| 1. |
- Bibikova, E. V., et al.
(author)
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Sarmatia-Volgo-Uralia junction zone: Isotopic-geochronologic characteristic of supracrustal rocks and granitoids
- 2009
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In: Stratigraphy and Geological Correlation. - 0869-5938. ; 17:6, s. 561-573
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Journal article (peer-reviewed)abstract
- The geochronologic (U-Pb isotopic system of zircons) and isotopic-geochemical (Sm-Nd isotopic system of the bulk rock) studies were performed along the profile extending from the eastern Sarmatia (in the west) to the Middle Volga megablock of Volgo-Uralia (in the east), i.e., across the entire junction zone for dating the integration of Sarmatia and Volgo-Uralia, representing two segments of the East European Craton. It is established that the examined rocks are characterized by the Paleoproterozoic Nd isotopic model age, which varies from 2.1 and 2.4 Ga, except for some samples indicating a similar age of the crust through the entire Sarmatia-Volgo-Uralia junction zone. The highly metamorphosed complexes of the granulite and amphibolite facies constituting the southwestern margin of Volgo-Uralia are Paleoproterozoic, not Archean, in age, contrary to previous views. Two Early Paleoproterozoic lithotectonic complexes are defined in Volgo-Uralia: South Volga metasedimentary and Tersa metasedimentary-volcanogenic. The obtained data confirm the asynchronous integration of individual segments into the East European Craton: the integration of Sarmatia and Volgo-Uralia approximately 2100-2000 Ma ago was followed by the conjunction of this newly-formed continent with Fennoscandia ca. 1800 Ma ago.
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| 2. |
- Bogdanova, Svetlana, et al.
(author)
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The 1.80-1.74-Ga gabbro-anorthosite-rapakivi Korosten Pluton in the Ukrainian Shield: a 3-D geophysical reconstruction of deep structure
- 2004
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In: Tectonophysics. - : Elsevier BV. - 0040-1951. ; 381:1-4, s. 5-27
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Journal article (peer-reviewed)abstract
- The deep structure of the gabbro-anorthosite-rapakivi granite ("AMCG-type") Korosten Pluton (KP) in the northwestern Ukrainian Shield was studied by 3-D modelling of the gravity and magnetic fields together with previous seismic data. The KP occupies an area of ca. 12,500 km(2) and comprises several layered gabbro-anorthositic intrusions enveloped by large volumes of rapakivi-type granitoids. Between 1.80 and 1.74 Ga, the emplacement of mafic and associated granitoid melts took place in several pulses. The 3-D geophysical reconstruction included: (a) modelling of the density distribution in the crust using the observed Bouguer anomaly field constrained by seismic data on Moho depth, and (b) modelling of the magnetic anomaly field in order to outline rock domains of various magnetisation, size and shape in the upper and lower crust. The density modelling was referred to three depth levels of 0 to 5, 5 to 18, and 18 kin to Moho, respectively. The 3-D reconstruction demonstrates close links between the subsurface geology of the KP and the structure of the lower crust. The existence of a non-magnetic body with anomalously high seismic velocity and density is documented. Most plausibly, it represents a gabbroic stock (a parent magma chamber) with a vertical extent of ca. 20 km, penetrating the entire lower crust. This stock has a half-cylindrical shape and a diameter of ca. 90 kin. It appears to be connected with a crust-mantle transitional lens previously discovered by EUROBRIDGE seismic profiling. The position of the stock relative to the subsurface outlines of the KP is somewhat asymmetric. This may be due to a connection between the magmatism and sets of opposite-dipping faults initially developed during late Palaeoproterozoic collisional deformation in the Sarmatian crustal segment. Continuing movements and disturbances of the upper mantle and the lower crust during post-collisional tectonic events between 1.80 and 1.74 Ga may account for the long-lived, recurrent AMCG magmatism.
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| 3. |
- Bogdanova, Svetlana V., et al.
(author)
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Palaeoproterozoic reworking of early Archaean lithospheric blocks : Rocks and zircon records from charnockitoids in Volgo-Uralia
- 2021
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In: Precambrian Research. - : Elsevier BV. - 0301-9268. ; 360
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Journal article (peer-reviewed)abstract
- The Volgo-Uralia segment, which constitutes one fourth of the East European Craton, is covered by sedimentary deposits. From geophysical studies and examination of thousands of drillcores, Volgo-Uralia has been recognised as a vast high-grade terrain with a complex crustal history extending from the Palaeoarchaean to the Palaeoproterozoic. Our recent studies are focused on the search for the oldest crust formation event by extracting whole rock Sm-Nd and zircon U-Th-Pb and Lu-Hf isotope information from samples recovered by drilling in southern Volgo-Uralia. Particular attention is devoted to the Kolyvan charnockitoid rock suite, which makes up several large areas of gneisses and granitoids of enderbite, charnockite and tonalite composition. The zircon from the granitoids show complex internal structures and consists of large magmatic cores with oscillatory zoning, surrounded by CL black-and-bright bands of metamorphic rims. The crystallisation age of the cores is defined as 3140 ± 7 Ma (SHRIMP) and 3127 ± 46 Ma (LA-ICPMS), while the CL-bright rims are dated at 1950 ± 25 Ma (LA-ICPMS). The ingressive recrystallisation of primary magmatic zircon correlates with depletion in REE, which is observed in each studied core-rim pair. No differences in O-isotopic compositions have been detected between the cores and the rims. δO18 values with an average of 5.8 ± 0.3‰ (1SD) implying that no supracrustal rocks were involved in the source of the Kolyvan melts. The Hf-isotope compositions of magmatic cores (−3 to −9 εHfT) and metamorphic rims (−14 to −28 εHfT), and their similar crustal model ages from 3.42 to 3.86 Ga indicate Eo- to Palaeoarchaean crustal sources for the charnockitic magmas. Sm-Nd model ages of ca 3.46 Ga for the Kolyvan rocks are consistent with the zircon Hf-isotope data and indicate a long crustal prehistory of a source of the Mesoarchaean magmas. We conclude that the Mesoarchaean Kolyvan suite rocks was formed by reworking of Eo- to Palaeoarchaean lithosphere, which probably had been widespread throughout Volgo-Uralia. The obtained geochemical and isotope data can be reconciled in a model of deep mantle-plume activity at 3.1 Ga causing mantle underplating, extension of the Palaeoarchaean crust and high-T magmatism.
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| 4. |
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| 5. |
- Bibikova, E. V., et al.
(author)
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The early crust of the Volgo-Uralian segment of the East European Craton: Isotope-geochronological zirconology of metasedimentary rocks of the Bolshecheremshanskaya Formation and their Sm-Nd model ages
- 2015
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In: Stratigraphy and Geological Correlation. - 0869-5938. ; 23:1, s. 1-23
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Journal article (peer-reviewed)abstract
- We present the results of isotope-geochronological study of metasedimentary rocks of the Bolshecheremshanskaya Formation of the Volgo-Uralian segment of the East European Craton carried out to identify their protoliths. 16 samples of high-alumina gneisses from well cores were studied using the Sm-Nd isotope method and T-Nd(DM) model ages. Accessory zircons were selected from rocks with the most ancient model ages (more 3.2 Ga) in three wells: Minnibaevskaya 20000, Novo-Elkhovskaya 20009, and Zai-Karatayskaya 12930 in South Tatarstan. The isotope U-Pb dating of 200 zircon grains was performed on a Cameca 1280 NORDSIM secondary ion mass spectrometer at the Natural History Museum (Stockholm, Sweden). The most applicable sites for analysis of zircon crystals were pre-selected based on cathodoluminescence images. The analytical results demonstrate the diversity of zircon groups in age from 3.8 to 2.6 Ga and together with geochemical features of metasedimentary rocks of the Bolshecheremshanskaya Formation suggest the heterogeneous composition and age of provenance areas under denudation. Occurrence of Eoarchean and Paleoarchean zircons in the clastic material of the protolith of the Bolshecheremshanskaya gneisses indicates the existence of Early Archean crustal terrains in Volgo-Uralia.
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| 6. |
- Bogdanova, Svetlana, et al.
(author)
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Late Palaeoproterozoic mafic dyking in the Ukrainian Shield of Volgo-Sarmatia caused by rotation during the assembly of supercontinent Columbia (Nuna)
- 2013
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In: Lithos. - : Elsevier BV. - 0024-4937. ; 174, s. 196-216
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Journal article (peer-reviewed)abstract
- The Ukrainian Shield comprises the exposed crust of the large Palaeoproterozoic protocraton Volgo-Sarmatia, which together with the Fennoscandian crustal segment constitutes the East European Craton ("Baltica"). Geological and geophysical data indicate that 1.80 to 1.75 Ga mafic dykes related to anorthosite-mangerite-charnockite-granite (AMCG) plutons are widespread within the Ukrainian Shield. We examined their ages, distribution patterns, orientations and compositions in three different crustal blocks (Volyn, Ingul and Azov), and found close spatial relationships with major strike-slip fault systems developed during two phases of extension. The early, 1.80-1.77 Ga, generation of mafic dykes mostly follows NW (330 +/- 20 degrees) and more rarely N-S- or E-W-trending faults corresponding to major NE-SW extension (the Submoshorino phase). These dykes contain olivine dolerites, picrites, camptonites, lamprophyres, kimberlites and other rocks belonging to tholeiitic and subalkaline jotunitic series. The compositions of these dykes differ between the host blocks, but all feature upper mantle geochemical signatures such as high contents of Ni and Cr, and positive values of epsilon Nd-(1800) up to + 2.8. High degrees of REE fractionation indicate deep levels of mantle melting, which is particularly characteristic of the Ingul block as marked by the most extensive and dense mafic dyke swarms. The later, 1.76-1.75 Ga, dyke swarms occur close to the most voluminous AMCG suites of similar age and were emplaced during the second (Korsun) phase of faulting when all the older strike-slip fault zones were reactivated and partly transformed to tensional faults by E-W extension. These dyke swarms mainly trend 030 +/- 20 degrees. They are jotunitic and their isotopic signatures indicate a greater participation of crustal sources in the parent melts. The overall transtensional tectonic setting of the mafic dyking associated with the AMCG magmatism in Volgo-Sarmatia was created by convergent tectonics and postcollisional collapse of the thickened lithosphere, as well as by mantle delamination coupled with the rotation of Volgo-Sarmatia between 1.80 and 1.75 Ga. This agrees with palaeomagnetic reconstruction suggesting rotation(s) of Volgo-Sarmatia during its protracted oblique docking with Fennoscandian terranes and Laurentia as supercontinent Columbia (Nuna) was assembled. (C) 2012 Elsevier B.V. All rights reserved.
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| 7. |
- Bogdanova, Svetlana, et al.
(author)
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Volgo-Uralia: The First U-Pb, Lu-Hf and Sm-Nd Isotopic Evidence of Preserved Paleoarchean Crust
- 2010
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In: American Journal of Science. - : American Journal of Science (AJS). - 0002-9599. ; 310:10, s. 1345-1383
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Journal article (peer-reviewed)abstract
- The crustal segment Volgo-Uralia is the least known part of the East European Craton. Its crystalline crust is hidden beneath a thick Neoproterozoic to Phanerozoic cover but disclosed by thousands of drill holes. In conjunction with the recent "Tatseis" reflection seismic profile, we conducted the first isotopic study of the Bakaly granitoid block in eastern Volgo-Uralia, which represents a subsurface section of the layered upper-middle crust. The study included whole-rock Sm-Nd and ion-probe zircon U-Th-Pb (SIMS) and Lu-Hf (LA-ICPMS) analyses of granitoids from seven drill cores. The Bakaly block was also targeted because its rocks have never been subjected to granulite facies metamorphism, making it possible to date pristine, pre-metamorphic zircon. Our study showed that the four principal suites of granitoids in the Bakaly block are different in age, each corresponding to a particular stage of Archean crustal evolution between 3.3 and 2.6 Ga. The Tashliar monzonitic suite, belonging to an alkaline series yielded zircon ages of 3.3 and 3.2 Ga, which are the oldest ages yet found in Volgo-Urafia. The epsilon(Hf)(T) values of the dated zircon and the epsilon(Nd)(T) values of their host rocks indicate that a Paleo- to Eoarchean protolith with model T-DM ages up to 3.8 Ga had been involved in the formation of the Tashliar melts. Three Neoarchean rock suites, one comprising quartz dioritic and tonalitic gneisses (the Bak 1), another K-rich granodiorites, granites and migmatites (the Bak 2), and the third monzonitic granitoids (the Aktanysh suite) were formed sequentially between 2.72 and 2.60 Ga. The 2.72 Ga Bak 1 suite is chemically diverse. It includes granitoids of the TTG type related to slab/subduction melts as well as rocks formed by the re-melting of older crust with whole-rock Nd T-DM and Hf T-DM model ages of 3.4 to 3.2 Ga. The 2.69 to 2.65 Ga Bak 2 suite was probably associated with a major collisional event, which defined the stacked structure of the Archean crust in Volgo-Uralia and its seismic layering. Our data suggest that the Bak 2 melts originated partly from juvenile sources with epsilon(Hf)(T) zircon values up to +4.8, as well as mixed crustal and juvenile mantle materials. Some crustal contamination of the melts appears to have occurred as evidenced by incorporated xenocrystic zircon. The chemical compositions of Bak 2 granitoids from the different plutons, their zircon epsilon(Hf) values, and the Hf- and Nd T-DM ages all mirror a heterogeneous, collisional, crustal structure. During post-collisional extension at 2.6 Ga, the intrusion of Aktanysh monzonitic granitoids took place. These rocks also bear evidence of a long crustal pre-history with Nd and Hf T-DM model ages of 3.3 to 3.5 Ga. The Aktanysh rocks are coeval with the Tuymazy gabbro-norite-anorthosite intrusions, which are widely distributed along post-collisional shear zones in the Bakaly block. They could have provided the heat necessary to melt the crust at this stage. Altogether, the isotopic evidence suggests several episodes of crustal growth and recycling possibly reaching back to 3.6 and 3.8 Ga. Metamorphic zircon rims show that the Archean crust in the Bakaly block were subjected to several tectonothermal overprints in the Paleoproterozoic between 2.4 and 1.9 Ga ago.
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| 8. |
- Li, Z. X., et al.
(author)
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How not to build a supercontinent: A reply to JDA Piper
- 2009
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In: Precambrian Research. - : Elsevier BV. - 0301-9268. ; 174:1-2, s. 208-214
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Journal article (other academic/artistic)abstract
- The hypothesized existence of a Neoproterozoic supercontinent called Rodinia is based on a series of geological and paleomagnetic observations, with details about the configuration and evolution of this supercontinent still a matter for debate. Regrettably, we found that the comment by Piper (this volume) lacks scientific objectiveness. The 'Palaeopangaea' that he promotes is, in our view, based on incorrect application of paleomagnetic data, and is not supported by geological evidence. (C) 2009 Elsevier B.V. All rights reserved.
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| 9. |
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| 10. |
- Puchkov, Victor N., et al.
(author)
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The ca. 1380 Ma Mashak igneous event of the Southern Urals
- 2013
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In: Lithos. - : Elsevier BV. - 0024-4937. ; 174, s. 109-124
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Journal article (peer-reviewed)abstract
- A review of the geochronology, geochemistry and distribution of the 1380 Ma Mashak Large Igneous Province (LIP) of the eastern margin of the East European craton indicates a potential link to a major breakup stage of the Mesoproterozoic supercontinent Columbia (Nuna), link to a major stratigraphic boundary (Lower-Middle Riphean), and economic significance for hydrocarbons and metallogeny. Specifically, the Mashak event likely has much greater extent than previously realized. Two U-Pb baddeleyite (ID TIMS) age determinations on dolerite sills obtained from borehole (Menzelinsk-Aktanysh-183) confirm the western extent of the Mashak event into the crystalline basement of the East European Craton (1382 +/- 2 Ma) and into the overlying Lower Riphean sediments (1391 +/- 2 Ma), and the imprecise ages reported elsewhere indicate the possible extension into the Timan region, with an overall areal extent of more than 500,000 km(2) (LIP scale). It has tholeiitic compositions and is associated with breakup on the eastern margin of the craton - in addition, precise SHRIMP zircon ages of 1386 +/- 5 Ma and 1386 +/- 6 Ma (this paper) provide confirmation of previous approximate 1380-1383 Ma zircon age determination of the same formation, and suggest an age of ca. 1.4 Ga for the Lower/Middle Riphean boundary which was formerly considered to be 1350 +/- 10 Ma. Contemporaneous magmatic rocks in the northeastern Greenland part of Laurentia (Zig-Zag Dal and Midsommerso formations) and Siberia (Chieress dykes and other dolerites) together with the Mashak event are suggested to be fragments of a single huge LIP and to correspond to breakup stage of the Columbia (Nuna) supercontinent. The Mashak LIP also has some significance, at least in Volgo-Uralia, for hydrocarbons and metallogeny. (C) 2012 Elsevier B.V. All rights reserved.
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| 11. |
- Arkhipov, Victor P., et al.
(author)
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Dynamic and structural properties of oxyethylated isononylphenols
- 2016
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In: Mendeleev communications (Print). - : Elsevier BV. - 0959-9436 .- 1364-551X. ; 26:4, s. 355-357
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Journal article (peer-reviewed)abstract
- Diffusion coefficients, dielectric relaxation times and refraction coefficients were measured, and activation energies of translational and rotational mobilities were determined for a series of oxyethylated phenols (neonols AF9-n) p-C9H19C6H4-O(CH2CH2O)nH, n = 4, 6, 8, 9, 10, 12, at different temperatures. The results demonstrated the existence of contraction and transition phenomena that changed the structure of neonol molecules at n ∼ 9 from a zigzag to a meander form.
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| 12. |
- Bogdanova, Svetlana, et al.
(author)
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Danopolonian migmatization of Mesoproterozoic sedimentary rocks in southernmost Sweden: a SIMS zircon study
- 2014
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In: GFF. - : Informa UK Limited. - 2000-0863 .- 1103-5897. ; 136:2, s. 410-428
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Journal article (peer-reviewed)abstract
- To assess the age and origin of the metasedimentary migmatites in southernmost Sweden and their relationships with the Mesoproterozoic granitoid magmatism in the area, we have dated migmatite zircon using the secondary ion mass spectrometry U-Pb method. The studied metasedimentary migmatites, here called the Noteboda migmatites, occur along the southwestern boundary of the 1442 Ma Taghusa granitoid intrusion in southeastern Skane. They contain the mineral assemblage garnet + biotite +/- muscovite + cordierite + sillimanite + quartz + plagioclase + K-feldspar and were formed during a retrograde evolution from c. 750-720 degrees C and 6 kbar (peak conditions) to c. 675 degrees C and 4 kbar. Zircon is characterized by detrital cores surrounded by U-rich rims and overgrowths. Separate rounded metamorphic grains also exist. The age probability-density distribution peaks for detrital zircon are at c. 1700, 1670, 1650, 1610, 1570 and 1530 Ma. These ages suggest Gothian orogenic rocks in the present west as the most probable principal source. Sedimentation occurred after c. 1530 Ma, the age of the youngest detrital zircon, indicating the existence of a previously unknown period of Mesoproterozoic sedimentation in southernmost Sweden. A homogeneous zircon overgrowth yielded a concordant Pb-207/Pb-206 age of 1439 +/- 5 Ma, which dates the migmatization and is close to the age of the Taghusa intrusion. We conclude that the burial of the sediments down to c. 20 km, their metamorphism and progressive migmatization took place concurrently with granitic magmatism, NE-SW compression, folding and shearing of the crust between 1460 and 1440Ma during the Danopolonian orogeny.
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| 13. |
- Lubnina, Natalia V., et al.
(author)
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A new key pole for the East European Craton at 1452 Ma: Palaeomagnetic and geochronological constraints from mafic rocks in the Lake Ladoga region (Russian Karelia)
- 2010
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In: Precambrian Research. - : Elsevier BV. - 0301-9268. ; 183:3, s. 442-462
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Journal article (peer-reviewed)abstract
- Palaeomagnetic and geochronological studies on mafic rocks in the Lake Ladoga region in South Russian Karelia provide a new, reliably dated Mesoproterozoic key paleopole for the East European Craton (Baltica). U-Pb dating on baddeleyite gives a crystallisation age of 1452 +/- 12 Ma for one of the studied dolerite dykes. A mean palaeomagnetic pole for the Mesoproterozoic dolerite dykes. Valaam sill and Salmi basalts yields a paleopole at 15.2 degrees N, 177.1 degrees E, A(95) = 5.5 degrees. Positive baked contact test for the dolerite dykes and positive reversal test for the Salmi basalts and for the dykes confirm the primary nature of the magnetisation. Comparison of this Baltica palaeopole with coeval paleomagnetic data for Laurentia and Siberia provides a revised palaeoposition of these cratons. The results verify that the East European Craton, Laurentia and Siberia were part of the supercontinent Columbia from the Late Palaeoproterozoic to the Middle Neoproterozoic. (C) 2010 Elsevier B.V. All rights reserved.
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| 14. |
- Pisarevsky, Sergei A., et al.
(author)
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Preface
- 2015
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In: Precambrian Research. - : Elsevier BV. - 0301-9268. ; 259, s. 1-4
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Journal article (other academic/artistic)
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