The results of U–Pb (ID-TIMS) geochronological studies of zircon from biotite–hypersthene plagiogneiss (metadacite) of the Kurumkan Formation, Aldan Shield, are presented. The obtained crystallization age of the biotite–hypersthene plagiogneiss protolith is 2395 ± 6 Ma. Metasedimentary rocks of the Kurumkan Formation, some of which are characterized by Nd model ages tNd(DM) = 2.3–2.2 Ga, are clearly younger than metavolcanic rocks. This indicates that the formation includes rocks of different ages, whose origin is associated with distinct stages of the Early Proterozoic geological evolution of the Aldan Shield.

The oldest granitoids of the Kan–Chingiz Complex with quartz diorites, granodiorites, plagiogranites, and granites are dated for the first time in the Chingiz–Tarbagatai region of eastern Kazakhstan. The U‒Pb (ID-TIMS and SIMS) age of granites and plagiogranites is 509 ± 2 and 512 ± 3 Ma, which corresponds approximately to the Early–Middle Cambrian boundary. These data indicate the Early Cambrian age of volcanosedimentary sequences host granitoids. The peculiarities of the composition of granitoids of the Kan–Chingiz Complex point to their formation within an ensimatic island arc.

The paper presents the results of geochemical and Sm-Nd isotopic-geochemical studies of metavolcanic rocks of the Djagdagle formation of the northwestern part of the Bureya continental massif. As a result of reconstruction of the primary composition of the metavolcanic rocks, the correspondence of their protoliths to the pantelleritic, comenditic rhyolites is shown. Nd-features of metavolcanic rocks of the Djagdagle formation indicate the melting of rocks of continental crust with Paleoproterozoic model ages during the formation of their initial melts. Geochemical features, close spatial position with Mongol-Okhotsk orogenic belt allow us to link the formation of initial melts of metavolcanic rocks of the Djagdagle formation with within-plate magmatism in the rear zone of subduction of the Mongol-Okhotsk Ocean beneath the northern (in modern coordinates) margin of the Bureya continental massif.

Geochronological (U-Pb on zircons, ID-TIMS), isotope-geochemical (Nd, Sr, Pb), and geochemical studies of rocks of the Amanan and Amudzhikan intrusive complexes and volcanic rocks of the Ukurey Suite in the eastern part of the West Stanovoy superterrane of the Central Asian Fold Belt were performed. The belonging of granitoids of these complexes to high-potassium C-type adakites is substantiated. The cogeneticity of the studied rocks has been established, which makes it possible to unite them into one Amudzhikan volcano-plutonic association formed in the age range of 133±1–128±1 Ma. The igneous complexes of this association are part of the Stanovoy volcano-plutonic belt, which extends in the sublatitudinal direction from the Pacific Ocean deep into the North Asian continent for more than 1000 km subparallel to the Mongol-Okhotsk suture zone and stitches the tectonic structures of the Dzhugdzhur-Stanovoy and West-Stanovoy superterranes. The formation of the Stanovoy Belt is connected with the closure of the Mongolo-Okhotsk Ocean and the collision of the continental masses of the North Asian and Sino-Korean continents at the turn of ~140 Ma. The subsequent collapse of the collisional orogen, accompanied by large-scale lithospheric extension and delamination of the lower part of the continental lithosphere, led to upwelling of the asthenospheric mantle. This caused the melting of the lithospheric mantle and continental crust and, as a consequence, the formation of both mafic melts of the shoshonite type and anatectic crustal melts of the adakite type. The mixing of these melts led to the formation of the parent magmas of the Amudzhikan magmatic association. The crustal component in the source was of a heterogeneous nature and was finally formed as a result of the Early Cretaceous collision event. It is characterized by upper-crustal isotopic parameters: an increased Rb/Sr and U/Pb ratio and a decreased Sm/Nd ratio in the source. The mantle component is represented by the material of the enriched lithospheric mantle of the Central Asian fold belt, the formation of which is associated with subduction processes at the stage of closure of the Mongol-Okhotsk paleoocean. Metasomatic transformation of the mantle with the introduction of melts and fluids with isotopic parameters of an EMII-type source or upper crust occurred at this stage.

The Late Ordovician and Silurian ages, previously considered as the Precambrian, were established for the first time for plutonic and volcanic complexes of the Karakamys block of Southwestern Kazakhstan. U–Pb (SIMS, and ID-TIMS) geochronological study of gneiss–granites and felsic volcanic rocks was carried out, and age estimates of 443 ± 5 Ma and 436 ± 2 Ma, consequently, were obtained. These data allow us to refer gneiss–granites to the very end of the Ordovician and the beginning of the Silurian, and felsic volcanic rocks and tuffs, to the Llandovery series of the Silurian. Special features of the composition of granitoids and felsic volcanic rocks indicate their formation in supra-subduction settings.

The paper presents the results of U–Pb (ID-TIMS) geochronologic, geochemical, Sm–Nd isotopic-geochemical studies of metavolcanic rocks of the Djagdagle formation, which are among the key elements in the structure of the Bureya continental massif. It was established that the age of metavolcanic rocks of the Djagdagle formation is 217 ± 7 Ma and corresponds to the Late Triassic. This fact contradicts the traditional ideas, according to which the Early Precambrian age is attributed to the Djagdagle formation. The results of Sm–Nd isotope studies of the considered metavolcanic rocks indicate the melting of rocks of continental crust with Paleoproterozoic model ages during the formation of their initial melts. The new geochronologic data and previously published data allow us to distinguish at least two stages of magmatic activity in the Triassic within the northwestern part of the Bureya massif ~243 and 219–201 Ma. On the basis of synchronous manifestation of Neoproterozoic, Early Paleozoic, Late Paleozoic and Early Mesozoic magmatic events in the history of geologic development of the Bureya and Songnen– Zhangguangcai Range massifs, an assumption about their common geological history at least since the Late Neoproterozoic has been put forward. The close spatial position of metavolcanic rocks of the Djagdagle formation with Mongol–Okhotsk orogenic belt, their Late Triassic age (217 ± 7 Ma) and geochemical features allow us to link the formation of initial melts of metavolcanic rocks of the Djagdagle formation with within-plate magmatism in the rear zone of subduction of the Mongol–Okhotsk Ocean beneath the northern (in modern coordinates) margin of the Bureya continental massif.

--We carried out a detailed geological, geochronological, geochemical, and isotope study of diorites from a dike located in the central part of the Baikal uplift of the Siberian craton. The geochemical and isotope data obtained for diorites of the studied intrusion were compared with coeval mafic and intermediate igneous rocks of the southern part of the Siberian craton. The U-Pb (ID-TIMS) baddeleyite age of 1862 +/- 7 Ma has been estimated for diorite from a dike located in the area of the Onguren Village. The obtained data are the first reliable age determination for the Paleoproterozoic mafic and intermediate igneous rocks of the Baikal uplift, which are part of the South Siberian postcollisional magmatic belt. The dike is of NE strike. The dike rocks correspond in chemical composition to diorites and are highly differentiated varieties (mg# = 36.5-37.4). There are no significant variations in the composition of diorites in the marginal and central parts of the dike. The rocks are characterized by low contents of TiO2, P2O5, and Nb, high contents of Th, Zr, Ba, and LREE, and low negative values of epsilon Nd(T) (-5.9 to -6.2). We assume that the diorites formed from the enriched subcontinental lithospheric mantle. The obtained geochemical and isotope data show similar negative values of epsilon Nd(T) from -4.3 to -11.6 for most of Paleoproterozoic mafic and intermediate igneous rocks of the South Siberian postcollisional magmatic belt within the Aldan Shield, the Baikal uplift, and the Irkut block of the Sharyzhalgai uplift. These rocks correspond in geochemical features to rocks resulted from the melting of subduction-modified lithospheric mantle sources in the postcollisional extension setting at the final Paleoproterozoic stage of formation of the Siberian craton.

New geochronological (U–Pb ID-TIMS) data on zircons from pegmatites of the Mama mica belt in the Baikal Highlands are presented. The ages obtained for the plagioclase pegmatites (388 ± 2 and 389 ± 2 Ma, Mochikit deposit) and two-feldspar pegmatites (333 ± 1 and 332 ± 3 Ma, Slyudyanka deposit) demonstrate a significant age gap (50–60 Ma) between them. Based on the entire set of geological and new geochronological data available, it is proposed to divide the Mama complex, to which they were previously assigned, into two separate granitoid complexes.

The Hercynian mobile belts in Central Asia include the proper Hercynian and late Hercynian (Indo-Sinian) belts, whose formation is associated with the evolution of the South and Inner Mongolian basins with oceanic crust. Within the South Altai metamorphic belt (SAMB), rock complexes compose tectonic slivers of different ranks. At the early stages, their metamorphic alteration occurred under conditions of the high-temperature subfacies of the amphibolite and, in places, granulite facies. Structurally, the band of the outcrop of these complexes is confined to the Caledonian North Asian continental margin and stretches along the southern slope of the Gobi-Mongolian-Chinese Altay Mountains from southeast to northwest (East Kazakhstan), where they occur in the Irtysh strike-slip zone. We assign these complexes to the Hercynian SAMB running for more than 1500 km. The latter comprises poly- and monometamorphic complexes. Late metamorphic granitoids of the Tseel tectonic sliver (Gobi Altay) in the southeast of the SAMB have been dated at 374 +/- 2 and 360 +/- 5 Ma. The previous data and these results show that the early (similar to 390-385 Ma) low-pressure and late (375-360 Ma) high-pressure metamorphism proceeded almost along the entire belt. The interval between them was a short tectonic lull. These processes took place during the closure of a Tethyan basin of the South Mongolian Ocean (Paleo-Tethys I). The spatial position of the SAMB was controlled by the structural asymmetry of the basin, with an active continental margin at its northern edge and a passive one at the southern edge (in the present-day coordinates).

In our study we analyzed the composition of granitoid rocks within the Kongo magmatic zone of the Omolon median mass. The studied calc-alkaline granitoids cut through the Early Precambrian crystalline basement and the terrigenous–carbonate rocks of the Riphean‒Paleozoic cover. Based on analysis data, we found that the granitoids contain moderate amounts of silica and alkalis, similar amounts of potassium and sodium, and an elevated amount of alumina. The granitoids are enriched in barium, iron group elements, and most high field strength elements and are depleted in large-ion lithophile elements, rare earth elements, and yttrium. On discrimination diagrams, the elements plot in volcanic arc granitoid fields. According to the results of U‒Pb dating (ID-TIMS), the ages of zircons from the granitoids range from 86.4 ± 0.3 to 86 ± 1 Ma. In age, chemical composition, and rare earth element distribution, the studied granitoids are similar to the rocks of the Penzhina segment of the Okhotsk‒Chukotka volcanic belt and, therefore, the Kongo zone is a constituent part of it.

The geological position, U-Pb monazite age, and composition of charnockites from the central part of the Anabar shield are presented. The charnockites are localized in a block of the Paleoproterozoic metasedimentary granulite-facies rocks, which include aluminous schists, sapphirine-bearing schists, and hypersthene plagiogneisses typical of the Archean Daldyn granulite complex. Moderate-K charnockites form small pockets and lenses in the hypersthene plagiogneisses, inherit their gneissic appearance, and are related with them by gradual transitions. High-K charnockites compose large vein bodies with cutting contacts. The charnockites differ in the structural position, but have similar age (1982 Ma) and are separated in time from metasedimentary rocks, whose age is estimated at 2.4–2.5 Ga. Hypersthene plagiogneisses correspond to igneous rocks of predominantly intermediate composition, while charnockites are granodiorites and granites. Compared to the plagiogneisses, charnockites are enriched in Th, light REE, Zr, Nb, Rb, and Ba. Hypersthene plagiogneisses and charnockites are characterized by a highly fractionated REE distribution pattern with an increase in (La/Yb)n and Eu minimum in charnockites. According to geochemical data and close Nd isotopic composition, high-K charnockites could have been generated during the high-temperature melting of hypersthene plagiogneisses. Charnockites (~2.0 Ga) are almost coeval to the Paleoproterozoic granulite metamorphism and emplacement of granite intrusion in collision zones. All these processes are caused by the accretion of Early Precambrian terranes into the structure of the Siberian craton. Charnockitization was superimposed on the hypersthene plagiogneisses, which have been already deformed in folds and migmatized, and on the metasedimentary sequence. This process completes the formation of the granulite complex of the Anabar Shield.

The paper reports geochemical, geochronological (ID–TIMS zircon U–Pb) and isotope–geochemical (Nd, Pb) study of granitoids of the Kodar complex developed in the western part of the Aldan shield. It has been established that these rocks can be classified as postcollisional A–type rapakivi granites, which together with the mafic–ultramafic rocks of the Chinei complex compose a single magmatic association formed within 1876 ± 4–1859 ± 2 Ma. The massifs of this association are a part of the giant South Siberian magmatic belt over 2500 km in length, which was formed at the final stage (1.88–1.84 Ga) of evolution of the Paleoproterozoic orogen. Globally, this belt is the largest stitching suture, which marks the formation of the Siberian craton and its entrance into the Paleoproterozoic Nuna supercontinent. The formation of the initial magmas of the Kodar granitoids was related to the mantle–crustal interaction during the mixing of primary mafic mantle magmas or their derivatives with anatectic melts derived through partial melting of the Archean lower continental crust of the region under the thermal influence of mafic magma. The crustal component in the source clearly predominates and has a heterogeneous nature. The mantle component is mainly represented by ancient enriched mantle, with the possible contribution of the OIB–type component.