Search

• Zircons from studded crustal xenoliths do not record the age peak at 1.9 Ga. • Sodalite was found in mafic granulite xenoliths of the Yakutian kimberlite province. • Superplumes triggered the crustal growth and reworking at 2.7 and 1.9 Ga. • There is no collision zone between the Daldyn and Markha terranes. The tectonic framework of the Siberian craton is still under debate. It is generally assumed that the Markha and Daldyn terranes collided at 2.2–2.1 Ga and the final assembly of the Siberian craton occurred at 1.9–1.8 Ga. However, previous study on zircons from xenoliths of the Zapolyarnaya pipe, which is located in the Upper Muna kimberlite field and close to the boundary between the Markha and Daldyn terranes, do not show tectonothermal evidence younger than 2.7 Ga. To clarify the tectonothermal evolution of the Siberian craton, we present U-Pb ages and Hf isotope data of zircons from crustal xenoliths in the Novinka and Komsomolskaya Magnitnaya kimberlite pipes in the Upper Muna field. The zircon ages confirm only one major tectonothermal event at 2.7 Ga in the Upper Muna field, which doubts the existence of the collision zone between the Markha and Daldyn terranes. The middle-lower crust beneath the Upper Muna field is mainly composed of mafic and intermediate granulites and experienced long-term cooling. The negative values of ε Hf (2.7) suggests ignorable addition of juvenile component during partial melting of the Paleoarchean crust at 2.7 Ga. Compared with crustal xenoliths from other kimberlite pipes in the Yakutian diamondiferous province, the crust of the Anabar province shows vertical and lateral heterogeneity and the absence of a relationship between the crustal reworking degree and the main collision zones. We propose that the widespread 2.7 and 1.9 Ga tectonothermal events in the Anabar tectonic province were associated with the episodic rise of superplumes, which not only caused the crustal growth and reworking but also facilitated collision and amalgamation of terranes. [ABSTRACT FROM AUTHOR]

• Rift-related anorogenic magmatism of the Yenisey Ridge correlated with the breakup of Columbia and Rodinia supercontinents. • Age correlation supports long-lived connection between southwestern Siberia and North Atlantic cratons in the Proterozoic. • Intraplate magmatism compatible with paleogegrahic location of southern Siberia adjacent to northern Laurentia. The tectonic evolution of the Siberian Cratonic margins offers important clues for global paleogeographic reconstructions, within the complex continental collage of Central Asia. The Yenisey Ridge fold–and–thrust belt at the western margin of the Siberian Craton forms part of the Central Asian Orogenic Belt (CAOB) and is a key to understand the Precambrian tectonic evolution of the Siberian Craton and crustal growth in the CAOB, the world's largest Phanerozoic accretionary orogenic belt. Here we report the occurrence of A-type granites with geochemical features indicating intraplate setting from the Yenisey Ridge and provide evidence for rift-related magmatism. Zircon SHRIMP U–Pb analyses coupled with in situ U–Th–Pb geochronology of monazite constrain the timing of emplacement of the rift–related granitoids and suggest two consequential breakup events. The magmatic events at 1380 Ma and 800–720 Ma along the western margin of the Siberian Craton and other continental blocks can be associated with the breakup of the Precambrian supercontinents Nuna-Columbia (1.8–1.3 Ga) and Rodinia (1.2–0.7 Ga). These pre-Grenville and post-Grenville episodes of regional crustal evolution are correlated with the synchronous successions and similar style of rocks along the Arctic margin of Nuna–Columbia and Rodinia and supports the spatial proximity of Siberia and North Atlantic cratons (Laurentia and Baltica) over the long period 1.38–0.72 Ga. Our data confirm the proposed Neoproterozoic paleogeographic reconstructions of Columbia and Rodinia as constrained from the large igneous province (LIP) record. [ABSTRACT FROM AUTHOR]

• Palaeoproterozoic terrigenous rocks of the Udokan Complex, Aldan Shield were studied. • Sediments have been deposited over a very short time interval of ca. 1.90–1.88 Ga. • Palaeoproterozoic (ca. 2.02 Ga) and Archean rocks were sources of the sediments. • Unknown Palaeoproterozoic juvenile rocks existed within/near the Chara-Olekma terrane. • Detrital zircons reveal "hidden" Palaeoproterozoic crust-forming event. In this study, new geological, geochronological, and Hf isotopic data are presented for the metaterrigenous deposits of the Kemen Group of the Udokan Complex in the Chara-Olekma terrane of the Aldan Shield, Siberian Craton. Their age of deposition and possible provenances are discussed, along with crust-forming events in the Aldan Shield. The Palaeoproterozoic carbonate-terrigenous deposits of the Udokan Complex in the Kodar-Udokan basin are the hypostratotype of the Lower Proterozoic deposits of the Eastern Siberia and the Far East, and host one of the largest and oldest sediment-hosted copper deposits. Concordia ages of detrital zircons demonstrate age peaks of ca. 2.02, 2.15, 2.38, 2.54, 2.73, 2.82, 2.93, 2.96, 3.00, 3.04 and 3.14 Ga on the probability plot. The morphology, internal texture, and Hf isotopic composition of the Meso- and Neoarchean detrital zircons indicate reworked Paleo- to Mesoarchean crustal sources in provenance areas. No rocks with the ages of ca. 2.02 Ga have been previously recognised in the Chara-Olekma terrane. Characteristics of the ca. 2.02 detrital zircons indicate their primary magmatic origin and proximal sedimentary transport. Hf isotopic data imply that the Palaeoproterozoic rocks in provenance area originated mainly from juvenile sources in a subduction-related setting. The Palaeoproterozoic island arc or an active continental margin probably existed within the western Aldan Shield or its framing and were later completely eroded or partially overlain by younger sediments. Erosion of the Palaeoproterozoic orogen led to deposition of the Chinei and Kemen groups of the Udokan Complex over a short time interval of ca. 1.90–1.88 Ga. Detrital zircons from the Kemen Group deposits reveal for previously unrecognised and lost from geological record Palaeoproterozoic crust-forming event on the western Aldan Shield. Available data show that significant part of the Siberian Craton was formed during ca. 2.07–1.98 Ga crust-forming events that indicate the discrete episodic nature of the continental crust formation and must be considered in models of its growth. The differences in isotope structure and geological history of the Siberia and the Laurentia are in agreement with palaeogeographic reconstructions suggesting that Siberia and Laurentia were not joined together in the Columbia/Nuna supercontinent. [ABSTRACT FROM AUTHOR]

The Anabar shield in northern Siberia is one of the world’s least studied Precambrian areas, and provides a ‘window’ into the crustal basement of the central and northern Siberian craton. We report U-Pb and Hf isotope data for detrital zircons sampled in a profile across its major structural units. They define a U-Pb age range from 1.8 to 3.4 Ga with three main periods: 1.8–2.0 Ga, 2.4–2.8 Ga and 3.0–3.4 Ga. The oldest zircons yield super-chondritic ε Hf (t) implying that the parental magmas of their source rocks were juvenile, i.e. formed from depleted mantle (DM). Thus, the crustal basement of the Anabar shield, and probably the whole central and northern Siberian craton, started to form in the mid-Paleoarchean, and included no recycled crust. Zircons with 2.5–2.7 Ga ages define two ε Hf (t) intervals. One is super-chondritic (+2 to +7) implying juvenile sources, the other is sub-chondritic (−3 to −12) indicative of recycled crust, probably formed at 3.2–3.4 Ga, in magma sources. Nearly all 1.8–2.0 Ga zircons have sub-chondritic ε Hf (t) (−2 to −29) implying derivation from sources dominated by recycled crust formed at ∼2.6 Ga and ∼3.4 Ga and little or no juvenile addition. These events accompanied amalgamation of the entire craton by welding of Archean domains. The Bekelekh unit of the Daldyn series has the highest proportion of ∼2.6 Ga zircons and may be the oldest ‘nucleus’ of the Anabar shield, whereas the Kilegur unit of the same series is essentially Proterozoic (1.95 Ga). The largest amount of 3.1–3.4 Ga zircons, as well as common 2.6–2.7 Ga zircons, occur in the Ambardakh unit of the Upper Anabar series. Our data suggest alternation of areas with dominant ages of 1.95 Ga and ∼2.6 Ga, with the younger zircons coming from granites and granulites, and the older ones from gneisses. They show no evidence for significant ages differences for the Anabar and Olenek provinces. The final amalgamation of the entire Siberian craton by welding of Archean blocks, may have taken place at around 1954 ± 6 Ma. [ABSTRACT FROM AUTHOR]

• The Srednecheremshansk dyke-shaped intrusion in southern Siberia has an age of ca. 1.26 Ga. • This intrusion contains ultramafic and mafic rocks and pentlandite mineralization. • The rocks of the intrusion were generated from a subcontinental lithospheric mantle source. • Paleomagnetic data demonstrate variety of Laurentia-Siberia reconstructions in Mesoproterozoic. • The Srednecheremshansk intrusion may be part of Mackenzie event of Laurentia in Siberia. Several published Mesoproterozoic paleogeographic reconstructions suggest proximity of northern Laurentia and southern Siberia. However, the apparent absence of the traces of the ca. 1.27 Ga giant Mackenzie magmatic event in southern Siberia was somewhat contradictory to this hypothesis. Here we present geochronological, mineralogical, geochemical, Nd isotopic, and paleomagnetic data from the Srednecheremshansk dyke-shaped intrusion, which was recently found in the Sharyzhalgay uplift of the southern part of the Siberian craton and which can be related to the Mackenzie event. The plagioclase-bearing peridotite of this intrusion yielded U-Pb (ID-TIMS) baddeleyite concordia age of 1260 ± 3 Ma, which is interpreted as the time of their emplacement. This age is close to the previously published baddeleyite age of gabbro from the same intrusion (1258 ± 5 Ma). The Srednecheremshansk intrusion is composed of ultramafic and mafic rocks. The main rock-forming minerals of the intrusion are olivine, orthopyroxene, clinopyroxene, phlogopite, and plagioclase in various proportions. Sulfide mineralization of the intrusion is represented by pentlandite nodules. The chemical composition of Srednecheremshansk ultramafic and mafic rocks correspond to subalkaline peridotite gabbro and gabbro. These rocks are characterized by negative ɛNd(t) values range from −6.3 to −6.9. Ultramafic and mafic rocks have similar geochemical and isotopic characteristics, indicating their generation from a single subcontinental lithospheric mantle source. The chemical composition of the Srednecheremshansk intrusion is similar to those of the ca. 1.27 Ga Muskox mafic–ultramafic intrusion of the Mackenzie Large Igneous Province in northern Laurentia. Paleomagnetic data permit a variety of possible Laurentia-Siberia reconstructions in Mesoproterozoic. The combination of geochronological, geochemical, and paleomagnetic data allows the relation of the Srednecheremshansk intrusion with the Mackenzie magmatic event. [ABSTRACT FROM AUTHOR]

We present new LA ICP-MS detrital zircon data from Meso- and Neoproterozoic sedimentary basins located in the northern and western parts of the Siberian Craton. Along the western cratonic margin (Turukhansk Uplift, northern Yenisei Ridge), the basins accumulated predominantly 2.6–2.5 Ga and 1.9–1.85 Ga erosional products, while the main sources for the fill of intracratonic basin to the northeast near the Anabar Shield (East Anabar basin) were 2.9–2.7 Ga and 2.1–1.95 Ga old igneous rocks. The studied Meso- to Early Neoproterozoic sandstones were deposited in rift-related or passive margin settings, and underwent major craton-wide recycling to produce late Ediacaran silicilastic successions. Meso- to Early Neoproterozoic sandstones are immature to submature pointing to erosion of proximal Archean and Paleoproterozoic crustal units. The unique detrital age spectra for the northeast and western basins indicate provinciality and provide a basis for unravelling the age of buried domains of the Siberian Craton basement. [ABSTRACT FROM AUTHOR]

The Baikal–Muya Foldbelt is one of the oldest and the most enigmatic terrain among the Central Asian Orogenic Belt. During the Early (1.0–0.8 Ga) and Late (0.8–0.6 Ga) Neoproterozoic orogenic cycles a notable amount of juvenile crust has been formed in subduction–collision settings along with the reworking of the existing Early Precambrian continental crust. The latter is perfectly presented within the North Muya metamorphic block (Anamakit–Muya zone) including the oldest high-pressure subduction-related rocks in the Central Asia. In order to evaluate the process of the juvenile crust formation in the Precambrian continental unit, whole-rock trace elements along with zircon U–Pb ages and Hf-isotopic composition were analyzed in granites of unknown age that intrude the Precambrian volcanic-sedimentary rocks of the Parama series in the southern North Muya Block. Combined geochemical and zircons isotopic studies indicate the formation of granites with the main pulse at ∼810 Ma due to partial melting of a juvenile mafic crust accompanied by reworking of the older crustal material from the continental arc basement. The composition of the granites was controlled by processes of intracrustal differentiation together with a probable contamination by older crustal substrate. Geochemistry and age of the studied granites are comparable to the granites of the Muya complex observed in the volcano–plutonic Kelyana–Irokinda zone. It is assumed that the Muya block and the Kelyana–Irokinda zone (terrane) had possibly been parts of the large continental-arc system beyond the Siberia margins. [ABSTRACT FROM AUTHOR]

Paleomagnetic studies on Paleoproterozoic rocks of the Ulkan massif from the south-eastern Siberian platform yielded two ancient paleomagnetic directions and made it possible to calculate poles corresponding to them for two time intervals in the late Paleoproterozoic: (а) ∼1732 Ma for volcanogenic-sedimentary rocks of the Elgetey Formation – Plat = 7.1° (−7.1°), Plong = 183.5° (3.5°), d p = 10.5°, d m = 16.4° (positive fold, reversals and conglomerates tests); and (b) less than 1720 Ma for granites of the Ulkan Complex – Plat = 42.1° (−42.1°), Plong = 249.4° (69.4°), d p = 3.4°, d m = 5.6°. The analysis of the existing paleomagnetic data for Siberia in late Paleoproterozoic–early Mesoproterozoic times allowed a total of 12 new poles to be defined with five of them considered key poles (Table 3), based on which the APWP for Siberia was generated. On the basis of the data presented here, one can conclude that in the context of the Paleoproterozoic supercontinent model, preference is given to the position of Paleoproterozoic north poles of Siberia in the Indian Ocean and Australia, rather than in the Atlantic Ocean. [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied paleomagnetically 760Ma mafic dykes from southern Siberia. [•] The primary remanence is supported by the contact test. [•] New data suggest transpressional movement of Siberia closer to Laurentia by 760Ma. [Copyright &y& Elsevier]

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: The Akitkan orogenic belt separates the Aldan and Anabar superterranes of the Siberian craton and was previously suggested to consist exclusively of Palaeoproterozoic juvenile crust. Foliated granitoids in the Baikal basement salient within the Akitkan belt were studied geochronologically and geochemically. Thermal ionisation mass spectrometry (TIMS) analysis of six zircons of a tonalite sample yielded a discordia line with an upper concordia intercept age of 2884±12Ma which is interpreted as the time of tonalite emplacement. Geochemical data of the foliated granitoids confirm their affinity to the tonalite–trondhjemite–granodiorite (TTG) series. They are characterized by high Al2O3 contents (14.4–17.2wt.%), high Sr/Y ratios (18–99) and show significant rare-earth element (REE) fractionation with La n /Yb n =11–89. The ɛNd(T) values vary from −1.6 to +0.8 and Nd mean crustal residence ages range from 3.23 to 3.07Ga. Geochemical and isotopic data confirm their genesis through interaction of mantle and crustal material under high pressure near the base of thickened crust either after accretion of ancient continental crust and an oceanic plateau, or after underplating of oceanic plateau-like basaltic magmas. The Akitkan orogenic belt is a composite crustal unit of Archaean and Palaeoproterozoic age. We propose two possible scenarios of its evolution. In the first scenario Palaeoproterozoic complexes developed along the active margin of the Archaean Anabar superterrane at 2.1–2.0Ga. Alternatively Archaean and Palaeoproterozoic components of the Akitkan belt could have a distal origin and were accreted to the Anabar superterrane. These accretional processes were followed by a major collision of the Aldan and Anabar superterranes at ∼1.9Ga finalised by post-collisional granitoid magmatism at 1.87–1.84Ga. [Copyright &y& Elsevier]

[Display omitted] • The Doros dolerites and East Anabar dolerites have ages of 1.76 and 1.78 Ga, respectively. • There is a 20 my difference between late Paleoproterozoic mafic magmatism in the north and south Siberia. • 1.78–1.75 Ga mafic dykes and intrusions of Siberia were generated mainly from the subcontinental lithospheric mantle. • For this period there is continuous mafic magmatism in some continents and short magmatic events in other continents. • 1.79–1.75 Ga mafic intrusions around the world demonstrate the prevalence of subcontinental lithospheric mantle source. The paper presents new geological, geochronological, geochemical, and Nd isotopic data on the late Paleoproterozoic dolerites of the Siberian craton. U-Pb baddeleyite ages of the Doros dolerites (Aldan shield, south-eastern Siberia) and East Anabar dolerites (Anabar shield, northern Siberia) are 1757 ± 4 and 1774 ± 6 Ma, respectively. This new geochronological data together with published 1.76–1.75 Ga ages for Timpton-Algamay dolerites of the Aldan shield and Chaya dolerites of the Baikal uplift (southern Siberia) revealed a 20 my difference between this magmatism in the north and south Siberia. The Doros dolerites in their chemical compositions correspond to sub-alkaline basaltic andesites, but the East Anabar dolerite is chemically close to basaltic trachyandesite. The Doros dolerites demonstrate negative and close to zero ɛNd(t) values (from −7.0 to +0.1), which correlate well with SiO 2 and Mg#. All Doros dolerites have Nb–Ta and Ti anomalies in multielement spectra. The geochemical and Nd isotopic data suggest that the Doros dolerites have been formed by the mixing of mantle and crustal material. The East Anabar dolerites are characterized by a negative ɛNd(t) value of −3.7, negative Nb–Ta anomaly in multielement spectra, high concentrations of TiO 2 and P 2 O 5. The 1775 Ma East Anabar dolerites could be generated from a subcontinental lithospheric mantle source, possibly with some mantle plume interaction (possibly centred at the convergence with the 1.76–1.75 Ga fanning Aldan swarm). Geochemistry and Nd isotope systematics of all 1.78–1.75 Ga mafic dykes and intrusions of the Siberian craton indicate the subcontinental lithospheric mantle source or mantle source contaminated by crustal material. Geochronological data from the 1.79–1.75 Ga magmatic rocks of Siberia and other continents suggest continuous magmatism over this interval in some continents, but a series of short magmatic events/pulses (from one to four) separated by intervals of quiescence in other continents. We locate the analysed dykes and sills on new 1750 Ma and 1790 Ma global paleogeographic reconstructions. Analysis of 1.79–1.75 Ga geochemical data on mafic intrusions from Late Paleoproterozoic continents suggests the prevalence of subcontinental lithospheric mantle source for the mafic intrusions over the pure mantle plume source. [ABSTRACT FROM AUTHOR]

Abstract: The results of geological, petrological, geochemical, and geochronological investigations of the Teya, Kalami, and Yeruda granites are discussed in the context of the formation the western margin of the Siberian craton and the Central Asian Orogenic Belt. These granites occur within Meso- to Neoproterozoic greenschist and amphibolite facies metamorphic rocks of the Central Angara terrane in the Yenisey Ridge region. Based on previous geochronology, these rocks have been implicated in alleged late Mesoproterozoic (Grenville-age) collision events along the western Siberian craton margin during the assembly of Rodinia. In all three plutons, the granites have mostly subaluminous—slightly peraluminous chemical compositions, and are characterized by variable normative corundum (1.1–3.3%) and Na2O/K2O (0.4–1.8). Sm–Nd and Rb–Sr isotopic data show that they could be formed from continental crust magmatic sources with Paleoproterozoic model ages (T Nd(DM-2st)=1.8–2.1Ga). SHRIMP U–Pb zircon ages of 868–864Ma were obtained for three samples from the Teya granite and 875Ma for a sample from the Kalami granite. Together with the previously dated 878Ma Yeruda granite, these intrusive rocks are the most ancient granites in the Transangara region of the Yenisey Ridge. It is likely that the Teya, Kalami, and Yeruda granites were part of the Central Angara terrane prior to its collision with Siberia at 760–720Ma. [Copyright &y& Elsevier]

Abstract: This U–Pb zircon geochronological study using TIMS and SHRIMP dating reveals new insights into the magmatic and metamorphic evolution of the Siberian Craton. Granulites, granites and one migmatite substantiate a multistage history. For the granulites an Archean protolith (3.4Ga) is documented, followed by a first granulite formation at 2.6Ga. In the Palaeoproterozoic a migmatisation event at 2.0Ga and two stages of granulitisation and granite emplacement at 1.88Ga and 1.85Ga are detected. The latter event (1.85Ga) is interpreted to mark the final consolidation of the Siberian Craton. Therefore this part of the craton was protected from younger overprints during the assembly of Rodinia in the Mesoproterozoic. [Copyright &y& Elsevier]

Geochemical, petrographic, mineralogical and geochronological study of mafic dikes in the Sharyzhalgai massif of the south Siberian craton has revealed the presence of three distinct generations of dikes. The youngest and most abundant dikes are non-metamorphosed and largely unaltered dolerites. They include both tholeiitic and subalkaline types that were probably intruded during a single magmatic episode. A 3-point whole rock-mineral Sm–Nd isochron age of 743±47 Ma indicates that these dikes are Neoproterozoic. The 40Ar/39Ar plateau age of 758±4 Ma is broadly in accord with the Sm–Nd age. A geochemical study of these dikes indicates that both tholeiitic and subalkaline dolerites have similar trace element abundances, suggesting that they were derived from a single mantle source. On the basis of their age, it is possible that these dikes were part of either the well-known Franklin swarm in northern Canada, or of the 780 Ma swarm in western Laurentia. However, more evidence is needed to test this hypothesis. [Copyright &y& Elsevier]

• For the first time in crustal xenoliths from Yakutian kimberlites, zircon ages of 3.22–3.15 Ga have been established. • Zircons with the most primitive hafnium ratios (0.28047–0.280661) give Eoarchean T C H U R C ages. • The data imply 4 main stages in the evolution of the Archean crust of Anabar tectonic province (3,2, 2,9, 2,8–2,7, 1,9 Ga). The Siberian craton is one of the largest Precambrian cratons in the world. However, unlike other cratons, the Siberian craton can only provide a relatively limited amount of geochronological data since a large part of it is covered by younger sedimentary deposits. Xenoliths from numerous kimberlite and lamprophyre pipes and alkali basalts allow us to investigate the composition and evolution of the Siberian Craton crust. The available isotopic and geochemical data show that the crust of the Anabar tectonic province of the Siberian craton is not age stratified, and consists of variably reworked Paleoarchean rocks and juvenile Proterozoic rocks at all crustal levels. Hence, a detailed geochronological study of crustal xenoliths (mainly zircon U-Pb age and Hf isotopic composition) in the kimberlite pipes of the Yakutian kimberlite province is required. In this study, we present U-Pb ages and Hf isotope data of zircons derived from crustal xenoliths in the Zarnitsa (Daldyn kimberlite field) and the Nyurbinskaya (Nakyn kimberlite field) kimberlite pipes. The obtained data provided grounds for identifying four main tectono-thermal events during the evolution of the Archean crust in the Anabar tectonic province of the Siberian craton. The first event at 3.2 Ga denotes the beginning of zircon crystallisation. These zircons are eventually recrystallised during the second event at 2.9 Ga, and radiogenic Hf (formed from 176Lu decay in the host rock) was introduced into the system. The third event at 2.8–2.7 Ga featured further recrystallisation of zircons and the incorporation of additional radiogenic 176Hf. The minor addition of radiogenic Hf during the final event at 1.9 Ga indicates a relatively large range for the initial 176Hf/177Hf ratio. Our data indicate that Eoarchean or even Hadean crust, which were reworked in the Paleoproterozoic, may be present beneath the Daldyn and Nakyn kimberlite fields. Zircon grains with low 176Hf/177Hf (0.28047–0.280661) were found in the xenoliths of the mafic garnet granulite (Zar-1–02) and garnet biotite gneisses (Nrb-13 and Nrb-65). [ABSTRACT FROM AUTHOR]

[Display omitted] • The South Siberian post-collisional magmatic belt contains 1.88–1.86 Ga igneous rocks. • The belt records the final event of the Siberian craton assembly. • The belt consists mainly of granitoids and coeval felsic volcanics. • Mafic rocks and carbonatites are less abundant in the belt. • The igneous rocks have dissimilar chemical and isotopic signatures. The paper presents an overview of geological, geochronological, geochemical, and isotopic data on 1.88–1.84 Ga igneous rocks from the South Siberian post-collisional magmatic belt that records the final event of craton assembly. The belt consists mainly of granitoids and coeval felsic volcanics, less abundant mafic rocks, and sporadic carbonatites. In spite of the chronological and geodynamic proximity, the igneous rocks from different parts of the belt have dissimilar chemical and isotopic signatures, which are well consistent with the events that preceded the final assembly of the craton. Samples from the southwestern part of the belt show the greatest diversity, with an affinity of granitoids and felsic volcanics to different granite types (I-, S-, and A), and large ε Nd (T) ranges from positive to strongly negative for both felsic and mafic rocks. The compositional diversity of post-collisional igneous rocks here may be due to their origin shortly after the collisional events (1.90–1.87 Ga) during the orogen collapse. The diversity can have different explanations for felsic and mafic rocks: melting of heterogeneous sources assembled in the thickened orogen, as well as lithospheric delamination and asthenospheric upwelling, respectively. In the latter case, a source for mafic melts can be both asthenospheric material and subcontinental lithospheric mantle. The rocks of the southeastern belt segment are less diverse. Almost all granitoids and felsic volcanics have ferroan compositions, A -type granite affinity, and variable negative ε Nd (T) values similar to those in mafic rocks and in the Aldan shield carbonatites. The granitoids and volcanics here have compositions that commonly form in within-plate extension settings, which correlate with the 2.00–1.90 Ga age of collisional events in the area prior to the belt formation. The cessation of collisional movements in the southwestern craton part led to extension throughout its southern (and southeastern) areas. The ensuing melting of continental crust and subcontinental lithospheric mantle produced, respectively, felsic and mafic melts. The igneous rocks of the easternmost part of the South Siberian belt include also alkaline carbonatites and host diverse mineral deposits indicates that this part of the craton may have been exposed to the effect of a hot spot. [ABSTRACT FROM AUTHOR]

• Mafic granulites from xenoliths were formed under amphibolite facies P-T conditions. • Phase equilibria modeling reveals reduced oxygen fugacity during metamorphism. • The metamorphism was fluid-deficient. • Granulites were equilibrated at temperatures above the cratonic conductive geotherm. It is widely accepted that granulite xenoliths from kimberlites provide a record of granulite facies metamorphism at the basement of cratons worldwide. However, application of the phase equilibria modeling for seven representative samples of mafic granulites from xenoliths of the Udachnaya kimberlite pipe, Yakutia, revealed that a granulitic garnet + clinopyroxene + plagioclase ± orthopyroxene ± amphibole ± scapolite mineral assemblage was likely formed in the middle crust under amphibolite facies conditions (600–650 °C and 0.8–1.0 GPa) in a deficiency of fluid. Clinopyroxene in the rocks is characterized by elevated aegirine content (up to 10 mol.%) both in the earlier magmatic cores and in the later metamorphic rim zones of the grains. Nevertheless, the phase equilibrium modeling for all samples indicates surprisingly reduced conditions, i.e. oxygen fugacity 1.6–3.3 log units below the FMQ (Fayalite-Magnetite-Quartz) buffer. In contrast, the coexistence of Fe-Ti oxides indicates temperatures of 850–990 °C and oxygen fugacity about lg(FMQ) ± 0.5, conditions which correspond to earlier stages of rock evolution. Reduction of oxygen fugacity during cooling is discussed in the context of the evolution of a complex fluid. The reconstructed P-T conditions for the final equilibration in the mafic granulites indicate that temperatures were ~250 °C higher than those extrapolated from the continental conductive geotherm of 35–40 µW/m2 deduced from peridotite xenoliths of the Udachnaya pipe. Although the granulites resided in the crust for a period for at least 1.4 Ga, they did not re-equilibrate to the temperatures of the geotherm, likely due to the blocking of mineral reactions under relatively low temperatures and fluid-deficient conditions [ABSTRACT FROM AUTHOR]

• Dolerite sills in the Biryusa inlier of the southern Siberian craton have age ca. 1.61 Ga. • The dolerites were generated from mantle source produced by interaction between OIB and ACR-like magmas. • The dolerites and coeval rift-related sedimentary strata suggest an overall extensional tectonic environments at 1.65 – 1.60 Ga. • Ca. 1.65 – 1.58 Ga mafic and felsic intrusions within Nuna supercontinent suggest the overall extensional tectonic environments. The paper presents a new geological, geochronological, geochemical and Nd isotopic data on the latest Paleoproterozoic dolerite sills, exposed in the Biryusa inlier of the southern Siberian craton among the sandstones of sedimentary sequence traditionally suggested as Neoproterozoic. One dolerite sill yielded U-Pb (ID-TIMS) baddeleyite concordia age of 1613 ± 5 Ma, which interpreted as time of their emplacement. New geochronological data allow reconsider previously reported Neoproterozoic age of sedimentary sequence hosting dolerite sills studied and suggest for them at least Paleoproterozoic age. The dolerites correspond to subalkaline and alkaline tholeiitic basalts and less often subalkaline tholeiitic basaltic andesite according to their major-element compositions with lower to moderate mg#, varying from 26 to 58. All dolerites demonstrate a similar slightly negative ɛNd(t) values range from −2.2 to −2.5. Geological, geochemical and Nd isotopic data suggest that mafic melts responsible for genesis of the dolerites were generated in an intracontinental extensional setting from homogeneous mantle source produced by interaction between OIB and ACR-like magmas. Geochemical features of the studied dolerites together with geological observations, namely – a presence of coeval rift-related sedimentary strata in the neighboring Urik-Iya graben (paleorift), suggest an overall extensional tectonic environments in the southern part of the Siberian Craton at 1.65–1.60 Ga. Synthesis of data on ca. 1.65–1.58 Ga magmatism around the world showed that the spatial distribution of various ca. 1.65–1.58 Ga mafic and felsic intrusions, including dyke swarms, anorogenic granites, as well as intracontinental basins within Nuna supercontinent suggest the overall extensional tectonic environments, probably related to the retreat of subduction slabs surrounded the supercontinent. [ABSTRACT FROM AUTHOR]

• The Siberian craton had completed its assembly in the Paleoproterozoic. • Paleoproterozoic granitoids record the history of the Siberian craton assembly. • Granitoids in the Siberian craton reveal major events of magmatic activity. The paper presents a synthesis of geochronological, geochemical, and isotopic data on Paleoproterozoic granitoids in the Siberian craton and, in some cases, on volcanics related to these granitoids. Different evolution stages of the craton, including its assembly, are recorded in several major events in the history of Paleoproterozoic granitic magmatism. They are 2.52–2.40 Ga and 2.15–2.04 Ga granitoids of different tectonic settings; 2.06–2.00 Ga subduction-related granitoids; 2.00–1.87 Ga collisional granitoids; 1.88–1.84 postcollisional granitoids, and 1.76–1.71 Ga within-plate (anorogenic) varieties. Granitoids with ages of 2.5–2.4 Ga and 2.15–2.04 Ga are distributed locally in separate blocks and terranes which later entered the craton structure. These rocks are of different types and represent different tectonic settings of the respective blocks and terranes, i.e., the Siberian craton did not exist yet as a single unit at that time. The 2.06–2.00 Ga subduction-related granitoids and volcanics are found in the southern and southeastern craton parts. Magmatism of that time interval probably was associated with subduction beneath the Archean Olekma-Aldan and Anabar continental microplates and with the formation of their active margins. Granitoids of the 2.00–1.87 Ga age interval represent a collisional stage of the craton evolution. Collisional granitoids that intruded between 2.00 and 1.95 Ga record the first large-scale stage of craton assembly with collisions of terranes that had built the core of the Anabar, Aldan, and Olenek superterranes. The intrusions of 1.95–1.90 Ga granitoids mark the consolidation of the southeastern craton part. Collisional granitoids with the 1.90–1.87 Ga ages, which are especially abundant in the south and southwest of the craton but almost lack from the north, led to general assembly of the craton. The granitoid and volcanic magmatic activity of 1.88–1.84 Ga in the craton south produced the South Siberian postcollisional magmatic belt that had completed the assembly of the craton which, in its turn, may have been part of the Paleoproterozoic supercontinent of Columbia. Granitic intrusions at 1.76–1.71 Ga are limited to the southwestern and southeastern craton parts and correspond to a setting of continental extension which never led to the breakup of the craton. [ABSTRACT FROM AUTHOR]

• The main tectonic-thermal events modified the crust at 2.7, and 1.9–1.8 Ga, which is consistent with ages of mantle depletion events from previous studies. • The crust of the Anabar tectonic province consists of variably reworked Paleoarchean rocks and juvenile Proterozoic rocks at different crustal levels. • The crust and mantle of the Siberian Craton has been coupled since the Paleoarchean. To clarify the tectonic-thermal evolution of the Anabar tectonic province in the central Siberian Craton, we performed an isotope-geochemical study of 20 xenoliths from the Udachnaya, Zarnitsa, and Komsomolskaya kimberlite pipes to represent different crustal levels. Most mafic granulites have Proterozoic Nd model ages and geochemical characteristics close to those of intraplate basalts, whereas some mafic and intermediate granulites with Archean model ages exhibit geochemical features of supra-subduction ophiolitic basalts. Analysis of U-Pb ages and hafnium isotopic composition of zircon indicates that the main tectonic-thermal events modified the crust at 2.7 and 1.9–1.8 Ga, which is consistent with ages of mantle depletion events from previous studies. All zircons have Archean Hf model ages (T DM C 3.6 - 3.2 Ga). Overall, thermal events with ages of 2.9–2.8, 2.7, 2.4, 1.97 and 1.8 Ga have remarkable influence on the studied zircons. Tectono-thermal events at 2.4 1.97, 1.9 and 1.8 Ga with no addition of juvenile material are recorded by zircons from xenoliths of mafic and intermediate granulites and metadiorites. A compilation of isotope-geochemical data demonstrates that instead of age-stratified, the crust of the Anabar tectonic province consists of variably reworked Paleoarchean rocks and juvenile Proterozoic rocks at all crustal levels. Hence the crust and mantle of the Siberian Craton has been coupled since the Paleoarchean. [ABSTRACT FROM AUTHOR]