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—Electrical resistivity tomography has been widely applied in prospecting and exploring gold deposits, but its potential for studying placers has not been sufficiently revealed. It is shown on the basis of numerical simulation and the example of field studies that linear anomalies with high electrical resistivity identified in floodplains correspond to gold-promising stream pool and riffle facies. It is concluded from working with alluvial placers in Kamchatka, Altai, and the Baikal Region that electrical resistivity tomography has a high resolution for solving geological problems, which means that it can be used as the main method for prospecting and exploring placers.

Geochemical and geophysical investigations were performed in an area of the Darasun ore cyanidation tailings impoundment, which is located in a permafrost region. The tailings contain up to 40 wt% pyrite and 5.7 wt% arsenopyrite. The purpose of this work was to determine the composition and mechanisms of transformation of the tailings and species of As, Au, Ag, Be, and Tl in drainage waters and the Darasun River before and after mixing with technogenic flows from the mining area. When the waste is oxidized because of the repeated seasonal freezing and thawing of water, three groups of chemical elements are leached: typical ore metals and impurity elements (Pb–Co–Ni–Zn–Cd and Fe–Al–Tl–Be–In), noble metals, metalloids (Au–Ag–Cu–As–Sb–Se), and post-transition metals and metalloids (Bi–Sn–Te). Drainage waters with salinities up to 5 g/L form, with concentrations of sulfate ions up to 2 g/L and cyanide up to 4 g/L, high concentrations of Au (up to 130 µg/L), Ag (3.8 µg/L), As (up to 350 µg/L), and Sb (up to 1100 µg/L), and impurity elements (Tl, In, Be, and Bi). The drainage water flows into the Darasun River, resulting in hydrochemical anomalies tens of kilometers downstream.

The efficiency of archaeological studies inside caves could be greatly enhanced by geophysical methods because of their potential for examining deposit structure and features. Application of those methods in caves entails a number of problems caused by limited space for measurements and the complexity of the surrounding medium s structure as compared to above-ground measurements. In 2017, Selungur Cave in the Fergana Valley, Kyrgyzstan, was examined using electrical resistivity tomography. Because of the above concerns, in the course of the work the question of the reliability of the results arose. To clarify the issue, a numerical experiment was performed to assess the effect of the three-dimensional cave geometry on the results of a two-dimensional inversion. It was found that variations of cave geometry parameters result in unexpected false anomalies, and considerable errors in bedrock location and resistivity can occur. In the case of downward diverging cave walls, an accurate resistivity section can be obtained by using the inversion based on a two-dimensional model. Therefore, electrical resistivity tomography in caves with similar geometry can yield reliable results concerning the shape of bedrock surface, the thickness of sedimentary layers, and size and position of inclusions such as fallen fragments of roof therein.

Ore mining and processing dumps are open and technogenic systems, which change intensively with time under the influence of environmental factors. Active transformations of such “technogenic deposits” are in close relationship with environmental factors. The purpose of this paper is to determine the nature and causes of the electrical resistivity (ER) changes in the mine tailings dump over time. The investigations were carried out by the method of electrotomography by determining the ER of the section to a depth of 1.5 m with an interval of one hour during the day with simultaneous recording of the substance temperature at a depth of 0.1 m. The maximum daily ER dynamics is observed over intensely transformed technogenic ores. ER is in a numerical relationship with the temperature of the solid matter by an exponential law with a certainty of 96%. A direct dependence of the ER daily changes amplitude on the cementation index m was revealed with the help of the Archie law. The primary material of the heap has a monodisperse composition and small values of m, so the amplitude of the ER dynamics is minimal. As a result of oxidative transformations, the solid matter of the dump becomes polydisperse, which is reflected in the cementation index and the amplitude of the ER daily oscillations increase.

The article presents the results of studies of freezing talik under lake with using of electrical resistivity tomography. The research was conducted on one of paleolake – khasyrey. The measurements performed in two perpendicular profiles by pole-dipole array with a maximum spacing of 435 m. According to results of two-dimensional inversion, an area of low electrical resistivity of rocks at a depth of 25-30 m associated with a freezing talik under lake was identified. It was determined that the depth of freezing within drained lake for the period from 1996 to 2018 is 17-22 m. The approximate rate of freezing is 1 m/year. Formation of talik have a resistance of 5-15 Ω·m. Frozen formations in the contours of young paleolake have apparent resistivity hundreds Ω·m. Within the boundaries of the more ancient khasyrey apparent resistivity of the frozen rocks up to several thousand Ω·m.

Climate warming and anthropogenic impact causes transformation of geocryological conditions in the river basins of the North-East of Russia. Changes in the thickness of the active layer, configuration of taliks, types of landscapes and other factors lead to transformation of water exchange processes between surface and groundwater runoff. This is manifested in the seasonal redistribution of the components of the water balance, accelerated melting of aufeis, change in the ratio of waters of different genesis in the structure of river runoff. As a result, natural and anthropogenic risks that affect the safe and efficient development of infrastructure and socio-economic processes are increasing. At the same time the system of observations developed in the Soviet period has been practically destroyed in the region. This paper offers a vision of organizing complex multidisciplinary research to assess and project the changes in the conditions of underground and surface water interaction in natural and disturbed river basins of the cryolithozone of the North-East of Russia, including for solving applied problems, based on permafrost, hydrology, hydrogeology, landscape science and geophysics with applications of remote sensing and field research integrated through mathematical modeling methods. To achieve the goal, the identification of natural and disturbed landscapes using remote sensing data, and key areas for detailed research will be selected. Geophysical and drilling works will be carried out within the sites to establish permafrost-hydrogeological conditions, monitoring stations will be equipped to determine hydrogeological, hydrometeorological and geocryological characteristics, including sampling for isotopic and hydrogeochemical studies. As the main key sites, it is proposed to use the area of ​​the Kolyma water-balance station and the site on Anmangynda aufeis, for which there are long-term observation series in the 20th century. Field data will become the basis for improving the mathematical model of runoff formation, considering the relationship between groundwater and river runoff in the conditions of permafrost. Mathematical modeling will make it possible to quantitatively analyze the water balance of rivers considering various factors and project water availability both for specific industrial facilities and for the region as a whole.

Rapid climate warming at northern high latitudes is driving geomorphic changes across the permafrost zone. In the Yamal and Gydan peninsulas in western Siberia, subterranean accumulation of methane beneath or within ice-rich permafrost can create mounds at the land surface. Once over-pressurized by methane, these mounds can explode and eject frozen ground, forming a gas emission crater (GEC). While GECs pose a hazard to human populations and infrastructure, only a small number have been identified in the Yamal and Gydan peninsulas, where the regional distribution and frequency of GECs and other types of land surface change are relatively unconstrained. To understand the distribution of landscape change within 327,000 km2 of the Yamal-Gydan region, we developed a semi-automated multivariate change detection algorithm using satellite-derived surface reflectance, elevation, and water extent in the Google Earth Engine cloud computing platform. We found that 5% of the landscape changed from 1984 to 2017. The algorithm detected all seven GECs reported in the scientific literature and three new GEC-like features, and further revealed that retrogressive thaw slumps were more abundant than GECs. Our methodology can be refined to detect and better understand diverse types of land surface change and potentially mitigate risks across the northern permafrost zone.

Summary The paper presents the capabilities of the electrical resistivity tomography for determining the thickness of loose sediments and the topography of an alluvial placer bedrock. Particular attention pays to identifying induced polarization anomalies associated with zones of gold-sulfide mineralization in bedrocks. These zones are the primary sources of placer gold in the region.

Summary Soil thawing occurred during the operation of the frozen embankment dam. This led to the formation of leaks through the dam body and at the foundation along the fault in bedrocks. The main goal of the research was to identify leak locations for planning wells of the groundwater cut-off. Electrical resistivity tomography was carried out over parallel survey lines, 3-D inversion was performed, and electrical resistivity maps at depths of 4, 10, and 20 m were made. Anomalies of low electrical resistivity showed the line of water filtration in the body of the dam body and foundation. The 3-D model provide insight into thawing from the upper pool and filtering along the fault.

Summary Alluvial gold deposits are associated with alluvium. We found that the channel facies of alluvium has an increased electrical resistivity as compared with the host rocks. This makes it possible to use the method of electrical resistivity tomography (ERT) for the prospecting for alluvial gold placers. The paper presents the results of geophysical studies by the method of ERT with measurement of induced polarization in the Baikal region. ERT was performed using a system of parallel profiles, 3-D inversion was performed, and resistivity and polarization maps were constructed. Perspective local dives in the bedrocks (pockets) are highlighted on the loose rocks thickness map. Linear anomalies of increased polarization associated with the alleged bedrock sources of gold have been discovered.

The article presents the results of the study of the vapor streams from sulfide-containing tailings after gold mining by cyanidation (Ursk waste heaps, Kemerovo region, Russia). The gas survey of sulfur dioxide, dimethyl sulfide, dimethyl sulfoxide, carbon disulfide, and N-containing substances concentrations was carried out using a portable device GANK-4 on a series of profiles covering the waste heaps and the surrounding area with simultaneous measurement of temperatures in the air and soil. The concentration maps-schemes of the studied gases in the surface layer were constructed. The high positive correlation of gases between themselves is established, which indicates similar mechanisms of their formation. The electrical resistivity tomography determined the internal structure of the waste heap. Active “breathing” zones were identified in which the maximum fluctuations in the concentrations of sulfur, selenium, and nitrogen-containing compounds in the near-surface air layer were recorded. Such zones are marked with lower resistances in comparison with other areas on the geo-electric profiles. There is an inverse correlation between the resistivity of the tailings and its temperature and a direct correlation between the concentration of gas in the air and the temperature of the soil. High concentrations of CS2, the volatile gas compound of the second hazard class, were found in the concentrations that exceed 6–8 times the daily average norm. Further investigation of the mine tailings seasonal transformation with the production of toxic gases deserves special attention due to high environmental risks and poor knowledge of this problem. The oxidation of ore cyanidation wastes in summer and methylation in winter due to seasonal temperature fluctuation lead to production of gases of great concern including toxic СS2.

Geochemical and geophysical investigations were performed in the area of the Komsomolsk tailings impoundment. Gold ore tailings produced with cyanidation have been generated by the Komsomolsk Gold Extraction Plant. The relatively low sulfide content in the Komsomolsk tailings and the presence of carbonates result in a low acid production potential (AP) for these tailings. The tailings pond is characterized by neutral to slightly alkaline conditions and metal concentrations, except for those of As and Sb, below the maximum permissible concentration (MPC). The situation is complicated by the fact that the displaced Berikul tailings are stored in the southern part of the Komsomolsk tailings impoundment. Sulfide concentrate cyanidation tailings were produced by the former Berikul Gold Extraction Plant. In the Berikul tailings, the sulfide content is approximately 25%. This high content has resulted in a high AP and the formation of acidic and ultra-acidic surface ponds (pH ∼2) with extremely high concentrations of metals and metalloids (As up to 4.1 g L−1). The estimated duration of acid drainage generated by the Berikul tailings is approximately 2400 years. Surface drainage from the tailings enters the Voskresenka River; as a result, the concentrations of As and Sb in the river water approach the MPCs established by the Russian Ministry of Health. Based on electrical resistivity tomography (ERT), the uncontrolled leakage of acidic and highly mineralized solutions through a natural geological fault into groundwater horizons was revealed. Groundwater contamination was confirmed via an analysis of drinking water from a well located near the fault.

We assess the potentialities of ultrawideband (UWB) electromagnetic pulse sounding of low-resistivity geoenvironments using the ground-penetrating radar (GPR) system developed by us and compare the obtained results with 2D electrical resistivity tomography and standard GPR data. The research was performed in an area of Quaternary clay deposits with a resistivity of 20–50 Ohm⋅m. For an OKO-2 GPR antenna with a center frequency of 150 MHz, the sounding depth is 2–4 m, whereas UWB sounding provides penetration of the GPR pulse to a depth of 30–40 m. Deep UWB sounding of low-resistivity environments is possible under the following conditions: use of generators based on drift step recovery diodes (DSRDs), high matching of the UWB receiving and transmitting antennas to the environment, and an increase in the noise immunity of the recording system, in particular, due to a decrease in the intensity of air waves.

Under consideration is a multiple well platform where the metal pipes of various diameters that are located above and below ground act as interferences together with boreholes with metal tubing. The sought-for objects of study are the thawing zones located near the boreholes. Numerical calculations of direct problems are performed by the nodal finite element method implemented in the author’s software package for solving the problems of electrical resistivity tomography.

The present study shows the results of field and laboratory studies of trace element transfer from waste heaps of metallurgical slags (Kemerovo region, town of Belovo). Temperature anomalies were observed, with high temperatures up to 81.2 °C on the top of the heap. A visual geophysical model of the inner parts of the heap with contrasting resistivity zones was obtained using the electrical resistivity tomography (ERT) method, and quantitative characteristics were derived. Dry and frozen slag zones were characterized by resistivity of 50–500 Ohm·m. The resistivity of wet slag varied from 5 to 10 Ohm·m for slag with low humidity of 1–2 Ohm·m for slag saturated with highly mineralized solutions. The local anomaly of extremely low resistivity (0.3–0.5 Ohm·m) might be associated with a combustion centre or high pore solutions TDS. Basic major elements (Ca, Mg, K, Na, Si, and Al), metals (Cu, Zn, Pb, and Cd) and anionic elements (As, Sb, and V) were determined in gas condensates in situ . The most volatile elements were basic elements: Ca > Cu > Mg > Na > Mn > Fe, Zn. Lower concentration in the condensates was determined for Si > K > As > Sr > Al > V and Pb, Ba, La were also found. The observed mineral paragenetic sequences were primary minerals of barite-polymetallic ores and sphalerite concentrate, high-temperature minerals formed during pyrometallurgical processing and/or permanent combustion of the heap surface, efflorescence minerals formed by atmospheric oxidation accelerated by acid steam condensation. An experimental investigations using stepwise and 500 °C heating of the same samples were performed to compare the elements that were released into the gas phase in situ and off-site.

Sulphide-bearing mill wastes of the Ursk Ore Processing Plant situated in the Kemerovo region (Russia) were investigated in the 2013 – 2015. Multipurpose studies of the Ursk mining tailings allowed to determine the composition of the wastes pore waters, acid mine drainages and affected groundwater. Electrical resistivity tomography (ERT) was used to trace the geoelectric zoning of the wastes, expressed as a consistent change of the electrical resistivity from zone to zone. Layers with low resistivity indicate areas with pore spaces filled by highly mineralized solutions with high concentrations of Cu, Zn, Cd, As, and Sb up to 12 g/L in total.

Thawing of subsea permafrost can impact offshore infrastructure, affect coastal erosion, and release permafrost organic matter. Thawing is usually modeled as the result of heat transfer, although salt diffusion may play an important role in marine settings. To better quantify nearshore subsea permafrost thawing, we applied the CryoGRID2 heat diffusion model and coupled it to a salt diffusion model. We simulated coastline retreat and subsea permafrost evolution as it develops through successive stages of a thawing sequence at the Bykovsky Peninsula, Siberia. Sensitivity analyses for seawater salinity were performed to compare the results for the Bykovsky Peninsula with those of typical Arctic seawater. For the Bykovsky Peninsula, the modeled ice‐bearing permafrost table (IBPT) for ice‐rich sand and an erosion rate of 0.25 m/year was 16.7 m below the seabed 350 m offshore. The model outputs were compared to the IBPT depth estimated from coastline retreat and electrical resistivity surveys perpendicular to and crossing the shoreline of the Bykovsky Peninsula. The interpreted geoelectric data suggest that the IBPT dipped to 15–20 m below the seabed at 350 m offshore. Both results suggest that cold saline water forms beneath grounded ice and floating sea ice in shallow water, causing cryotic benthic temperatures. The freezing point depression produced by salt diffusion can delay or prevent ice formation in the sediment and enhance the IBPT degradation rate. Therefore, salt diffusion may facilitate the release of greenhouse gasses to the atmosphere and considerably affect the design of offshore and coastal infrastructure in subsea permafrost areas., Key Points The thawing of ice‐bearing subsea permafrost was modeled by coupling heat and salt diffusionThe boundary conditions reflect sea ice dynamics during the transition from terrestrial to marine permafrostThe modeled ice‐bearing permafrost depths were validated with geoelectric surveys

Summary Electrical resistivity tomography and cone penetration test were carried out on the slope of the M–7 Volga highway. The main goal of the research is to localize areas of increased landslide hazard. Electrical resistivity and the mechanical properties of soils depend on their moisture content, lithological composition and porosity. This made it possible to determine the correlation links between the electrical resistivity and the mechanical parameters of the soil, to predict the deformative and strength characteristics of the soil. Soils with abnormally low resistivity have low values of drag under the cone and friction of the side surface of the probe. They correspond to areas of potential landslide formation.

A new approach to interpretation of shallow electrical resistivity tomography (ERT) data discussed for the case of the Olkhon area (western Baikal region) stems from tectonophysical ideas of faulting phases and deformation levels in rocks. The deformation levels, identified statistically from ERT responses, constrain fault boundaries and subboundaries associated with the formation of main and subsidiary fault planes. Information of this kind creates a basis for solving various fundamental and applied problems of tectonics, mineral exploration, and engineering geology.

Combined geophysical and geochemical investigations of drainage streams from sulfide-containing waste dumps of the Novo-Urskoe deposit allow determining two directions of highly mineralized toxic solutions. Surface drainage stream flows over the natural slope of the valley. In addition, along the natural fault, vertical penetration of drainage solutions into groundwater occurs to a depth of 20 m. Based on geophysical-data interpretation, we assume that penetration of solutions into geologic environment leads to their dilution by groundwater, followed by a six-fold decrease in total mineralization.

Based on comprehensive geophysical and hydrogeochemical study of mud volcanism within Bulganak center (Kerch Peninsula), periodicity of ejections of Andrusov mud volcano are defined during its activity.

The effect the metal casing of a vertical borehole may exert on transient electromagnetic (TEM) responses has been studied in a field experiment. Eddy currents in the casing affect transients only slightly at early times, but the casing effect predominates at late times. Therefore, early-time TEM response measured near a borehole can provide information on shallow subsurface. The late-time TEM signals induced by the eddy currents in the casing show exponential behavior b⋅ exp(–t/τ). The time constant τ refers to the rate of eddy current decay in the casing; the amplitude b is M12⋅ M23⋅ L–1⋅ τ–1, where L is the casing self-inductance, and M12 and M23 are the mutual inductances between the transmitter loop and the borehole and between the borehole and the receiver, respectively. Both M12 and M23 are controllable, while M23 is especially important for survey applications: by reducing it, one can reduce the casing effect on the TEM data. © 2014, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.