Hydrodynamical simulations of the stream–core interaction in the slow merger of massive stars     

N. Ivanova  Ph. Podsiadlowski  H. Spruit 《Monthly notices of the Royal Astronomical Society》2002,334(4):819-832

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Structural Position and Typification of Alteration Zones,Polar Urals: First Experience of Modern Space Sensing of the Earth     

Vikentyev  I. V.  Ivanova  Yu. N.  Nafigin  I. O.  Bortnikov  N. S. 《Doklady Earth Sciences》2021,500(2):803-808

Doklady Earth Sciences - A new approach to statistical analysis of the data from the Landsat 8 spacecraft was developed for the first time for the territory of the Urals on the basis of the method...  相似文献   

A photometric and dynamic study of comet C/2013 A1 (Siding Spring) from observations at a heliocentric distance of ~4.1 AU     

Yu. S. Andrienko  A. V. Golovin  A. V. Ivanova  V. N. Reshetnik  S. N. Kolesnik  S. A. Borisenko 《Solar System Research》2016,50(2):102-112

An analysis is presented for the photometric data on comet C/2013 A1 (Siding Spring) from observations at a large heliocentric distance (~4.1 AU). Comet C/2013 A1 (Siding Spring) displays intense activity despite the relatively large heliocentric distance. The morphology of the comet’s coma is analyzed. The following parameters are measured: the color indices V-R, the normalized spectral gradient of the reflectivity of the comet’s dust S', and the dust production rate Afρ. A numerical simulation is performed for the evolution of the comet’s orbit after a close encounter with Mars. The most probable values are obtained for the Keplerian orbital elements of the comet over a hundred-year period. The comet’s orbit remains nearly parabolic after passing the orbits of all the Solar System planets.  相似文献   

First U-Pb age of detrital zircons from sandstones of the Upper Emsian Takaty formation of the Western Urals with regard to the problem of primary sources of the Uralian diamond placers     

N. B. Kuznetsov  T. V. Romanyuk  A. V. Shatsillo  S. Yu. Orlov  V. M. Gorozhanin  E. N. Gorozhanina  E. S. Seregina  N. S. Ivanova  J. Meert 《Doklady Earth Sciences》2014,455(2):370-375

Several alternative points of view currently exist on the origin of the primary sources of diamonds from the Cenozoic Western Urals placers. Some researchers suppose that their economic diamond resource potential is related to diamonds from tuffisitic facies of the mantle kimberlites-lamproites or impact structures. Other researchers suggest that diamonds originated from the eroded sandstones of the Upper Emsian Takaty Formation of the Lower Devonian, which represents ancient (fossil) placers or intermediate reservoirs. It is assumed that these reservoirs collected diamonds from worn kimberlite bodies, which were located in the Urals or on the East European platform (EEP). This paper presents the first U-Pb (LA-ICP-MS) age of detrital zircons from quartz sandstones of the Takaty Formation, which spans a range from 1857.5 ± 53.8 to 3054.0 ± 48.0 Ma. The absence of detrital zircons younger than 1.86 Ga excludes that the structural complexes of the Uralian, Fennoscandian, and Sarmatian EEP parts were the provenance areas that supplied the clastic material to the sedimentary basin, which accumulated the Takaty Formation. The similar age of our zircons and ancient crystalline complexes of the Volga-Uralian EEP part allows consideration that it was a single provenance area. If we assume that the diamond resource potential of the Western Urals is completely or partly related to the ancient diamond placers from the Takaty Formation, then the intermediate diamond reservoirs from its structure originated due to redeposition of destruction products of primary diamond-bearing rocks of the Volga-Uralia area. Thus, within the Volga-Uralian part of the EEP basement, we may expect identification of a previously unknown stage of kimberlite formation, which is significantly older than that responsible for the diamond resource potential of the Arkhangel’sk province.  相似文献   

Selenium-bearing goldfieldite and fischesserite AuAg3Se2-petzite AuAg3Te2 solid solutions in ores of the Ozernovskoe volcanogenic deposit (Kamchatka)     

E. M. Spiridonov  Yu. N. Ivanova  V. O. Yapaskurt 《Doklady Earth Sciences》2014,458(1):1139-1142

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Thermodynamic Evaluation of Mineral Balance in Water Thickness of the Soda Lake Doroninskoe(Eastern Transbaikalia,Russia)     

Svetlana V. BORZENKO  Leonid V. ZAMANA  Daria S. SUVOROVA 《《地质学报》英文版》2014,88(Z1):123-124

正In recent years,lakes,including salted,attract the attention of researchers,also when reconstructing last climate changes using the bottom sediments(Solotchina et al.,2008,et al.).In this case the different geochemical  相似文献   

Vulnerability of Bulgarian agriculture to drought and climate variability with focus on rainfed maize systems     

Z.?Popova  M.?Ivanova  D.?Martins  L.?S.?PereiraEmail author  K.?Doneva  V.?Alexandrov  M.?Kercheva 《Natural Hazards》2014,74(2):865-886

Bulgarian agriculture is affected by droughts and, likely, by climate change. Thus, aiming at assessing its vulnerability, this study includes a general characterization of climate variability in eight selected locations, both in northern and southern Bulgaria. Trend tests were applied to monthly precipitation, maximum and minimum temperature and to the Standardized Precipitation Index with two-month time step (SPI-2) relative to the period of 1951–2004. Negative trends were identified for precipitation and SPI-2 at various locations, mainly in the Thrace Plain, indicating that dryness is likely to be increasing in Bulgaria. The vulnerability of rainfed maize systems to drought was studied using the previously calibrated WinISAREG model and the Stewart’s yield model to compute both the relative yield decrease (RYD) due to water stress and the corresponding net irrigation required to overcome those losses. Results identified a strong relation between SPI-2 for July–August (SPI-2_July–Aug) and RYD. Results also show that yield losses are higher when the soils have a smaller soil water holding capacity. For the various regions under study, thresholds for RYD were defined considering the related economic impacts and the influence of soil characteristics on the vulnerability of the rainfed maize systems. Finally, to support drought risk management, SPI-2_July–Aug thresholds were developed to be used as indicators of the economic risk of rainfed maize for various climate regions and soil groups in Bulgaria.  相似文献   

Seasonal Dynamics of Algal Flora in the Stratified Kislo-Sladkoe Lake Partially Separated from the White Sea     

Ivanova  D. A.  Krasnova  E. D.  Voronov  D. A.  Radchenko  I. G. 《Oceanology》2022,62(2):207-220

Oceanology - The article presents data on the composition and abundance of algal flora in the coastal stratified Kislo-Sladkoe Lake (the Karelian coast of the White Sea) after its flushing with...  相似文献   

Ozone content over the Russian Federation in the third quarter of 2013     

A. M. Zvyagintsev  N. S. Ivanova  G. M. Kruchenitskii  I. N. Kuznetsova 《Russian Meteorology and Hydrology》2013,38(11):792-795

The review is compiled on the basis of the results of monitoring the total ozone (TO) in the CIS and Baltic countries that functions in the operational regime at the Central Aerological Observatory (CAO). The monitoring system uses the data from the national network with M-124 filter ozonometers under methodological supervision of the Main Geophysical Observatory. The quality of the functioning of the entire system is under operational control based on the observations obtained from the OMI satellite equipment (NASA, the United States). The basic TO observation data are generalized for each month of the first quarter of 2013 and for the quarter as a whole. The data on the development of the Antarctic spring ozone anomaly in August and September 2013 are presented as well as the results of regular observations of the surface ozone content carried out in Moscow region by GPBU Mosekomonitoring and CAO.  相似文献   

Experimental simulation of oxygen isotopic exchange in olivine and implication for the formation of metamorphosed carbonaceous chondrites     

Marina A. Ivanova  Cyril A. Lorenz  Ian A. Franchi  Andrei Y. Bychkov  Jeffrey E. Post 《Meteoritics & planetary science》2013,48(10):2059-2070

We have conducted hydration–dehydration experiments on terrestrial olivine to investigate the behavior of oxygen isotopic fractionation to test the hypothesis that multiple cycles of aqueous and thermal processing on a parent asteroid comprise a genetic relationship between CM2s and metamorphosed carbonaceous chondrites (MCCs). Two experiments were undertaken. In the first experiment, serpentine was obtained by hydrating terrestrial olivine (Fo_90.9) in the laboratory. During this experiment, olivine was reacted with isotopically heavy water (δ¹⁸O 21.5‰) at T = 300 °C,  = 300 bar, for 100 days. The oxygen isotopic composition of the experimental serpentine was enriched in ¹⁸O (by 10 ‰ in δ¹⁸O) due to exchange of oxygen isotopes between olivine and the ¹⁸O‐rich water. Dehydrated serpentine was then produced during laboratory heating experiment in vacuum, at T = 930 °C, for 1 h. The oxygen isotopic composition of the dehydrated serpentine was enriched in ¹⁸O by a further 7 ‰. The net result of the hydration–dehydration process was an enrichment of ¹⁸O in the final material by approximately 17‰. The new experimental results suggest that the oxygen isotopic compositions of MCCs of the Belgica‐like group, including Dhofar 225 and Dhofar 725, could be derived from those of typical CM2 chondrites via several cycles of hydration–dehydration caused by aqueous alteration and subsequent thermal metamorphism within their parent asteroids.  相似文献