Physicochemical peculiarities of absorbed oil in core samples of gas condensate deposit

The problem of the composition of absorption hydrocarbons and liquid condensate arises in the study of gas condensate reservoirs. From the examples of the gas condensate part of the Karachaganak, Astrakhan, and Yamburg deposits, it is shown that absorption hydrocarbons (absorption oil) contain polar components with S and O atoms in molecules. The differences in the physicochemical properties of absorbed oil and precipitated liquid condensate are revealed, as are the regularities in the composition and properties of the absorbed oil and condensate. The criteria for division of absorption oil and liquid condensate are given.     

Smectite-bearing clays of the Middle Eocene Kievskaya Formation in the Russian Plate and their genesis

The component composition and specific features of the structure of smectite-bearing clays in the Middle Eocene Kievskaya Formation of the Russian Plate were studied by the scanning electron microscopic, X-ray phase analysis, and complete chemical analysis methods. The clays are characterized by metastable (unstable) state of material expressed as abundance of the semidissolved clasts of felsic volcanic ashes and radiolarian skeletons, as well as colloidal segregations of siliceous, aluminosiliceous (Al-Si) and ferroaluminosiliceous (Fe-Al-Si) gel-type materials and newly formed smectite. Three stages of the diagenetic alteration of Middle Eocene dacite ashes are identified. Mechanism of the further transformation of rocks into smectite clays with siliceous nodules is proposed. The viewpoint suggesting the volcanosedimentary origin of clays of the Kievskaya Formation is confirmed. Sources of the pyroclastic material (suppliers of material for clays) in the Kievskaya Formation could be related to active explosions in the Caucasian volcanic arc in the Middle Eocene.     

Structure and metamorphism of the Antarctic Shield

The information on the composition, structure, P-T conditions of metamorphic facies, evolution, and time of the metamorphic events in the largest Precambrian tectonic provinces of the Antarctic Crystalline Shield gained over more than a half-century is summarized in this paper. The joining up of the ortho- and paracrystalline rocks into complexes and groups according to their geographic position, composition, age, and the character of their metamorphism allowed us to consider the main features of the structure and evolution of the provinces including (1) the near-latitudinal polycyclic Late Precambrian-Early Paleozoic Wegener-Mawson Mobile Belt, extended for more than 4000 km, which started to evolve in the Mesoproterozoic and stabilized only at the end of Cambrian; (2) the Early Precambrian relict crystalline protocratonic blocks adjoining this mobile belt; their history is traced from the Eoarchean; and (3) the near-latitudinal Late Precambrian-Early Paleozoic aulacogen in the southern protocratonic block. The P-T conditions of the metamorphism from the pyroxene-granulite subfacies in the protocratonic blocks to the greenschist facies in aulacogen, as well as the age of the magmatic and metamorphic events in all the tectonic provinces of the shield, are characterized. This made it possible to consider the metamorphic history and conditions of the continental crust’s formation in Antarctica, where the oldest crystalline rocks are dated to the Eoarchean (4060–3850 Ma) and the youngest rocks are ～500 Ma old.     

Optical spectra and redshifts of radio sources from the Zelenchuk survey

We performed spectroscopic observations of 22 radio sources from the Zelenchuk survey (Sternberg Astronomical Institute) using the 6-m and 1-m Special Astrophysical Observatory telescopes. For 18 objects, we determined the redshifts. Ten, seven, and one of these objects were identified with quasars, elliptical galaxies, and a Seyfert galaxy, respectively. Four radio sources have a continuum spectrum, and three of them are BL Lac objects. We failed to classify one object.     

Investigation of the radio emission from active galactic nuclei: Determining the spin of a supermassive black hole

The results of radio observations for ten kinetically dominated quasars are presented. The observations have been performed at 3.5 cm with the RTF-32 radio telescopes at the Zelenchukskaya and Badary observatories of the Institute of Applied Astronomy of the Russian Academy of Sciences. The kinetic power of the relativistic jets and the spins of the supermassive black holes in these objects have been determined from radio luminosity measurements. The rotation of the black hole in these objects is shown to be retrograde with respect to the Keplerian rotation in the accretion disk in the case of an approximate equality between the magnetic and gas pressures near the black hole event horizon.     

Intraday variability of three flat-spectrum radio sources

Searches for intraday variability in the flat-spectrum radio sources J0527+0331, J0721+0406, and J1728+0427 have been carried out at 3.5 cm using the 32-m radio telescope of the Zelenchuk Observatory of the Kvazar-KVO complex of the Institute of Applied Astronomy of the Russian Academy of Sciences (located near the Zelenchuk Village, Karachaevo-Cherkesskaya Republic). Intraday variabiility with characteristic time scales from one to five hours was detected in all three sources.     

Lineament fabric from airborne LiDAR and its influence on triggered earthquakes in the Koyna-Warna region,western India

We present the results of the first airborne LiDAR survey flown in the Koyna-Warna region and examine the relationship between the lineament fabric and the ongoing seismicity in the region. Our studies reveal that earthquakes of M≥4.0 for the period 1968 to 2016 are strongly correlated with a 10 km wide N-S fracture zone, which not only represents the surface expression of seismically active basement faults, but also act as conduits for water percolation between the Koyna and Warna reservoirs. A decreasing trend in the annual distribution of earthquakes was observed from 1985. A new burst of seismic activity in 1993 followed the impoudment of the Warna reservoir. We report a change in annual seismicity pattern, where seismicity peaks during September and December in the pre-Warna period, with a new peak emerging during March-April subsequent to the impoundment of Warna reservoir. A model is proposed to explain the seismicity along dominant N-S lineaments and the impact of Warna reservoir impounding which altered the hydrogeologic regime in the region.     

A dynamo in a torus as an explanation of magnetic fields in the outer rings of galaxies

It is currently generally believed that magnetic fields in the disks of spiral galaxies are generated by the dynamo mechanism, which is based on the joint action of differential rotation and the alpha effect, associated with turbulent motions in the interstellar gas. Together with their disks, outer rings are also encountered in galaxies, where magnetic fields may be present. In earlier studies, the generation of magnetic fields has been described in a planar approximation, whose essence is that the size of rings perpendicular to the plane of the galaxy is much smaller than their size in the radial direction. However, it is plausible that these sizesmay sometimes be comparable, so that it would be more logical to suppose that a ring has a toroidal form. A model for a dynamo in a toroidal ring is constructed in this study. This model describes the magnetic field using two functions, corresponding to the toroidal component of the field and the part of the vector potential characterizing its poloidal component. The possible generation of magnetic field in various cases is shown, with both quadrupolar symmetry (close to the fields obtained in the planar approximation) and dipolar symmetry (when two layers with oppositely directed magnetic fields form in the ring). The parameter values for which the generation of fields with one or the other type of symmetry is possible are estimated. The results can also be used to describe the evolution of the magnetic fields in other toroidal astrophysical objects.     

Hydrological and morphological processes at the Zhujiang River mouth area, China

Hydrological and morphological processes in the Zhujiang River (Pearl River) mouth area of China are discussed. The hydrological regime of the Xijiang River, which is the largest river of South China and the main source of water inflow into the Zhujiang mouth area, is described. The basic features of the hydrological regime of the delta and the near-shore zone of the Zhujiang River mouth are characterized, much attention being given to the role of tides and mixing of river and sea water in the hydrological regime. Special emphasis is placed on morphodynamic processes at the mouth area and the history of the Zhujiang Delta evolution.     

Some aspects of interpretation of tensor gradiometry data

Aspects of the interpretation of measured data on the gravity gradient tensor (GGT) are examined. The problem is posed in relation to the great progress achieved in recent years in the development of instrumentation and the method of GGT measurements on mobile carriers. In our opinion, the new methods of measurement and the new data obtained with their help require the development of new methods of interpretation of potential fields. The paper addresses two methods taking advantage of simultaneous measurements of all components of the GGT and anomalies of the gravitaty field V _z. It is shown that the joint analysis of all GGT components can provide independent constraints on the noise level in various components. The method of tensor deconvolution proposed in the paper is a tensor analogue of the Euler method. The method is based on the calculation of invariants and is, therefore, stable with respect to the orientation uncertainties of the measuring system. The method provides means for estimating the structural index and, therefore, is particularly effective in the treatment of fields that contain isometric and/or elongated anomalies. The calculation of invariants and the tensor ratio can also be used for the development of procedures enabling automatic estimation of the axis strike azimuths of elongated anomaly-forming bodies.