Том 72, № 5 (2017)

Semi-empirical and quantum chemical studies of Al atom energy in CaSiO₃ and MgSiO₃ with the perovskite-type structure at pressures and temperatures of the Earth’s mantle are reported. The phase diagram for CaSiO₃ is reproduced and refined. Probable mechanisms of Al incorporation in the structures studied are considered. According to the results of the calculations, Al is preferably incorporated into MgSiO₃, rather than into CaSiO₃. Evaluation of the isomorphic capacity of perovskite phases in relation to Al shows that the Al content in MgSiO₃ may reach 2.4 mol % at 120 GPa and 2400 K. CaSiO₃ cannot be a source of Al atoms in the Earth’s mantle.

A concept for the interpretation of the initial provenance signal in rocks of the Taratash block (in the Southern Urals) using the zircon isotope dating of the Archean and Early Proterozoic igneous and metamorphic rocks was substantiated and carried out. Based on 132 zircon-age datings with a discordance of as much as 10%, a probability-density diagram was compiled first to compare these age data with those of detrital zircons from Lower Riphean sandstones of the Ai Formation and, secondly, with the probability density of zircon ages in metamorphic rocks of the Aleksandrovsk block, which is located to the east. The similarity of the distributions was verified using the Kolmogorov–Smirnov test.

This paper reports the data on the uranium content in Dictyonema shale and phosphate rock in the Kaibolovo–Gostilitsy Area of the Baltic Basin (Leningrad Region). Specific features of the uranium ore in the studied area and stratigraphic rock sequence of the Early Ordovician Pakerort horizon are considered. A high uranium concentration in the Dictyonema shale layer has been determined, the correlation of uranium with other elements was defined, probable conditions of uranium ore genesis are described, and predicted uranium resources within the studied area are estimated.

The influence of temperature on rock samples of the Bazhenov Formation is shown. The samples underwent pyrolysis at 300–480°C, as well as in closed autoclaves in the presence of water under formation pressure. The temperature impact at 400°C resulted in a decrease in the S2 pyrolytic peak by 90–95% and almost complete formation of the generation potential of the rocks. Microtomographic studies of samples combined with raster electron microscopy revealed a correlation between the variable reservoir properties of the rocks. At 350°C, the rocks are characterized by a system of fractures; as a result of impacts, the porosity and permeability can increase from several to several tens of times. Our results will allow more precise modeling of the influence of tertiary processes on the rocks of the Bazhenov Formation in order to increase the final oil recovery of the bed.

The success of drilling oil and gas wells is largely determined by a high hydrocarbon content and reservoir permeability at the point of penetration. Microseismic emission and scattered reflection waves are used for the reliable study of these parameters. The Seismic Location of Emission Centers and Side-View Seismic Location technologies have been developed for the observation, selection, and positioning of waves in a geological environment, which significantly extend the range of problems that are solved during seismic exploration of hydrocarbon deposits. Examples of application of these technologies in the exploration and development of hydrocarbon deposits are described.

A structural–geomorphic analysis, including visual and computer interpretation of the topographic maps and satellite images, as well as statistical processing of the results of the interpretation, has been carried out to reveal an arch-block style of the recent dislocations in the central West Siberian Plate. The kinematics, formation environments, and character of the relationship with deep structures are determined for these dislocations. It is shown that the recent structure formed as a result of submeridional shortening.