Redkinian Biota of Macroscopic Fossils from the Northwestern East European Platform (South Ladoga Region)     

E. Yu. Golubkova  E. A. Kushim  A. B. Kuznetsov  A. S. Yanovskii  A. V. Maslov  S. D. Shvedov  Yu. V. Plotkina 《Doklady Earth Sciences》2018,479(1):300-304

The stratigraphic distribution of microfossils and macroscopic fossil biota in Vendian deposits of the South Ladoga region (northwestern East European Platform) is analyzed. In the sequence of the Shotkusa- 1 well, three taxonomically heterogeneous microfossil assemblages are distinguished: two of them refer to the Redkinian age (Starorusskaya Fm.) and one to the Kotlinian age (Vasileostrovskaya Fm.). Deposits of the Starorusskaya Fm. contain Redkinian biota of macroscopic fossils, of which the most characteristic representatives are Chuaria circularis, Doushantuophyton lineare, Morania zinkovi, Orbisiana simplex, and Redkinia spinosa. These new findings expand the paleontological characteristics of Upper Vendian deposits, also providing additional criteria for distinguishing the Redkinian horizon in the northwestern East European Platform.  相似文献   

The First Results of U–Pb Isotope Dating of Detrital Zircons from the Upper Mesoproterozoic Gulliksenfellet Quartzite (Southern Part of Wedel Jarlsberg Land,Southwest Spitsbergen)     

N. B. Kuznetsov  T. V. Romanyuk  E. A. Belousova 《Doklady Earth Sciences》2018,479(1):305-309

The first results of U–Pb isotopic dating (LA–ICP–MS) of detrital zircons from metasedimentary rocks of the pre-Devonian basement of the SW part of western Spitsbergen (from Upper Mezoproterozoic Gulliksenfellet quartzite) showed ages ranging from 1700 ± 25 to 2948 ± 27 Ma.  相似文献   

Geodynamic Evolution Model of the Major Structures of Amerasian Basin     

L. I. Lobkovsky  I. A. Garagash  D. A. Alekseev 《Doklady Earth Sciences》2018,480(2):753-757

We have analyzed the geodynamic evolution of the lithosphere and upper mantle of the Amerasian basin based on the stress-strain state simulation. It is shown that the asthenospheric spreading in the return upflow region of the mantle convection, results in formation of two local uplifts, which can be interpreted as Lomonosov Ridge and Mendeleev/Alfa Ridge. The further long-term action of the mantle convection leads to formation of Makarov and Podvodnikov Basins.  相似文献   

First Find of Ga-Bearing Minerals in Ores of Ural Massive Sulfide Deposits     

N. P. Safina  N. R. Ayupova  E. V. Belogub  V. V. Maslennikov  I. A. Blinov  I. G. Zhukov  D. A. Artem’ev 《Doklady Earth Sciences》2018,480(2):746-749

Gallium-containing chlorite, mica, and magnetite (up to 14, 13, and 5–7 wt % of Ga) along with Ga hydroxides (oxyhydroxides?) were found for the first time in massive sulfide deposit in the Urals. The minerals identified within the cement of chalcopyrite–sphalerite breccias of the Shemur copper–zinc–massive sulfide deposit (Northern Urals) are associated with Ga-enriched sphalerite, chalcopyrite, and, less commonly, pyrite (33–364, 67–363, and 4–230 g/t, respectively).  相似文献   

Shear Tectonic Fabric in the Atlantic Ocean and Its Relation to the Geodynamic Condition of the Upper Mantle and Intraplate Deformations     

S. Yu. Sokolov 《Doklady Earth Sciences》2018,480(2):715-719

The tectogenesis of the Atlantic Ocean segments is complicated by the axial difference in spreading half-velocities, which causes additional shear displacements between the lithospheric blocks along the transform faults. The intensity of these processes and density of the fault zones iis related to the presence of “cold” sublithospheric lenses along the MAR at a depth of 500 km.  相似文献   

Comparison of Supercontinent Cycles in the Metallogeny of Rare Earth Elements     

A. V. Tkachev  D. V. Rundqvist  N. A. Vishnevskaya 《Doklady Earth Sciences》2018,480(2):730-734

The distribution of integrated resources of large and superlarge deposits (LSLDs) of rare earth elements (REEs) is compared to the current model of supercontinent cyclicity during Earth’s evolution. It is found that REE LSLDs are related predominantly to igneous complexes (carbonatite, nepheline syenites, syenite-alkaline granites, subalkaline granites), which are often additionally enriched in the hypergenic zone. A certain part of the resources is concentrated in independent hypergenic formations represented by placers and ion-adsorbed clays. Each supercontinent cycle—Kenoran, Columbian, Rodinian, Pangean, and Amasian—is expressed in the REE metallogeny in particular way: we revealed significant intercycle variations in the amount of REE LSLDs, the variety of their types, total accumulated resources, and some other characteristics.  相似文献   

Estimating the Contributions of the Atlantic Multidecadal Oscillation and Variations in the Atmospheric Concentration of Greenhouse Gases to Surface Air Temperature Trends from Observations     

I. I. Mokhov  D. A. Smirnov 《Doklady Earth Sciences》2018,480(1):602-606

We have quantitatively estimated the contributions of anthropogenic forcing characterized by variations in the atmospheric content of greenhouse gases and of natural variability characterized by the Atlantic Multidecadal Oscillation to the trends of global surface air temperature from observations since the middle of the nineteenth century on the basis of three-component autoregressive models.  相似文献   

First Data about Mercury in Modern Hydrothermal Process in the Ocean,Juan de Fuca Ridge     

Yu. I. Konovalov  L. N. Luchsheva  V. B. Kurnosov 《Doklady Earth Sciences》2018,480(1):575-579

The results of studying Hg in an underwater hydrothermal system in the ocean using the Middle Valley of the Juan de Fuca ridge as an example are presented. A significant part of Hg is accumulated in the basalt fundament (Holes 858F, G), forming anomalously high concentrations (up to 29.30 ppm) in certain parts. The high Hg contents were established in metalliferous sediments (323 ppm) of the sedimentary cover (Hole 858D) and in sulfide deposits (up to 10.30 ppm). In other parts of the section, Hg content is 0.02–0.76 ppm (Holes 858B, D, F), background Hg contents in sediments—0.08–0.28 ppm and in basalts—0.17–0.31 ppm (Holes 855A, C, D).  相似文献   

Comparison of Organic Matter from Upper Jurassic Oil Shale of the East European Platform and the Bazhenov Formation by Molecular and Isotopic Data     

D. A. Bushnev  N. S. Burdelnaya  I. V. Goncharov  V. V. Samoylenko  M. A. Veklich 《Doklady Earth Sciences》2018,480(1):611-614

The molecular and isotopic composition of an extract from the rocks of the Bazhenov Formation in the southeast part of Western Siberia, oils that are genetically related to this formation, and products of hydrous pyrolysis of the organic matter of oil shale (Middle Volgian) of the East European Platform were studied. Common features and differences in their molecular composition were shown. The carbon isotope composition for C₁₄–C₃₀n-alkanes was determined for the first time; a negative isotope anomaly was revealed for C₂₆n-alkane in all samples studied. It was concluded that in spite of the geographical distance, specific biota was revealed in the Volga Basin. This biota conditioned an isotopic indicator, which is genetically significant.  相似文献   

The Nature and Age of Plagioclasites in the Ultrabasic Rai-Iz Massif (Polar Urals)     

N. V. Vakhrusheva  K. S. Ivanov 《Doklady Earth Sciences》2018,480(1):587-590

Corundum-containing and corundum-free plagioclasites localized in chromite-bearing ultramafites of the Rai-Iz Massif were explored for the composition and age. The composition of rock-forming minerals was studied, and the geochemical characteristics of the rocks were ascertained. The isotope age of plagioclasites determined by zircons using the U–Pb mode with a SHRIMP II device was equal to 398 ± 3 Ma. The age found conformed to the boundary on most of the Rai-Iz Massif took place against the background of a starting powerful collision, which caused the formation of the chromium mineralization of a high-chromic type, as well as the separation of a series of essentially plagioclase rocks of ruby mineralization at the discharge zones of the vein series.  相似文献