Late Cretaceous-Paleogene Palynostratigraphy from the Arkhara-Boguchan Brown Coal Mine of Zeya-Bureya Depression, Russia

1IntroductionThe Arkhara-Boguchan brown coal mine is lo-cated in the western Arkhara depression,southeast-ern part of the Zea-Bureya Basin (Fig.1). Late Creta-ceous-Paleogene coal-bearing strata are well out-cropped at the Arkhara-Boguchan quarry. It contains four coal-bearing beds (in descending order): “Ve-likan”, “Promezhutochny”,“Dvoinoy”and “Nyzhny”, and composed of three sedimentary cycles (Fig.2). The lower cycle can be divided into two sub-cycles:the lowest sub-cycle is …     

Model estimates for the mean gas exchange between the ocean and the atmosphere under the conditions of the present-day climate and its changes expected in the 21st century

Annual mean fluxes of CO₂ and oxygen across the sea surface are estimated with the use of numerical modeling for several regions located in the Gulf Stream and Kuroshio zones. The present-day climatic conditions and the climatic conditions expected in the middle and at the end of the 21st century are considered. Specific features of gas exchange under a strong wind that are associated with gas exchange by bubbles and with changes in the air-water difference of the gas concentrations were taken into account in the calculations. The estimates obtained differ substantially from the results based on the traditional approach, which disregards the above features. A considerable increase in the absorption of CO₂ by the ocean, which is mainly caused by the continuing increase in the CO₂ concentration in the air during its small changes in the ocean, is expected in the 21st century. At the same time, no trends are revealed in the annual mean fluxes of oxygen across the ocean surface. The conclusion is made that, in calculations of CO₂ absorption by the world ocean, it is necessary to take into account both specific features of gas transfer under a strong wind and an increase in the atmospheric concentration of CO₂.     

Study of the seawater transparency field in the Crimea-Caucasus shelf area

This paper discussesin situ observational data on the directed light attenuation index in the near-surface layer, collected in September 1987. The absolute light attenuation index has been evaluated for a near-shore strip of water 10–15 miles in width. When multidisciplinary research is conducted in the open sea, this part of the sea surface remains unstudied, as the observational grid for it is made larger than the spatial-temporal parameters of the biophysical processes producing optical inhomogeneities.Translated by Vladimir A. Puchkin.     

In-bearing potential of tin‒sulfide mineralization in ore deposits of the Russian Far East

The increased demand for indium has made it necessary to revise prospects of In-bearing tin ore deposits in the Russian Far East on the basis of geological data and results of recent analytical methods (X-ray fluorescence with synchrotron radiation, atomic absorption, and ICP-MS). The average In contents in ores of the Tigrinoe and Pravourmiiskoe deposits vary from 55 to 70 ppm, which allows tin ore deposits with Sn?sulfide mineralization to be considered as quite promising with respect to In production from ores of Russian deposits. By their estimated In reserves, the Tigrinoe and Pravourmiiskoe deposits may be attributed to large ore objects.     

Authigenic rhodochrosite from a gas hydrate-bearing structure in Lake Baikal

International Journal of Earth Sciences - Early diagenetic carbonates are rare in Lake Baikal. Siderite (Fe carbonate) concretions in the sediments were discovered only recently. Here, we discuss...     

Biogeochemical processes in the Chukchi Sea

Study of biogeochemical processes in water and sediments of the Chukchi Sea in August 2004 revealed atypical maximums of the concentration of biogenic elements (N, P, and Si) and the rate of microbial sulfate reduction in the surface layer (0–3 cm) of marine sediments. The C: N: P ratio in the organic matter (OM) of this layer does not fit the Redfield-Richards stoichiometric model. Specific features of biogeochemical processes in sea are likely related to the complex dynamics of water, high primary productivity (110–1400 mg C/(m² day)), low depth of basin (<50 m in 60% of the water area), reduced food chain due to low population of zooplankton, high density of zoobenthos (up to 4230 g m^?2), and high activity of microbial processes. Drastic decrease in the concentration of biogenic elements, iodine, total alkalinity (Alk), and population of microorganisms beneath the 0–3 cm layer testify to a large-scale OM decay at the water-seafloor barrier. Our original experimental data support the high annual rate of OM mineralization at the bottom of the Chukchi Sea.     

Land use changes in the environs of Moscow

This paper focuses on several aspects of land use change in Russia during the 1990s with a particular focus on the environs of Moscow. These aspects include modes of farming, recreation, ownership of land, and concentric zones of outwardly declining land use intensity that resemble Von Thunen's economic landscape. These zones are given special attention. In contrast to other land use aspects, the analysis of which indeed reveals a fair amount of change bringing the environs of Russian cities one step closer to their Western counterparts, concentric agricultural land use patterns with outwardly declining productivity suggest continuity rather than change.     

Assessment of potential transport of pollutants into the Barents Sea via sea ice--an observational approach

The present estimates of ice drift in the Arctic include utilization of satellite imagery data (special sensor microwave/imager) and a reconstruction of air pressure for the period 1899-1998. A significant part of the sea ice in the Arctic Ocean has its origin in the Kara Sea and melts in the Greenland and the Barents Sea (BS). Consequently there may be a particular risk of pollutants in the Kara Sea entering the food webs of the Greenland and BS. The ice export from the Kara Sea between 1988 and 1994 was about 208,000 km2 (154 km3) per year. The import of ice into the BS was during the same period 161,000 km2 (183 km3) per year while the ice drift through the Fram Strait into the Greenland Sea was 583,000 km2 (1859 km3) per year. Ice which formed adjacent to the Ob and Yenisey rivers in early January, drifted into the BS within two years (with a probability of about 50%.     

Modern climate-related changes in heat supply,moistening, and productivity of the agrosphere in Russia

Climate changes observed in recent decades are analyzed, and the respective climate-related tendencies of changes in heat supply, moistening, and productivity of the agrosphere that determine the natural resourse of potential Russia are determined. The grain crop yield trends are used additionally as climate change indicators. It is shown that climate changes observed in the last 30 years promote the increase in potential agriculture productivity in most of the Russian Federation, where not less than 85% of agricultural products are produced. At the same time, the increase in climate aridity is observed in several regions of Siberia and Chernozem Center, which results in a reduced productivity of agriculture.     

The earthquake of March 4, 1977, its recording peculiarities and source parameters

A detailed analysis of recording peculiarities at seismic stations of the Uniform System of Seismic Observations (USSO) is presented a complicated nature of the source being shown. Consideration is given to parameters of the earthquake source, including the seismic moment and the length of the rupture.Comparison of magnitudes M_LH and M_PV indicates an anomalous attenuation in surface waves, itis is 3–4 times weaker than it had been noticed in case of other intermediate-depth Carpathian earthquakes.On the basis of comparison of the logarithm of the ratio of P-wave spectra at different epicentral distances (30° –70° ), the fac tor characterizing the absorption of P wave is found to remain practically unchanged.Average value of the seismic moment is estimated to be 2.6 × 10²⁷ dyne × cm, the most reasonable length of the rupture 58 km, and its focus 100 –130 km. The source parameters of the earthquake in question are compared with those of the earthquake of November 10, 1940.