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The paper summarizes major, trace, and Sm-Nd isotopic data on metabasites of the Urik greenstone belt (GB) (Sharyzhalgai uplift, southwestern Siberian craton). The Archean metabasalts (amphibolites and garnet amphibolites) of the supracrustal complex and sheeted bodies represent four geochemical types. The first type includes low-Ti amphibolites of the Urik area. Their characteristic features are a clear LREE depletion ((La/Sm)n = 0.8–1.1), the absent negative Nb anomaly, and positive eNd(t) values (up to +4.1). The second type corresponds to moderate-Ti amphibolites of the Urik area. They differ from the rocks of the first type in the higher (La/Sm)n ratio (1.0–1.5), Th, Zr, Nb, Y contents, and lower eNd(t) values (+0.4…–1.6), but, like the low-Ti amphibolites, they do not show Nb depletion. The third type includes amphibolites of the Tagna area, which show an increase in the concentrations of TiO2, LREE, Th, Zr, and Nb with a decrease in Mg# and have eNd(t) values from +1.3 to –0.5. They are characterized by the elevated (La/Sm)n ratio (1.1–2.3) and Zr and Nb contents and the presence of a clear Nb minimum. The fourth type includes all high-Ti amphibolites of sheeted bodies, which are enriched in LREE ((La/Sm)n = 1.9–3.4), Th, Zr, and Nb, have an increased (Gd/Yb)n (1.4–2.0), a sharp Nb depletion, and negative eNd(t) values. Geochemical modeling coupled with trace element and isotopic composition indicates the formation of the low- and moderate-Ti metabasalts of the Urik area from weakly depleted and nearly primitive mantle sources, respectively. Their protoliths were oceanic basalts. The metabasalts of the Tagna area were formed from a weakly depleted and hydrated mantle source contaminated with crustal material. The enrichment of the source with incompatible elements could be caused by sediment subduction shortly before basalt formation. The metabasalts of the fourth type originated from a long-lived enriched source such as subcontinental lithospheric mantle. They resemble the present-day intraplate continental basalts. None of the three dominant types of metabasalts of the Urik GB shows signatures of sharply depleted or sharply enriched mantle sources, which indicates a weak differentiation of the mantle by the Meso- Neoarchean boundary (~2.8 Ga). The formation of a subduction-modifed lithospheric mantle (hydrated mantle) has only occurred since ~ 2.8 Ga. Different compositional and isotopic characteristics of the metabasalts of the Urik GB suggest that the Bulun terrane was formed by accretion and tectonic juxtaposition of fragments of the oceanic crust, an oceanic island arc, and an older TTG continental crust at ~ 1.86 –1.82 Ga.

Data on the carbon and oxygen isotopic composition of carbonates from the rocks of the Giyani greenstone belt, Kaapvaal craton, South Africa are presented. This belt is immediately adjacent to the Hout River Shear Zone, along which the Southern Marginal Zone (SMZ) of the Limpopo granulite complex is overthrusted onto the Kaapvaal craton. The δ13C values are –2.1 and –2.2‰ for carbonates from two metapelite samples, –5.1‰ for a meta ultrabasite sample, and –7.1 and –7.7‰ for two metabasite samples, respectively. The δ18О values are 17.1 and 17.5‰ for carbonates from the metapelites, 14.3‰ for carbonates from the metaultrabasite, and 12.9 and 13.0‰ for carbonates from the metabasites. The comparison of the data obtained to the published data on the isotopic composition of carbonates from the rocks of the different greenstone belts indicates both hydrothermal (in the metabasites and the metaultrabasite) and sedimentary (in the metapelites) origins of the carbonate material in the rocks studied. Based on the comparison of these data to δ13C of magnesite that formed in ultrabasic granulites during the interaction of the Limpopo complex with the craton, the graphite and fluid inclusions in leucocratic garnet-bearing granitoids that transported fluids, and the carbon isotopic composition of graphite from metapelites of the SMZ, it is concluded that the carbon source was located outside the SMZ and represented a heterogeneous carbonate-bearing lithologies. It could be carbonate-bearing volcanogenic–sedimentary sequences of the greenstone belts of the Kaapvaal craton, which underwent prograde metamorphism during the interaction with the SMZ granulites.

The tectonomagmatic evolution of the Sangilen massif has been described in detail in numerous publications, but little attention was given to heat sources related to the HT/LP metamorphism. Modeling of the magma transport to the upper‐crust levels in West Sangilen shows that the NT/LP metamorphism is related to gabbromonodiorite intrusions. This article is focused on the thermo‐mechanical modeling of melting and lifting of melts in the crust, taking into account the density interfaces. The model of the Erzin granitoid massif shows that in case of fractional melting, the magma ascent mechanism is fundamentally different, as opposed to diapir upwelling – percolation take place along a magmatic channel or a system of channels. An estimated rate of diapiric rise in the crust amounts to 0.8 cm/yr, which is more than an order of magnitude lower than the rate of melt migration in case of fractional melting (25 cm/yr). In our models, a metamorphic thermal ‘anticline’ develops in stages that differ, probably, due to the modes of crust melting: batch melting occurs at the first stage, and fractional melting takes place at the second stage. It is probable that the change of melting modes from melting conditions in a ‘closed’ system to fractional melting conditions in ‘open’ systems is determined by tectonic factors. For the Sangilen massif, we have estimated the degrees of melting in the granulite, granite, and sedimentary‐metamorphic layers of the crust (6, 15, and 5 vol. %, respectively).

This paper reports the results of thermodynamic modeling of the formation of the Birkhin volcanoplutonic association by means of geochemical thermometry. The obtained liquid line of descent for the magma chamber of the Birkhin Massif indicates that the melt evolved into the field of subalkaline composition. The melts of the volcanics of the Tsagan-Zaba complex are identical to the melts in the magma chamber in both major components and REEs. It was concluded that the Birkhin and Tsagan-Zaba complexes are comagmatic. A scenario was proposed for the development of the Birkhin volcanoplutonic association involving multiple eruptions of volcanic rocks during its formation. It was shown that the intermediate rocks are not derivatives of basic magmas, but were produced by interaction of basic volcanic rocks with felsic intrusions cutting them.

We consider a hypothesis for the origin of PGE-bearing ultramafic rocks of the Inagli massif (Central Aldan) through fractional crystallization from ultrabasic high-potassium magma. We studied dunites and wehrlites of the Inagli massif and olivine lamproites of the Ryabinovy massif, which is also included into the Central Aldan high-potassium magmatic area. The research is focused on the chemistry of Cr-spinels and the phase composition of Cr-spinel-hosted crystallized melt inclusions and their daughter phases. Mainly two methods were used: SEM-EDS (Tescan Mira-3), to establish different phases and their relationships, and EPMA, to obtain precise chemical data on small (2–100 μm) phases. The obtained results show similarity in chromite composition and its evolutionary trends for the Inagli massif ultramafites and Ryabinovy massif lamproites. The same has been established for phlogopite and diopside from crystallized melt inclusions from the rocks of both objects. Based on the results of the study, the conclusion is drawn that the ultramafic core of the Inagli massif resulted from fractional crystallization of high-potassium melt with corresponding in composition to low-titanium lamproite. This conclusion is consistent with the previous hypotheses suggesting an ultrabasic high-potassium composition of primary melt for the Inagli ultramafites.

An assemblage of Cr-spinels widespread in Carnian (Upper Triassic) diamondiferous deposits in the northeastern Siberian Platform is studied. Analysis of their morphology and chemical composition has revealed two dominant varieties of Cr-spinels and has demonstrated certain regularities in their distribution in the study area. Correlations have been established between the areal distribution of the recognized types of Cr-spinels and diamond varieties typical of kimberlite sources and between the distribution of Cr-spinels and rounded diamond dodecahedrons. The phase and chemical compositions of polyphase inclusions in the Cr-spinels are studied. The spatial arrangement of inclusions along the crystal growth zones indicates their primary genesis and trapping from the melt during crystallization. Compositional features of some minerals in the inclusions—SiO2 impurity in apatite and high CaO contents (0.2–0.8 wt.%) in olivines—point to a nonkimberlite source of these Cr-spinels. The presence of K- and Na-containing phases and calcite in the inclusions indicates saturation of the initial melt with alkalies, Ca, and CO2. The data obtained suggest that the numerous Late Vendian diatremes in K-rich alkaline basites of the Olenek Uplift area are the source of the dominant Cr-spinel variety.

Late Cretaceous explosion pipes (diatremes) and dikes of alkali basalts with mantle xenoliths of lherzolites and pyroxenites are unique magmatic formations of Khakassia. They are concentrated in the North Minusinsk (Chebakovo-Balakhta) basin and are associated with a Late Mesozoic tectonomagmatic activation and the processes of intracontinental rifting.

Obtained data shows that high-potassic dyke rocks of the Ryabinoviy massif (Central Aldan) belong to low-titanium lamproite series (Mediterranean type) and are distinct with “classic” high-titanium lamproites. Based on Al-in-olivine thermometer, temperature of olivine–chrome-spinel pair crystallization varies in range between 1100 and 1250°C. This suggests lithospheric mantle source for the parental melt and makes role of mantle plume insignificant. High-precision data on olivine composition and bulk rock traceelement composition imply mixed source for the parental melt, consisted of depleted peridotite and enriched domains, originated during ancient subduction.

Geological, mineralogical, petrochemical and geochronological data are considered for the Khairkhan dunite-troctolite-gabbro massif in the Lake zone of Western Mongolia. The massif intrude the Lower Cambrian molasse stratum and intruded by the Middle Cambrian diorite-plagiogranite bodies (507 Ma). Mineralogical, petrographic and geochemical data show typical suprasubduction characteristics: high An component of plagioclases with increased iron content of olivines, high whole-rock alumina content, low contents of titanium and alkalis, Ta, Nb, Zr and Hf minima. The layered series is characterized by a layers of orbicular gabbros, which can be considered as gabbro-gabbro mingling. At the same time, high-temperature viscous-plastic deformations are characteristic of the layered series, which cover the entire volume of the intrusion. These observations, together with geological and geochronological data related to the melting of the suprasubduction mantle in the Cambrian-Ordovician time, allow treating the Khairkhan massif as an example of syncollisional stratified gabbroids.

The study provides new petrologic and isotope geochemical data for rocks of the 465 ± 5 Ma Bulka massif (Borodina et al., 2011). The primary amphibole from granitoid stocks cutting across the layered series of the massif yielded an Ar–Ar age of 415.9 ± 3.7 Ma. The rocks of the Bulka massif have 143Nd/144Nd ratio of 0.513243 and eNd (Т) values of +12.00. The granitoids have 143Nd/144Nd ratios between 0.512919 and 0.512961 and eNd (Т) values between +8.03 and +9.25. The Nd isotope composition indicates that the rocks of the Bulka massif and granitoids were derived from a depleted mantle source. Depletion of the rocks of the massif in LILE, LREE, and HFSE over LILE is inherited from the mantle source, which has geochemical signatures of N-MORB and subduction-related components. Granitoids are metaluminous I-type granites, which were probably generated either by differentiation of intermediate to mafic mantle-derived magmas or by melting of metabasites. The rocks of the granitoid stocks are characterized by enrichment in LILE and LREE and depletion in HFSE over LILE, which suggests derivation from arc-related parental magmas.

We report the first data on 40Ar/39Ar dating, trace-element geochemistry, and isotope (Nd, Sr, O) composition of the Belaya Gora gabbro–foidolite–foyaite intrusive massif, one of typical representatives of the alkaline province of the northeastern Kuznetsk Alatau. The established age of rock-forming amphibole, ~401–403 Ma, is taken as the time of the pluton formation in the Early Devonian. The distribution and ratios of LILE and HFSE in the rocks suggest that the intrusion took place in the setting of “superposition” of Devonian mantle plume on the Early Paleozoic accretion–collision complexes. Therefore, the source of magmatic products had a heterogeneous composition as a result of mixing of plume material with the substances of suprasubduction and crustal substrates. The mantle component might have been a PREMA + EM combination, which is confirmed by the parameters of the Nd isotope composition (ɛNdT - 3.2-4.6; TNd(DM) - 0.8 Ga) of alkaline rocks. The effects of crustal contamination are reflected in the high ratios of strontium and oxygen isotopes (87Sr/88Sr)T = 0.7046–0.7054; δ18O = 8.5–9.2‰, SMOW).

Major and trace elements and whole rock Sr–Nd isotope data of Late Permian silicic plutonic and volcanic rocks from the Phan Si Pan–Tu Le region in NW Vietnam were collected in order to establish their petrogenetic relationship with the magmatic rocks of the Song Da zone (NW Vietnam) and the alkaline silicic rocks of the Panxi area of the Emeishan large igneous province (ELIP) in SW China. The granites and rhyolites have geochemical characteristics of anorogenic granites (e.g. high Fe# and high Ga/Al) and are further subdivided based on mineralogy. The Phu Sa Phin and Muong Hum granites contain sodic to sodic–calcic amphiboles and sodic pyroxene, while the Phan Si Pan granite does not. The Phu Sa Phin and Muong Hum granites occasionally show peralkaline to metaluminous compositions, while the Phan Si Pan granites and the Tu Le rhyolites have metaluminous to peraluminous compositions. The chondrite-normalized REE patterns [(La/Yb)N = 3.6–51.3, (Gd/Yb)N = 1.4–3.4] and the primitive mantle-normalized spidergrams (enrichment in high field strength elements) are similar to those of the Song Da silicic rocks and the Panzhihua and Taihe granites in the Panxi area. Rhyolite-MELTS modeling suggest that the silicic magmas were likely generated by fractionation of the Song Da high-Ti basalts. The eNd(t) values range from weakly negative to moderately positive values (−2.2 to +2.2), suggesting the silicic rocks may be assimilated by basement rocks during magma emplacement. Permian magmatic rocks in the Phan Si Pan–Tu Le region are petrologically, geochemically and geochronologically comparable to those of the inner zone of ELIP. Although Permian lithospheric mantle and lower crustal structure of the Phan Si Pan–Tu Le region may be destroyed by a lithospheric removal in response to Cenozoic India–Eurasia collision, our results along with recent geophysical analyses in NW Vietnam suggest that the upper to middle crust of Phan Si Pan–Tu Le region represent a remnant upper to middle crust of inner zone of ELIP.

Stable carbon isotope chemostratigraphy has been applied for correlation of Ordovician marine sedimentary successions of many continents, but not yet for those located on the Siberian Craton. In this study we present the first δ13C data from the Middle and Upper Ordovician successions of the Tungus Basin, the extensive Palaeozoic intracratonic basin on the Palaeocontinent Siberia. Carbon isotope curves from two separate areas of the craton, from the Kulyumbe River and Podkamennaya Tunguska River regions, demonstrate a great similarity. Three global carbon isotope events can be recognized in the Tungus Basin: the Mid-Darriwilian Excursion (MDICE), the Upper Kukruse Low, and the lower rising interval of the Guttenberg Excursion (GICE). These data partly support the previous inter-continental stratigraphic correlations but also suggest that the base of the Upper Ordovician in the Siberian succession lies at a lower level than previously thought. Although the conodont fauna in Siberia differs almost completely from that in Baltoscandia, the distribution of selected Upper Ordovician conodont taxa do not contradict the isotope chemostratographic conclusions.

The first detailed isotope-geochemical study of carbonate deposits has been performed in the Lower Famennian stratotype section of the northwestern Kuznetsk Basin (Kosoy Utyos), which was localized in the middle latitudes of the Northern Hemisphere in the Late Devonian. The δ13Ccarb, δ13Corg, and δ18O variation curves were constructed for the section deposits. Geochemical and petrographic studies of carbonates allowed allocation of samples that underwent postsedimentation alteration and exclude them from further interpretation. Compared with coeval sections in the other world’s regions, the Kosoy Utyos section is characterized by higher δ13Ccarb values, up to 5.4‰, whereas the maximum value in subequatorial area sections is 4‰. The isotope shift amplitude of the studied section reaches 4.6‰, which is 1.5‰ higher than those in other regions. The δ18O values are 3‰ lower than the ones of the world’s coeval sections. The results obtained show that δ13C and δ18O variation trends differ from those of coeval subequatorial sections. The high shift amplitude and maximum δ13Ccarb values in the Kosoy Utyos section are due to the shallow-water carbonate sedimentation environments on the Siberian continental shelf and, probably, the lower temperatures of waters in the middle latitudes as compared with the subequatorial areas.

Based on new data on the age, mineralogy, and geochemistry of ultramafic–mafic complexes in the Precambrian structures of the southern periphery of the Siberian Platform, the East Siberian metallogenic (PGE–Cu–Ni) province is recognized. It includes the Yenisei Ridge, Precambrian Kan uplift, Alkhadyr terrane with the adjacent structures of the Biryusa block, and northern Baikal region (Yoko-Dovyren and other massifs of the Baikal–Patom basin). We have established that the U–Pb and Ar–Ar ages of ore-bearing complexes of dunite–peridotite– pyroxenite–gabbro association correspond to the Late Riphean (728–710 Ma). The mineralogical and geochemical similarity of ore-bearing complexes in different areas testifies to their genetic entity. All parental melts were similar in composition to picrites. The calculation results and the PGE enrichment of rocks and ores show high degrees of melting of the mantle source, which agrees with the plume model of formation of the ore-magmatic system. The recognized province is similar in the type of magmatism and time of its occurrence to the Franklin LIP in northern Canada. It is one of the highly promising ore districts of East Siberia.

A 2000 km long dextral Talas-Fergana strike–slip fault separates eastern terranes in the Kyrgyz Tien Shan from western terranes. The aim of this study was to constrain an age of dextral shearing in the central part of the fault utilizing Ar–Ar dating of micas. We also carried out a U–Pb–Hf zircon study of two different deformed granitoid complexes in the fault zone from which the micas for Ar dating were separated. Two samples of the oldest deformed Neoproterozoic granitoids in the area of study yielded U–Pb zircon SHRIMP ages 728 ± 11 Ma and 778 ± 11 Ma, characteristic for the Cryogenian Bolshoi Naryn Formation, and zircon grains analyzed for their Lu–Hf isotopic compositions yielded eHf(t) values from −11.43 to −16.73, and their calculated tHfc ages varied from 2.42 to 2.71 Ga. Thus varying Cryogenian ages and noticeable heterogeneity of Meso- to Paleoproterozoic crustal sources was established for mylonitic granites of the Bolshoi Naryn Formation. Two samples of mylonitized pegmatoidal granites of the Kyrgysh Complex yielded identical 206 Pb/ 238 U ages of 279 ± 5 Ma corresponding to the main peak of Late-Paleozoic post-collisional magmatism in the Tien Shan ( Seltmann et al., 2011 ), and zircon grains analyzed for their Lu–Hf isotopic compositions yielded eHf( t ) values from −11.43 to −16.73, and calculated tHfc ages from 2.42 to 2.71 Ga indicating derivation from a Paleoproterozoic crustal source. Microstructural studies showed that ductile/brittle deformation of pegmatoidal granites of the Kyrgysh Complex occurred at temperatures of 300–400 °C and caused resetting of the K–Ar isotope system of primary muscovite. Deformation of mylonitized granites of the Bolshoi Naryn Formation occurred under high temperature conditions and resulted in protracted growth and recrystallization of micas. The oldest Ar–Ar muscovite age of 241 Ma with a well defined plateau from a pegmatoidal granite of the Kyrgysh Complex is considered as a “minimum” age of dextral motions along this section of the fault in the Triassic while younger ages varying from 227 Ma to 199 Ma with typical staircase patterns indicate protracted growth and recrystallization of micas during ductile deformations which continued until the end of the Triassic.

The obtained new data on conodonts, brachiopods, ammonoids, and ostracods from the Stolb Island section indicate the predominantly Early Famennian (triangularis–Lower rhomboidea Zones) age of sedimentation. The Upper Kellwasser global biotic event, which marks the Frasnian/Famennian boundary, has been distinguished for Arctic Siberia for the first time. It was found that carbonate-terrigenous sequences accumulated in basinal sedimentary environments. Fine-clastic material was supplied to the sediments from different sources. A flow of dolomite debris is associated with the most distant source—areas of evaporite sedimentation. The presence of calcareous fragments is due to destruction of skeletal material (close provenance areas). Siliciclastics, which make up a considerable part of the sediments, were produced by partial rewashing and eolian differentiation of felsic pyroclastics. The existence of organic-rich horizons and beds of well-washed and well-sorted clastic sequences suggests that the Upper Devonian sediments have a high general petroleum potential.

One of the problems faced by researchers when paleogeodynamic reconstructions are carried out for deeply eroded orogenic terranes is the limited usage of geological and isotopic geochemical data on volcanic associations. The utilization of information on gabbroids and granitoids considered separately also fails to resolve this problem. The convergence of features of arc, collisional, and within-plate magmatic processes leads the researcher to search for indicator plutonic associations, such as paired gabbrogranite intrusive series. The latter were distinguished using geoinformation databases (including those compiled by the authors of this paper), which were composed for the Early Caledonides in the Altai-Sayan folded area and adjacent territories. This makes it possible to characterize mantle-crustal magmatism in suprasubductional and collisional environments and the conditions under which these geodynamic regimes (plate- and plume-tectonic factors) interact. This paper presents estimates of the composition of the parental basic magmas, distinctive features of their differentiation, and the compositional specifics of the accompanying extensive granite-forming processes. The example of the Altai-Sayan folded area and adjacent territories is employed to correlate the composition of the basic-ultrabasic and granitoid magmas and, on this basis, distinguish (a) differentiated gabbro-tonalite-plagiogranite intrusive series corresponding to accretionary-collisional geodynamic environments, and (b) gabbro-monzonite-granosyenite-potassic granite intrusive series, which were produced when the accretionary-collisional system was affected by a plume.

A volcanosedimentary complex of Middle–Late Devonian deposits in northwestern Rudny Altai is described. Analysis of sedimentologic processes, the kind of manifestation and specific composition of volcanism, and petrographic and chemical compositions of sedimentary rocks permitted reconstruction of paleogeographic and geodynamic settings, which confirmed the hypothesis of the island-arc nature of the Rudny Altai zone in the Middle–Late Devonian. Also, an alternative variant of its rift nature is considered. The rift buildings are referred to as local isolated complexes confined to positive paleovolcanic structures rising above the bottom in the fore-arc basin. The denudated part of the rift system is formed mainly by slope facies. Clastics of rift buildings, together with fragments of silicite and felsic-volcanics layers, compose widespread olistostrome breccias. We have established the humid type of lithogenesis, which, together with minor sea level fluctuations, favors karst processes and the formation of red-colored and bauxite-like rocks. The coeval volcanics composing lava flows and tuff layers are mainly rhyolites and are often of ultrafelsic composition.

The Lukinda dunite–troctolite–gabbro massif in the Selenga–Stanovoy superterrane on the southeastern framing of the Siberian Platform was earlier considered Precambrian. The performed 40Ar/39Ar dating of the massif plagioclase yielded an Early Permian age (285 ± 7.5 Ma). The main specific petrochemical features of the intrusion rocks during their crystallization differentiation are an increase in SiO2 and CaO contents and a decrease in FeOtot content, with TiO2 content remaining low and showing minor variations. A specific geochemical feature of the Lukinda massif ultrabasite–basites is a slight domination of LREE over HREE, with (La/Yb)N = 1.0–8.2. The depletion of the massif rocks in LILE (except for Sr and Ba), REE, and HFSE suggests that the massif formed on an active continental margin.

The Sokhatnyi intrusion is an example of a later Mesozoic deferential massif referred to the gabbro-monzodiorite type in Northeastern Russia; according to geological data, it precedes high-alumina granitoids of the Yano-Kolymskaya folded system. It is shown that formation of the layered series of the massif is caused by the crystallized and gravitational fractioning of the high-alumina olivine basalt with increased potassium alkalinity in shallow water media. The boundary facies of the massif are represented by manzogabbroidnorites and monzodiorites. The U-Pb age determinations of zircon (SHRIMP-II) from the taxitite striped biothite gabbro in the lower boundary facies showed 148 ± 1 million years. Thus, taking into account the geological relations and geochronological data on the Sokhatinyi gabbro-monzodiorite, a differential intrusion was formed within the same age period as granite batholites of the Main belt.

The Kuznetsk Basin volcanic rocks are close in age (from 252.3 ± 0.6 to 246.2 ± 1.4 Ma) to the traps of the West Siberian Plate and Siberian craton, which formed as a result of the Permo-Triassic plume activity. The geologic and petrographic features evidence that the andesitic basalts exposed in the Karakan and Elbak quarries are effusive rocks; most of them are andesitic basalts, and the rest are trachyandesitic basalts. The mineral composition is as follows: olivine Fo59–66, plagioclase An47–60, and clinopyroxene En47–42Fs25–12Wo42–33; Mg# = 82–63. Using the COMAGMAT 3.5 program, the magma crystallization conditions during the andesitic-basalt formation were determined: 1109–1105 ºC, buffer QFM-NNO. The studied rocks are enriched in LREE ((La/Yb)ch = 4.7–7.5) and are depleted in HREE ((Sm/Yb)ch = 2.0–2.8). A specific geochemical feature of the rocks is strong Nb, Ta, Ti, and Eu negative anomalies ((La/Nb)PM = 4.5–1.6, (La/Ta)PM = 3.2–2.0, Eu/Eu* = 0.7) and a positive U anomaly on their normalized element patterns; ɛNd(T) varies from +2.3 to +3.1. The HREE depletion of the Kuznetsk Basin volcanic rock points to the presence of garnet in the mantle source during their generation. The low Mg# indicates that the parental melts are not of the primary-mantle genesis but are probably the product of differentiation in deep-seated intermediate magma chambers.

Late Permian mafic-ultramafic volcanic and sub-volcanic rocks in the Song Đa Rift include four different associations in terms of low-Ti and high-Ti types. Low-Ti, high-Mg volcanic and sub-volcanic rocks are composed of komatiite, komatiitic basalt and basalt and are divided into three groups according to their petrological and geochemical features. Chemical composition of rocks of the komatiite-basalt association is alkali-low (but rather Na-high), very Ti-low, varying from Al-high komatiite to Al-low basalt. They are characterized by high content of Mg, Al, Ni, Co, Cu and Cr, and low of Ti, Fe, Na, K, P, Rb, Ba, Sr, Nb, Ta, Nd, Hf, Zr and REE. In general, based on geochemical and isotopic characteristics the Song Đa mafic-ultramafic rocks of the komatiite-basalt association may be products of a melt derived from depleted mantle suffering the impact of mantle plume. Digital modeling showed that the initial melt composition was correspondent to komatiitic basalt. Eruption ages of the magmas are 257 ± 24 Ma (by Rb/Sr age dating), and 270 ± 21 Ma (by Re/Os age dating).

Major and trace elements and whole rock Sr–Nd isotope data of Late Permian silicic plutonic and volcanic rocks from the Phan Si Pan–Tu Le region in NW Vietnam were studied in order to establish their petrogenetic relationship with the magmatic rocks of the Song Da zone (NW Vietnam) and the alkaline silicic rocks of the Panxi area of the Emeishan large igneous province (ELIP) in SW China. The granites and rhyolites have geochemical characteristics of anorogenic granites (e.g. high Fe# and high Ga/Al) and are further subdivided based on mineralogy. The Phu Sa Phin and Muong Hum granites contain sodic to sodic–calcic amphiboles and sodic pyroxene, while the Phan Si Pan granite does not. The Phu Sa Phin and Muong Hum granites occasionally show peralkaline to metaluminous compositions, while the Phan Si Pan granites and the Tu Le rhyolites have metaluminous to peraluminous compositions. The chondrite-normalized REE patterns and the primitive mantle-normalized spidergrams (enrichment in high field strength elements) are similar to those of the Song Da silicic rocks. The eNd(t) values range from weakly negative to moderately positive values (−2.2 to +2.2), suggesting the silicic rocks may be assimilated by basement rocks during magma emplacement. Permian magmatic rocks in the Phan Si Pan–Tu Le region are petrologically, geochemically and geochronologically comparable to those of the inner zone of ELIP.

The Mesozoic Chuya dike complex was recognized by R.V. Obolenskaya based on the similar mineral composition of dikes and their age characteristics. Lamprophyres occur along the large Terekta–Tolbonur and Kurai–Kobda shear zones. The Chuya complex was studied by the example of two areas, South Chuya and Yustyd, with different levels of erosional truncation. The dikes of the first area are localized in the South Chuya Ridge, where they cut Cambrian–Ordovician metamorphic rocks, and the dikes of the Yustyd area occur in the Devonian terrigenous blackshale deposits of the Yustyd trough. The dikes of these areas differ in structures, textures, the degree of carbonatization, and mineral composition. The performed studies of rocks and minerals confirmed that the dikes of both areas belong to the same complex. They helped to establish the regularities of the lithologic composition of the entire complex and its local areas and to substantiate the recognition of areas not only from their geologic position but also by the composition, structures, and textures of rocks and their mineral composition. Geochronological data show two stages of the complex formation: 236–234 and 250–242 Ma. The results of studies also demonstrate that the lamprophyres and coeval syenites of the Tarkhata massif are fractionates of the same parental melt and can be united into a hypabyssal-plutonic complex. Comparison with other Permo-Triassic lamprophyre complexes showed that the wide variations of the composition of the Chuya rocks and its trend as well as the geochemical anomalies are specific features of complexes of high-K lamprophyres.

40Ar/39Ar isotopic ages of magnesioarfvedsonite (725.9 ± 6.3 myr) and phlogopite (637.6 ± 5.7 myr) from carbonatites of the Penchenga rock complex located in the South Trans Angara segment of the Yenisei Ridge have been determined. Based on this, the formation of the rock complex is associated with the start of the period of Neoproterozoic (725–700 Ma) rifting and alkaline magmatism in the region, the latter being associated with the former. The appearance of zones penetrable for magma of the “disseminated” rifting type is associated with the development of late collision shear dislocations in a consolidated marginal continental crust. The primary melts had a plume nature, but matter from different mantle sources intermixed in the environment of the changing geodynamic regime. The younger age of the mica was apparently caused by partial remelting of carbonatites under the influence of heat and fluids generated during the formation of the adjacent large granite massif of a younger age.

With U-Pb zircon dating, the ages of the Ul’degit (228 ± 1 Ma) and Chek-Chikan (203 ± 1 Ma) mafic massifs were determined. These massifs were earlier considered to form at the Early Precambrian stage of the geologic evolution of the Dzhugdzhur–Stanovoi superterrane. In geochemical features the igneous rocks of the massifs show relation with a within-plate source, on the one hand, and are similar to igneous rocks of subduction zones, on the other. They might have formed after subduction, which caused the intrusion of gabbroids of the Lucha massif (248 ± 1 Ma) and diorites of the Tok-Algoma complex (238 ± 2 Ma), followed by the fracturing of the subducted plate.

The new petrochemical and isotope-geochronological characteristics for picritoid and associated alkali-basaltic complexes of the Northern Mongolian Belt (NMB) are given. They are composed in small intrusions, dykes, sills, and volcanic covers with rocks of a higher potassium and titanium content. The studied areas with these units belonged to the western part of the NMB, which stretches sublatitudinally from Uureg Nuur Lake in the west to the south of Trans-Hovsgol Region in the east. By the petrochemical parameters, the complex corresponds to subalkaline basites and lamprophyres, including micaceous plagioperidotites and picrodolerites. The obtained values of Ar-Ar age (342–319 Ma B.P.), together with the known data on other areas in this complex where these rocks are distributed, evidences for a relatively wide (Middle-Late Paleozoic) interval of its origination.

The paper presents data on the structure, composition, and age of granitoid associations (Tokhtogeshil’skii Complex) composing the Kharanur and Sharatologoi polychronous plutons in the northern part of the Ozernala zone in western Mongolia. The Tokhtogeshil’skii Complex was determined to consist of a number of independent magmatic associations, which were formed at 540–450 Ma, within three age intervals (540–520, 510–485, and 475–450 Ma), have different composition, were derived from different sources, and were emplaced in different geodynamic environments. During the first, island-arc stage (540–520 Ma), high-Al plagiogranites were produced, which belong to tonalite-plagiogranite (531 ± 10 Ma) and diorite (529 ±6 Ma) associations in the Kharanur pluton, low-Al plagiogranites of the tonalite-plagiogranite association (519 ± 8 Ma) in the Sharatologoi pluton, and rocks of the Khirgisnur peridotite-pyroxenite-gabbronorite complex (Kharachulu and Dzabkhan massifs). The rocks of the diorite and plagiogranite associations of the Kharanur pluton have ɛNd(T) from +7.9 to +7.4, TNd(DM) = 0.65 Ga, and (87Sr/86Sr)0 = 0.7038–0.7039. The plagiogranites of the Sharatologoi pluton (tonalite-plagiogranite association) are characterized by ɛNd(T) from +6.5 to +6.6, TNd(DM) = 0.73–0.70 Ga, and (87Sr/86Sr)0 = 0.7038–0.7039, which suggest predominantly juvenile subduction sources of the parental melts at a subordinate role of ancient crustal material. During the second, accretionary stage (510–485 Ma), low-Al plagiogranites of the diorite-tonalite-plagiogranite association of the Sharatologoi pluton (494 ± 10 Ma, M type) were formed. The Sr-Nd isotopic characteristics of these rocks ɛNd(T) = +6.6, (87Sr/86Sr)0 = 0.7039 are analogous to those of the plagiogranitoids of the early type. This suggests that the melted sources were similar in composition. During the third, postcollisional stage (475–450 Ma), rocks of the diorite-granodiorite-granite association were formed (459 ± 10 Ma, type I) in the Kharanur pluton. These rocks have ɛNd(T) = +5.1, TNd(DM) = 0.74 Ga, and (87Sr/86Sr)0 = 0.7096. The parental melts were supposedly derived by means of partial melting of “the Caledonian” juvenile crust with the addition of more ancient crustal material.

Three zones of layered series — lower, middle, and upper — composed of dunites and plagiodunites, troctolites and olivine gabbros, gabbros and gabbronorites, respectively, have been recognized in the Luchina massif. The melt that produced the massif rocks was of picrite-basaltic composition (15–16% MgO), and its crystallization took place at 1300–1000 °C and ∼7 kbar. The Early Mesozoic age (248±1 Ma), geochemistry, and location of the massif on the northern periphery of the eastern segment of the Mongolo-Okhotsk fold belt suggest that it formed either in the hinterland of subduction zone dipping beneath the southern margin of the Dzhugdzhur-Stanovoy superterrane or on the periphery of the Siberian superplume during the mantle heating.

We have shown that the occurrences of Permo-Triassic magmatism in northern Vietnam compose the southwestern and southeastern flanks of the Emeishan large igneous province, shifted along the large-amplitude Ailao Shan-Red River shear zone. Based on new geochronological (U-Pb and Ar/Ar) data, two stages of magmatism related to the Emeishan plume have been recognized. At the first, Permian, stage (260 Ma), abundant picritoids of the Song Da and Song Hien zones formed, and at the second, gabbro-syenite and gabbro-monzodiorite associations of the Lo Gam zone, layered peridotite-gabbro massifs of the Nui Chua complex, high-alumina granites of the Phia Bioc complex, and basalt-rhyolite association of the Song Hien zone were produced. The metallogenic specialization of the Permo-Triassic magmatism of northern Vietnam is considered.

We present new data on the age and geochemistry of the Veselyi and Petropavlovsk ultramafic-mafic massifs of the Selenga-Stanovoy (West Stanovoy) superterrane on the southeastern framing of the North Asian craton. The massifs are composed of rocks of peridotite-websterite-gabbro and peridotite-gabbro-monzodiorite associations, respectively. The latter combine normal, subalkalic, and alkaline rocks and thus are of diverse composition: from ultrabasites and pyroxenites through gabbroids to monzodiorites. The U-Pb zircon age of these massifs is 154 ± 1 and 159 ± 1 Ma, respectively, which permits them to be referred to as the youngest rocks of ultramafic-mafic complexes on the southern framing of the North Asian craton. The rocks of the studied massifs are enriched in LILE (K, Rb, Sr, Ba, LREE) and are depleted in HFSE (Zr, Nb, Hf, Ta). These rocks formed, most likely, in the rear of subduction zone or in the setting of the subducting-slab detachment.

The Veselki peridotite-websterite-gabbronorite massif was dated by U-Pb zircon method at 154 ± 1 Ma. This is the first Late Jurassic date obtained for ultramafic-mafic massifs in the eastern part of the Selenga-Stanovoy superterrane bounding the southeastern margin of the Siberian craton. The mineralogical specifics of the massif is expressed in the presence of three-pyroxene assemblage [bronzite-pigeonite-augite (diopside)] and exsolution lamellae of Cr-spinel and Cr-magnetite in Fe-Cr picotite and suggests unstable crystallization at shallow depths. Geochemical similarity between the Upper and Lower series attests to their genetic relation through intrachamber differentiation. The massif was generated from a highly evolved melt, as is seen from the LREE enrichment (La/Yb)N = 3.89–30. Plagioclase varieties display a weak positive Eu anomaly (Eu/Eu* = 1.1–1.25), whereas other rocks have an insignificant negative Eu anomaly (Eu/Eu* = 0.85–0.97). Model calculations show that parental melt was close to subalkaline picrite, which evolved along two fractionation trends into dunites and subalkaline gabbroids and monzodiorites.

[1] Paleomagnetic results obtained from the early Triassic Semeitau igneous series (SIS) yield a high-quality pole for eastern Kazakstan that is concordant with reference poles for Siberia and Europe, strongly supporting the hypothesis that Kazakstan was already joined with Eurasia at this time. Of the 25 sites that were measured, data were straightforward for 20 sites, 2 of which recorded normal polarity and 18 of which recorded reverse; 5 sites were discarded because of severe overprinting, unstable demagnetizations, or extremely scattered within-site directions. Combining sites judged to be the same cooling unit and taking the average of 15 cooling units of equal weight, we calculated a pole located at 56°N, 139°E (N = 15, K = 24.6, α95 = 7.9) for the SIS. We consider this pole to be reliable. The sampling of temporally spaced extrusives and more slowly cooled intrusives and the presence of both polarities strongly suggest that this pole averages secular variation. The 40Ar/39Ar determinations on sanidine crystals from two extrusive units yielded highly consistent ages of 248.2 ± 0.5 and 248.8 ± 0.5 Ma. Comparison of our pole for the SIS with the Siberian reference pole shows relative translation (−8° ± 10°) and rotation (1°±16°) that are indistinguishable from zero at 95% confidence. This result fails to confirm hypothesized post-Permian rotation of the Siberian craton relative to its margins and provides no evidence for left-lateral motion on the east-west shear zones in which the Semeitau is located. The similarity of ages between the SIS and the Siberian Traps supports speculation of a genetic relationship between the two.