. The section of the Nepa formation is characterized by a terrigenous sediment, the Tira Formation is composed mainly of carbonate rocks. The terrigenous rocks of the Nepa formation are composed of ill-sorted and poorly rounded clasts. Towards the higher part of the section of the Tira formation, there is observed an increase in the degree of sorting and roundness of detrital grains. It has been established that clastic rocks of the lower Nepа subformation are the products derived from rocks of mixed (acidic, basic) composition. The terrigenous rocks of the upper Nepa Subformation and the Tira formation accumulated mainly due to acid decomposition of rocks. The U-Pb (LA-ICP-MS) geochronological studies of detrital zircons from terrigenous rocks of the Nepa and Tira formations led to the conclusion that the sedimentary basin of these formations was contributred to by both the Archean-Early Proterozoic rocks in the basement of the Siberian Platform and the adjacent areas of the Central Asian foldbelt. It is assumed that the sediments of the lower Nepa subformation deposited in the residual basin, formed by joining of terrains and island arcs in the Paleoasian Ocean to the southern margin of the Siberian Platform during the Vendian accretionary-collisional events. This was followed by a transformation into a peripheral sedimentary basin and an occurrence of a transgression of the sea, which favored the accumulation of terrigenous-carbonate rocks of the Tira formation.

The paper presents a petrographic, geochemical, and Sm-Nd isotopic data on the gneisses from different tectonic zones of the Olkhon terrane of the Central Asian Orogenic Belt, as well as the composition of garnets and the age of zircons in these metaterrigenous rocks. The garnet-biotite gneisses of the Anga-Sakhurta zone, as well as the garnet-bearing and garnet-free gneisses (granulites) of the Chernorud zone may result from metamorphism of immature terrigenous rocks of polymictic or greywacke compositions similar in geochemical characteristics to rocks of continental arcs. At the same time, the gneisses of these zones show both similarities and some differences in geochemical and isotopic characteristics, including variations in ɛNd(T) values from –0.2 to –9.0, which may indicate different proportions of one or another source in their protoliths. The age of most detrital zircons in the gneisses of the Chernorud and Anga-Sakhurta zones corresponds to 530–1000 Ma, and the youngest detrital zircons have an age of 522–537 Ma. The geochemical and geochronological data on the gneisses of the Chernorud and Anga-Sakhyurta zones suggests that the protoliths of these gneisses could be formed from the same sources of predominantly Neoproterozoic age. We assumed that gneiss protoliths could initially be sediments of the continental slope of Neoproterozoic composite terrane assembled to the Siberian Platform at 600‒610 Ma. The transport of clastic material being gneiss protoliths from this composite terrane, took place towards the Paleo-Asian Ocean. The youngest zircons with an age of about 530 Ma could be generated from igneous complexes intruding the Neoproterozoic composite superterrane. The garnet-biotite gneisses of the Krestovskaya zone are similar in chemical composition to immature graywacke sandstones, The ɛNd(T) value in these gneisses is –3.7. Detrital zircons in the gneisses of the Krestovskaya zone form age peaks at 780–820 and 498–515 Ma. Based on geochemical and geochronological data we assume that these gneisses could be formed in an intracontinental basin formed at the orogenic stage during accretionary-collisional events at the amalgamation the Orso block and the Birkhin island arc into the Krestovskaya zone.All terrigenous rocks being gneiss protoliths were metamorphosed at 460–510 Ma under granulite or amphibolite facies associated with accretionary and collisional events, which led to the formation of the Early Paleozoic Olkhon composite terrane.

The paper presents petrographic, geochemical, and new U-Pb zircon (LA-ICP-MS) geochronological data on the Upper Lena Fm. sediments which make part of the Cambrian sedimentary cover of the Siberian craton. The composition of lithic fragments in these clastic sediments, including mafic and felsic volcanics and granitoids, along with the correlation of major element ratios and the values of trace-element ratios point to predominant igneous (mainly felsic) rocks in the provenance. The U-Pb ages of detrital zircons from the sampled Upper Lena Fm. sandstones are mostly Early Paleozoic (∼500 Ma), with very few Archean-Paleoproterozoic determinations and quite many Neoproterozoic zircons. Ediacaran and Earliest Cambrian clastic sediments bearing Early Precambrian and Neoproterozoic detrital zircons, as well as Neoproterozoic and Early Paleozoic complexes of the Central Asian Orogenic Belt, could provide material for the Upper Lena clastic deposition. The geochronological evidence shows that the Upper Lena Fm. sandstones were deposited over vast territories of the southern Siberian craton in the Late Cambrian, in a single sedimentary basin, and originated from the same provenance. The Upper Lena deposition event in the Late Cambrian, immediately before the Ordovician period, makes a key milestone in the geological history of Siberia: the end of a large-scale Early Cambrian transgression and the beginning of gradual uplift of the southern craton margin, at least till the Carboniferous, which was associated with the formation of the Central Asian Orogenic Belt, a major tectonic unit of Asia.

We have studied terrigenous-carbonate rocks in the area near the Sayan mountains in the Irkutsk Region (Russia), specifically at the Shaman Cliff, being the stratotype area of rocks that belong to the Moty group. The cliff’s lower part is composed of sandstones, which fragments gradually decrease in size upward the cross-section. The middle and upper parts are composed of sandy dolomites and dolomites, respectively. In terms of material characteristics, the terrigenous rocks correspond to arkoses. According to the genetic typification, the arkoses are composed of destructed primary igneous rocks. The terrigenous-carbonate rocks contain a carbonate component that gradually increases in the upper part of the cross-section. In the Shaman Cliff cross-section, we distinguish 32 lithological units and eight lithologicalgenetic types of deposits. Paleogeodynamic conditions are reconstructed for the formation of the sedimentation basin. Our study of the Shaman formation reveals specific features of the lithological facies, which suggest that these rocks accumulated in a coastal environment affected by tides. In the study area, clastic materials were mainly removed from an orogen that formed due to the Vendian accretion-collision events in the southern folded frame of the Siberian platform. Dolomites composing the upper part of the cliff are attributed to the Irkutsk formation of the Moty group. Their lithological features give evidence of shallow-marine conditions of their formation, without any supply of clastic material, which contributed to mass dispersal of the Cambrian biota described in [Marusin et al., 2021]. It is our first initiative to draw a boundary between the Shaman and Irkutsk formations of the Moty Group along the base of the carbonate eluvial breccia unit that marks the stratigraphic break. In the cross-section, this boundary represents the border between the Upper Vendian and Lower Cambrian. Our conclusions are generally consistent with the ideas of most researchers about the Late Vendian evolution of the southern margin of the Siberian platform. The results of our study can be used in further investigation of this area and provide a basis for correlating the studied strata with the same-age reference cross-sections of other regions in Siberia.

The paper presents a new geological, geochronological, geochemical and Nd isotopic data on the latest Paleo-proterozoic dolerite sills, exposed in the Biryusa inlier of the southern Siberian craton among the sandstones of sedimentary sequence traditionally suggested as Neoproterozoic. One dolerite sill yielded U-Pb (ID-TIMS) bad-deleyite concordia age of 1613 +/- 5 Ma, which interpreted as time of their emplacement. New geochronological data allow reconsider previously reported Neoproterozoic age of sedimentary sequence hosting dolerite sills studied and suggest for them at least Paleoproterozoic age. The dolerites correspond to subalkaline and alkaline tholeiitic basalts and less often subalkaline tholeiitic basaltic andesite according to their major-element compositions with lower to moderate mg#, varying from 26 to 58. All dolerites demonstrate a similar slightly negative epsilon Nd(t) values range from -2.2 to -2.5. Geological, geochemical and Nd isotopic data suggest that mafic melts responsible for genesis of the dolerites were generated in an intracontinental extensional setting from homogeneous mantle source produced by interaction between OIB and ACR-like magmas. Geochemical features of the studied dolerites together with geological observations, namely - a presence of coeval rift-related sedimentary strata in the neighboring Urik-Iya graben (paleorift), suggest an overall extensional tectonic environments in the southern part of the Siberian Craton at 1.65-1.60 Ga. Synthesis of data on ca. 1.65-1.58 Ga magmatism around the world showed that the spatial distribution of various ca. 1.65-1.58 Ga mafic and felsic intrusions, including dyke swarms, anorogenic granites, as well as intracontinental basins within Nuna super-continent suggest the overall extensional tectonic environments, probably related to the retreat of subduction slabs surrounded the supercontinent.

This work presents the results of the isotope dating of detrital zircons from sandstones of the Bratsk (O 3 ), Kezhemskaya (S 1 ), and Baeronovka (C 1 ) formations of the sedimentary cover of the southwestern part of the Siberian Platform. It was established that Paleoproterozoic igneous and metamorphic complexes of the Siberian Platform basement with ages of 2.00–1.85 Ga were the dominant source of the clastic material. The Central Asian Orogenic Belt, namely, rock complexes with age of 490–450 Ma, was a second important source of the clastic material. Furthermore, it was noted that the age spectra obtained for detrital zircons from rocks of the Siberian Platform sedimentary cover reflect two global orogenic events: the Paleoproterozoic one, which is responsible for the formation of the most ancient cratons, including the Siberian one, and the Early Paleozoic one, marking the beginning of the development of one of the largest orogenic structures of the world (Central Asian Orogenic Belt).

—We performed geological, geochronological, geochemical, and isotope-geochemical studies of igneous rocks of the Ust’-Ignok gabbrodiorite massif in the Urik–Iya graben of the Siberian craton and summarized the obtained and published data on early Proterozoic mafic igneous rocks in the South Siberian postcollisional magmatic belt. It has been established that the Ust’-Ignok massif is composed of rocks of the continuous series from biotite gabbro via gabbrodiorites and diorites to quartz diorites. U–Pb zircon dating of quartz diorites of the Ust’-Ignok massif yielded an age of 1836 ± 10 Ma, i.e., the massif rocks might have originated at the final stage of the formation of the South Siberian postcollisional magmatic belt. The rocks of the Ust’-Ignok massif are of normal and medium alkalinity. All igneous rocks from gabbro to quartz diorites show distinct negative anomalies of Nb–Ta and Ti in their multielement patterns, and their εNd(T) values vary from +0.3 to –0.9. The geochemical indicator ratios in the gabbroids point to insignificant contamination of their source with continental-crust material and to their formation through the melting of an enriched lithospheric-mantle source. Gabbrodiorites–quartz diorites of the Ust’-Ignok massif resulted, most likely, from the fractional crystallization of gabbroids. Analysis of the geochemical and isotope characteristics of mafic igneous rocks of the South Siberian postcollisional magmatic belt shows that most of them resulted from the melting of the subcontinental lithospheric mantle with suprasubductional geochemical features. This mantle might have formed during subduction processes preceding the formation of the Siberian craton.

We are presents the results of petrographic and geochemical studies of the Late Precambrian terrigenous rocks of the Shangulezh and Tagul suites of the Karagas group of the Biryusa Sayan Region (South-West of the Siberian Craton). The results of reconstruction of the sources clastic material and the degree of their chemical conversion are presented. The studied terrigenous deposits of the Shangulezh and Tagul suites of the Karagas group are represented by arkoses sandstones and siltstones, and are characterized by similar characteristics. For the majority of the studied rocks, mineralogical signs of epigenetic transformations at the stage of late catagenesis are recorded, expressed by fouling of potassium feldspar fragments by freshly formed autigenic potassium feldspar, regeneration of quartz clastic grains, and also by fouling of quartz fragments and potassium feldspar clay-micaceous clay-micaceous aggregate (ithlitehydrite). A characteristic petrochemical feature of most of the studied samples is sharply increased K2O concentrations relative to very low Na2O contents. The presence of fragments of granitoids, quartzite's, flints in the clastogenic component of the studied sandstones and siltstones indicates the basement rocks of the Siberian craton as the main feeding province for sedimentary strata of the Shangulezh and Tagul suites of the Karagas group. The set of accessory minerals in the heavy fraction of most of the studied samples, as well as the distribution pattern of rare and trace elements that are not mobile during epigenetic transformations, indicate the predominance of acidic rocks in the region in the sours area, and a distinct europium minimum in the REE spectra of the studied terrigenous rocks indicates the prevalence of granitoids in source of demolition. Taking into account the geological structure of the study area, it is assumed that one of the main rocks in the sources area for these sediments could be granitoids of the Sayan complex, which are widespread in the Cissayan marginal ledge of the Siberian craton basement. Similar petrographic and petro- and geochemical characteristics of the studied terrigenous rocks indicate that they accumulated in the same tectonic regime, in a single sedimentation basin, when clastic material came from the same feeding province.

Geological, geochronological, and geochemical isotope studies are carried out for metamorphosed volcanic rocks and dolerites of the Maltsevka sequence of the Elash Group in the Biryusa block of the Siberian craton. It is found that mafic igneous rocks (dolerites and basaltic andesites) are close in composition to intraplate basalts. Flat or slightly fractionated REE patterns ((La/Yb)(n) = 1.3-2.3) and positive epsilon(Nd)(T) values of +3.7 and +4.1 are observed. It is assumed that the depleted asthenospheric mantle and, possibly, plume mantle were the sources of these rocks, while the lithospheric mantle had no significant effect. Meta-andesites of the Maltsevka sequence belong to the tholeiitic series and have high La, Th, and U contents. Pronounced negative Nb and Ti anomalies are observed in the multielement patterns of these rocks, along with negative epsilon(Nd)(T) values of -4.6. It is assumed that meta-andesites were resulted from the late Archean crustal melting with the participation of the mantle material. Metarhyolites prevalent in the Maltsevka sequence are divided into two groups similar in REE composition to A-type and I-type granites. A-type metarhyolites show high contents of Zr, Y, Nb, Th, and REE (except for Eu) and positive epsilon(Nd)(T) values of +2.2 and might have resulted from the melting of the source with geochemical isotope parameters close to those of mafic igneous rocks of the Maltsevka sequence. I-type metarhyolites have low contents of Y, Yb, Zr, and Nb but high contents of Th and show negative epsilon(Nd)(T) values of-3.7. They might have resulted from the melting of lower crustal diorite-tonalite rocks with addition of juvenile mantle material to the magma generation area. U-Pb zircon dating of metarhyolites of the Maltsevka sequence corresponding to A- and I-type granites showed that they are close in age, 1872 +/- 10 and 1874 +/- 10 Ma, respectively, which agrees with the age estimated earlier for granitoids of the Sayan complex of the Biryusa block. The similar ages and structural positions, along with the localization within the same structure, made it possible to unite volcanic rocks of the Elash Group and granitoids of the Sayan complex of the Biryusa block into a Paleoproterozoic volcanoplutonic association. The rocks of the association form the Sayan-Biryusa volcanoplutonic belt stretching for about 300 km along the zone of junction of the Biryusa block of the Angara fold belt and the Archean Tunguska superterrane of the Siberian craton. The belt is part of the large Paleoproterozoic South Siberian postcollisional magmatic belt formed at the final formation stage of the Siberian craton, when it was possibly part of the Paleoproterozoic Columbia supercontinent.

The geological position, composition, and age of detrital zircons of sedimentary deposits of the Nugan Formation of the Western Baikal region underlying the Golousta Formation of the Baikal series of Ediacaran age have been studied. The formation of both stratigraphic units due to the same sources of detrital material, located within the southern flank of the Siberian Craton, has been proved. The deposits of the Nugan Formation have been demonstrated to mark the rifting stage of the formation of the passive margin of the Paleo-Asiatic Ocean: their accumulation occurred in the Late Cryogenian during the interval 720–640 Ma.