Fission–track Ages and Magnetic Susceptibility of Cretaceous to Paleogene Volcanic Rocks in Southeastern Sikhote Alin, Far East Russia     

Takaaki MaTSUDA  Tohru SAKIYAMA  Ryo ENAMI  Yo–ichiro OTOFUJI  Vladimir G. SAKHNO  Anatoly P. MATUNIN  Ruslan G. KULINICH  Petr S. ZIMIN 《Resource Geology》1998,48(4):285-290

Abstract: Seven zircon fission-track ages and 30 magnetic susceptibilities were measured on welded pyroclastic rocks from the Bogopol and Sijanov Groups of the Cretaceous to Paleogene volcanic rocks in the southeastern part of the eastern Sikhote Alin volcano-plutonic belt, Far East Russia. The fission-track ages range from 42. 7 Ma to 64. O Ma which indicate that both the groups are of Early Paleogene time. Two thirds of the samples from the Bogopol Group have high magnetic susceptibility values, more than 3 A- 10^-3 SI unit, which imply that they are of the magnetite–series, whereas the samples from the Sijanov Group show 3 A- 10^-3 to 8 A- 10^-5 SI unit which suggest this group of probably the ilmenite-series.
The Paleogene age and high magnetic susceptibility of the Bogopol Group are quite similar to the Paleogene igneous rocks of the San'in belt, Southwest Japan. This suggests, taking accounts of the opening of the Japan Sea, that the eastern Sikhote Alin volcano-plutonic belt continued to the San'in Belt, and that the Paleogene igneous rocks along the Japan Sea coast of Northeast Japan were situated along the volcanic front of the eastern Sikhote Alin volcano-plutonic belt.  相似文献   

Sn, B and Pb-Zn Skarn, Vein and Disseminated Deposits in the East Sikhote–Alin, Russia     

Vladimir V. Ratkin  Anatoly N. Sokarev  Margarita D. Rysantseva 《Resource Geology》1998,48(1):7-11

Abstract: Sn, B and Pb-Zn skarn, vein and disseminated deposits occur in the eastern part of Sikhote-Alin fold system associated with the late Cretaceous-earliest Paleogene volcano-plutonic complexes, which are products of a continental margin-type subduction along the East Sikhote-Alin belt. There are two metallogenic zones where the ore deposits are concentrated. The Taukha metallogenic zone combining B and Pb-Zn skarn, vein and disseminated deposits occurs on the main volcanic chain along the Japan Sea coast. Late Cretaceous-earliest Paleogene calc-alkaline plutonic and volcanic rocks of magnetite series predominate here. Volcanic rocks overlie on the lower Cretaceous Taukha terrane which consists of abundant olistostromes with numerous olistoliths of Triassic limestones. During the middle-late Cretaceous time, an ignimbrite erupted and formed a huge borosilicate skarn deposit. A later subduction related volcanism of the late Cretaceous-earliest Paleogene stage (70–55 Ma) was predominated by andesites and rhyodacites. Many Pb-Zn skarn and vein deposits were formed. Sulfur isotope compositions of galena in the B and Pb-Zn deposits of the Taukha metallogenic zone vary from –1. 3 to +2. 0%, averaging 0% in the δ³⁴S.  相似文献   

Calcite and dolomite in intrusive carbonatites. I. Textural variations     

Anton R. Chakhmouradian  Ekaterina P. Reguir  Anatoly N. Zaitsev 《Mineralogy and Petrology》2016,110(2-3):333-360

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Biostratigraphy of the Upper Pleistocene (Upper Neopleistocene)–Holocene deposits of the Lemeza River valley of the Southern Urals region (Russia)     

Guzel Danukalova  Anatoly Yakovlev  Liliana Alimbekova  Tatyana Yakovleva  Evgenija Morozova  Andrey Eremeev  Pavel Kosintsev 《Quaternary International》2008,190(1):38

Numerous caves and terraces with late Late Pleistocene (Upper Neopleistocene according to the Russian stratigraphic scale)–Holocene deposits are located in the Lemeza River valley in the surroundings of the Atysh waterfall, the native reserve territory of the Bashkortostan Republic. Lemeza River runs in the southern part of the western slope of the Urals and belongs to the Belaya River valley system (Russian Federation). A summary of the biostratigraphical investigations between 1992 and 2007 in this area is given. Deposits of cave and fluvial origin are characterized in the framework of the regional stratigraphy. The results of mammalian investigations and radiocarbon dating provide the basis for the stratigraphical subdivision. Palynology, mollusca, fishes, amphibian and reptiles are used for the reconstruction the palaeoenvironments. The Southern Urals stratigraphic subdivisions are correlated with Western European (Weichselian-Holocene), Eastern European (Russia) (Leningrad–Ostashkov–Shuvalov) and Uralian (Nevyansk–Polar Urals–Gorbunovsky) stratigraphic schemes.  相似文献   

The late Pleistocene environment of the Eastern West Beringia based on the principal section at the Main River,Chukotka     

Svetlana A. Kuzmina  Andrei V. Sher  Mary E. Edwards  James Haile  Evgeny V. Yan  Anatoly V. Kotov  Eske Willerslev 《Quaternary Science Reviews》2011,30(17-18):2091-2106

Chukotka is a key region for understanding both Quaternary environmental history and transcontinental migrations of flora and fauna during the Pleistocene as it lies at the far eastern edge of Asia bordering the Bering Sea. The now submerged land bridge is the least understood region of Beringia yet the most critical to understanding migrations between the Old and New Worlds. The insect fauna of the Main River Ledovy Obryv (Ice Bluff) section, which is late Pleistocene in age (MIS 3-2), is markedly different from coeval faunas of areas further to the west, as it is characterized by very few thermophilous steppe elements. From the fauna we reconstruct a steppe-tundra environment and relatively cold conditions; the reconstructed environment was moister than that of typical steppe-tundra described from further west. The data from this locality, if typical of the Chukotka Peninsula as a whole, may indicate that a barrier associated with the environments of the land bridge restricted trans-Beringian migrations, particularly the more thermophilous and xeric-adapted elements of the Beringian biota, supporting the hypothesis of a cool but moist land-bridge filter inferred from evidence from several other studies.  相似文献   

How did the suspended sediment load change in the North Caucasus during the Anthropocene?     

Anatoly Tsyplenkov  Valentin Golosov  Pelagiya Belyakova 《水文研究》2021,35(10):e14403

Quantifying and understanding catchment sediment fluxes is crucial both from a scientific and environmental management perspective. To deepen the understanding of landuse impacts and climate change on sediment load, we explore factors controlling the suspended sediment load formation in the Northern Caucasus during the Anthropocene. We examine how sediment flux of various river basins with different land-use/landcover and glacier cover changes during the 1925–2018 period. Our analysis is based on observed mean annual suspended sediment discharges (SSD, kg s⁻¹) and annual fluxes (SSL, t year⁻¹) from 33 gauging stations of The Federal Service for Hydrometeorology and Environmental Monitoring (Russia). SSL series have been analysed to detect statistically significant changes during the 1925–2018 period. The occurrence of abrupt change points in SSD was investigated using cumulative sum (CUSUM) charts. We found that SSL has decreased by −1.17% per year on average at most gauges. However, the decline was not linear. Several transition years are expected in the region increasing trends from the 1950s and decreasing trends from 1988 to 1994. Correlation analyses showed that variation in SSL trend values is mainly explained by gauging station altitude, differences in landuse (i.e. the fraction of cropland), and catchment area. Nonetheless, more accurate quantifications of SSL trend values and more refined characterizations of the catchments regarding (historical) landuse, soil types/lithology, weather conditions, and topography may reveal other tendencies.  相似文献   

Implementation of the ground level enhancement alert software at NMDB database     

Helen Mavromichalaki  George Souvatzoglou  Christos Sarlanis  George Mariatos  Athanasios Papaioannou  Anatoly Belov  Eugenia Eroshenko  Victor Yanke 《New Astronomy》2010,15(8):744-748

The European Commission is supporting the real-time database for high-resolution neutron monitor measurements (NMDB) as an e-Infrastructures project in the Seventh Framework Programme in the Capacities section. The realization of the NMDB will provide the opportunity for several applications most of which will be implemented in real-time. An important application will be the establishment of an Alert signal when dangerous solar particle events are heading to the Earth, resulting into a ground level enhancement (GLE) registered by neutron monitors (NMs). The cosmic ray community has been occupied with the question of establishing such an Alert for many years and recently several groups succeeded in creating a proper algorithm capable of detecting space weather threats in an off-line mode. A lot of original work has been done to this direction and every group working in this field performed routine runs for all GLE cases, resulting into statistical analyses of GLE events. The next step was to make this algorithm as accurate as possible and most importantly, working in real-time. This was achieved when, during the last GLE observed so far, a real-time GLE Alert signal was produced. In this work, the steps of this procedure as well as the functionality of this algorithm for both the scientific community and users are being discussed. Nevertheless, the transition of the Alert algorithm to the NMDB is also being discussed.  相似文献   

The structure of voids     

Stefan Gottlöber  Ewa L. &#;okas  Anatoly Klypin  Yehuda Hoffman 《Monthly notices of the Royal Astronomical Society》2003,344(3):715-724

Presented here are high spatial and spectral resolution Chandra X-ray observations of the famous interacting galaxy pair, the Mice, a system similar to, though less evolved than, the well-known Antennae galaxies. Previously unpublished ROSAT High Resolution Imager data of the system are also presented.
Starburst-driven galactic winds outflowing along the minor axis of both galaxies (but particularly the northern one) are observed, and spectral and spatial properties, and energetics are presented. That such a phenomenon can occur in such a rapidly evolving and turbulent system is surprising, and this is the first time that the very beginning – the onset, of starburst-driven hot gaseous outflow in a full-blown disc–disc merger has been seen.
Point-source emission is seen at the galaxy nuclei, and within the interaction-induced tidal tails. Further point-source emission is associated with the galactic bar in the southern system. A comparison of the source X-ray luminosity function and of the diffuse emission properties is made with the Antennae and other galaxies, and evidence of a more rapid evolution of the source population than the diffuse component is found. No evidence for variability is found between the Chandra and previous observations.  相似文献   

Phase-space structure of dark matter haloes: scale-invariant probability density function driven by substructure     

Itai Arad  Avishai Dekel  Anatoly Klypin 《Monthly notices of the Royal Astronomical Society》2004,353(1):15-29

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Neoproterozoic Alkaline Igneous Rocks,Carbonatites and Gold Deposits of the Yenisei Ridge,Central Siberia: Evidence of Mantle Plume Activity and Late Collision Shear Tectonics Associated with Orogenic Gold Mineralization     

Igor GERTNER  Platon TISHIN  Vassily VRUBLEVSKII  Anatoly SAZONOV  Elena ZVYAGINA  Yuriy KOLMAKOV 《Resource Geology》2011,61(4):316-343

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.  相似文献