Concerning the issue of paleotectonic reconstructions in the Arctic and of the tectonic unity of the New Siberian Islands Terrane: New paleomagnetic and paleontological data     

V. A. Vernikovsky  D. V. Metelkin  T. Yu. Tolmacheva  N. A. Malyshev  O. V. Petrov  N. N. Sobolev  N. Yu. Matushkin 《Doklady Earth Sciences》2013,451(2):791-797

The New Siberian Islands terrane, represented on the Arctic shelf by the archipelagos of the New Siberian Islands and De Long Islands, is one of the key structures of the Arctic. However many questions of its structure, borders and formation history are under intense discussion. During the international expedition in 2011 we solved many problems concerning structural geology, paleontology, petrology and geochronology. A particular attention was given to obtaining paleomagnetic data for the sedimentary and igneous rocks of the archipelago. The primary objects of paleomagnetic studies were the Early Paleozoic sedimentary rocks of the Kotelny (Anzhu) and Bennett (De Long) islands. In this paper we present new paleontological data, including the first one for conodonts of the New Siberian Islands, which help us to specify the age of the Early Paleozoic deposits of the studied sections. In these sections we took a series of paleomagnetic samples. The match of the paleomagnetic directions we determined for Bennett Isl. and Kotelny Isl. indicates the tectonic unity between the territories of the Anzhu and De Long archipelagos. These first paleomagnetic data allow us to affirm that at least from the Early Ordovician the rocks of the Anzhu and De Long archipelagos formed within the same New Siberian Islands terrane, that is to say, on the same basement.  相似文献   

Minerals of mantle peridotites: Indicators of chromium ores in ophiolites     

G. N. Savel’eva  V. G. Batanova  A. V. Sobolev  D. V. Kuz’min 《Doklady Earth Sciences》2013,452(1):963-966

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Triggering of repeated earthquakes     

G. A. Sobolev  N. A. Zakrzhevskaya  D. G. Sobolev 《Izvestiya Physics of the Solid Earth》2016,52(2):155-172

Based on the analysis of the world’s earthquakes with magnitudes M ≥ 6.5 for 1960–2013, it is shown that they cause global-scale coherent seismic oscillations which most distinctly manifest themselves in the period interval of 4–6 min during 1–3 days after the event. After these earthquakes, a repeated shock has an increased probability to occur in different seismically active regions located as far away as a few thousand km from the previous event, i.e., a remote interaction of seismic events takes place. The number of the repeated shocks N(t) decreases with time, which characterizes the memory of the lithosphere about the impact that has occurred. The time decay N(t) can be approximated by the linear, exponential, and powerlaw dependences. No distinct correlation between the spatial locations of the initial and repeated earthquakes is revealed. The probable triggering mechanisms of the remote interaction between the earthquakes are discussed. Surface seismic waves traveling several times around the Earth’s, coherent oscillations, and global source are the most preferable candidates. This may lead to the accumulation and coalescence of ruptures in the highly stressed or weakened domains of a seismically active region, which increases the probability of a repeated earthquake.  相似文献   

Star formation around the H ii region Sh2-235     

M. S. Kirsanova  A. M. Sobolev  M. Thomasson  D. S. Wiebe  L. E. B. Johansson  A. F. Seleznev 《Monthly notices of the Royal Astronomical Society》2008,388(2):729-736

We present a picture of star formation around the H  ii region Sh2-235 (S235) based upon data on the spatial distribution of young stellar clusters and the distribution and kinematics of molecular gas around S235. We observed ¹³CO (1–0) and CS (2–1) emission toward S235 with the Onsala Space Observatory 20-m telescope and analysed the star density distribution with archival data from the Two Micron All-Sky Survey (2MASS). Dense molecular gas forms a shell-like structure at the southeastern part of S235. The young clusters found with 2MASS data are embedded in this shell. The positional relationship of the clusters, the molecular shell and the H  ii region indicates that expansion of S235 is responsible for the formation of the clusters. The gas distribution in the S235 molecular complex is clumpy, which hampers interpretation exclusively on the basis of the morphology of the star-forming region. We use data on kinematics of molecular gas to support the hypothesis of induced star formation, and distinguish three basic types of molecular gas components. The first type is primordial undisturbed gas of the giant molecular cloud, the second type is gas entrained in motion by expansion of the H  ii region (this is where the embedded clusters were formed) and the third type is a fast-moving gas, which might have been accelerated by winds from the newly formed clusters. The clumpy distribution of molecular gas and its kinematics around the H  ii region implies that the picture of triggered star formation around S235 can be a mixture of at least two possibilities: the 'collect-and-collapse' scenario and the compression of pre-existing dense clumps by the shock wave.  相似文献   

The classification of potassium basaltic trachyandesites that were discharged by the 2012–2013 parasitic eruption on Ploskii Tolbachik Volcano,Kamchatka using geochemical criteria     

S. A. Khubunaya  T. S. Eremina  A. V. Sobolev 《Journal of Volcanology and Seismology》2016,10(1):33-49

This study is concerned with the petrographic, mineralogic, and geochemical features in the K-high basaltic trachyandesites that were discharged by the 2012–2013 parasitic eruption on Ploskii Tolbachik Volcano. These K-high basaltic trachyandesites exhibit some obvious characteristics that testify to their suprasubduction origin. They are deeply differentiated rocks with strongly fractionated plagioclase. A study of the Sr, Nd, and Pb radiogenic isotope ratios in the K-high basaltic trachyandesites provided evidence of their mantle origin and of the fact that the crust has exerted no influence on their compositions. We performed a comparative analysis of the ratios of the concentrations for some incoherent elements in the K-high basaltic trachyandesites, as well as in intraplate, riftogenic, and island-arc moderate potassium basalts and basaltic andesites in relation to the concentrations of these elements in the primitive mantle. The geochemical features of these K-high basaltic trachyandesites classify them as belonging to the suprasubduction subalkaline formation of the potassium series.  相似文献   

Flow Structure in the Eclipsing Polar V808 Aur. Results of 3D Numerical Simulations     

Zhilkin  A. G.  Sobolev  A. V.  Bisikalo  D. V.  Gabdeev  M. M. 《Astronomy Reports》2019,63(9):751-777

Astronomy Reports - The structure of the flows in the eclipsing polar V808 Aur is studied. Comparison of computations with observed light curves is used to identify and clarify a number of features...  相似文献   

The role and conditions of second-stage mantle melting in the generation of low-Ti tholeiites and boninites: the case of the Manihiki Plateau and the Troodos ophiolite     

Roman?Golowin  Maxim?PortnyaginEmail author  Kaj?Hoernle  Alexander?Sobolev  Dimitry?Kuzmin  Reinhard?Werner 《Contributions to Mineralogy and Petrology》2017,172(11-12):104

High-Mg, low-Ti volcanic rocks from the Manihiki Plateau in the Western Pacific share many geochemical characteristics with subduction-related boninites such as high-Ca boninites from the Troodos ophiolite on Cyprus, which are believed to originate by hydrous re-melting of previously depleted mantle. In this paper we compare the Manihiki rocks and Troodos boninites using a new dataset on the major and trace element composition of whole rocks and glasses from these locations, and new high-precision, electron microprobe analyses of olivine and Cr-spinel in these rocks. Our results show that both low-Ti Manihiki rocks and Troodos boninites could originate by re-melting of a previously depleted lherzolite mantle source (20–25% of total melting with 8–10% melting during the first stage), as indicated by strong depletion of magmas in more to less incompatible elements (Sm/Yb < 0.8, Zr/Y < 2, Ti/V < 12) and high-Cr-spinel compositions (Cr# > 0.5). In comparison with Troodos boninites, the low-Ti Manihiki magmas had distinctively lower H₂O contents (< 0.2 vs. > 2 wt% in boninites), ~ 100 °C higher liquidus temperatures at a given olivine Fo-number, lower fO₂ (ΔQFM < + 0.2 vs. ΔQFM > + 0.2) and originated from deeper and hotter mantle (1.4–1.7 GPa, ~ 1440 °C vs. 0.8–1.0 GPa, ~ 1300 °C for Troodos boninites). The data provide new evidence that re-melting of residual upper mantle is not only restricted to subduction zones, where it occurs under hydrous conditions, but can also take place due to interaction of previously depleted upper mantle with mantle plumes from the deep and hotter Earth interior.  相似文献   

Stratigraphy of Upper Cretaceous and Cenozoic deposits of the Bakchar iron ore deposit (southwestern Siberia): New data     

N. K. Lebedeva  O. B. Kuzmina  E. S. Sobolev  I. V. Khazina 《Stratigraphy and Geological Correlation》2017,25(1):76-98

The results of complex palynological and microfaunistic studies of Upper Cretaceous and Cenozoic deposits of the Bakchar iron ore deposit are presented. Geochronologically, the age of the deposits varies from Campanian to Quaternary. It was established that the Slavgorod, Gan’kino, and Jurki (?) formations contain four biostratons in the rank of beds with dinocysts and three biostratons in the rank of beds with spores and pollen. The Cenozoic continental deposits contain four biostratons in the rank of beds, containing spores and pollen. As a result of the study, a large stratigraphic gap in the Cretaceous–Paleogene boundary deposits, covering a significant part of the Maastrichtian, Paleocene, Ypresian, and Lutetian stages of the Eocene, was established. The remnants of a new morphotype of heteromorphic ammonites of genus Baculites were first described in deposits of the Slavgorod Formation (preliminarily, upper Campanian). The distribution features of the different palynomorph groups in the Upper Cretaceous–Cenozoic deposits in the area of study due to transgressive-regressive cycles and climate fluctuations were revealed.  相似文献   

Synthesis of hydrocarbons by CO2 fluid conversion with hydrogen: Experimental modeling at 7.8 GPa and 1350°C     

Sokol  A. G.  Tomilenko  A. A.  Bul’bak  T. A.  Sobolev  N. V. 《Doklady Earth Sciences》2017,477(2):1483-1487

Doklady Earth Sciences - Synthesis of hydrocarbons by the interaction of a CO2 fluid with hydrogen mantle domains has been simulated in an experiment at 7.8 GPa and 1350°C. The synthesized...  相似文献   

Multiharmonic model of seismic activity in Kamchatka     

G. A. Sobolev  S. G. Valeev  V. A. Faskhutdinova 《Izvestiya Physics of the Solid Earth》2010,46(12):1019-1034

Based on the uniform catalogue of earthquakes of the minimum energy class 8.5 for 1962–2008, multiharmonic models of seismic activity in Kamchatka are developed. The main harmonic components with periods from a few days to 12 years are identified. Both the entire catalogue and its modified versions obtained by the elimination of aftershocks and clusters, as well as nonoverlapping time series were used to study the stability of the models. The forward-prediction testing showed that in the models with weekly averaged initial data, periods of increased and reduced seismic activity lasting for several weeks are predicted with high confidence on an interval of up to 1.8% of the education period. This testifies for the presence of deterministic components in the seismic activity.  相似文献