Sources of Eocene Magmatism in Western Kamchatka by the Geochemical and Sr–Nd–Pb Isotope Characteristics of Basites

Doklady Earth Sciences - The isotope and geochemical characteristics of Eocene–Oligocene igneous rocks of Western Kamchatka were studied. It was shown that igneous rocks of the Eocene Kinkil...     

Vertical structure of currents in the upper part of the continental slope of the Black Sea in the Region of Gelendzhik

The results of a joint analysis of the synchronous-profile ensemble of density and current velocity measured using the autonomous moored Aqualog profiler at the Gelendzhik experimental site of the Shirshov Institute of Oceanology in 2013–2015 are presented. The distribution of probability density of current velocity by directions reveals the presence of two well-pronounced maxima in the southeastern and northwestern sectors at all depths of measurements, which confirms the bimodal direction of the currents in the study site. We consider in detail the vertical structure of the density stratification and the current velocity corresponding to the modes determined from the maximum of the probability density distribution of the current velocity by directions. The averaged profiles of the kinetic, potential, and total energies are given. The results of isopycnic averaging over the entire ensemble of profiles indicate that possible self-similarity exists in the dependence of the vertical distribution of density and kinetic energy.     

The western part of the West Siberian petroleum megabasin: geologic history and structure of the basement

On the basis of complex research into the western part of the West Siberian Plate, a new scheme of the structure-formation zones of its basement has been developed and a new geological map of its pre-Jurassic basement has been compiled. Ophiolites and other mafic-ultramafic complexes (fragments of the oceanic Earth's crust) were studied. The most complete Late Ordovician ophiolite complex comprising a melange of serpentinites, gabbroids, plagiogranites, and basalt with jasper interbeds lies in the Shaim area. Weakly altered spinel lherzolites were also examined there. The research has revealed not only Ordovician but also Devonian basalts as well as gabbroid complexes (392 Ma, Sm-Nd dating). The Paleozoic geodynamic history of the region was terminated with collision, which was accompanied by tectonic piling and the intrusion of granite plutons, metamorphism, and formation of new continental crust. These crucial events, which consolidated Paleozoic complexes throughout the vast area of the future West Siberian megabasin, date from the Early Permian. The composition, age, and nature of granitoid plutons in western West Siberia were studied, and isochrons and isotope characteristics were obtained, which give an insight into both the genesis and age of granite plutons and their subsequent transformations.     

On surface seismic waves formation

Summary The interpretation of surface seismic waves records is rather complicated as they include a superposition of oscillations of the fundamental mode and higher modes. Besides recorded oscillations depend on spectral characteristics of motions in earthquakes sources. The consideration of these problems is based on results of surface waves two-dimensional modelling [1]³. Some physical ideas about their formation deals with the change of the nature of the oscillation propagating with dispersion. This report represents a condensate of several independent works. , , . , . , . () . .Scientific communication presented to the IASPEI Assembly, Madrid, 1969.     

Stoneley waves in the Biot–Johnson and continuum filtration theories

The paper concerns with mathematical modeling of two-velocity media with reference to data on Stoneley wave propagation at the fluid-porous solid interface from experiments by K.W. Winkler, H.L. Liu, and D.J. Johnson. Models obtained within the limits of two theories, that of Biot (Biot–Johnson) and continuum filtration, are investigated in comparison. On this basis, it is discussed whether it is reasonable to include pore tortuosity and frequency-dependent permeability and tortuosity when modeling the mechanics of deforming fluid-saturated porous solids.     

Observations of magnetic anomaly signatures in Mars Express ASPERA-3 ELS data

Mars Express (MEX) Analyser of Space Plasmas and Energetic Atoms (ASPERA-3) data is providing insights into atmospheric loss on Mars via the solar wind interaction. This process is influenced by both the interplanetary magnetic field (IMF) in the solar wind and by the magnetic ‘anomaly’ regions of the martian crust. We analyse observations from the ASPERA-3 Electron Spectrometer near to such crustal anomalies. We find that the electrons near remanent magnetic fields either increase in flux to form intensified signatures or significantly reduce in flux to form plasma voids. We suggest that cusps intervening neighbouring magnetic anomalies may provide a location for enhanced escape of planetary plasma. Initial statistical analysis shows that intensified signatures are mainly a dayside phenomenon whereas voids are a feature of the night hemisphere.     

Regularities in the transformation of oil pollution in watercourses based on long-term observational data

Results of long-term studies of crude oil transformations in water and bottom sediments of river ecosystems polluted as a result of oil spills are presented. Regularities in changes in the concentration ratio of hydrocarbon and resinous components of oil in water and bottom sediments under the effect of natural selfpurification processes of aquatic ecosystems are found out.     

First ENA observations at Mars: Subsolar ENA jet

The Neutral Particle Detector (NPD), an Energetic Neutral Atom (ENA) sensor of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) on board Mars Express, detected intense fluxes of ENAs emitted from the subsolar region of Mars. The typical ENA fluxes are (4-7) × 10⁵ cm⁻² sr⁻¹ s⁻¹ in the energy range 0.3-3 keV. These ENAs are likely to be generated in the subsolar region of the martian exosphere. As the satellite moved away from Mars, the ENA flux decreased while the field of view of the NPD pointed toward the subsolar region. These decreases occurred very quickly with a time scale of a few tens of seconds in two thirds of the orbits. Such a behavior can be explained by the spacecraft crossing a spatially constrained ENA jet, i.e., a highly directional ENA emission from a compact region of the subsolar exosphere. This ENA jet is highly possible to be emitted conically from the subsolar region. Such directional ENAs can result from the anisotropic solar wind flow around the subsolar region, but this can not be explained in the frame of MHD models.     

Cosmic-ray propagation in inhomogeneous large-scale magnetic fields: A pitch-angle diffusion and convection

The CIV and SiIV resonance doublets of 43 Be stars are investigated. Measurements of the equivalent widths seem to reveal a correlation between the strenght of the lines and the projected rotational velocity (v sini). it is discussed whether this result indicate that the wind region is not spherically symmetric.     

Turbulent exchange over a surface with chessboard-type inhomogeneities

The results of an experiment carried out in the summer of 1988 in the forest-steppe region of the USSR are given. The aim of the experiment was to study turbulent exchange between the atmosphere and a non-homogeneous underlying surface consisting of a patchwork quilt of agricultural lands sown with different crops (hereafter called chessboard-type inhomogeneities). Simultaneous measurements of turbulent fluxes of heat, momentum and humidity by the eddy-correlation methods and also the measurements of the mean wind velocity and temperature are described. The values of turbulent fluxes calculated from the profile measurements are in good agreement with those obtained from the eddy-correlation measurements. Thus it may be concluded that the universal functions of Monin-Obukhov similarity theory (determined from measurements over a flat and homogeneous underlying surface) pertain also to a non-homogeneous (chessboard-type) underlying surface.