Том 485, № 1 (2019)

The results of Sr–Nd–Pb–Hf isotope analysis of Late Paleozoic granitoids of Central Chukotka, which are exemplified by the Kibera and Kuekvun plutons, are presented. The ages of these granitic plutons and of granite pebbles from conglomerates at the base of the overlying Lower Carboniferous strata are 351–363 Ma (U–Pb zircon, TIMS, SIMS, LA–ICP–MS). Thus, granitic magmatism is contemporaneous to tectonic events of the Ellesmerian orogeny in the Arctic region. The Sr–Nd–Pb–Hf isotopic compositions of the granitoids indicate the contribution of mantle and crustal components to the granite melt source. The formation of granitoids probably occurred in the geodynamic settings of an Andean type continental margin with interaction between mantle melts, forming in a mantle wedge under suprasubduction conditions, and the continental crust.

This work is a link in a series of studies of Late Cenozoic submarine volcanoes of the island arcs in the western part of the Pacific Ocean, representing the first detailed Russian-language description of the material composition of the Minami-Hiyoshi submarine volcano, which is involved in the Hiyoshi volcanic complex (the norther5th cn part of the Mariana arc). This study was based on rock material dragged from the volcano during the 5th cruise of the R/V Vulkanolog. New original data on the structure, chemical and mineral compositions, and origin of volcanic lava were obtained. It was shown that all the lava flows studied are genetically linked and originated from the same magma chamber. Structural–petrographic differences in the lava flows are explained by different dynamics in the melt transportation to the surface of the bottom of the ocean.

Our investigations have made it possible to estimate the age of hydrothermal ore metasomatic rocks at the Burinda Au–Ag deposit, one of the best known in East Asia, at 126–128 Ma. This deposit was formed due to hydrothermal processes at the final development stages of the Taldan volcanic complex.

Analysis of the data of seismoacoustic investigations and engineering-geological drilling in the eastern Barents Sea has shown the following. The Quaternary sedimentary cover of the region with a sharp angular unconformity overlying the pre-Cenozoic strata consists primarily of five seismostratigraphic units (SUs). Lower three of them are represented by moraines: Upper Saalian (SU VII), Lower Weichselian (SU V), and Upper Weichselian (SU III) that includes seismic facies (SFs), SF III-T and SF III-C. The Late Glacial SU II and Holocene SU I, forming the top of the Quaternary section, are composed of glaciomarine and marine sediments, respectively. The SU VII and SU V moraines with eroded upper and lower boundaries (the result of glacial erosion) are partly preserved. The deposits of SUs III, II, and I belong to the last glaciosedimentation cycle, are regionally spread, and have their own features of area development. The sediment thicknesses in all SUs vary from <1–3 to 25–30 m and greater. A heterogenous spatially variable structure of the Quaternary cover in the eastern Barents Sea, manifested in the complex behavior of its thicknesses (from <25 m to 75–100 m), is associated with the processes of the geological development of the region as a part of the Barents Sea glaciated shelf.

The statistical relationships characterizing the concentrations of minor elements in the organic part and mineral impurities in fossil coals are allocated. The confidence ranges for these concentrations are calculated. The concentrations of minor elements within the confidence ranges relate to the clarke distributions; those exceeding the upper boundary of the confidence level, to extremely high values.

The isotopic characteristics (εNd, ²⁰⁷Pb/²⁰⁶Pb, and ⁸⁷Sr/⁸⁶Sr) of the modern bottom sediments sampled in the Barents Sea during the 67th voyage of the R/V Akademik Mstislav Keldysh are considered. It is shown that the major contribution to the formation of the sediments in the central Barents Sea is made by rocks of the North European continental margin, which are found in the zone of influence of the North Cape Current. The values of εNd, ⁸⁷Sr/⁸⁶Sr are lower in the bottom sediments of this part of the sea than the corresponding characteristics of sedimentary material incorporated into ices and carried by the Transpolar Drift Stream. This allows one to conclude that such material has not contributed much to the sedimentation in the Barents Sea.

It is suggested to dispose of radioactive wastes of nuclear energetics with long-lived actinides in the form of titanates and zirconates in boreholes up to 5 km deep. The low leaching rate of the waste imitator (Nd) from samples is shown during their interaction with chloride brine at 200°C. The elements in the liquid phase mostly occur in soluble form, and the role of their colloidal form is insignificant. Our results allow substantiation of a choice of promising materials for actinide immobilization.

The Sm–Nd isotope ages of apoamphibolite eclogites and eclogite-like garnet-clinopyroxene crystalline schists collected in the Chupa and Engozero segments of the Belomorian mobile belt are estimated. Eclogites and eclogite-like garnet–clinopyroxene rocks demonstrated nearly the same isotope age (2119 ± 170 and 2191 ± 39 Ma, respectively) on the same pair of minerals (garnet–clinopyroxene). The age obtained (about 2.1 Ga) is the oldest indicator of the onset of Paleoproterozoic metamorphism in the Belomorian mobile belt.

Experimental study of leaching of the main cations (Na, K, Mg, and Ca), alkaline and alkali-earth microelements (Li, Rb, Cs, Be, Sr, and Ba), heavy metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Tl, and Pb), hydrolyzate elements (Y, RZ, Ti, Th, and U), and anionic elements (F, Si, P, and V) from rocks of different acidity with distilled water and a multicomponent solution of organic acids, having the distribution of dissociation constants corresponding to natural dissolved organic matter was carried out. It has been shown that carboxylic acids, which are part of the dissolved organic matter contained in surface waters, cause a sharp increase in the mobilization of both the main cations and trace elements from silicate rocks. The chemical properties of the elements are of secondary importance, as was shown by the general correlation between the parameter related to the mobility of the elements at the initial stage of the leaching and their content in the rocks.

A modification of the commonly used Price–Rind scheme for lightning flash frequency (LFF), which can be used in calculations with large spatial and time steps, has been developed. If such steps are applied, the exponent in the relationship of LFF as function of convective cloud heights is smaller by a factor of two over land and smaller by one-fourth over the ocean in comparison to the original Price–Rind scheme. The modified version has been implemented in the Climate Model of the Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). The results of LFF simulations with the modified scheme agree better with the satellite data than with the original version. In the IAP RAS CM, global warming (cooling) leads to an LFF increase (decrease) in all seasons. The sensitivity of the LFF to surface air temperature changes at the global level is estimated at 10%/K.

Based on the Chelyabinsk (February 13, 2013) and Lipetsk (June 21, 2018) events, disturbances in the Earth’s geomagnetic field, which were induced by the fall of these meteorites, were studied. Based on the data provided by geomagnetic observatories of the INTERMAGNET network and the mid-latitude Mikhnevo geophysical observatory (IGD RAS), it was established that the fall of meteorites through the Earth’s atmosphere, in general, induces geomagnetic disturbances of up to 5 nT at distances up to 2700 km from the impact point of a cosmic body; the maximum effect is reached with a delay time ranging from ~5 to ~10 min, and the duration of the period of the induced geomagnetic field disturbances varies from ~5 to ~20 min. The estimation dependencies of the amplitude and duration of induced geomagnetic disturbances from a distance from the meteorite impact points are proposed.

The results of studies of the regularities of evolution of soils and the environment in the steppe zone of the East European Plain are presented. Different culture-based chronological stages of the Bronze Age, Iron Age, and Middle Ages (3rd millennium BC–2nd millennium AD) are considered on the basis of buried soils at archeological monuments (burial mounds).

The contemporary radiation situation in the Arctic Basin and Russian Arctic seas is assessed on the basis of data from 2013 to 2017. Statistically significant differences are revealed in the mean volumetric activity of ¹³⁷Cs in the surface water layer. The tendency toward a west-to-east decrease in seawater pollution is noted. The maximum ¹³⁷Cs concentrations are characteristic of the Barents and Kara seas. The least polluted waters are reported in the Laptev and East Siberian seas, which are the most remote from the sources of technogenic radionuclides in Europe.

The patterns of the seasonal and interannual variability in the development of phytoplankton, including coccolithophores, were studied in the northeastern part of the Black Sea in various seasons. The research was carried out on the basis of long-term observations and data provided by the Modis Aqua ocean color scanner. This paper reports that, in the coastal and open waters of the Black Sea, the development of phytoplankton reaches the highest level in the fall–winter and winter–spring seasons, i.e., in the periods of active winter convection. Coastal waters are also characterized by expressed spring peak of chlorophyll “a” concentrations associated with phytoplankton bloom in March. Winter and spring coccolithophore blooms, which are unusual for the Black Sea, were registered on the basis of satellite data. It was noted that there is a relationship between the level of coccolithophore development in the summer period and the minimal temperature of the sea surface layer in the preceding winter. The most active coccolithophore blooms, which were registered in 2006 and 2012, were observed after the coldest winters.