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It is evident that the Yangtze Craton was involved in the formation and breakup of the Columbia supercontinent. However, due to the scarcity of Mesoproterozoic geological records and reliable paleomagnetic data, little is known about the timing, paleogeographic position, and geological processes of the Yangtze Craton. We conducted detailed geological mapping, petrographic, geochemical, and in situ zircon U-Pb and Lu-Hf isotopic investigations on newly recognized Mesoproterozoic quartz syenite and monzogranite in the Dabie orogen, northern Yangtze Craton. The results show that the quartz syenite and the monzogranite were emplaced at 1369 ± 12 Ma and 1372 ± 5 Ma, respectively. Both rocks are high in total alkali (K2O + Na2O) content and FeOt/(FeOt + MgO), with elevated diagnostic 10,000*Ga/Al ratios and Zr + Nb + Ce + Y concentrations, and enrichment in light rare earth elements. They are also depleted in heavy rare earth elements with significant negative Eu anomalies but remarkably low Sr, Cr, and Ni contents. These compositions define affinity to A1-type granite. In addition, the quartz syenite displays variable zircon Hf and homogeneous whole-rock Nd isotopic compositions with positive εHf(t) values of +0.7 to +5.7 (average +2.4) and εNd(t) values of -0.1 to +2.5 (average +1.0). In contrast, the monzogranite has homogeneous zircon Hf and whole-rock Nd isotopic compositions with negative εHf(t) values of -5.7 to -2.6 (average -4.8) and εNd(t) values of -3.5 to -1.5 (average -2.2). We propose that the quartz syenite was likely generated by the partial melting of juvenile, crust-derived melt with involvement of minor mantle-derived material, while the monzogranite was likely derived from the partial melting of ancient crust in an extensional tectonic regime (e.g., continental rift). Based on the newly recognized ca. 1.37 Ga granitic magmatism and previously reported magmatic events, we argue that the mid-Mesoproterozoic (ca. 1.37 Ga) magmatism in the Yangtze Craton occurred in response to the breakup of Columbia, and represents the separation of the Yangtze Craton from Columbia. Furthermore, according to comparable magmatic and sedimentary events, we propose that the Yangtze Craton, along with central Hainan Island, may have been linked to northwestern Laurentia, southwestern Siberia, and northeastern Australia during 1.6-1.4 Ga. [ABSTRACT FROM AUTHOR]

The Kotuy intrusive complex was identified from the geological survey of the western slope of the Anabar Massif in the middle reaches of the Kotuy River. It is represented by dolerite–gabbrodolerite sills and dikes of Vendian age (556 ± 28 Ma). A number of sills are characterized by 30–80 m thickness, and dikes often have a length of a few dozen kilometers. The distribution area of the complex is a few hundred square kilometers. However, the geodynamic evidence for the formation of extensive intrusive bodies in the northern part of Siberia in the Vendian is not clear. We present new geochronological, geochemical, and paleomagnetic data indicating that at least part of the Kotuy magmatic complex intrusions in the middle reaches of the Kotuy River should be attributed to the ~1500 Ma Kengede magmatic complex (Kuonamka large igneous province). In this light, the very existence of Vendian intrusive magmatism on the western slope of the Anabar massif appears questionable. [ABSTRACT FROM AUTHOR]

In this study, we present the results of U–Pb (ID-TIMS) geochronological studies of calcic garnet from the alkaline ultramafic complexes of Eastern Sayan province (eastern Siberia). New U–Pb ID–TIMS garnet ages obtained from different rocks of Bolshaya Tagna (632 ± 2 Ma) and Srednaya Zima intrusions (624 ± 5 Ma), as well as previously published garnet ages of the Belaya Zima complex (646 ± 6 Ma), allow us to constrain the timing and duration of episodes of alkaline ultramafic magmatism in Eastern Sayan province (619–651 Ma). Variations in the chemical compositions of rocks from three massifs indicate that the parental melts were separated from different magmatic chambers generated during the same episode of mantle melting. This study further highlights garnet U–Pb dating as a potentially robust, high-resolution geochronometer to constrain the evolution of the main pulse of alkaline ultramafic magmatism in the large magmatic provinces. [ABSTRACT FROM AUTHOR]

Tracing coupled ocean closure and intra-continental orogenic processes using tectonomagmatic thermal events is important for performing plate reconstructions. In this study, we collected geochronological data obtained from Jurassic–Early Cretaceous volcanic sequences in the Great Xing apos; an Range (GXR) and compared and merged the data to obtain a better understanding of the timing of volcanism in the GXR. Jurassic–Early Cretaceous volcanism, which is mainly represented by the Tamulangou, Manketouebo, and Manitu formations, are ubiquitous in the GXR and do not contain a magmatic hiatus. Thus, 'diachronous' volcanism did not occur in the GXR. The volcanic sequences in these formations are also slightly ambiguous and therefore cannot be used to determine the timing of volcanism. However, absolute ages and rock assemblages can provide better constraints on this timing. Combined with data from Jurassic–Early Cretaceous tectonomagmatic thermal events in Mongolia, Siberia, and NE China, we re-evaluated the influences of the Jurassic–Early Cretaceous closure of the Mongol–Okhotsk Ocean (MOO), as well as the subduction and rollback of the Izanagi Plate, at different times in the GXR. The GXR likely underwent flat-slab subduction during the Late Jurassic–early Cretaceous as the MOO closed in an irregular 'scissor-like' fashion (i.e. not in a progressive west to east manner). Large-scale lithospheric delamination likely led to a large pulse of magmatism and mineralisation in the GXR during the late Early Cretaceous. [ABSTRACT FROM AUTHOR]

Mesoproterozoic period included several global tectonic events like break-up of Nuna and formation of Rodinia. However, although Siberia is a significant piece of both supercontinents, Mesoproterozoic time is marked by quiescence of magmatic and tectonic activity in it. We report here a mafic dyke (named Gornostakh dyke) in the southeastern Siberian Craton dated at 1419 ± 32 Ma by LA-ICPMS U–Pb geochronology of apatite. The dyke has tholeiitic compositions with high MgO and alkaline content, low-Ti, and arc-like trace element pattern. Due to the absence of subduction tectonics in the study area, geochemical data could be attributed to a significant contribution from metasomatically enriched subcontinental lithospheric mantle previously modified by subduction processes. That kind of composition is common for low-Ti dykes of intraplate flood basalt provinces similar to, for example, Permian–Triassic Siberian large igneous province (LIP). Paleogeographic reconstructions suggest that Siberia was connected to Laurentia and Baltica and their reconfiguration interrupts a prolonged tectonic quiescence in the Siberian Craton from ca. 1.88 Ga reflecting a transition from Nuna to Rodinia configuration. The mafic magmatism on 1419 Ma on the southeastern margin of the Siberian Craton together with coeval extensional tectonics observed in the structure of the Sette-Daban ridge proposes a hypothetical LIP which may be a direct consequence of the beginning of this transition. [ABSTRACT FROM AUTHOR]

This work is the first in situ U–Pb geochronological study of perovskite and calcic garnet (andradite) from the Guli complex in the Maimecha–Kotuy alkaline province (Polar Siberia, Russia). The U–Pb isotopic compositions of perovskite from contact zones of the two carbonatite stocks (Southern and Northern) and from jacupirangite separating the stocks were determined by laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICPMS) and isotope-dilution thermal-ionisation mass-spectrometry (ID-TIMS). The LA-ICPMS and ID-TIMS data for perovskite from the Northern carbonatite stock are in good agreement, yielding 206Pb/238U ages of 250.4 ± 1.1 Ma and 249 ± 2 Ma, respectively. These ages are also within the analytical uncertainty from the ID-TIMS results for perovskite from jacupirangites (250 ± 1 Ma). The LA-ICPMS results for perovskite from the Southern carbonatite stock indicate its somewhat older age (255.3 ± 2.4 Ma), implying the possibility of small-volume mantle magmatism predating the eruption of the Siberian flood basalts at ca. 252–251 Ma. This interpretation is supported by reports of pre-flood magmatism elsewhere in eastern Siberia. Andradite crystals from the contact between the Southern stock and metasomatised melilitolite were analysed by ID-TIMS. These measurements are inconclusive (247 ± 6 Ma) and could not be used to constrain further the timing of carbonatitic magmatism in the southern part of the complex. The present contribution also presents a refined methodology for LA-ICPMS geochronological studies of perovskite with elevated levels of common lead, and addresses some of the problems with previously proposed calibration standards. [ABSTRACT FROM AUTHOR]

Paleomagnetic studies of the Early, Middle Ordovician and Early Carboniferous strata of Tuva have been carried out. It has been established that the Ordovician strata of Tuva accumulated in the latitude range from 4° to 12° S. The coordinates of the Ordovician paleomagnetic pole for Tuva (for the southern hemisphere) are Φ = –41° N, Λ = 127° E, A95 = 5.4°. The lower Carboniferous strata of Tuva accumulated at high latitudes: 51°–70.5° N. Coordinates of the paleomagnetic pole for the Lower Carboniferous of Tuva: Φ = 53.8° N, Λ = 141.7° E, A95 = 9.6°. The Tuva block as a whole did not experience significant rotations relative to Siberia in the Phanerozoic. Nevertheless, there were local deformations and rotations of rocks, which led to differences in the declination of the magnetization of the strata of Siberia and the Tuva block. Tuva, already from the Ordovician, was part of the structure of Siberia and experienced latitudinal movement along with it. Caledonian structures were formed on the margin of Siberia. Postcollisional Phanerozoic magmatism of the Altai-Sayan region has an intraplate genesis. [ABSTRACT FROM AUTHOR]

Geological, petrological, isotope-geochemical (40Ar/39Ar analysis, petrochemical data, and geochemistry of trace elements and REE), and mineralogical researches testify that the formation of the early Paleozoic basalt and picrite complexes of the West Siberian Plate basement was related to the development of the Cambrian subduction zone of the Paleo-Asian Ocean. Using the compositions of clinopyroxenes and amphiboles (and also programs of computational modeling), we have established the P-T conditions of formation of early Paleozoic picrite complexes. Crystallization of clinopyroxenes began at significant depths (25-20 km) and at high temperatures (1300-1275 °C). Olivine might have formed at elevated pressures (8-7 kbar) and temperatures of 1540-1490 °C. Amphiboles formed, most likely, at 6.1-4.5 kbar and much lower temperatures, 1105-1060 °C. Petrochemical analysis and data on trace elements and REE in the rocks of the studied early Paleozoic complexes in West Siberia testify to their intricate formation involving magmatic systems with basalt (island arc and back-arc basins), picrite, and shoshonite (and also WPB type) melt characteristics. Taking into account the similar geochemical characteristics of the early Paleozoic basaltoids and picrites of the West Siberian Plate basement and the Kamchatka volcanics, we suggest that a considerable part of the studied ancient complexes formed by the model implying (as in the case of the Sredinnyi Ridge in Kamchatka) the action of enriched magmatic systems during the development of a destructive window ("slab-window") under rupture of subducted plate on the background of common island arc magmatism. [ABSTRACT FROM AUTHOR]

Reproducing the geological evolution of the Yenisei Range is important not only to understand how mobile belts at boundaries between ancient cratons tectonically evolved but also to gain an insight into how the Siberian craton was incorporated into the Nuna and Rodinia supercontinents. The paper presents geological, geochemical, and isotope geochronologic evidence of Meso- to Neoproterozoic events in the western margin of the Siberian craton and demonstrates that multiple pulses of intraplate magmatism occurred during the late evolution of the Yenisei Range. The rocks produced by these processes crystallized from high-temperature and hydrous magmas, which were rich in alkalis, iron, and most incompatible elements, as is typical of A-type anorogenic granites in intraplate environments. According to U–Pb zircon and monazite dates, the emplacement age of the granites is constrained between two peaks at 1380–1360 and 800–720 Ma. These magmatic events well correlate with the breakup ages of the Precambrian Nuna and Rodinia supercontinents and provide evidence that the Siberia was close to the North-Atlantic cratons (Laurentia and Baltica) during a long time span starting at 1.38 till 0.72 Ga, which is consistent with modern paleomagnetic reconstructions of the position of the supercontinents and the age spans when LIPS were formed. [ABSTRACT FROM AUTHOR]

• A new robust U-Pb baddeleyite age of 1385 ± 5 Ma for Virei dyke swarm, Angola. • A new 1385 Ma paleomagnetic pole for Congo-São Francisco (CSF) craton. • A refined Nuna model with SW Congo / W Siberia cratonic connection at 1700–1500 Ma. The location of the Congo-São Francisco (CSF) craton, one of the largest cratons in Proterozoic paleogeography, has been poorly constrained for the supercontinent Nuna interval (ca. 1800–1300 Ma). Initial models of Nuna suggested that the CSF craton was part of the Atlantica continent, together with Amazonia, West Africa, and perhaps Río de la Plata, as a separate continental block from other Nuna constituents. In other Nuna models the CSF craton has been placed adjacent to Baltica and Siberia, the core of Nuna, based mainly on ages of mafic magmatism and sparse paleomagnetic data. Through a geochemical, geochronological and paleomagnetic study of the WNW-trending Virei mafic dykes, which extend outward from the Mesoproterozoic Kunene Igneous Complex in southwest Angola, we provide a U-Pb baddeleyite age of 1385 ± 5 Ma, geochemical signatures, and a robust Mesoproterozoic paleomagnetic pole to test the CSF craton's placement within Nuna. Including our new pole with quality-filtered poles from the other cratons during the Nuna interval, we propose a refined Nuna model with (1) southwest Congo / west Siberia cratonic connection at 1700–1500 Ma, (2) proximity of Amazonia and West Africa cratons, and (3) connection of southwest Congo craton with northwest West Africa at 1380 Ma. Our proposed 1500–1380 Ma reconstructions are further supported by matching large igneous province (LIP) records from these crustal blocks. The new 1385 Ma Virei pole, when considered relative to an earlier CSF pole at ca. 1500 Ma, requires substantial azimuthal rotation (∼85°) of CSF in the intervening time interval. To accommodate both the matching LIP records and paleomagnetic data from CSF and neighboring cratons in Nuna, we propose an interval of transform motion near the supercontinent's periphery prior to more widespread mid-Mesoproterozoic supercontinental breakup. [ABSTRACT FROM AUTHOR]

The world-class Katugin deposit (Eastern Siberia, Russia) in the high-F alkaline granite of the Katugin complex is located within the Early Proterozoic Stanovoy orogenic belt on the southeastern periphery of the Siberian craton. The deposit stores economic amounts of Nb, Y, Zr, REE, Ta, Th, U, and cryolite. Its formation was previously interpreted in terms of a single-stage model, but new zircon data reveal an additional stage in its history. That stage was separated in time from the magmatic activity and led to a redistribution of REE + Y and, probably, additional enrichment of rocks in these components. Zircon in the deposit area occurs ubiquitously in alkaline granite and forms zones at granite contact with cryolite veins and lenses. Four types of zircon have been identified based on their microstructure. Type I zircon with magmatic signatures makes relict cores in zircon grains and has an age of 2064 ± 5 Ma in granite and 2080 ± 10 in ores (> 20 vol% of zircon), which is coeval with the emplacement of the Katugin granite. This type of zircon exhibits positive ɛHf(t) values, from +3.3 to +1.1, testifying for a juvenile source. Type II zircon (1921 ± 11 Ma) occurs within a core at the granite-cryolite contact. Type III zircon (1900 ± 6 Ma), heterogeneous in cathodoluminescence (CL) images, overgrows Type I and II zircon grains. The zircon zones with low or no CL response are characterized by high concentrations of REE 2 O 3 , Y 2 O 3 and P 2 O 5. This type of zircon contains abundant multiphase (solids + fluid) and polycrystalline inclusions, with a large percentage of REE + Y fluoride and fluorocarbonate among solids and a high-density CO 2 -enriched fluid phase. Type IV homogeneous zircon (1909 ± 10 Ma) rims are observed in most zircon grains. Types II, III and IV zircon have negative ɛHf values, from −2.2 to −3.8. They are coeval and crystallized during high-grade metamorphism and magmatism, which accompanied the final amalgamation of the Siberian craton at 1.93–1.88 Ga. The formation of Type III zircon occurred in the presence of high-F CO 2 -rich fluids, possibly, coming from a mantle source, which supposedly led to redistribution and additional inputs of REE in the granite. • The world-class Katugin rare metal deposit was formed in two stages: magmatic and metasomatic. • The economic Zr mineralization was formed during the magmatic stage (2064 ± 5 Ma). • REE + Y and cryolite ores result from metasomatic stage (1904 ± 6 Ma). • Nb mineralization developed during all stages, including metamorphic events. [ABSTRACT FROM AUTHOR]

The Kolyvan–Tomsk folded zone (KTFZ) represents part of the Central Asian Orogenic Belt (CAOB). The KTFZ is mainly composed of detrital Late Palaeozoic sedimentary deposits, with minor intrusions. Detrital zircon geochronology on the Upper Devonian to Lower Permian sedimentary sequences of the KTFZ and the associated Gorlovo foreland basin yields four age peaks, reflecting the magmatic events in the source terranes. These events consist of (a) a minor Neoproterozoic peak (0.9–0.7 Ga), (b) a significant Early Palaeozoic peak (550–460 Ma), with a maximum at 500 Ma, and two well‐defined Late Palaeozoic peaks during (c) the Middle–Late Devonian (385–360 Ma) and (d) the Carboniferous–Early Permian (360–280 Ma), with a maximum at 320 Ma. Older zircons (>1 Ga) are quite rare in the sampled sedimentary sequences. Slightly negative εNd values and associated relatively young Nd model ages were obtained (εNd(T) = −0.78, T (DM) ~1.1 Ga for Upper Devonian sandstones, εNd(T) = −1.1, T (DM) ~1.1 Ga for Lower Permian sandstones), suggesting only minor contribution of ancient continental crust to the main sedimentary units of the KTFZ. All intrusive and volcaniclastic rocks on the contrary are characterized by high positive εNd(T) values in the range of 3.78–6.86 and a Late Precambrian model age (T (DM) = 581–916 Ma), which corroborates its juvenile nature and an important depleted mantle component in their source. The oldest unit of the KTFZ, the Bugotak volcanic complex formed at the Givetian–Early Frasnian transition, at about 380 Ma. Upper Devonian detrital deposits of the KTFZ were formed in the Early Palaeozoic accretion belt of the Siberian continent and specifically in a passive continental margin environment. Deposits of the Gorlovo foreland basin, adjoining the KTFZ, were accumulated as a result of erosion of the Carboniferous–Early Permian volcanic rocks, which are now buried under the Meso–Cenozoic sedimentary cover of the West Siberian Basin. The magmatic events, recorded in the KTFZ zircon data, correspond to the most significant magmatic stages that affected the western part of the CAOB as a whole. [ABSTRACT FROM AUTHOR]

In the northern part of the Siberian Platform, east of the Anabar Shield, several massifs of alkaline rocks with carbonatites identified (Tomtor, Bogdo, Promezhutochnyi) and projected according to geophysical data (Bualkalakh, Chuempe, Uele) form a large alkaline–carbonatite province. The first data on the composition of alkaline rocks of the Bogdo massif indicate that the latter belong to a group of feldspathoid rocks of basic composition: rischorrites, biotite–aegirine liebenerite syenites, carbonatized pseudo-leucite nepheline syenites with symplectites, and nepheline–feldspar aggregates. Sphene grains were extracted from various rocks of the Bogdo massif, and their U‒Pb age was determined using the SHRIMP-II secondary-ion microprobe. The calculated U‒Pb age is 394.4 ± 3.2 Ma, which is similar to the age of the Tomtor massif and the age of the rocks of the Kola alkaline province. One of the reasons for the manifestation of alkaline plume magmatism on this territory may be the effect of the peripheral zone of the African Large Low Shear Velocity Province ("Tuzo") on the Baltic area and Siberia during the Devonian age. [ABSTRACT FROM AUTHOR]

Geochemical and isotope–geochronological evidence of Late Riphean intraplate magmatism within the Chernorechenskii massif at the western margin of the Siberian Craton has been obtained. These rocks crystallized from high-temperature and water-unsaturated magmas with a high content of alkalis, iron, and most noncoherent elements, which is typical of anorogenic A-type granites of intraplate settings. Their U–Pb age is 723 ± 6 Ma, coeval to the Franklin rifting event widespread in the north of Laurentia, which is associated with the break-up of Rodinia. The simultaneity of the magmatic activity and concomitant rifting, as well as a similar sequence of analogous tectonothermal events at the Arctic margin of Rodinia, confirms modern paleoreconstructions, suggesting the territorial proximity of Siberia and the cratons of the North Atlantic at that time. [ABSTRACT FROM AUTHOR]

Abstract The fragmentation of the Columbia supercontinent is thought to have begun as early as ~1.7 Ga; however, the breakup of its core domain occurred only at ~1.5–1.25 Ga. This study presents the integrated petrological and chemical characteristics of gabbro and granite porphyry intrusions in the Haizi region of China, which record the oldest magmatism associated with the initial breakup of Columbia in the southwestern Yangtze Block. The dating of gabbro and granite porphyry samples using laser ablation–inductively coupled plasma–mass spectrometry zircon U Pb geochronology gives crystallization ages of 1754 ± 14 Ma and 1743 ± 4 Ma, respectively. The gabbro is characterized by low La/Ta, Th/Y, (La/Yb) N , and (Dy/Yb) N ratios, negligible Nb Ta anomalies, moderately depleted Nd isotope signatures (ε Nd (t) = +2.4 to +5.3), and enriched zircon Hf isotopes (ε Hf (t) = −1.8 to −7.8), indicating derivation of the primary magma from ambient asthenospheric mantle and complex petrogenetic processes before emplacement. Geochemical modeling indicates a variable but low degree of partial melting (1%–15%) and minor crustal contamination during magma ascent. The gabbro samples have relatively high TiO 2 (1.94–3.73 wt%) and Zr (95–271 ppm) contents, typical of rocks formed in an intraplate tectonic setting. The granite porphyry samples display high FeOT/MgO and Ga/Al ratios, high contents of high-field-strength elements, and low CaO–Sr contents, resembling A-type granites. Compared with the gabbros, these porphyries show wider geochemical gaps, more variable ratios between incompatible elements, and lower radiogenic Nd isotopic compositions (ε Nd (t) = +0.3 to +2.7 and T DM2(Nd) = 2226– 2028 Ma). However, the porphyries have more radiogenic zircon Hf isotopes (ε Hf (t) = 0 to +3.7 and T DM2(Hf) = 2421–2189 Ma) than those of the gabbros, suggesting their derivation from the partial melting of a Paleoproterozoic crustal source triggered by an upwelling basaltic magma in an intraplate extensional setting. The ~1.75 Ga bimodal magmatism reported in this study, together with the ~1.75–1.65 Ga mafic magmatism documented in other cratonic blocks, suggests a possible spatial linkage between the Yangtze Block, northern Australia, northwestern Laurentia, and southern Siberia in the late Paleoproterozoic Columbia supercontinent. Highlights • ~1.75 Ga bimodal magmatism is identified in the SW Yangtze Block of China. • Gabbro was derived from asthenospheric mantle with minor crustal assimilation. • A-type granite porphyry was generated by partial melting of Paleoproterozoic mafic crust. • The earliest magmatism related to Columbia supercontinent fragmentation in the SW Yangtze Block. [ABSTRACT FROM AUTHOR]

It is commonly believed that very large basalt volumes produced by Early Triassic magmatism had effused synchronously in both the Siberian Platform and Western Siberia in a very short time interval 249.4 ± 0.5 Ma ago ([15] and others). This magmatism and the climate changes it induced are considered as the main reason for the most catastrophic (Permian–Triassic) extinction event in the Earth's history. However, these conclusions are based on incomplete and unrepresentative data on Western Siberia. Based on analysis of the pyroxene monofraction from kainotypic basalts of the Guslinskaya P-430 well, we obtained an Ar–Ar age of 268.4 ± 7.5 Ma. The respective age for the Taurovskaya 503 well is 268.1 ± 7.5 Ma. Hence, volcanism in the axial rift zones of the West Siberian Plate basement began earlier than was thought and significantly earlier than that in the Siberian Platform. [ABSTRACT FROM AUTHOR]

In the late Neoproterozoic a prolonged active continental margin mode dominated the southwestern margin of the Siberian craton. Based on results of geological, petrological-geochemical, U-Th-Pb and Sm-Nd, Rb-Sr isotope investigations, for the first time we established that on the final evolution stage of this margin 576-546 Ma, intrusions of adakites and gabbro-anorthosites of the Zimoveyniy massif were emplaced in the South Yenisei Ridge. These new data indicate genetic relationships of the studied adakites and host NEB-metabasites. The formation of adakites could have been due to a crustal or a mantle-crustal source in a setting of transform sliding of lithospheric plates after the subduction stopped. [ABSTRACT FROM AUTHOR]

The petrological-geochemical and isotopic-geochronological studies of contrasting rocks of the Yenisei Regional Tectonic Zone of the Yenisei Ridge allowed identification of the period of formation of riftogenic structures accompanied by intraplate magmatism. The extension processes are reflected in dike swarms of bimodal associations of anorogenic granites and intraplate mafic rocks with an intrusion age of 797-792 Ma. The formation of this belt is related to the Neoproterozoic extension along the western margin of the Siberian Craton, which occurred during breakup of the Rodinia Supercontinent and origination of the Paleoasian Ocean. [ABSTRACT FROM AUTHOR]

A new large igneous province (LIP), the 1501 ± 3 Ma Kuonamka LIP, extends across 700 km of northern Siberia and is linked with coeval dikes and sills in the formerly attached Sao Francisco craton (SFC)-Congo craton to yield a short-duration event 2000 km across. The age of the Kuonamka LIP can be summarized as 1501 ± 3 Ma (95% confidence), based on 7 U-Pb ID-TIMS ages (6 new herein) from dolerite dikes and sills across the Anabar shield and within western Riphean cover rocks for a distance of 270 km. An additional sill yielded a SIMS (CAMECA) age of 1483 ± 17 Ma and sill in the Olenek uplift several hundred kilometers farther east, a previous SIMS (SHRIMP) age of ca. 1473 Ma was obtained on a sill; both SIMS ages are within the age uncertainty of the ID-TIMS ages. Geochemical data indicate a tholeiitic basalt composition with low MgO (4–7 wt%) within-plate character based on trace element classification diagrams and source between E-MORB and OIB with only minor contamination from crust or metasomatized lithospheric mantle. Two subgroups are distinguished: Group 1 has gently sloping LREE ((La/Sm) PM = 1.9) and HREE ((Gd/Yb) PM = 1.8) patterns, slightly negative Sr and moderate TiO 2 (2.2 wt%), and Group 2 has steeper LREE ((La/Sm) PM = 2.3) and HREE ((Gd/Yb) PM = 2.3), strong negative Sr anomaly, is higher in TiO 2 (2.7 wt%), and is transitional from tholeiitic to weakly alkaline in composition. The slight differences in REE slopes are consistent with Group 2 on average melting at deeper levels. Proposed reconstructions of the Kuonamka LIP with 1500 Ma magmatism of the SFC-Congo craton are supported by a geochemical comparison. Specifically, the chemistry of the Chapada Diamantina and Curaga dikes of the SFC can be linked to that of Groups 1 and 2, respectively, of the Kuonamka LIP and are consistent with a common mantle source between EMORB and OIB and subsequent differentiation history. However, the coeval Humpata sills and dikes of the Angola block of the Congo craton represent a different magma batch. [ABSTRACT FROM AUTHOR]

We have revealed the spatio-temporal regularities of distribution of platinum group elements (PGE) in basaltoids related to the activity of the Siberian mantle plume. As objects of study, we chose rift and flood basalts from the Norilsk district (sampled from the SD-9 borehole), flood basalts from the central part of the Tunguska syneclise (Lower Tunguska), Kuznetsk Basin traps, and subalkalic basalt from the Semeitau volcanoplutonic structure in eastern Kazakhstan. Based on the PGE patterns of basaltoids related to the activity of the Permo-Triassic Siberian plume, we have shown that the rocks that formed in the central part of the Siberian Large Igneous Province (LIP) at the early rift stage have low contents of PGE, whereas picrites and tholeiitic flood basalts have high contents. The rift (Semeitau structure) and flood (Kuznetsk Basin traps) basalts from the peripheral regions are characterized by extremely low PGE contents. The high PGE contents in magmas of the plume head are responsible for the high productivity of ultramafic-mafic trap magmatism. The elevated K contents in magmas and the high PGE contents in the mantle plume head are probably due to the ascent of deep-seated material from the core-lower-mantle boundary, as follows from the thermochemical model of the Siberian plume. [ABSTRACT FROM AUTHOR]

The Siberian large igneous province (LIP) forms the world's most extensive continental exposure of basalt and has several sub-provinces surrounding it, which may be genetically related. The Taimyr peninsula of north Siberia is one of these sub-provinces and is frequently assumed to be the northerly continuation of the basalts exposed at Noril'sk, the best-studied area of the Siberian LIP. However, the correlation is uncertain. We present new major and trace element data from 35 samples of extrusive and intrusive rocks from Taimyr, with Sr and Nd isotope data from a subset of ten. The Taimyr rocks fall into two groups with low (~ 7 wt.%) and elevated (~ 9 wt.%) MgO concentrations. The high-MgO rocks display a restricted range of initial 87 Sr/ 86 Sr (0.705 to 0.706) and 143 Nd/ 144 Nd (0.5122 to 0.5124) ratios, and share bulk silicate earth normalised rare earth element patterns strikingly similar to data observed in the ore-related Noril'sk intrusions. The remaining low-MgO group samples have a broader range with higher Sr and lower Nd isotope values and higher incompatible trace element ratios (e.g., Th/Ta > 5.3 and La/Sm n > 1.7) similar to the crustally-contaminated Nadezhdinsky and Morongovsky suite basalts of the Noril'sk region. The major and trace element data for both groups are consistent with a process of fractional crystallisation coupled with small degrees of assimilation of incompatible-element-enriched lower crust involving different contaminants. Trace element model calculations indicate a process of magma formation at large degrees of partial melting and at pressures of less than 3 GPa, probably within the garnet–spinel transition zone or the spinel stability field of the asthenospheric mantle. We obtained an argon plateau age of ~ 252 (252.7 ± 1.5) Ma and a ~ 239 Ma total fusion age from a Taimyr lava and intrusive sample, respectively, confirming that volcanism is only partly contemporaneous with the activity of the Siberian LIP. Although this is in agreement with previous interpretations, we argue that the age difference between both events is only ~ 13 Ma and probably less (~ 5 Ma) although further investigation of the relationship is required. Our data allow correlation with distinct Noril'sk members and most importantly to the ore-bearing (Ni–Cu) intrusions implying that whole rock chemistry could have value as a prospecting tool in Taimyr. [ABSTRACT FROM AUTHOR]

The Mariinsky Taiga Alkaline Province (MTAP) is located in the Kuznetsk Alatau terrane of southwestern Siberia, which is part of Altai-Sayan orogenic system, of the Central Asian Orogenic Belt. The MTAP consists of a wide distribution of Paleozoic alkaline-basite magmatism (volcanic, subvolcanic and intrusive), which has been recently characterized with the recognition of at least two main timings, ca. 500 and ca. 400 Ma (herein labeled MTAP-1 and MTAP-2, respectively). We newly characterize the petrology, geochemistry, and age constraints of NNW and NNE trending alkaline dikes which cross-cut the alkaline intrusions and host volcanogenic and carbonate units and which are inferred to belong to MTAP-2. The dikes consist of ultrabasic foidolites (urtites, urtite-porphyry, ijolite-porphyry, microijolites), basic foidolites (plagioclase ijolites), alkaline basites (gabbro-diabase, labradorite porphyrites, camptonites and tamaraites), and nepheline, analcime and alkaline syenites. Their chemical composition is characterized by a wide range in silica (SiO 2 = 38.7–60.7 wt%), and alkalinity (Na 2 O + K 2 O = 4–18.7 wt%; Na 2 O/K 2 O = 0.5–8.3 wt%), low titanium (TiO 2 = 0.07–2.15 wt%) and high alumina content (Al 2 O 3 = 11.1–28.5 wt%), which corresponds to the K-Na differentiates of the basic alkaline magmatic series. The sum of rare-earth elements (ΣREE) increases from alkaline basite (ΣREE = 103.58–218.94 ppm), to the main foidolites (ΣREE = 137.74–217.61 ppm), and then to the ultrabasic foidolites (ΣREE = 55.56–268.88 ppm). Maximum REE content occurs in nepheline syenites and microsyenites (ΣREE = 73.24–1566.96 ppm) and they are the final product of the differentiation of foidite and basite melts. All dike varieties are characterized by low concentrations of the most highly charged elements (Th, Nb, Ta, Hf, and Y), which, according to their concentrations, plot between oceanic island basalt (OIB) and island arc basalt (IAB). The presence of a negative Nb-Ta anomaly and the relative enrichment of Rb, Ba, Sr and U indicate probable interaction of a mantle plume melts with lithospheric mantle metasomatized in an earlier subduction event. The primary isotope ratio 87Sr/86Sr(t) = 0.705388–0.706025 and the range of ɛNd(t) from +3.5 to +6.53 in the rocks indicate interaction of mantle derived melts with crustal components. Sm-Nd and U-Pb dating of the alkaline-basite dikes matches the boundary of the Early-Middle Devonian (406–389 Ma) and indicates membership in MTAP-2, which can be linked to the regional ca. 400 Ma Altai-Sayan Large Igneous Province/Rift System. Both the NNW and NNE trending dikes are associated with, and probably fed from, nearby alkaline intrusions such as i.e. Kiya-Shaltyr pluton which are also ca. 400 Ma (part of MTAP-2), but are independent of older ca. 500 Ma intrusions (which belong to MTAP-1) such as the University pluton and which are suggested to belong to a older plume-generated regional event. [Display omitted] • Characterization of NNW and NNE trending dike belts in the MTAP, western Siberia. • They formed in the Middle Paleozoic (406–389 Ma) in a plume-rifting event. • Isotopic parameters ɛSr(t) indicate a strong contamination by crustal components. • The dike represent intraplate magmas emplaced in a shear setting. [ABSTRACT FROM AUTHOR]

We report combined U–Pb ages and Sr–Nd isotope compositions of perovskites from 50 kimberlite occurrences, sampled from 9 fields across the Yakutian kimberlite province on the Siberian craton. The new U–Pb ages, together with previously reported geochronological constraints, suggest that kimberlite magmas formed repeatedly during at least 4 episodes: Late Silurian–Early Devonian (419–410 Ma), Late Devonian–Early Carboniferous (376–347 Ma), Late Triassic (231–215 Ma), and Middle/Late Jurassic (171–156 Ma). Recurrent kimberlite melt production beneath the Siberian craton – before and after flood basalt volcanism at 250 Ma – provides a unique opportunity to test existing models for the origin of global kimberlite magmatism. The internally consistent Sr and Nd isotope dataset for perovskites reveals that the Paleozoic and Mesozoic kimberlites of Yakutia have distinctly different initial radiogenic isotope compositions. There exists a notable increase in the initial 143 Nd/ 144 Nd ratios through time, with an apparent isotopic evolution that is intermediate between that of Bulk Earth and Depleted MORB Mantle. While the Paleozoic samples range between initial 87 Sr/ 86 Sr of 0.7028–0.7034 and 143 Nd/ 144 Nd of 0.51229–0.51241, the Mesozoic samples show values between 0.7032–0.7038 and 0.51245–0.51271, respectively. Importantly, perovskites from all studied Yakutian kimberlite fields and age groups have moderately depleted initial ε Nd values that fall within a relatively narrow range between +1.8 and +5.5. The perovskite isotope systematics of the Yakutian kimberlites are interpreted to reflect magma derivation from the convecting upper mantle, which appears to have a record of continuous melt depletion and crustal recycling throughout the Phanerozoic. The analyzed perovskites neither record highly depleted nor highly enriched isotopic components, which had been previously identified in likely plume-related Siberian Trap basalts. The Siberian craton has frequently been suggested to represent a type example of an association between kimberlite eruptions and flood basaltic volcanism within a single large igneous province (LIP), but our new extensive age and isotopic tracer constraints do not support a genetic link between these contrasting types of mantle-derived magmatism. [ABSTRACT FROM AUTHOR]

The article discusses the formation of large igneous provinces (LIP) in east Siberian craton and challenges associated with estimation of phanerozoic intraplate magmatism in the region. Topics discussed include basaltic magmatism, formation of magmatic rocks in early cretaceous High Arctic large igneous province (HALIP) in Siberia and petrogeochemical characteristics of the region.

The article discusses the study done on the tectonic setting, composition, and age of deeply metamorphosed rocks and the associated magmatic complexes in Svyatoi Nose Peninsula in Russia. Topics discussed include granulites providing reconstruction of geodynamic environments in the earth crust, representation of metamorphic rocks by alternating bands of basic gneiss and a triad of graphite marble, and quartzite-schist marble formation.

Abstract: A Middle Paleozoic tectonothermal event in the eastern Siberian craton was especially active in the area of the Vilyui rift, where it produced a system of rift basins filled with Devonian–Early Carboniferous volcanics and sediments, as well as long swarms of mafic dikes on the rift shoulders. Basalts occur mostly among Middle Devonian sediments and are much less spread in Early Carboniferous formations. The dolerite dikes of the Vilyui–Markha swarm in the northwestern rift border coexist with the Mirnyi and Nakyn fields of diamond-bearing kimberlites. The voluminous dikes and sills intruded before the emplacement of kimberlites. The Mir kimberlite crosscuts a dolerite sill and a dike in the Mirnyi field, while a complex dolerite dike (monzonite porphyry) cuts through the Nyurba kimberlite in the Nakyn field. Thus, the kimberlites correspond to a longer span of Middle Paleozoic basaltic magmatism. The basalts in Middle Paleozoic sediments have faunal age constraints, but the age of dolerite dikes remains uncertain. The monzonite porphyry dike in the Nyurba kimberlite has been dated by the 40Ar/39Ar method, and the obtained age must be the upper bound of the dike emplacement. The space and time relations between basaltic and kimberlitic magmatism were controlled by Devonian plume–lithosphere interaction. [Copyright &y& Elsevier]

The Siberian Traps flood basalts have been invoked as a trigger for the catastrophic end-Permian mass extinction. Widespread aberrant plant remains across the Permian-Triassic boundary provide evidence that atmospheric stress contributed to the collapse in terrestrial diversity. We used detailed estimates of magmatic degassing from the Siberian Traps to complete the first three-dimensional global climate modeling of atmospheric chemistry during eruption of a large igneous province. Our results show that both strongly acidic rain and global ozone collapse are possible transient consequences of episodic pyroclastic volcanism and heating of volatile-rich Siberian country rocks. We suggest that in conjunction with abrupt warming from greenhouse gas emissions, these repeated, rapidly applied atmospheric stresses directly linked Siberian magmatism to end-Permian ecological failure on land. Our comprehensive modeling supplies the first picture of the global distribution and severity of acid rain and ozone depletion, providing testable predictions for the geography of end-Permian environmental proxies. [ABSTRACT FROM AUTHOR]

Based on the paleomagnetic study of intrusive and explosive Permian-Triassic traps in the Angara River basin, Siberian Platform, it is established that the formation of the traps was marked by three short and highly intense bursts in magmatic activity, which resulted in the intrusion of three large dolerite sills (Tolstomysovsky, Padunsky and Tulunsky) and the deposition of the tuffs of the Kapaevsky Formation. These magmatic bursts occurred against the long-lived less intense background magmatism, which caused the formation of small intrusive bodies and tuff sequences. The geochronological data and correlation of the Angara traps to the effusive trap sequences in the north of the Siberian Platform (Norilsk and Maymecha-Kotuy regions) indicate that intrusion of the Tolstomysovsky sill and eruption of its comagmatic tuffs of the Kapaevsky Formation occurred in the Early Triassic. The obtained paleomagnetic data contradict the existing idea that the Padunsky and Tulunsky sills are coeval. Moreover, these data show that the magmatic bodies of different ages were mistakenly referred to the same sill. [ABSTRACT FROM AUTHOR]

Abstract: The interplay of geodynamic and sedimentation processes in the Central Asian orogen and the Siberian craton is discussed in several aspects: (i) general tectonics of the Central Asian orogen, (ii) correlation of deposition and collision events, (iii) deposition history and sediment sources on the northern and eastern margins of the Siberian craton, compared, and (iv) history of the Central Asian orogen (Altaids) and formation of Early Mesozoic sedimentary basins. Chemical and isotope compositions and geochronology of Neoproterozoic–Paleozoic sedimentary sequences indicate deposition synchronicity in basins of different types, within both the craton and the orogen. Thus geodynamic models of deposition in separate basins provide reliable evidence of the history of orogens flanking the Siberian craton. The study has confirmed the existence of the Vendian–Early Paleozoic Charysh–Terekta–Ulagan–Sayan–Olkhon strike-slip suture between the continental-margin complexes of Siberia and Kazakhstan, with the crust of juvenile and mixed types, respectively. Late Paleozoic large-scale strike-slip faulting deformed the previous tectonic framework and caused tectonic mixing of the older structures on different margins. This superposed deformation makes it difficult to decipher the paleogeography, paleotectonics, and paleogeodynamics of the Central Asian orogen. [Copyright &y& Elsevier]

Abstract: Neoproterozoic and Devonian mafic flows, sills and dykes associated with synchronous rifting events are widely distributed along the long-lived Mesoproterozoic to Mesozoic passive eastern margin of the Siberian Craton. Early Paleozoic magmatic events are also present, but are poorly studied, including Early Cambrian volcanic rocks in the Kharaulakh Range and ca. 450Ma age mafic intrusions of the Suordakh event in the Sette–Daban Range. Both suites of early Paleozoic magmatic rocks are characterized by high Ti concentrations (>3wt.% TiO2), ocean island basalt (OIB)-type trace element and rare earth element (REE) patterns, and high εNd(t) values that generally vary between 6 and 9. The Kharaulakh magmas were formed during low degree partial melting of an enriched region of mantle at depths >90km, generating a suite of alkaline basalts. In comparison, the Suordakh magmas were formed during higher degree partial melting of less enriched mantle at depths <90km, forming alkaline to subalkaline basalts. Both suites are characterized by εNd(t) values suggestive of interaction between enriched and depleted magmas and both were emplaced in within-plate tectonic settings. Although Kharaulakh and Suordakh magmatic rocks have relatively small areal extents, significant parts of them are likely hidden below clastic rocks of the Lower Carboniferous–Jurassic Verkhoyansk Complex. The Kharaulakh magmatic rocks may have counterparts in the Canadian Cordillera, that together could be of sufficient scale to define a Large Igneous Province (LIP). Early Cambrian mafic volcanic rocks in the study area are associated with locally distributed terrigenous units in both the Kharaulakh and Sette–Daban ranges, suggesting that this magmatism was related to a rifting event. Modeling of sedimentary basin subsidence in the Sette–Daban area is also supportive of an Early Cambrian rifting event. However, the intrusive rocks associated with the ca. 450Ma Suordakh mafic magmatic event are not related to any rift-related sediments or structures. Contemporaneous granites may be interpreted as silicic magmatism associated with a LIP event. [Copyright &y& Elsevier]

A significant part of the Precambrian basement of the Siberian platform is overlapped by a platform cover of sedimentary rocks of various thickness and is inaccessible for study with direct geological methods. However, intense Proterozoic magmatism, to which the largest mineral deposits on various platforms of the world are related, may be manifested in its separate blocks. In such cases, geological information notably increases owing to application of deep geophysical (seismic, graviand magnetometric, and geoelectric) methods. Using these methods, in the eastern part of the Siberian platform, we identified the Proterozoic Lena-Aldan zone of basaltic protoactivation extended in the northwesterly direction for 1500 km from the Aldan to Anabar shields of the Siberian platform. Ultramafic and mafic intrusive magmatism and kimberlites are widely manifested in this zone. By the character and intensity of magmatism, it is a homologue of the South African province (South African Republic, Namibia, Zimbabwe) with large and giant Pt, Au, Ni, Co, Cr, and other deposits. [ABSTRACT FROM AUTHOR]

The Siberian Traps large igneous province is of enormous size (~7×106 km2) and volume (~4×106 km3). It contains effusive, intrusive and volcanoclastic rocks varying in compositions from ultramafic to felsic, though low-Ti basalts and their intrusive analogs are the predominant rock types. In this paper, we provide new 40Ar/39Ar ages for two lava units of the geographic center of the Siberian Traps, the Central Putorana region (240.9±1.3/2.6/5.5 and 246.6±1.4/2.7/5.6Ma, where ages are calculated relative to Bern4M with an assigned age of 18.7 (±0.096) Ma and errors are stated in the form ±x/y/z, where x and y and z are analytical, internal and external errors, respectively), three dolerite sills from the Angara-Taseevskaya syncline of the southeastern Siberian Traps (242.8±1.3/2.6/5.0Ma, 239.1±1.1/2.5/4.9Ma and 255.8±4.7/5.3/6.9Ma) and a lamproite dyke from the Noril'sk region (238.3±1.3/2.6/5.3Ma). In combination with available geochronologic data our results suggest that voluminous low-Ti basaltic magmatism appeared during different pulses. At least two volcanic pulses are recognized: at the Permo-Triassic boundary (~249Ma or 252Ma using the 40Ar/39Ar and U–Pb timescales, respectively) and about 10Ma later in the Middle Triassic. Granitic magmatism overlapped in time with the two flood basalt pulses, but continued into the Late Triassic (~229Ma using the U–Pb timescale). Prolonged magmatism of the Siberian Traps province is also supported by geologic observations and paleomagnetic data. New geochronologic findings are discussed in light of the different models for the origin of the Siberian Traps and applied to a Middle Triassic mass extinction event. [ABSTRACT FROM AUTHOR]

Abstract: The first data on PGE contents in the volcanic rocks of the West Siberian Plate are presented. Analysis has shown that most of the studied rocks have clarke contents of these elements. Rocks from the central areas of paleorift valleys are enriched in ΣPGE (2.0–32.0 ppb), particularly in Pt (0.1–24.2 ppb) and Pd (0.3–8.0 ppb), which might be related to the action of plume. The magmatic PGE pattern confirms the earlier conclusions about the mantle genesis of the studied rocks. [Copyright &y& Elsevier]

The article focuses on a study that examines the first evidence of Paleoproterozoic late-collision basite magmatism in the presence of near-Sayan salient of the Siberian craton basement in Russia. It defines the role of Late Paleoproterozoic in the evolution of the Siberian craton. It discusses the methodologies and materials used in the study including isotopic analysis, a multi-collector mass-spectrometer, and cathodo-luminescence images. As per near-Sayan salient, the presence of basites is common feature of the South Siberian Paleoproterozoic belt of late-collision granitoids.

The article discusses the first data gathered on the neoproterozoic granitoid magmatism found in Siberian craton's Sayan marginal uplift, a large structural element that spreads in the northwesterly direction from Lake Baikal to the basin of the Agul and Tumanshet rivers. It notes that the uplift's structures include the Buryusa and Sharyzhalgai superterranes that are connected to the Uriksko-Tumanshet collisional zone that contains widely abundant postcollision granitoid magmatism. It presents an exception by orphyry granodiorite of the Chernoziminskii Complex intruding coarse-clastic terrigenous rocks of the Ermosokhinskaya Suite that are deposited in the rift depression.

Abstract: The paper reviews geological, geochronological and geochemical data from the Late Paleozoic – Mesozoic magmatic complexes of the Siberian continent north of the Mongol-Okhotsk suture. These data imply that these complexes are related to the subduction of the Mongol-Okhotsk Ocean under the Siberian continent. We suggest that this subduction started in the Devonian, prior to the peak of magmatic activity. Studied magmatic complexes are of variable compositions possibly controlled by changes of the subduction regime and by possible input from enriched mantle sources (hot spots). The oceanic lithosphere of the Mongol-Okhotsk Ocean had shallowly subducted under the Siberian continent in the Devonian. Steeper subduction in the Early – Late Carboniferous led to switching from an extensional to compressional tectonic regime resulting in fold-thrust deformation, to the development of duplex structures and finally to the thickening of the continental crust. This stage was marked by emplacement of voluminous autochthonous biotite granites of the Angara-Vitim batholith into the thickened crust. The igneous activity in the Late Carboniferous – Early Permian was controlled by the destruction of the subducted slab. The allochthonous granitoids of the Angara-Vitim batholith, and the alkaline granitoids and volcanics of the Western Transbaikalian belt were formed at this stage. All these complexes are indicative of extension of the thickened continental crust. A normal-angle subduction in the Late Permian – Late Triassic caused emplacement of various types of intrusions and volcanism. The calc-alkaline granitoids of the Late Permian – Middle Triassic Khangay batholith and Late Triassic Khentey batholith were intruded near the Mongol-Okhotsk suture, whereas alkaline granitoids and bimodal lavas were formed in the hinterland above the broken slab. The Jurassic is characterized by a significant decrease of magmatic activity, probably related to the end of Mongol-Okhotsk subduction beneath the studied area. The spatial relationship of the Late Permian – Middle Triassic granitoids, and the Late Triassic granitoids is typical for an active continental margin developing above a subduction zone. All the Late Carboniferous to Late Jurassic mafic rocks are geochemically similar to subduction-related basalts. They are depleted in Nb, Ta, Ti and enriched in Sr, Ba, Pb. However, the basaltoids located farther from the Mongol-Okhotsk suture are geochemically similar to a transition type between island-arc basalts and within-plate basalts. Such chemical characteristics might be caused by input of hot spot related enriched mantle to the lithospheric mantle modified by subduction. The Early Permian and Late Triassic alkaline granitoids of southern Siberia are of the A2-type geochemical affinities, which is also typical of active continental margins. Only the basaltoids generated at the end of Early Cretaceous are geochemically similar to typical within-plate basalts, reflecting the final closure of the Mongol-Okhotsk Ocean. [Copyright &y& Elsevier]

The article offers information regarding formation of the Siberian Craton which ended in the Paleoproterozoic. It mentions that the craton was repeatedly subjected to destruction in response to interaction between the lithosphere and the mantle plumes. It discusses the most significant events of that time which were the Neoproterozoic and Middle Paleozoic rifting epochs, determining the configuration of the Siberian Craton. It describes the characterization of the geological positions and compositions of occurrences of various ages of early Cambrian and devonian intraplate magmatism involved in lithospheric destruction that results in the formation of the northeastern boundary of the Siberian Craton.

Abstract: The formation and evolution conditions for alkaline magmatism and associated igneous rocks in the western framing of the Siberian craton are shown by the example of alkaline and subalkaline intrusive bodies of the Yenisei Ridge. Here we present petrographic, mineralogical, geochemical, and geochronological data for the rocks of the Srednetatarka and Yagodka plutons located within the Tatarka–Ishimba suture zone. Ferroan and metaluminous varieties enriched with rare elements (Nb, Ta, Zr, Hf, and REE) are making up most of the studied rocks. They formed at the stages of fractional crystallization of alkaline magma in a setting of active continental margin in the west of the Siberian craton in the Late Neoproterozoic (710–690 Ma). As differentiates of mantle magmas, these rocks associate with Nb-enriched rocks—A-type leucogranites and carbonatites. Sm/Nd and Rb/Sr isotopic data imply a predominance of the mantle component in the magmatic sources of the mafic and intermediate rocks as well as contamination processes of various volumes of continental crustal material by this magma. [Copyright &y& Elsevier]

Geological data on the Precambrian basic complexes of the Siberian Craton and their isotopic age are considered. The three main episodes of Precambrian basic magmatism of Siberia correspond to certain stages of the geodynamic evolution of the craton and the Earth as a whole. In the Late Paleoproterozoic, largely in the south and the north of the craton, the basic rocks were emplaced against the background of post-collision extension, which followed the preceding collision-accretion stage responsible for the formation of the craton. In the Mesoproterozoic, primarily in the north of the craton, basic magmatism was controlled by dispersed within-plate extension apparently caused by the impact of a mantle plume. Neoproterozoic basic magmatism widespread in the southern and southeastern parts of the craton was caused by rifting, which accompanied breakdown of the Rodinia supercontinent and opening of the Paleoasian ocean along the southern margin of the Siberian Craton. [ABSTRACT FROM AUTHOR]

The phanerozoic within-plate magmatism of Siberia is reviewed. The large igneous provinces (LIPs) consecutively arising in the Siberian Craton are outlined: the Altai-Sayan LIP, which operated most actively 400-375 Ma ago, the Vilyui LIP, which was formed from the Middle Devonian to the Early Carboniferous, included; the Barguzin-Vitim LIP (305-275 Ma); the Late Paleozoic Rift System of Central Asia (318-250 Ma); the Siberian flood basalt (trap) province and the West Siberian rift system (250-247 Ma); and the East Mongolian-West Transbaikal LIP (230-195 Ma), as well as a number of Late-Mesozoic and Cenozoic rift zones and autonomous volcanic fields formed over the last 160 Ma. The trace-element and isotopic characteristics of the igneous rocks of the above provinces are reviewed; their mantle origin is substantiated and the prevalence of PREMA, EM2, and EM1 mantle magma sources are shown. The paleogeographic reconstructions based on paleomagnetic data assume that the Iceland hot spot was situated beneath the Siberian flood basalts 250 Ma ago and that the mantle plumes retained a relatively stable position irrespective of the movements of the lithospheric plates. At present, the Iceland hot spot occurs near the northern boundary of the African large low shear velocity province (LLSVP). It is suggested that the within-plate Phanerozoic magmatism of Siberia was related to the drift of the continent above the hot spots of the African LLSVP. [ABSTRACT FROM AUTHOR]

This paper discusses the plausible genetic relationship between disseminated Au-sulfide mineralization and mantle plume-related magmatism in the context of the tectonic evolution of the Yenisei ridge in central Siberia. The relationship is inferred based on structural and geochemical studies of the Blagodat Au deposit, and the Transangara alkaline syenite and Penchenga fenite-carbonatite complexes. Analyses of Nd, Sr and Ar isotopic compositions of samples from these geological features show their possible close temporal relationships but different sources. Nevertheless, the present data sets suggest that thermal effects of mantle plume activity likely controlled hydrothermal fluid mobilization in metamorphic suites and further enrichment of gold. The structural setting of the Blagodat Au deposit demonstrates the typical example of Au-sulfide mineralization controlled by late collisional shear deformations. The present example of Au deposit associated temporally and spatially with carbonatites and alkaline rock complexes is an exclusive case in the Earth's history supporting a plausible genetic relationship between mantle plume-related magmatism and orogenic-Au mineralization. [ABSTRACT FROM AUTHOR]

Abstract: The origin of PGE–Cu–Ni sulfide deposits of Norilsk and Talnakh located in the northwest flank of the Triassic basalt trap formation of Siberia is considered. It is shown that ore elements of these deposits (probably, except Fe) are derived from the crust rather than from the mantle. They entered the basalts owing to a remobilization (recycling) of ore elements from the Paleoproterozoic sediments and from the rocks of the Siberian platform’s basement. Prospecting criteria for similar deposits are as follows: (1) a presence of a large Paleoproterozoic aulacogen and a related magmatic sulfide Cu–Ni mineralization; (2) a confinement of perspective areas to troughs associated with long-lived deep fault zones; (3) association with mobile orogenic belts, island-arc systems and tectonomagmatic activation zones; (4) temporal association with boundaries of global periods characterized by active processes of continental breakup and large-scale trap magmatism. A combination of several factors (the first one is obligatory) is favorable for the discovery of a large ore body. [Copyright &y& Elsevier]

Geological, petrologeochemical, and geochronological studies of the rocks from the Shivei alkali-granitic pluton were conducted. A pluton about 500 km in area is a part of the larger (more than 30 000 km) Kaakhem magmatic area. The data obtained allow us to characterize the magmatic complex of the Shivei pluton as a bimodal association with picrobasalts, subalkali basalts, and subalkali and alkali granitic rocks differentiated from syenites to leucogranites. The SHRIMP_II zircon dating from quartz syenites and alkali granites indicate the Permian age of the pluton (293.8 ± 3.8 Ma and 297.1 ± 3.8 Ma, respectively). Mafic-alkali-granitic associations similar in age and type, which are traced in the meridional direction along the Eastern Sayan toward the Siberian Platform, were distinguished as the Eastern Sayan zone of the Late Paleozoic alkaline magmatism. Its location corresponds to the western periphery of the Angaro-Vitim batholite and fits well into the zonal structure of the Barguzin magmatic province. We relate the geodynamic position of the Barguzin province with the mantle plume that was overlapped by the edge of the Siberian Pale-ocontinent in the course of its Paleozoic migration above the African hot spot. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic fabric research on the emplacement of the Taimyr fold-belt is still absent. Therefore, we have performed magnetic fabric studies on samples collected from 23 sites from mafic igneous rocks (75°N, 100°E) in South Taimyr. This study indicates a correlation between the anisotropy of magnetic susceptibility (AMS), magma flow and fold-related compression in the rocks. AMS measurements on 183 unheated and 122 heated samples reveal the magma flow directions. The magma flow direction is mainly parallel to the ESE–WNW and secondarily parallel to the SSW from the NNE in the mafic sills. The unheated and heated basaltic flows reveal a NE-trending flow vector. In some of the sills, AMS shows a tight clustering of the maximum K 1 axes close to the bedding pole, which is not thought to define the flow direction. Corresponding AMS measurements on igneous rocks allow us to infer the existence of magnetic fabrics of tectonic origin linked to the main folding episode that occurred subsequent to the Mid-Triassic magmatic event in latest Triassic–Early Jurassic times. In the sills, the distribution of most maximum K 1 axes is close to NS that corresponds to the maximum compressive stress or folding directions; contrarily, the minimum K 3 axes have an elongated distribution along the EW direction or parallel to the fold axis before exchanging K 1 and K 3 axes for inverse fabrics, but close to the NS stress direction after exchanging K 1 and K 3 axes for inverse fabrics. In the basaltic flows, the minimum K 3 axes almost parallel to the NS folding direction. The structural interpretation of all AMS data taken from the igneous bodies is in accordance with a NNW–SSE stress-related folding taking place around 198Ma in the Taimyr Peninsula (Arctic Siberia). The relationship of susceptibility axes to bedding surfaces and magnetic foliation planes is a criterion that permits differentiation of normal magnetic fabrics from inverse fabrics in the igneous samples. Single-domain (SD) and small pseudo-single-domain (PSD) magnetite crystals in the sill samples are the main carriers of the AMS fabrics, implying the abundance of inverse magnetic fabrics. PSD and multidomain (MD) titanomagnetite (TM) grains as well as minor hematite are identified in the basalt flows, suggesting the occurrence of more normal magnetic fabrics in the basalts than in the sills. [Copyright &y& Elsevier]

/Ar 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. [ABSTRACT FROM AUTHOR]

Abstract: We present a summary of late Paleoproterozoic to Neoproterozoic mafic magmatism in the Siberian craton, including recently published U–Pb and 40Ar–39Ar dates. These new precise ages suggest that at least some of the previously published K–Ar ages of Siberian mafic bodies should be ignored. The time–space geochronological chart, or the ‘barcode’ of mafic magmatic events shows significant differences between northern and southern Siberia. Both are characterized by ∼1900–1700Ma magmatic events, but then there was an almost 1Ga mafic magmatic ‘pause’ in south Siberia until ∼800Ma. Meanwhile there are indications of multiple mafic magmatic events in North Siberia (Anabar shield and Olenek uplift) between ∼1600 and 1000Ma. A series of magmatic events probably related to the breakup of Rodinia occurred in southern Siberia after ∼800Ma. So far, there are no indications of late Neoproterozoic mafic magmatism in North Siberia. Ca. 1000–950Ma mafic sills were reported from Meso- to Neo-Proterozoic sedimentary successions in the Sette-Daban area on the east side of the Siberian craton, but their tectonic setting is debated. Recent Ar–Ar dates of ∼1750Ma for NW-trending dykes in the Aldan and Anabar shields, together with similar-age NNE-trending Baikal uplift dykes in south-eastern Siberia suggest the existence of a giant radial dyke swarm possibly related to a mantle plume centred in the Vilyui River area. [ABSTRACT FROM AUTHOR]

Abstract: Recently it has been suggested that the major influence on the environment from Siberian Traps magmatism was due to the interaction of magma and organic-rich shale and petroleum-bearing evaporites, with the subsequent creation and outburst of toxic gases (Siberian gas venting: SGV model). In part this idea was supported by a U-Pb age of 252.0 ± 0.4 Ma for one of the dolerite sills in the southeastern Siberian Traps: the age corresponds to the Permo-Triassic boundary and its known mass extinctions of biota. In this study two other dolerite sills were dated using zircons by the U-Pb SHRIMP method at 254.2 ± 2.3 Ma and 249.6 ± 1.5 Ma. The former age is in agreement within error with the age previously published for the dolerite sills, whereas the latter age is in agreement with U-Pb ages published for lava and intrusions from the northern Siberian Traps. The new ages corresponds to the Cahngshingian/Wuchiapingian or Permian/Triassic and Spathian/Smithian boundaries, respectively. Review of 40Ar/39Ar and U-Pb SHRIMP ages previously published for the southeastern Siberian Traps shows that three other pulses of magmatism probably took place at respectively Anisian/Spathian, Late/Middle Anisian and Landian/Anisian boundaries. Thus it is possible that the SVG model can be applied also to lesser biotic extinctions and recoveries in proximity and aftermath to the main Permo-Triassic extinction. [Copyright &y& Elsevier]

Abstract: Complex petrological, geochemical, and isotope studies of igneous rocks sampled from the core of parametric Maizasskaya BH-1 showed a predominance of dolerite sills, which formed earlier (~263 ± 4 Ma) than most of basalts in the basement of the West Siberian sedimentary basin and in the Siberian Platform traps (248–251 Ma). Their formation took place during the crystallization of basaltic melt in intrusive chambers existing between layers of Silurian sedimentary rocks. The petrochemical, geochemical, mineralogical, and thermobarogeochemical data show that the sills resulted from the activity of complex magmatic systems different from typical oceanic and plateau-basalt melts and related, most likely, to the formation of rift structures under the influence of mantle plume. Study of melt inclusions provided data on the conditions of generation of primary melts from mantle substratum (≤1570 ºC, depths to 105–120 km) and crystallization parameters of dolerites—1130–1155 ºC, 1.5–2 kbar. The results obtained show that the studied basalt complexes in West Siberia are genetically related to the mantle plume activity, which led to the breakup of ancient crust and rifting. Formation of oceanic crust took place in the largest rifts; the ascending magma penetrated into the enclosing ancient strata to form sills. [Copyright &y& Elsevier]

Abstract: The Phanerozoic history of mafic magmatism in the southern Siberian craton included three major events. The earliest event (∼500 Ma) recorded in dolerite dikes occurred during accretion and collision at the early stage of the Central Asian orogen. Injection of mafic melts into the upper crust was possible in zones of diffuse extension within the southern Siberian craton which acted as an indenter. The Late Paleozoic event (∼275 Ma) produced dikes that intruded in a setting of subduction-related extension at the back of the active continental margin of Siberia during closure of the Mongolia–Okhotsk ocean, as well as slightly older volcanics (290 Ma) in the Transbaikalian segment of the Central Asian orogen. Early Mesozoic magmatism in the southern Siberian craton resulted in numerous 240–250 Ma mafic intrusions in the Angara–Taseeva basin. The intrusions (Siberian traps) appeared as the subducting slab of the Mongolia–Okhotsk ocean interacted with a lower mantle plume. The post-Late Paleozoic ages of flood basalts (290–275 Ma) correspond to progressive northwestward (in present coordinates) motion of the slab beneath the southern craton margin which likely ceased after the slab had reached the zone of the Siberian superplume. Since its consolidation after the Early Mesozoic activity, the crust in the area has no longer experienced extension favorable for intrusion of basaltic magma. [Copyright &y& Elsevier]

The article focuses on the development of trap intrusions in the sedimentary cover of the Siberian Platform. It states that the most complete data for the wide development of trap intrusions was obtained as a result of oil and gas prospecting in the Siberian Platform. It says that three samples were collected from the holes of Kt-1, Gf-4 and SV-1 and the data were obtained using the 40Ar/39Ar method. It reveals that new data for the intrusive traps of the Siberian Platform shows evidence of the occurrence of trap magmatism in the different blocks of the sedimentary cover.