The Features of the Transformation of Organic Matter of Precambrian Carboniferous Rocks of the Ukrainian Crystalline Shield

The main features of the transformation of organic matter (OM) in the greenschist, amphibolite, and granulite facies of metamorphism are considered based on the example of the Ukrainian crystal shield. The occurrence area and OM content in highly carbonaceous ancient rocks are characterized. The composition of primary sedimentary rocks and the processes of accumulation of biophile elements under the OM transformation are reconstructed.     

Diagnosis of the interaction of tropical cyclones

At present the mutual influence of tropical cyclones (TCs) has been investigated to a much lesser extent than the cyclones themselves. Most frequently, such investigations are restricted to the study of the influence of the interaction of two TCs on their motion. However, actually, the mutual influence of TCs is much more diverse. For example, each cyclone alters the state of the medium (in particular, decreases the heat store of the upper ocean layer), i.e., affects the subsequent cyclones. Under conditions of a limited energy resource of the medium, cyclones, existing simultaneously, “compete,” to a degree, with each other. These and other similar circumstances have made it practical to consider tropical cyclones and the environment as interdependent elements of a complex open system. This study considers two versions of nonlinear models describing the interaction of TCs with the upper ocean layer and with one another similarly to a number of well-known and verified models of synergetics (interaction of populations, dynamics of optical quantum generators). It is shown that the models reproduce some very important qualitative features of the evolution of TC intensity.     

Accuracy estimates for some global analytical models of the Earth’s main magnetic field on the basis of data on gradient magnetic surveys at stratospheric balloons

Two global analytical models of the main magnetic field of the Earth (MFE) have been used to determine their potential in deriving an anomalous MFE from balloon magnetic surveys conducted at altitudes of ～30 km. The daily mean spherical harmonic model (DMSHM) constructed from satellite data on the day of balloon magnetic surveys was analyzed. This model for the day of magnetic surveys was shown to be almost free of errors associated with secular variations and can be recommended for deriving an anomalous MFE. The error of the enhanced magnetic model (EMM) was estimated depending on the number of harmonics used in the model. The model limited by the first 13 harmonics was shown to be able to lead to errors in the main MFE of around 15 nT. The EMM developed to n = m = 720 and constructed on the basis of satellite and ground-based magnetic data fails to adequately simulate the anomalous MFE at altitudes of 30 km. To construct a representative model developed to m = n = 720, ground-based magnetic data should be replaced by data of balloon magnetic surveys for altitudes of ～30 km. The results of investigations were confirmed by a balloon experiment conducted by Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation of the Russian Academy of Sciences and the Moscow Aviation Institute.     

Numerical Modeling of Sediment Mass Sliding and Tsunami Generation: The Case of February 7, 1963, in Corinth Gulf,Greece

Numerical modeling of a landslide process at the continental slope by taking into account slope parameters is performed for the tsunami event of February 7, 1963, reported in the Corinth Gulf, central Greece. A layered sediment structure was considered, and an initial external dynamic action at the landslide process was introduced. The results obtained were quite consistent with the observational runup data as well as with the results arrived at by conventional rigid-body and viscous-fluid models. However, this approach permits to describe in detail the formation of several wave groups and particular tsunami characteristics that are strongly dependent on the landslide model.     

Long-term variations of the location of the upper boundary of the hydrogen-sulphide zone in the Black Sea

We analyze the dependence of climatic variations of the location of the upper boundary of the hydrogen-sulphide zone in the Black Sea on the variations of the sea level and various types of atmospheric circulation (according to A.A. Girs). It is discovered that the level of correlation between the indicated parameters is high and that the corresponding plots are in good qualitative agreement. The accumulated results enable us to make an assumption that there exists an 80–100-yr cycle of variation of all analyzed parameters and that the long-term variations of the location of the upper boundary of the hydrogen-sulphide zone can be regarded as a manifestation of global climatic variations. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

The holocene biochronostratigraphy and paleoenvironment in Dvina Bay from benthic foraminiferal studies of the White Sea

The compositional changes and frequency variations in the foraminiferal communities through the sediment section across Dvina Bay allow us to identify 14 ecological-stratigraphic zones. Based on the ¹⁴C dates for the foraminiferal tests, the distinguished ecozones correspond to the appropriate Holocene stages and substages. Because most of the foraminiferal species identified in the Holocene sediments are abundant and diverse in the modern oceans, they provide a powerful tool for the reconstruction of the paleoenvironmental changes during the Holocene.     

Certain peculiarities in the distribution of mercury in meteorites

This paper presents chemical analyses of mercury in 123 specimens of 58 meteorites. A statistical comparison is made of the mercury content in meteorites (using all available data) as a function of their composition and texture.The average mercury abundance in stony meteorites is estimated as 6.6 ppm. Stony and iron meteorites differ significantly in mercury content. Among stones, chondrites and achondrites show significant differences in the mercury content. In ordinary cbondrites, mineralogy and texture do not seem to have a significant influence on the distribution of mercury, judging from the available number of analyses. Carbonaceous chondrites, in which we found up to 500 ppm mercury, stand out among all other varieties of chondrites. Iron meteorites fall at the other extreme, having the lowest mercury concentrations (generally 0-0x ppm). In specimens of several meteorite classes, troilite is a good mercury concentrator, having a consistently higher mercury content than the meteorite as a whole. Nonetheless, troilite generally accounts for less than one-half the total mercury content of the meteorite.     

Distribution of hot stars and interstellar dust in Carina

Translated fromAstrofizika, Vol. 36, No. 2 pp. 165–180, April–June, 1993.