Characteristic features of the occurrence of gas-fluid emanations on the northeastern slope of Sakhalin Island, Sea of Okhotsk

This paper summarizes the results of combined studies in the areas of the occurrence of gas-fluid emanations in the water column, on the seafloor, and in the upper part of the sedimentary section on the northeastern slope of Sakhalin Island (Sea of Okhotsk). The phenomena typical of methane seeps were characterized in detail: the presence of acoustic anomalies, high concentrations of methane in the water and sediments, and the specific features of the sedimentary section (the textural and structural features, the character of the mineral inclusions and gas hydrates, and the chemical composition). The component composition of the gases (including the accompanying gas hydrates), which is almost free of heavy hydrocarbon homologues of methane; the light carbon isotopic compositions of the methane and carbonate concretions; and the low temperatures of the near-bottom water and sediments suggest that the occurrence of numerous methane emanations is related to gas generation in the upper part of the sedimentary sequence. No evidence was found for the existence of a deep center of gas formation within the seafloor area considered. Typical submarine mud volcanic edifices were also not found.     

Strontium distribution patterns in groundwater and aquifer host rocks in the southeastern part of the Severnaya Dvina artesian basin

This study provides new data on the strontium distribution and behavior in groundwater from the Permian aquifer system, which is used for public water supply in the Velsk region of Arkhangelsk District. We used data from recent sampling of groundwater and host rocks as well as data from previous studies over the last 25 years. Measurements of exchangeable cations obtained in this study will be used in the further thermodynamic calculations and experimental observations.     

Out of Africa: detrital zircon provenance of central Madagascar and Neoproterozoic terrane transfer across the Mozambique Ocean

The Neoproterozoic East African Orogen reflects closure of the Mozambique Ocean and collision of the Congo and Dharwar cratons. This palaeogeographical change and its environmental consequences are poorly understood, but new detrital zircon ages from Madagascar and published data from elsewhere provide evidence for multiple ocean basins and two-stage collision. We propose that central Madagascar rifted from the Congo Craton and crossed a Palaeomozambique Ocean to collide with the Dharwar Craton at c. 700 Ma, opening a Neomozambique Ocean in its wake. Closure of the Neomozambique Ocean at c. 600 Ma juxtaposed the Congo and Dharwar cratons and resulted in prolonged collisional orogenesis concluding at c. 500 Ma.     

The form of the asymptotic depth-limited wind-wave spectrum: Part III — Directional spreading

The directional spreading of both the wavenumber and frequency spectra of finite-depth wind generated waves at the asymptotic depth limit are examined. The analysis uses the Wavelet Directional Method, removing the need to assume a form for the dispersion relationship. The paper shows that both the wavenumber and frequency forms are narrowest at the spectral peak and broaden at wavenumbers (frequencies) both above and below the peak. The directional spreading of the wavenumber spectrum is bi-modal above the spectral peak. In contrast, the frequency spectrum is uni-modal. This difference is shown to be the result of energy in the wind direction being displaced from the linear dispersion shell. A full parametric relationship for the directional spreading of the wavenumber spectrum is developed. The analysis clearly shows that typical dispersion relationships are questionable at high frequencies and that such effects can be significant. This result supports greater attention being focussed on the routine recording of wavenumber spectra, rather than frequency spectra.     

Polystyrene spherules in the Bristol Channel

Small polystyrene beads are becoming a common component of the plankton in certain areas. They are derived from the effluents of polystyrene manufacturers.     

Mesozoic magnetic lineations in the Mozambique Basin

East-west-trending Mesozoic magnetic anomalies M2 through M22 have been identified in the northern Mozambique Basin. These anomalies are best matched by sea floor created at 50°S trending N120°E and spreading at a rate of around 1.5 cm/yr. The northward increase in age inferred from the identifications of these anomalies are compatible with observed decrease in the “reliable” heat flow values from 1.4 to 1.1 μcal/cm² s to the north in the basin. The anomalies terminate in the southern part of the Mozambique Channel against a magnetic quiet zone to the north. Both the Mozambique Basin anomalies and those recently observed off Antarctica are strong evidence in favour of a Gondwanaland reconstruction that places Dronning Maud Land against southern Mozambique, and a late Jurassic or older separation between Africa and Antarctica.     

Masses of the local group and of the M81 group estimated from distortions in the local velocity field

Based on high precision measurements of the distances to nearby galaxies with the Hubble telescope, we have determined the radii of the zero velocity spheres for the local group, R₀ = 0.96±0.03Mpc, and for the group of galaxies around M 81/M 82, 0.89±0.05Mpc. These yield estimates of M_T = (1.29±0.14)· 10¹² M_⊙ and (1.03±0.17)· 10¹² M_⊙, respectively, for the total masses of these groups. The R₀ method allows us to determine the mass ratios for the two brightest members in both groups, as well. By varying the position of the center of mass between the two principal members of a group to obtain minimal scatter in the galaxies on a Hubble diagram, we find mass ratios of 0.8:1.0 for our galaxy and Andromeda and 0.54:1.00 for the M82 and M81 galaxies, in good agreement with the observed ratios of the luminosities of these galaxies. __________ Translated from Astrofizika, Vol. 49, No. 1, pp. 5–22 (February 2006).     

Main Sources of 134Cs in the Barents and Kara Seas (1960–2020)

Doklady Earth Sciences - The role of the short-lived 134Cs radionuclide in the formation of the radioecological background in the marine environment of the Arctic is studied. This paper analyzes...     

Microbiological Processes in the Gor'kovskoe Reservoir

The abundance of various groups of bacteria and the rate of microbiological processes of organic decay and methane cycle in the water and soils of the Gor'kovskoe Reservoir are determined, and the ecological characterization of its river reach is presented. The autochthonous and allochthonous impact on the bacterial community of the reservoir was found to be tolerable; however, some restricted areas were revealed, where the ecosystem is strongly affected by domestic and industrial wastewater, and where the abundance and activity of anaerobic methane-producing and sulfate-reducing soil bacteria increase.