Vol 466, No 1 (2016)

The new version of the geological structure of the Berdyaush pluton (a single intrusion of rapakivi granites in the Urals) presented in this paper is significantly distinct from the previous structural schemes. Rapakivi granites compose no more than 10–20% of the area of the pluton and they are widespread only in its northeastern and southwestern flanks. The contacts between gabbro (I phase), hybrid syenodiorites (II phase), and rapakivi granites (III phase) are transitional, metasomatic. The hybrid syenodiorites and rapakivi granites are formed after gabbroic rocks as a result of their intense thermal and metasomatic transformation by the deep fluids. The driving force of this process could be the unilateral compression of the Berdyaush pluton resulting from formation of the eastward continental rift in the beginning of the Middle Riphean.

The weathering crust of the Beden ultrabasite massif (the basin of Big Laba River) is identified and studied. Anomalously high contents of noble metals (Au, Pt, Pd) are revealed in the basal horizon of the Jurassic part of the weathering crust. For this reason we suspect an existence of a belt of noble metal miner-alization in the Paleozoic ultrabasites in the Peredovoi Range of the Northern Caucasus.

The data presented in this work introduce substantial corrections into the Upper Cenozoic stratigraphy and geological history of Gornyi Altai. They provide evidence for the most ancient Early Pleistocene glaciation in this region. This follows from finds of faceted boulders buried in the Bashkaus Formation. Pale-omagnetic investigations revealed in the latter a wide zone of negative polarity corresponding to the Matuyama Chron in the magnetostratigraphic scale and made it possible to correlate the formation with the Lower Pleistocene in the standard stratigraphic scale. It is shown that global cooling at the beginning of the Quaternary Period stimulated development of glaciation on the southern slope of the Kuraiskii Range exceeding in size its present-day scale.

The uneven character of the distribution of ¹⁸O/¹⁶O and ²³⁴U/²³⁸U values was established in the vertical cross section of the productive sequence of the Dybryn uranium deposit (Vitim uranium-ore region, Buryatia). Both a deficiency and an excess of ²³⁴U in relation to the equilibrium ²³⁴U/²³⁸U ratio in the vertical sequence may provide evidence for the extremely low rate of the infiltration water flow. The behavior of oxygen isotope characteristics for different size fractions of terrigenous rocks provides evidence for active uranium redistribution and openness of the isotope system of this element during interaction of terrigenous–sedimentary rocks with infiltration waters.

The general features of the processes of hydrothermal ore genesis in the slowly spreading Mid Atlantic Ridge with a separation rate of 2–4 cm/year are considered for the first time.

The discharge of major cations and dissolved organic carbon (C_org) with water of the Ob River and its tributaries along the natural zones within the Ob River basin was calculated, and the contribution of the underground component to the volumes of total discharge of the Ob River basin was estimated. It was demonstrated that the total chemical composition of river water and the geochemical discharge in the Ob River basin were consistent with the zoned hydroclimatic conditions controlling the character and duration of interaction in the water–rock system. It was established that the average ionic discharge of the Ob River increased from 6–7 × 10⁶ t/year near Barnaul to 46–47 × 10⁶ t/year near Salekhard; the discharge of dissolved C_org increased from 0.1 × 10⁶ to 3.8 × 10⁶ t/year. Multiple enrichment of underground waters of the Ob River in dissolved organic matter from the upper to the lower reaches was revealed.

The composition and evolution of the melts of trachytes from the volcano were studied based on examining the inclusions of mineral-forming media by means of X-ray and ion microanalysis. A correlation was shown between the degree of enrichment of these melts in rare elements and the processes of magmatic differentiation. It was found that trachytes of the volcano were generated in highly differentiated alkaline melts enriched in Hf, Nb, Zr, Ta, U, Th, Rb, Y, and REEs under 1020–1060°C. The evolution of melts was determined by the processes of crystal fractionation. The main volatile components in the melts are water, fluorine, and chlorine with the concentrations of 0.1–0.5, 0.2–0.5, and 0.2–0.3 wt %, respectively. The melt crystallization was accompanied by degassing caused by the decrease in the outer pressure. The low concentrations of water and fluorine represent the melt composition by these components exclusively at the time of the melt movement towards the Earth’s surface just before the eruption.

The Zelenodol porphyry Cu-(Au, Mo) deposit located about 65 km SSW of the city of Chelyabinsk is confined to the western part of the West Uralian Volcanogenic Megazone. The concordant U-Pb age of zircons from ore-bearing island-arc diorite porphyryis 418.3 Â ± 2.9 Ma.

It is found that the best results, in terms of the efficiency of detecting regional seismic phases from blast sources, are achieved by using the method of waveform cross correlation applied to the data from a small-aperture array of three-component sensors

Degradation of the underwater multiyear permafrost rocks (UMPR) together with intensification of thermal abrasion processes in the coasts are global risks on a planetary scale. Changes in the physical properties of sediments can occur after degradation of the UMPR and can lead to unpredictable consequences especially in the regions of technical development. Drifting ice bottom exaration (ice plucking of bottom sediments), which is increasing based on the data of recent expeditions, is no less dangerous. These processes are hazardous for practically all types of activity.

Objective and subjective uncertainties in modern estimates of the impact of long-term climate variations on the subsurface runoff and groundwater reserves are discussed. It is shown that the assessment of groundwater reserves should take into consideration the insufficient reliability of the main hydrogeological parameters and estimates of their likely changes. Therefore, the prediction of the influence of climate changes on groundwater reserves and its regime is now impossible. The mechanism of the natural floral damping of possible changes in the groundwater replenishment and temperature–moisture regime of large regions determined by climate changes due to the growing greenhouse gas concentration in the troposphere is described for the first time.

The soil cover of the Arctic zone of Russia is ∼330 million hectares. Permafrost restricts the thickness of the active layer but does not prevent the formation of significant diversity of soils and soil complexes, including Al–Fe humic and peat soils, gleysols, and others. The available data on soil resources are sufficient for organization and participation of Russia in scientific–practical international programs. At the same time, specific soil related targets and project tasks may require additional study of soils of the Arctic region.

The influence of the roughness of the underlaying water surface on turbulence is studied in a stably stratified boundary layer (SSBL). Direct numerical simulation (DNS) is conducted at various Reynolds (Re) and Richardson (Ri) numbers and the wave steepness ka. It is shown that, at constant Re, the stationary turbulent regime is set in at Ri below the threshold value Ri_c depending on Re. At Ri > Ri_c, in the absence of turbulent fluctuations near the wave water surface, three-dimensional quasiperiodical structures are identified and their threshold of origin depends on the steepness of the surface wave on the water surface. This regime is called a wave pumping regime. The formation of three-dimensional structures is explained by the development of parametric instability of the disturbances induced by the surface water in the air flow. The DNS results are quite consistent with prediction of the theoretical model of the SSBL flow, in which solutions for the disturbances of the fields of velocity and temperature in the wave pumping regime are found to be a solution of a two-dimensional linearized system with the heterogeneous boundary condition, which is caused by the presence of the surface wave. In addition to the turbulent fluctuations, the three-dimensional structures in the wave pumping regime provide for the transfer of impulse and heat, i.e., the increase in the roughness of the water–air boundary caused by the presence of waves intensifies the exchange in the SSBL.