An overview of the history of tectonic mapping in Russia is presented, and the principles of tectonic mapping are briefly described. Here, out attention is focused on the Tectonic Map of North, Central and East Asia (scale 1:2500000, 2014) and the Tectonic Map of the Arctic (scale 1:5000000, 2019) prepared by international projects of Karpinsky Russian Geological Research Institute (VSEGEI). The projects included participants from geological service agencies, universities and the academies of sciences of 13 countries. We describe the mapping approaches, structural features, legends, graphical design, and information at the map margins. The experience gained with the projects of these two tectonic maps will be used to compile the International Tectonic Map of Asia, scale 1:5000000 (ITMA-5000) and the Tectonic Map of Russia, scale 1:2500000.

The paper reports on the deep geophysical studies performed by the Geological Survey of Russia (VSEGEI) under the international project – Deep Processes and Metallogeny of Northern, Central and Eastern Asia. A model of the deep crustal structure is represented by a set of crustal thickness maps and a 5400-km long geotransect across the major tectonic areas of Northeastern Eurasia. An area of 50000000 km2 is digitally mapped in the uniform projection. The maps show the Moho depths, thicknesses of the main crustal units (i.e. the sedimentary cover and the consolidated crust), anomalous gravity and magnetic fields (in a schematic zoning map of the study area), and types of the crust. The geotransect gives the vertical section of the crust and upper mantle at the passive margin of the Eurasian continent (including submarine uplifts and shelf areas of the Arctic Ocean) and the active eastern continental margin, as well as an area of the Pacific plate.

The Ural mobile belt is an intracontinental epioceanic orogen that has already gone through all stages of the geodynamic development. Igneous rocks formed during each stage are important indicators for understanding the evolution of this belt and determining potential ore contents of its segments. We consolidated large datasets on petrogeochemistry and isotope geochronology of the Paleozoic (490–250 Ma) granitoids associated with the opening and evolution of the Ural paleoocean and the subsequent formation of the collisional orogen. Using these data, we have revised the ages of several tectono-magmatic events, clarified the paleogeodynamic settings for the generation of granitoids of different compositions, and described the roles of mantle-crust interactions and the plume factor in the formation of the mature continental crust in the study area. The results can be useful for geological mapping and improving the assessment of the potential ore contents in granitoid complexes that differ in origin and composition.

Study of the Ordovician sedimentary sequences of Gorny Altai and Salair has revealed lithological and paleontological features correlating with global sedimentary events:

(1) The Acerocare Regressive Event (an initial event in the Early Tremadocian);

(2) Black Mountain Transgressive Event (Early Tremadocian);

(3) Peltocare Regressive Event (Tremadocian);

(4) Kelly Creek Regressive Event (Late Tremadocian);

(5) Ceratopyge Regressive Event (Late Tremadocian);

(6) Billingen Transgressive Event (Early Floian);

(7) Stein Lowstand Event (Middle Darriwilian);

(8) Vollen Lowstand Event (Sandbian);

(9) Arestad Drowning Event (Middle Sandbian);

(10) Frognerkilen Lowstand Event (Early Katian);

(11) Linearis Drowning Events 1 and 2 (Middle Katian);

(12) Terminal Husbergoya Lowstand Event (Hirnantian); and

(13) Hirnantian Lowstand Event (HICE) (Late Ordovician).

The chronostratigraphic levels with traces of the global sedimentary events in the Uymen-Lebed structural-facies zone (SFZ) (Gorny Altai) differ from those in the Charysh-Inya and Anui-Chuya SFZ (Altai). In the Ordovician, the Altai basin located in the Charysh-Inya and Anui-Chuya SFZ was a marine area separated from both the Uymen-Lebed basin and the coeval Salair basin. The traces of the global sedimentary and/or biotic events in the Altai and Salair sections can be used as a precise basis for direct correlation of the local stratigraphic units with the units of the International Stratigraphic Chart.

The article presents new data on ages (U-Pb zircon dating, SIMS SHRIMP-II) and chemical compositions of rocks from gabbro-granitic and granite-leucogranitic magmatic associations. These rocks preceded the formation of Li-enriched spodumene pegmatites of the Tserigiyngol-Burchin ore cluster (Russian: ЦБРУ), one of the main clusters in the South Sangilen pegmatite belt (SSB) located in the Tuva-Mongolian massif being a part of the Central Asian Fold Belt. We investigated the rocks from the Upper Tserigiyngol, Uchuglyk and Temenchulu plutons, and pegmatites from two neighbouring fields. We distinguish three impulses of granitic magmatism (517±7, 508±7, and 488±6 Ma), which are attributed to different stages of the Early Paleozoic collision orogeny (520-480 Ma). The period when the Li-enriched pegmatites were formed (494±7 Ma) is close to the magmatism impulse at 488±6 Ma. Differences are discovered in compositional and isotopic (Sm-Nd) features of granites dominating at the following stages of collisional orogeny: (1) early collision (517±7 Ma) – I-type granites, eNd(T)=0–1.5, TNd (DM-2st)=1.2–1.1 b.y., and (2) late collision (488±6 Ma) – A-2-type granites, eNd(T)=–3.0…–1.6, TNd (DM-2st)=1.5–1.4 b.y., which are due to different sources. Our study shows that facies transitions are absent between the late-collision granites (488±6 Ma) and the spodumene pegmatites from the Tserigiyngol-Burchin ore cluster (494±7 Ma), although these rocks are close in age. In terms of geochemical features, the spodumene pegmatites from the cluster are strongly different from both the late-collision granites and spodumene pegmatites from other SSB fields, including the large Tastyg lithium deposit. We have analysed the role of interactions between the crustal and mantle materials in the formation of granitoid sources in the Tserigiyngol-Burchin ore cluster, and described their evolution in time and the influence on the pegmatite rare-element specialization.

This work presents the summarization of U–Pb (SIMS, TIMS) zircon dates and petrogeochemical signatures of granitoids of the north of the Urals (Polar, Subpolar, and Northern Urals) obtained over the last decade. Granitе melts were formed from melting of different substrates, highly heterogeneous in composition and age, at all geodynamic stages distinguished in the studied area. Preuralides include island arc–accretionary (735–720 Ma, 670 Ma), collisional (650–520 Ma), and rift-related (520–480 Ma) granitoids. Uralides includes primitive island-arc granitoids (460–429 Ma), mature island-arc granitoids (412–368 Ma), early collisional (360–316 Ma) and late collisional (277–249 Ma) granitoids. As a result, the general trend of variations of oxygen (δ¹⁸O_Zrn, ‰), neodymium (εNd_(t)wr), and hafnium (εHf_(t)Zrn) isotope compositions identified in time. Mantle isotope compositions (δ¹⁸O_Zrn (+5.6), εNd_(t)wr (+1.7), εHf_(t)Zrn (+8.7...+10.6)), common for island arc granitoids (Preuralides) are changed by crustal–mantle ones (δ¹⁸O_Zrn (+7.2...+8.5), εNd_(t)wr (–4.8...+1.8), εHf_(t)Zrn (+2.1 to +13)), typical of collisional granites. According to this, the crustal matter played a significant role during the formation of the latter. The crustal-mantle isotope compositions are changed by the mantle ones, characteristic of rift-related (δ¹⁸O_Zrn (+4.7...+7), εNd_(t)wr (+0.7...+5.6), εHf_(t)Zrn (–2.04...+12.5)) and island-arc (Uralides; δ¹⁸O_Zrn (+4.2...+5.7), εNd_(t)wr (+4.1...+7.4), εHf_(t)Zrn (+12...+15.2)) granitoids.

The study is focused on metapelitic granulites of Cape Kaltygei (Western Baikal region) that contain a diagnostic mineral assemblage of ultrahigh temperature (UHT) metamorphic rocks (orthopyroxene+sillimanite+quartz). The pseudosection-based thermobarometry yields peak metamorphic temperature and pressure values (T=950 °C, P=~9 kbar) and suggests near-isobaric cooling (IBC) conditions during the retrograde evolution of the granulites. The U/Pb zircon age estimates for metamorphism (~1.87 Ga) support the data published by other researchers. The SHRIMP-II U-Pb dating of zircon cores yields a minimum protolith age of 1.94–1.91 Ga. Biotites and amphiboles from granulites of Cape Kaltygei show the ⁴⁰Ar/³⁹Ar isotopic ages that are close to the Early Paleozoic accretion-collision system of the Western Baikal region.

Transformation of the oceanic crust into the continental one in orogenic belts is an important problem in petrological studies. In the paleocontinental sector of the Urals, a key object for tracing the stages of metamorphism and investigating the origin of anatectic granites is the Murzinka-Adui metamorphic complex. We have analyzed trace elements in zircons and established their genesis, sources, crystallization conditions, and stages of metamorphic events and granite generation in this complex. Zircons compositions were determined by the LA-ICP-MS method. Temperatures were calculated from Ti contents in the zircons. We distinguish three geochemical types of zircons, which differ in the ratios of light and heavy REE, U, Th, Ti, Y and show different values of Ce- and Eu-anomalies and Zr/Hf ratios, which are indicative of different crystallization conditions, as follows. Type I: minimal total LREE content; clear negative Eu- and Ce- anomalies; features of magmatic genesis; crystallization temperatures from 629 to 782 °C. Type II: higher contents of Ti, La, and LREE; low Ce-anomaly; assumed crystallization from highly fluidized melts or solutions. Type III: low positive Eu-anomaly; high REE content; low Th/U-ratio; zircons are assumed to originate from a specific fluidized melt with a high Eu-concentration. Ancient relict zircons (2300–330 Ma) in gneisses and granites show features of magma genesis and belong to types I and II. Such grains were possibly inherited from granitoid sources with different SiO2 contents and different degrees of metamorphism. Based on the geological and petrogeochemical features and zircon geochemistry of the Murzinka-Adui complex, there are grounds to conclude that the material composing this complex was generated from the sialic crust. The main stages of metamorphism and/or granite generation, which are traceable from the changes in types and compositions of the zircons, are dated at 1639, 380–370, 330, and 276–246 Ma. Thus, transformation of the oceanic crust into the continental one was a long-term and complicated process, and, as a result, the thickness of the sialic crust is increased in the study area.

Zr-Th-U minerals, namely baddeleyite, zircon and U-Th-oxide, were found in high-Mg diorite from the Late Devonian – Early Carboniferous synplutonic dyke in granodiorites of the Chelyabinsk massif, South Urals. Micron-sized minerals were investigated by electron microscopy and cathodoluminescence spectroscopy. Their chemical compositions were determined by electron probe microanalysis that was optimized to ensure more precise measurements of the composition of minerals. Baddeleyite grains are found as inclusions in amphibole crystals and reside in intergranular areas. The former retain their composition and show no traces of corrosion or substitution. In the intergranular areas, baddeleyite grains were replaced by polycrystalline zircon due to the reaction with an acid melt, and the U-Th-oxide precipitated inside baddeleyite simultaneously, which suggests the restite origin of baddeleyite. The main features of the baddeleyite composition are extremely high concentrations of ThO₂ and UO₂ (to 0.03 wt. % and 1.0 wt. %, respectively), which may be due to the metasomatic interaction between the mantle peridotite and the crustal or carbonatite fluid or melt.

The oceanic stage in the history of the South Urals completed in the Ordovician – Early Silurian. The Ordovician through Devonian events in the region included the formation of an island arc in the East Ural zone from the Middle Ordovician to Silurian; westward motion of the subduction zone in the Late Silurian – Early Devonian and the origin of a trench along the Main Ural Fault and the Uraltau Uplift; volcanic eruptions and intrusions in the Magnitogorsk island arc system in the Devonian. The Middle-Late Paleozoic geodynamic evolution of uralides and altaides consisted in successive alternation of subduction and collisional settings at the continent-ocean transition. The greatest portion of volcanism in the major Magnitogorsk zone was associated with subduction and correlated in age and patterns of massive sulfide mineralization (VMS) with Early – Middle Devonian ore-forming events in Rudny Altai. Within-plate volcanism at the onset of volcanic cycles records the Early (D₁e₂) and Middle (D₂ef₂) Devonian slab break off. The volcanic cycles produced, respectively, the Buribay and Upper Tanalyk complexes with VMS mineralization in the Late Emsian; the Karamalytash complex and its age equivalents in the Late Eifelian – Early Givetian, as well as the lower Ulutau Formation in the Givetian. Slab break off in the Late Devonian – Early Carboniferous obstructed the Magnitogorsk island arc and supported asthenospheric diapirism. A new subduction zone dipping westward and the Aleksandrovka island arc formed in the Late Devonian – Early Carboniferous. The Early Carboniferous collision and another event of obstructed subduction led to a transform margin setting corresponding to postcollisional relative sliding of plates that produced another slab tear. Postcollisional magmatism appears as alkaline gabbro-granitic intrusives with related rich Ti-magnetite mineralization (C₁). Transform faulting persisted in the Middle Carboniferous through Permian, when the continent of Eurasia completed its consolidation. The respective metallogenic events included formation of Cu-Ni picritic dolerites (C_2–3), as well as large-scale gold and Mo-W deposits in granites (P_1–2).

We present new age constraints for igneous rocks and ore-metasomatic formations of the gold deposits in the Akzhal-Boko-Ashalin ore zone. In terms of their ore formation, these deposits correspond mainly to the orogenic type, which generally reflects specific metallogeny of the West Kalba gold-bearing belt in East Kazakhstan. Gold-quartz veins and mineralized zones of the gold-sulphide formation are confined to fractures feathering regional NW-striking and sublatitudinal faults. Their common features include the following: gold-bearing veinlet-disseminated pyrite-arsenopyrite ores that are localized in carbonaceous-sandy-schist and turbidite strata of different ages; structural-tectonic control of mineralization, numerous dikes of medium-basic compositions in ore-control zones; and the presence of post-orogenic heterochronous granite-granodiorite rocks, although their relation to gold-ore mineralization is not obvious. Igneous rocks of the study area have similar ages in a narrow range from 309.1±4.1 to 298.7±3.2 Ma, which is generally consistent with the previously determined age of granitoid massifs of gold-ore fields in East Kazakhstan. A younger age (292.9±1.3 to 296.7±1.6 Ma) is estimated for felsic rocks of the dyke complex. For the ore mineralization, the 40Ar/39Ar dating of sericite from near-ore metasomatites yields two age intervals, 300.4±3.4 Ma and 279.8±4.3 Ma. A gap between of the ages of the ore mineralization and the igneous rocks is almost 20 Ma, which may indicate that the processes of ore formation in the ore field continued in an impulse-like pattern for at least 20 Ma. Nevertheless, this confirms a relationship between the hydrothermal activity in the study area and the formation and evolution of silicic igneous rocks of the given age interval, which belong to the Kunush complex, according to previous studies. This interpretation is supported by reconstructed tectonic paleostress fields, showing that directions of the main normal stress axes changed during the ore mineralization stage, which is why the ore bodies significantly differ in their orientations. The above-mentioned data are the first age constraints for the study area. Additional age determinations are needed to further improve understanding of the chronology of ore-forming processes. Actually, all the features characterizing the gold mineralization of the Akzhal, Ashalin and Dauba ore fields, including the data on lithology, stratigraphy, structural tectonics, magmatism, isotope geochronology, mineralogy and geochemistry, can be used as criteria when searching for similar ore fields in East Kazakhstan.

In the South Urals, we have identified and investigated two platinum-bearing formations – ophiolite chromitebearing complexes, and the Khudolaz differentiated mafic-ultramafic complex with sulfide Cu-Ni mineralization. The ophiolite chromite-bearing complexes include fragments of the upper mantle and lower crust of the Paleouralian Ocean, which were induced by collision onto the edge of the East European platform. The origin of the Khudolaz complex is related a mantle plume activity. Here, we review and compare the main features of platinum-metal mineralization (PMM) in these two formations.

The article presents the results of mineralogical and geochemical studies of PMM associated with chromite and sulfide Cu-Ni ores. In association with chromitites, two types of PMM are distinguished: (1) predominating refractory platinoids in chromitites of the mantle unit of the section, and (2) predominating platinum and palladium in chromitites of the transitional wehrlite-clinopyroxenite complex. Compositions of platinum group minerals (PGM) and relations between their elements and host minerals suggest that the minerals of the ophiolite chromite-bearing complexes are of a restite origin, while the Khudolaz complex results from a combination of magmatic processes and solid-phase redistribution of material. Palladium (michenerite, froodite, merenskyite, borovskite, sudburyite) and platinum (sperrylite, moncheite) minerals are found in magmatic sulfide ores of the Khudolaz complex, which were subjected to hydrothermal metasomatization. Texture observations using electron microscope and optical (reflected light) images, as well as LA ICP MS analyses of sulfides suggest late- and post-magmatic crystallization of PMM in three phases: (1) immiscible metalloid or highly fractionated residual sulfide melts trapped in sulfides; (2) segregation of isomorphic impurities of platinum group elements (PGE) and chalcogenide elements from sulfide solid solutions; and (3) interaction of hydrothermal fluids with soluble sulfides.

Prospective for PMM are extended bodies of disseminated chromitites in marginal dunites of the Kraka and Nurali massifs, and wehrlite-clinopyroxenite complexes of the same massifs containing PGE (above 500 ppb). In the Khudolaz complex, promising PMM bodies are low-metasomatized parts of sulfide ore bodies (1 ppm of ΣPGE and above) located in the largest massifs, Severny Buskun and Zapadny Karasaz. Exocontact zones of these intrusions are also promising for PMM.