Genesis of brines in the basement of the Western Siberian Artesian Basin based on the use of genetic coefficients

This work discusses the possible ways that the chemical composition of the waters in the crystalline basement within several southeastern areas of West Siberia may be formed. Based on an analysis of the ratios of the principal components of solutions (genetic factors), the conclusion is made that some peculiarities of brines contained in the basement cannot be explained from the standpoint of their sedimentogenic-infiltration genesis. Some of the chloride-calcium solutions, as well as hydrocarbonate-sodium waters, probably formed as a result of the supply of endogenous fluids with HCl and CO₂ into the crystalline rocks of the basement.     

Kinematic properties of the Galactic thick disk from data from the RAVE DR4 catalog

The analysis of the kinematic properties of the Galactic thick disk based on data from modern catalogs of stellar radial velocities and proper motions is presented. A new aspect of new determination of the kinematic characteristics of the thick disk is that the selected objects define this disk’s properties near the plane of symmetry. The velocity dispersion of stars in the Galactic thick disk in the radial direction and the direction of the Galactic rotation have been determined. The stellar-velocity distribution in the direction of the rotation is asymmetric. The parameters of this asymmetry have been determined, and the lag of the rotational velocity of the thick disk relative to objects in the thin disk estimated. The value of this “asymmetric drift,” about 20 km/s, suggests larger spatial scales for the kinematic characteristics in the radial direction for the Galactic thick disk than for the thin disk.     

The role of vertical migration of high-temperature fluids in the genesis of formation waters in oil-gas fields in the north of the Western Siberian basin

All northern areas of Western Siberia exhibit a discontinuity in the normal vertical hydrochemical zoning and formation of an inversion hydrochemcial profile characterized by total mineralization of formation waters that decrease with depth and by the discovery of waters with mineralization levels of 1–7 g/L and less, as well as a simultaneous “inconsistent” change in the chemical composition of formation waters with Cl-Na-Ca to HCO₃-Cl-Na deeper than 2–3 km and simultaneous “irregular’ change in the chemical composition of formation waters with Cl-Na-Ca to HCO₃-Cl-Na. Based on the use of the B/Br ratio and a Na-K geothermometer, a conclusion is made that the formation of slightly (<5 g/L) mineralized hydrocarbonate-sodium waters is caused by seepage of a considerable amount of deep high-temperature (>150°C) fluids saturated with CO₂ into water-bearing rocks. This indicates the formation of deposits of hydrocarbons that are found in the regions of inversion waters as result of the upward vertical, but not lateral formation migration of a water-oil mixture.     

Chemical Composition of Globular Clusters of Milky Way Subsystems from Gaia DR2 Data

Results of a study of the kinematic and chemical properties of globular clusters of the Milky Way based on data from the Gaia DR2 catalog and meaurements with the Hubble Space Telescope are presented. A new method for dividing globular clusters into Galatic subsystems based on the elements of their Galactic orbits is proposed. Samples of globular clusters belonging to the bar/bulge, thick disk, and halo of the Milky Way are obtained. The mean metallicities of the globular clusters in various subsystems are calculated. The mean metallicities of globular clusters of the thick disk and halo display statistically significant differences. At the same time, no statistically significant differences are present between the mean metallicities of halo globular clusters moving in the direction of rotation of the Galactic disk and those moving in the retrograde direction. This argues against the suggestion that retrograde and prograde globular clusters have different origins.