The Mendeleev Rise is located in the Amerasia Basin of the Arctic Ocean. The work is based on a synthesis of interpretation of regional seismic profiles of the OGT 2D DOM and data from rock sampling using special underwater vehicles on the slopes of seamounts and scarps. The uplift is represented by alternation of highs (horsts) and half-grabens. At the base of the horst sections, bright reflectors are distinguished, which are interpreted as volcanics. Half-graben sections are wedge-shaped in section and are similar in geometry to seaward-dipping reflectors (SDRs) of continental passive volcanic margins. Rock sampling has shown that the horsts are composed of sedimentary rocks of Palaeozoic age, penetrated by intrusions. Aptian-Albian sections with volcanics (basalts, trachybasalts, trachyandesites) were identified on the horsts. U/Pb dating of igneous rocks showed that typical age of rocks is 110–114 Ma. Magmatic Cretaceous rocks contain zircons with ages ranging from pre-Barremian Mesozoic to Palaeozoic and Precambrian. These zircons were captured by basaltic magma during its upward movement. The presence of these ancient zircons indicates that the Mendeleev Rise is composed of continental crust. A model of the crustal structure of the Mendeleev Rise is proposed. The base of the section visible on seismic profiles is dominated by volcanics (on horsts from basalts to trachyandesites, in half-grabens mainly basalts). The upper and lower crust is approximately 20–30 % saturated with intrusions of basic composition. At the base of the crust, a high-velocity layer up to 5 km thick is distinguished. It is assumed that its lower part is entirely represented by gabbro-type intrusions, and the upper part is the lowest part of the lower crust, maximally saturated with intrusions.
An astrochronological (cyclostratigraphic) binding of the lithological and geochemical characteristics of the Jurassic deposits of the Mountainous Crimea and the Caucasus to the cycles of eccentricity of the Earth’s orbit is carried out, an analysis of the relationship between the established variations of climate and paleotemperature with the moments of coincidence of different-order cycles of eccentricity and their paleoclimatic characteristics is given. New data on paleotemperatures of the Southern Demerdzhi mountain section are presented.
The results of a comprehensive study of the reference section of the Upper Maastrichtian of Mount Klementyev (South-Eastern Crimea), composed of a terrigeneous-carbonate strata. It was found that sedimentation occurred in relatively deep-water conditions. Biostratigraphic analysis of benthic and planktonic foraminifera assemblages made it possible to identify foraminiferal zones in the section and confirm the deep-water type of sedimentation in the basin at this interval.
The stratigraphy of the Kerch-Taman region has been refined by the foraminiferal assemblages from the clay pulp of the Semigorsky, Andrusova, and Borukh-Oba mud volcanoes. By comparison with the fauna from the reference section of the Paleogene along the river Belaya (Republic of Adygea) deposits of the Middle Eocene (Circassian, Kuma formations of the Lutetian and Bartonian) were revealed. Deposits of lower Oligocene (Pshekh Formation, Rupelian Stage), confirmed by finds of remains of pteropods. Middle Miocene (Konkian and Sarmatian stages of the Eastern Paratethys regional scale of the Miocene) were revealed too. Cretaceous deposits (Semigorsky volcano) belong to the late Campanian – Maastrichtian.
The paper summarizes data on the lithological and elemental composition of bottom sediments and permafrost from boreholes 1D-14, 3D-14 and 1D-15 drilled in Buor-Khaya Bay in 2014–2015. Based on the results of determining the percentage content of SiO2, Al2O3, Fe2O3, TiO2, MgO, Na2O, K2O, CaO, MnO, P2O5, Cl, Cr, S, Ni, Cu, Zn, Rb, Sr, Ba, Y, Zr, organic carbon in sediments, lithochemical modules values were calculated and comparative analysis of the lithological and geochemical composition was performed. Principal differences between near-continental (1D-14 and 3D-14) and relatively distant from land (1D-15) strata were established, which is explained by spatial and temporal variability in sedimentary fluxes and weathering crust activity in the studied area of the Laptev Sea. The results of the study allowed to conclude that the basis of the petrofund of the studied deposits are most likely sedimentary rocks of the Kharaulakh ridge of the Verkhoyansk mountain system (sandstones, siltstones and mudstones). The contribution of igneous and metamorphic rocks to the sedimentary supply in the strata uncovered by drilling was insignificant.
In this article, a univariate regression analysis of Fe, Mn, Mn/Fe and Corg distributions and marine sediment densities by depth in sections of studied boreholes drilled on the Vøring Plateau was used to investigate the intensity of diagenetic transformations. As a result, quantitative parameters of diagenesis processes in Eocene-Pleistocene sediments were obtained. In addition, the degree of intensity of diagenesis processes for the main lithological sediment types of the Vøring Plateau was studied on the basis of single-factor analysis of variance data. As a result, it was found that in addition to hiatuses, the effects of bottom currents and turbidites, the degree of diagenetic transformation in Eocene-Pleistocene sediments depended on the following main factors: sediment accumulation conditions; lithological composition; the amount of organic carbon included in the Eocene-Pleistocene sediments of the Vøring Plateau.
The paper presents data on the spatial distribution of activity concentration of natural (232Th, 226Ra, 40K) and anthropogenic (137Cs) radionuclides in the surface layer of bottom sediments of the Chaun Bay of the East Siberian Sea. The measured activity of 232Th and 226Ra is typical for bottom sediments of the Arctic coastal zone and corresponds to the global level. The level of 137Cs activity in bottom sediments showed the absence of local sources of anthropogenic contamination in Chaun Bay, while the mean 40K activity concentration was 1.8 times higher than the global average. The results of statistical analysis showed that the dynamics of riverine run-off, thermoabrasion and currents, as well as aeolian and sea ice transport of sedimentary matter, are the main factors that determined the differences in the behaviour of the studied radionuclides in the surface bottom sediments of the Chaun Bay.
Diamonds of the Pioneer pipe, compared with the Arkhangelsk and Karpinsky-1 pipes, formed at higher temperatures, as well as were in such conditions for a longer time (experienced high-temperature annealing). Pionerskaya pipe has slightly lower productivity, but higher quality of diamonds, especially in large size classes, it also has a higher proportion of octahedra and highly transparent crystals that are not subject to accessory etching.
The results of the study of the platinum group minerals of the Baimka gold placer cluster, Western Chukotka, Russia, are presented. Platinum group minerals belong to the iridium-platinum and platinum mineralogical-geochemical types with the Late Jurassic cumulative pyroxenite-gabbro complexes as a probable source. Platinum group minerals came to alluvial gold placers primarily from intermediate reservoirs, which is the Volgian volcanic-sedimentary sequence. Rounded silicate glass inclusions are a specific feature of platinum minerals from the Baimka placer cluster.
The acid-base properties of the surface of the Maikop series clays and mud volcano clays, as well as their adsorption properties with respect to mercury (II) ions, were studied. It is shown that pHPZC for the former is 7.1 on average; for the second — 9.0. The pHPZC value for mud volcano clays is consistent with the pH values in the waters of mud volcanoes in the Kerch-Taman region. When the mass ratio of the sorbent and solution is 1:900, adsorption equilibrium occurs after 4 days with active stirring. Experimental data on mercury adsorption from NaCl–NaHCO3 solution on natural sorbents are best described by the Redlich-Peterson and Toth equations. The process of mercury adsorption on clays of the Maikop series is more intense than on mud volcano clays.
The present paper focuses on the new results of elemental analysis of 94 metal objects attributed to the Christian and pagan artifacts. They have been found at the excavation of Medieval Novgorod and the Novgorod region. The analytical data obtained by EDXRF in the frame of interdisciplinary research project. It includes mostly pendant-crosses as well as the round pendants and mounts with Saints, fragments of the church polycandelons and the pagan pendant-amulets. Obtained results have been examined statistically. Tin-lead bronzes clearly dominate the selection. There are also mixed copper alloys (gunmetal) with tin, zinc, and lead and lead brass. The proportions of silver and pewter alloys as well as pure tin and lead are modest. Obtained data supplemented by further research on the base of Pb-isotope methods and ICP MS results and their geological interpretation will allow to trace the ore sources of the metal objects from Novgorod.
The paper considers four kinematic migration algorithms (procedures for converting the arrival times of reflected waves to the Earth’s surface into the depths of the reflecting boundaries) using medium-velocity and reservoir velocity models of layered media: a standard algorithm for converting times to depths through average velocities; a modified medium-velocity algorithm that takes into account the slope of seismic boundaries; an algorithm for layer-by-layer recalculation of t0 lines to depths; a variational kinematic migration algorithm based on the theory of ray tracing by integrating a system of differential equations with specified initial conditions by the Runge–Kutta method. To study the possibilities and limitations of each of the algorithms, calculations were carried out on a number of theoretical models of layered media that approximate real geological situations. Based on the results of numerical experiments using the four kinematic migration algorithms considered in the paper, conclusions were drawn about the effectiveness of using each of the algorithms to restore geological boundaries in media models of varying complexity.
Authors describe some processing and interpretation results of the very high resolution seismic data, acquired in RV “Academic Mstislav Keldish” cruise to Bennett island in Russian Arctic.
The purpose of investigations was to study underwater geological structures around the island, presence or absence of their connection to the ancient rocs on the surface of the island.
Interpretation of the seismic data gives some clues to these questions.
A three-dimensional resistivity model is presented that contains electrical resistivity anomalies of a complex shape on three structural levels: in the sedimentary cover, in the consolidated earth’s crust and in the upper mantle. The synthetic (model) magnetotelluric data obtained as a result of solving the forward problem are analyzed to identify anomalies associated with resistivity inhomogeneities at various depths. Quantitative estimates of the sensitivity of various components of magnetotelluric data to these inhomogeneities are given. Further, we plan to use the presented data to evaluate the effectiveness of various methods for solving inverse problems.
The comparative analysis of the effectiveness of various arrangements of blocking material in a thin, high-permeable water-cut layer of an oil reservoir is presented in order to reduce unproductive injection and increase oil recovery. Efficiency calculation was performed using high-resolution numerical simulation in the vertical section of the typical stream tube for a five-spot waterflooding scheme. Three types of location of isolation intervals are considered for two representative ratios of the viscosity of the water and oil phases.
