This paper presents an analysis of the structure and geological history of the shelf of the East Siberian continental margin, based on the interpretation of seismic data in conjunction with geological information. The article describes the main structural elements of the East Siberian Sea which formed as a result of rifting processes (barremian–aptian) — the Novosibirsky, the Mansky, North Melvillsky and Dremheadsky rifts in the northern part of the East Siberian basin, and the Mellvillsky rift in the southern part. Rifts are considered together with volcanic zones and the main relative elevations — De-Long, Wrangel, Kotelnichesky and Baranovsky elevations. It is assumed that the process of rifting thinned out the crust of the Podvodnikov basin. The sedimentary basin was formed by rifting.
The study of the paleocommunities of foraminifera of the reference section of the Paleogene-Neogene of the Kvachin Bay in Western Kamchatka made it possible, based on the qualitative composition and quantitative ratios of the species encountered, to identify 13 layers with foraminifera corresponding to certain section intervals and to establish their successive change. Layers with foraminifera are combined into 4 complex zones. In terms of distribution, the identified zones are regional and can traced in adjacent regions. The change in paleocommunities corresponds to the process of evolutionary development of foraminifera, as well as a change in paleoenvironments. The noted changes in the composition and structure of zonal communities reflected in a certain staged development of microfauna.
The article deals with the internal deep structure of the earth's crust of the East European platform and the surface of the mantle lithosphere. The presented charts of the three main layers of the earth's crust — the lower, middle and upper and the surface of the mantle lithosphere — for the first time identified deformation by changing the thickness of the layers. Deformations are compared on all layers that allowed to allot the active center, the main (through) and local (developed in separate layers) areas. The boundaries of these regions are active zones of different ranks. The observed end-to-end development of strain from layer to layer or expression of some of them only in separate layers indicates on the sub-horizontal stratification and vertical divisibility of the earth's crust. Deformations of the deep layers are compared with the latest near-surface platform structures. This made it possible to establish a connection of near-surface deformations with deep ones and to consider the latter as the latest. These studies are relevant for solving fundamental problems of the origin of new structures and a number of practical problems.
The shallow-marine sediments of the Middle Miocene (mainly the Konkian) of the Eastern Georgia (Eastern Paratethys, Kura basin) were investigated by cyclostratigraphy methods. Time series analysis (Lomb-Scargle and REDFIT periodograms, Gaussian filters) revealed statistically significant signal with 2,4–2,7 m wavelength corresponding most likely to the precession cycle. Based on statistical processes, a sedimentation rate of the studied sediments from 8,75 to 13,75 cm/kyr for different depositional setting was detected. We suggest that the studied Eastern Georgia Konkian sediments (Sartaganian and Veselyankian beds) accumulated during of at least 475–600 kyr. The Sartaganian (beds with most diverse marine fauna of the Konkian) can be correlated with interval of highest sea-level rise of TB 2,5 cycle.
An analysis of modeling the mineralization zones of ore deposits indicates that the inclusion of waste rocks in a zone of mineralization has little effect on the drift of the estimates towards a lower content. On the contrary, the extreme contents of a component often containing among exploration data influence towards an overestimating component.
In recent years, significant successes have been achieved in the search and exploration of oil and gas reservoirs in the Jurassic deposits on the eastern side of the Fukang depression, which is the least studied part of the Junggar oil and gas Basin. In order to find out the source of hydrocarbon generation, we studied source rocks, oil and oil-bearing sandstones (24 samples from 13 wells) from the Badaowan, Sangonghe, Xishanyao, Toutunhe and Qigu production beds of the Fukang depression research area. Based on these studies, the composition of the organic matter of the Jurassic source rocks, the properties and molecular composition of oils, as well as the characteristics of the composition of biomarkers in them are examined in detail. The results of research and interpretation of the data showed that the mudstones of the Badaowan formation were source rocks of oil from the Gumudi zone, the Fukan depression, the Bajiahai ledge and the Shaqi ledge.
The Siratur gold deposit is located in the northern part of the South Ural segment of the Main Ural Fault. Its ore zone is confined to the area of the tectonic junction of the serpentinite of the Nurali massif and the submeridional strip of carbonaceous schists of the Ordovician Polyakovka Formation. Its composition is widely represented basalts with chemical characteristics of the main effusive rocks of the mid-ocean ridges.
In the black shale deposits of the Siratur deposit, gold ore mineralization is mainly represented by the gold-sulfide vein-disseminated type, and in the listwanite-beresite complex, gold-quartz-low-sulfide vein-streaked type. Microprobe studies of zolotins showed that gold in ores of the first type has a low-qality of 670–820, and in the second — 940–970. The deposit can be attributed to the polygenic and polychronous type.
The Late Jurassic orogenic volcanogenic–plutonogenic gold deposit Darasun (the Eastern Transbaikal segment of Mongolo-Okhotsk folded zone) includes postgold ore antimony mineralization. Aggregates of rice-like quartz, minerals of jordanite–geocronite–schultzite, sphalerite, galena, arsenopyrite, tennantite-tetrahedrite, calcite and Mn-Mg siderite are its earlier formations; aggregates of rice-like quartz, low-iron sphalerite, Pb-Sb sulphosalts, antimonite and berthierite are its late formations. The Darasun trend of Pb-Sb sulphosalts sequence from bulangerite to fülöppite is typical for post-magmatic hydrothermal gold deposits and differs from telethermal ones. The are two fülöppite types in Darasun ores: fülöppite enriched in arsenic (up to 7,5 %wt), which is probably the product of replacement of geocronite and fahl ore row minerals and fülöppite without arsenic associating with antimonite and calcite. The arsenic-bearing fülöppite composition is (Pb2.90Ag0.06Cu0.05)3.01(Sb7.05As0.91Bi0.04)8.00S14.99 and the composition of fülöppite without arsenic is (Pb2.83Cu0.18)3.01Sb7.98S15.01, which are close to stoichiometry. Darasun fülöppite is characterized by positive correlation of As, Bi and Ag; füloppite without arsenic is enriched in copper.
The article presents the results of the hydrogeochemical study of thermal groundwaters from the Kuldur spa (Jewish Autonomous Region, Russia). The main characteristics of these groundwaters are high temperature (73 ᵒС), low TDS (up to 0,38 g/l), and alkaline (pH 9). The dominated cation is sodium, and the anion is hydrocarbonate. Water is enriched with fluorine, silicon, aluminum, tungsten, molybdenum, and some other anionic elements. This study provides detailed data on the chemical and mineral composition of host rocks and sources of solutes. Isotopic data from bubbling gases show that the main component of the gas phase (N2) comes from an atmogenic source, while CH4 and CO2 are biogenic. Argon and oxygen are also derived from air, while helium is predominantly radiogenic. The ϬD and Ϭ18О in the aqueous phase indicate the undoubtedly meteoric genesis of groundwater with an extended circulation period. Our results suggest that the studied groundwaters are results of the penetration of meteoric waters to 4 km depth and heating up to 100 ᵒC. The solutes come to aquifer via the dissolution of rocks, but since groundwater circulates within the poorly soluble rock (granitoids), respectively, the water TDS remains low.
The engineering-geological features of the sands included in the pre-Quaternary continental terrigenous formations (red and gray-colored, coal-bearing and lignite-bearing, molasses and molasses coal-bearing), which are widespread in Russia, are characterized. The results of studying the composition, structure, condition and properties of these soils within the various regions of Russia are presented.
Resistivity method is widely used in shallow surface geophysics. Capacitive resistivity is one of techniques which help to extend usage of resistivity method for environmentc where galvanic coupling of electrodes is difficult, for instance, frozen ground, hard rocks and engineered structures (roads, railways and others). This technique allows fast field work without galvanic coupling electrodes. The main problem is complicated calculation of forward resistivity for simple model. In results, the limitations to the usage of the technique are not clear in theoretical and practical aspects.
The authors determinate the limits of electrical properties and distances for capacity resistivity.
