Oil components in the mouth area of the Don R. and in the Sea of Azov: Results of many-year studies

The data given are the results of many-year studying the distribution of the concentrations of main oil components (hydrocarbons, surfactants, and asphaltene-tarry substances) in the water mass, vertically settling particulate matter, and bottom sediment cores taken from the section Lower Don-The Gulf of Taganrog-Russian sector of the Sea of Azov in summer and autumn periods in 2006–2011. Spatial and seasonal regularities in the distributions of the total concentration of oil components and the values of their ratios in water, as well as the spatial and annual features of their accumulation in bottom sediments have been established. Radiological methods have been used for layer-by-layer dating of bottom sediment cores and determine the thickness of the layer that had formed under the maximal anthropogenic impact on ecosystems. The presence of considerable amounts of hydrocarbons of modern biological origin has been revealed in all components of examined aquatic complexes.     

The effect of the radiation pressure on the orbital evolution of geosynchronous objects

The effect of the radiation pressure and Poynting-Robertson effect on the evolution of the orbits of geosynchronous satellites is studied, depending on their area to mass ratio. The qualitative changes of the orbital evolution caused by these disturbances are considered. The reflection coefficient of the satellite’s surface was assumed to be 1.44. In the vicinity of the stable point with the longitude of 75° the exit from the libration resonance mode was registered when the area to mass ratio value changed from 5.9 to 6.0 m²/kg; in the vicinity of the unstable point at 345° with the area to mass ratio of 1.4 it occurred at 1.5 m²/kg. Re-entry to Earth occurs at values of the area to mass ratio above 32.2 m²/kg, and hyperbolic exit from the low-Earth orbit occurs at values of the area to mass ratio over 5267 m²/kg. At high values of the area to mass ratio, slopes of initially equatorial orbits can reach 49°. It is shown that due to the Poynting-Robertson effect the secular decrease in the semimajor axis of orbit in libration resonance region is 3–4 orders of magnitude less than outside of it.     

Scenarios of nonlinear wave transformation in the coastal zone

On the basis of field experiments and numerical modeling, we show that coastal zones are classifiable according to manifestations of wind wave nonlinearity, which herein is recognized as periodic energy exchange between the first and second nonlinear wave harmonics depending on the average bottom slope and the Iribarren and Ursell numbers. The results offer a basis for developing vulnerability criteria for the coastal zone taking into account its nonlinear dynamics.     

The results of geochronological and isotope–geochemical study of zircons from tuff of the Sylvitsa Group (western slope of the Middle Urals): The origin of ash layers in Vendian rocks of the East European Platform

Doklady Earth Sciences - New LA-ICP-MS data on the U–Pb isotope age, Hf isotope characteristics, and concentrations of trace elements in zircons from volcanic tuff of the Upper Vendian...     

Refined δ<Superscript>13</Superscript>С trend of the Dal’nyaya Taiga series of the Ura uplift (Vendian,southern part of Middle Siberia)

New data were obtained on δ¹³С_carb and δ¹⁸O variations in the sequence of deposits of the Dal’nyaya Taiga series at the western and eastern flanks of the Ura anticline. The summary δ¹³С curve was plotted in view of the correlation of sequence–stratigraphic data of the basin analysis. A series of positive anomalies was found within the succession. Alternatives for global chemostratigraphic correlation of the Dal’nyaya Taiga series of the Ura uplift were considered.     

Statistical modeling of relative variations in the critical frequencies of the ionospheric F region

Relative variations in the critical frequency of the ionospheric F, region are considered as one of the main sources of information about the characteristics of plasma inhomogeneities in the region of the main ionization maximum and as a substantial factor responsible for the statistics of the decameter signal parameters on radio paths with different lengths. The functions defined on finite intervals are also used in statistical modeling in addition to the available methods. Such a consideration made it possible to remove a restriction, peculiar to previous models, in the form of the requirement that the fourth statistical invariant—excess— should be positive. This makes the generalized statistical model more universal, which is of special importance for high4atitude radio paths. The specified mo del more adequately corresponds to the experimental data, which are characterized by finite intervals where the quantities are measured.     

New data on mineral composition of noble metal mineralization of the stoilo iron ore deposit of KMA,Central Russia

Doklady Earth Sciences -     

A REMOTE SENSING METHOD FOR DETERMINING HEAT FLUX AT THE OCEAN-ATMOSPHERE BOUNDARY LAYER

Results of experiments in the measurement of heat flux at the ocean-atmosphere boundary layer are described. More specifically, an algorithm is presented for the calculation of the different components of total heat flux (from the ocean into the atmosphere) based on estimates of water temperature, wind velocity, and cloud cover obtained from remote sensing imagery. Use of the algorithm yields values for total heat flux which, when averaged over a ten-day period, are only 10% less accurate than those obtained according to traditional methods (research vessels, buoys, offshore platforms). Translated from: Izvestiya vysshykh uchebnykh zavedeniy, Geodezlya i aerofotos”yemka, 1986, No. 5, pp. 117-120.     

U-Pb age and Sr isotope signature of cap limestones from the Neoproterozoic Tsagaan Oloom Formation, Dzabkhan River Basin, Western Mongolia

The U-Pb and Pb-Pb methods were used for determining age of cap limestones from the Neoproterozoic Tsagaan Oloom Formation corresponding to the lower part of the sedimentary cover in the Dzabkahn microcontinent of Central Asia. The weighted average age value appeared to be equal to 632 ± 14 Ma (MSWD = 0.11, probability 0.74). This value allows the following assumptions: (1) the lower boundary of the Tsagaan Oloom Formation corresponds to the beginning of the Ediacaran; (2) Dzabkhan tillites are correlative with glacial sediments of the Marinoan Epoch. The low ²³⁸U/²⁰⁴Pb and ²³²Th/²³⁸U ratios observed in initial Pb sources of limestones from the Tsagaan Oloom Formation indicate that the Dzabkhan paleobasin received at its early development stages a bulk of material from eroded upper Riphean juvenile rocks. The ⁸⁷Sr/⁸⁶Sr ratio in fractions of Tsagaan Oloom limestones enriched with primary carbonate material and satisfying geochemical criteria of Rb-Sr systems retentivity (Mn/Sr < 0.20 and Fe/Sr < 1) varies from 0.70676 to 0.70691 and reflects this ratio in the World Ocean approximately 630 Ma ago.