Geophysical Studies Research Articles

Aerocosmogeological studies of the Piatyhorivka area of the Dnieper-Donets Depression (correction of the structure, identification of tectonic activation zones)

As a case study of the Piatyhorivka area of the Dnieper-Donets Depression with a level terrain is given to characterize the technology of computerized processing and structural identification of multiband remote sensing data. Its application enables to visualize the components of the terrestrial landscape for the research area more clearly. Moreover, as a result the identification of elements of a weakly incised (low-amplitude) erosion network, the differentiation of soils by spectral features, etc. became possible. On the basis of a combined analysis of a complex of landscape components, the structural interpretation of remote sensing data together with a priori data of geological and geophysical studies, the elements of the fault-block structure of the research area were refined. The zones of tectonic activation at the current stage of the development of the earth's crust were found within its limits.

TARİHİ DÖRT AYAKLİ MİNARE’DE ZEMİNE DAYALI STRÜKTÜREL SORUNLARIN YERALTI RADARI İLE BELİRLENMESİ

The Four-Legged Minaret, which has an important place thanks to its building period and unique architecture, is located in the southeastern part of the historical Suriçi region of Diyarbakır. This structure located outside the courtyard of Sheikh Mutahhar Mosque and inside the Dört Ayaklı Minare Street was built on a monolithic stone column from basalt material in a tetragon plan and is carried by four columns that are in cylindrical form. After 2015, partial damages occurred to the minaret. During the restoration works carried out between 2016-2019, these partial damages were tried to be repaired. But the condition of the ground was not instrumentally detected and investigated in these restoration works. In the present study, observational geological and instrumental geophysical studies were carried out on the Four-Legged Minaret and its surrounding area. The ground condition of the Four-Legged Minaret and the situation of its construction materials were determined by scannings achieved from the ground penetration radar and whether the damages in the structure were related to the ground condition was analyzed. As a consequence of the study, fractures and cracks were detected in the wall, and fractures, cracks, and water leakage-dependent collapses were detected on the floor. Besides, finally, repair recommendations for these damages are also presented in this study.

Geophysical studies of the area of groundwater pollution in Verkh-Neyvinsky village

The purpose of the research. The ecology of human habitation implies the absence of any pollution of the natural environment and special requirements are imposed on the quality of air and water. In this regard, the purpose of the research is to determine the sources of pollution of drinking water, the area of its distribution and the depth of contamination of the fracture space of rocks, as well as to give recommendations on how to more quickly eliminate pollution of the water basin. Methodology. In the course of the research, geophysical studies were carried out using the method of vertical electrical sounding of the coast of the Verkh-Neyvinsky pond, on the territory of which there is a gas station of BNP (Bashkirnefteprodukt). The area of contamination with oil products was outlined, and the depth of penetration of oil products was assessed. The work was performed using the ERA-MAX equipment with a standard set of active electrodes. Sections of electrical resistivity were constructed, which can be associated with the boundaries of the area and deep penetration of oil products along the fracture zones. Results. The results of the 2021 work confirmed the area of contamination previously made by the Gidrospetsgeologiya organization based on water analyzes from surface samples performed in 2017, and made it possible to assess the depth and presence of surface and underground pollution. Conclusions. Comparison of the area of pollution by oil products, in particular gasoline, is a complex environmental problem and requires a long time to eliminate pollution. Most of the existing literature describes cases of oil pollution. The problem of gasoline pollution elimination is more complicated due to significantly different coefficients of kinematic viscosity of oils and gasolines; therefore, the gasoline pollution area has a significantly larger size and depth. Recommendations are given for a more rational way to eliminate pollution.

Hydrogeochemical characterisation of the groundwater in the crystalline basement of Forsmark, the selected area for the geological nuclear repositories in Sweden

Numerous groundwater analyses from the crystalline bedrock in the Forsmark area have been performed between 2002 and 2019, together with thorough geological, geophysical, and hydrogeological studies, within the site investigations carried out by the Swedish Nuclear Fuel and Waste Management Company. The groundwater samples have been taken from boreholes down to ≈ 1000 m and the analysis include major- and trace-elements, stable and radiogenic isotopes, gases and microbes. The chemical and isotopic composition of these groundwaters evidences the presence of non-marine brackish to saline groundwaters with very long residence times (many hundreds of thousands of years) and a series of complex mixing events resulting from the recharge of different waters over time: glacial meltwaters, probably from different glaciations of which the latest culminated some 20,000 years ago, and marine waters from the Baltic starting some 7000 years ago. Later, meteoric water and present Baltic Sea water have recharged in different parts of the upper 100 m. These mixing events have also triggered chemical and microbial reactions that have conditioned some of the important groundwater parameters and, together with the structural complexity of the area, they have promoted a heterogeneous distribution of groundwater compositions in the bedrock. Due to these evident differences in chemistry, residence time and origin of the groundwater, several groundwater types were defined in order to facilitate the visualisation and communication. The differentiation (linked to the paleohydrological history of the area) was based on Cl concentration, Cl/Mg ratio (marine component), and δ18O value (glacial component).The work presented in this paper increases the understanding of the groundwater evolution in fractured and compartmentalised aquifers where mixing processes are the most important mechanisms. The model proposed to characterise the present groundwater system of the Forsmark area will also help to predict the future hydrogeochemical behaviour of the groundwater system after the construction of the repositories for the nuclear wastes.

Simulation and Analysis of the Dynamic Characteristics of Groundwater in Taliks in the Eruu Area, Central Yakutia

The perennially unfrozen zones (taliks) in the Eruu area of central Yakutia have a complex stratigraphic structure, and the dynamic characteristics of groundwater in this region have been insufficiently studied. This study analyzed the results of the explorations and geophysical studies conducted by the Melnikov Permafrost Institute of the Siberian Branch of the Russian Academy of Science. In addition, we simulated and analyzed the dynamic characteristics of groundwater in the area based on hydro-meteorological data, snow data, and remote sensing data. During the process, the dynamic changes in the attributes of aquifers due to the seasonal freeze–thaw processes of soils, including the active layer, were also taken into account. The results showed the following: (1) According to the analysis of the measured data on water levels in hydrogeological observation well 14E/2014, the difference between the simulated and measured values of groundwater levels in monitoring wells for over 99% of the measurements was less than 0.1 m. The average difference between the measured (excluding missing values) and simulated values of groundwater level in the monitoring wells was 0.028 m/d. (2) The annual average water level in the study area declined. The simulated value dropped at a rate of 0.10 m/a, with only a gap of 0.01 m/a with the measured value. Meanwhile, the simulated water head was greatly influenced by the terrain, especially in the central area, where the head decreased rapidly from the perimeter toward the lakes (8.9 m/km on average). (3) From 1 September 2014 to 31 August 2015, the mean value of the simulated discharge in the study area was 3888.39 L/d, which was in line with the results of previous monitoring (the average flow was 4147.20 L/d and 3715.20 L/d in 2014 and 2015, respectively). This study can provide a reference for the reasonable exploitation and utilization of groundwater under the influence of the distribution of perennially unfrozen zones, or taliks, and provides an effective three-dimensional modeling method for quantifying the analysis of groundwater dynamics in permafrost regions.

Unravelling geological controls on groundwater flow and surface water-groundwater interaction in mountain systems: A multi-disciplinary approach

Mountain water resources are considered to be the world’s water towers. Still, despite their importance for downstream societies and ecosystems and their vulnerability to climate change, they remain poorly understood – It is the case in particular of mountain groundwater systems. Their complexity makes them difficult to conceptualize, while their remoteness makes them difficult to study, both observationally and instrumentally. Understanding mountain hydrogeological systems is mostly limited by the lack of characterization of the subsurface geologic framework and by the limited understanding of the role of geological structures on groundwater flow and on surface water-groundwater interaction. Removing methodological barriers is therefore a necessary step for improving the understanding of mountain hydrogeological systems.To tackle this problem, we develop a comprehensive multi-disciplinary approach to gain insights into the hydrogeological role of geological structures in ungauged mountain catchments. The methodology consists of several complementary methods: (1) geological mapping at multiple scales; (2) a geophysical study including on-ground Electrical Resistivity Tomography (ERT) and, gravimetry transects, and a UAV-based magnetic survey; (3) hydraulic data, including a 9 km long transect of streamflow measurements in the recession period, the long-term Normalized Difference Vegetation Index (NDVI), and varied hydric markers (e.g., a thermal spring and a puddle). The methodology is tested in the Parque Nacional del Río Clarillo, an ungauged catchment in the Andes Mountains (≈130 km2) that is illustrative of the complexity of mountain hydrosystems featuring fault zones, weathered zones, intrusive rocks, and volcano-sedimentary successions.An increase of approximately 50% in the streamflow is observed over a short distance of 1 km. Such a localized and significant increase in the baseflow is not related to any superficial supply and can only be explained by groundwater exfiltration. Based on the multiscale geological mapping and geophysical survey, a regional N-S fault and a secondary set of E-W local faults are identified in the vicinity of the resurgence area, which conjointly are likely to export groundwater from a neighbouring subcatchment up to the resurgence area. Downstream of the resurgence area, no significant change in the baseflow is observed, corresponding to the presence of an impermeable granitic pluton identified by the geological and geophysical mapping. Finally, a fractured zone in the Andean foothills is identified in the volcanic unit, which coincides with a perennial thermal spring, indicating upwelling flow and hydrogeological connectivity between the mountain block and the alluvial basin.The results strongly support the ability of the proposed methodology to identify geological structures that substantially impact the evolution of the baseflow through the catchment. The complementary multi-disciplinary methods are used innovatively to infer the link between geological and hydrogeological structures. The methodology does not aim to fully characterize the geological framework of the catchment but pragmatically focuses on hydrogeologically pertinent structures that may impact baseflow and consequently catchment management.

The seismic structure of Villarrica Volcano revealed by ambient noise tomography

We compute the first ambient noise tomography of Villarrica Volcano, obtaining a 3D Vs model. Using ambient noise recorded from May to July 2014 from 18 seismic stations, we measured the Rayleigh wave group velocity by stacking daily cross-correlations between station pairs. The resulting group velocity curves were inverted into 2D tomographic maps with periods ranging between 1.0 and 4.9 s. These tomographic maps were locally inverted through the neighborhood algorithm to obtain an accurate Vs model in depth. Our findings reveal velocity variations within the Villarrica Volcano region, reaching a depth of around 7.5 km. The resulting 3D shear-wave velocity model has provided novel insights into the internal structure of the area. Our study has identified slow velocity anomalies in the area of the Liquiñe-Ofqui Fault Zone, and horizontal variations in shear-wave velocity that run parallel to the volcanic lineament from the Mocha-Villarrica Fault Zone. We also note the presence of a negative velocity anomaly located southeast of the Villarrica summit, in a position consistent with the magmatic plumbing system proposed by earlier geophysical studies conducted in the region.

The relationship between lowering the Earth's surface and bearing pressure above the advancing longwall face

This work aims to develop a method for determining the increase in stresses above an advancing longwall face of Western Donbas mines. The paper presents a solution to the problem. It is based on the analysis of geodetic instrumental observations of the earth's surface lowering and rock mass deformation above the advancing longwall face. Length and propagation in the roof and floor of the extracted seam are the main geometrical parameters of the zone of high rock pressure. Currently, the quantitative parameters of this zone are not considered. And its length under the conditions of Western Donbas is determined with an accuracy of 50%. Thus, research in this direction is relevant. The experimental basis for the research includes the results of observations performed at two vertical borehole extensometers and the results of data processing obtained at more than 30 observation stations on the Earth's surface. Thus, the research specified the geometrical parameters of the zone of high rock pressure and the nature of the vertical stress distribution within this zone. The paper introduces a method to determine a coefficient of stress increase above the advancing longwall face of Western Donbas mines. We also established the empirical coefficients of the vertical stress distribution function within the abutment pressure zone. There is a relationship between the lowering of the earth's surface and the values of the stress increase in the borehole edge part. The reliability of the obtained results is confirmed by geophysical studies in Western Donbas, as well as by the results of field observations.

A data-driven approach to estimating post-discovery parameters of unexplored oilfields

Consider a typical situation where an investor is considering acquiring an unexplored oilfield. The oilfield has undergone a preliminary geological and geophysical study in which pre-discovery data such as lithology, depth, depositional system, diagenetic overprint, structural compartmentalization, and trap type are available. In this situation, investors usually estimate production rates using a volumetric approach. A more accurate estimation of production rates can be obtained using analytical methods, which require additional data such as net pay, porosity, oil formation volume factor, permeability, viscosity, and pressure. We call these data post-discovery parameters because they are only available after discovery through exploration drilling. A data-driven approach to estimating post-discovery parameters of an unexplored oilfield is developed based on its pre-discovery data by learning from proven reservoir data. Using the Gaussian mixture model, and a data-driven reservoir typology based on the joint probability distribution of post-discovery parameters is established. We came up with 12 reservoir types. Subsequently, an artificial neural network classification model with the resilient backpropagation algorithm is used to find relationships between pre-discovery data and reservoir types. Based on k-fold cross-validation with k = 10, the accuracy of the classification model is stable with an average of 87.9%. With our approach, an investor considering acquiring an unexplored oilfield can classify the oilfield's reservoir into a particular type and estimate its post-discovery parameters' joint probability distribution. The investor can incorporate this information into a valuation model to calculate the production rates more accurately, estimate the oilfield's value and risk, and make an informed acquisition decision accordingly.

Triggering mechanism and brittle-ductile dynamics of active faults in the south-central Saurashtra horst, Gujarat, western India: A geospatial, geological, and geophysical approach

The seismically active Saurashtra horst is located within the intraplate volcanic continental margin of western India. The region is prone to moderate and low-magnitude earthquakes within the depth range of ∼ 3 to ∼ 24 km. We observed that the earthquakes in this region are associated with seismically active brittle and ductile crustal layers. To understand the dynamics of the earthquake generation process, we applied an integrated geological and geomorphological approach, supplemented by subsurface geophysical (magnetotelluric) studies. Additionally, the active surface deformation has been measured using the PSInSAR and GLA techniques. Based on the stream offset and geomorphic landform development pattern several NW-SE and NE-SW oriented strike-slip faults have been identified. The PSI-derived displacement analysis reveals that the area is deforming at the rate of ± 5 mm/yr. Furthermore, subsurface crustal heterogeneity with increasing depth has been identified using the magnetotelluric technique, which is reflected in the form of basaltic lava flows, plutonic emplacement within the granitic basement, and the presence of semi-crystallized magmatic bodies below the brittle-ductile level. Additionally, we proposed a model to depict the plutonic emplacement within the highly fractured/faulted granitic basement and their relationship to the earthquake generation process. Our model shows that crustal heterogeneity and the migration of hydrothermal fluid from the semi-crystallized magmatic body along the active fault cause earthquake nucleation processes within the brittle and ductile layers. We concluded that the upwelling magmatic fluid above the brittle-ductile transition (BDT) acted as a lubricant for the nucleation and triggering of the earthquake along the active faults. Similarly, the fractured ductile crust is weakened by fluid migration, which causes high fluid pressure in the ductile crust thereby decreasing the confining pressure and endorsing the velocity weakening in the aseismic layer, responsible for the shear instability that causes deep crustal earthquakes. More specifically, the lithological heterogeneity at brittle and ductile regimes is an important factor for the earthquake nucleation process in this part of the Indian plate.

FEATURES OF DETERMINING FILTRATION PARAMETERS OF COMPLEX CARBONATE RESERVOIRS AT THEIR OPERATION BY HORIZONTAL WELLS

Link for citation: Salnikova O.L., Chernykh I.A., Martyushev D.A., Ponomareva I.N. Features of determining filtration parameters of complex carbonate reservoirs at their operation by horizontal wells. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.137-147 In Rus. The relevance of the research is caused by the fact that in the conditions of continuous deterioration in the structure of hydrocarbon reserves, complex technologies for their development are being implemented, based, among other things, on the use of wells of complex design (horizontal wells). The increase in the share of horizontal wells in the total operating stock determines the relevance of the scientific and methodological justification of research technologies that comprehensively take into account the structural features of the reservoir and the geometry of the fluid flow. The most complete volume of geological and field information can be obtained by combining two main types of research – geophysical and hydrodynamic. The problem of data, in fact, of the indirect research methods, should be considered the need to assess the reliability of their results and the lack of approaches to reduce interpretation uncertainties, which is especially important in the conditions of the impossibility of coring in horizontal wells. This article proposes possible directions for solving these problems. The main aim of the study is the scientific substantiation of approaches to research and interpretation of their results, allowing reliably determining the filtration parameters of productive formations during their operation with horizontal wells. Object: complex Tournaisian-Famenian carbonate reservoirs in Perm region, operated by horizontal wells. Methods: geophysical and hydrodynamic studies of wells, laboratory core studies, multivariate statistical modeling. Results. It has been established that geophysical studies (interpretation was made in accordance with the algorithms for vertical wells) do not allow reliably estimating the length of the horizontal section of the wellbore and the filtration properties of the reservoir. It is recommended to determine the filtration properties when interpreting the data of hydrodynamic studies of wells. Algorithms of modern methods of interpretation of hydrodynamic studies, implemented in common software products, allow you to determine a large amount of geological and field data, including a number of parameters specific to horizontal wells. However, this procedure is accompanied by uncertainties, for example, in terms of the choice of interpretation models. The performed multivariate statistical modeling made it possible to substantiate the methodology for reliably determining the filtration properties of the reservoirs under consideration and the approach to reduce uncertainties when choosing interpretation models.

Geochemical, mineralogical and geophysical studies (VLF) in the prospecting for vein-type gold deposits in the former Klecza–Radomice Ore District in the Kaczawskie Mountains

Geochemical, mineralogical and geophysical studies (VLF) in the prospecting for vein-type gold deposits in the former Klecza–Radomice Ore District in the Kaczawskie Mountains

A Novel Method to Improve the Estimation of Ocean Tide Loading Displacements for K1 and K2 Components with GPS Observations

The accurate estimation of ocean tide loading displacements is essential and necessary for geodesy, oceanic and geophysical studies. It is common knowledge that K1 and K2 tidal constituents estimated from Global Positioning System (GPS) observations are unsatisfactory because their tidal periods are nearly same to the revisit cycle or orbital period of GPS constellation. To date, this troublesome problem is not fully solved. In this paper, we revisit this important issue and develop a novel method based on the unique characteristic of tidal waves to separate GPS-system errors from astronomical K1/K2 tides. The well-known credo of smoothness indicates that tidal admittances of astronomical constituents in a narrow band can be expressed as smooth functions of tidal frequencies, while the interference of GPS-system errors seriously damages the smooth nature of observed tidal admittances. Via quadratic fitting, smooth functions of tidal frequencies for tidal admittances can be determined, thus, astronomical K1 and K2 tides can be interpolated using fitted quadratic functions. Three GPS stations are selected to demonstrate our method because of their typicality in terms of poor estimates of K1/K2 tidal parameters related to GPS-system errors. After removing GPS-systematical contributions based on our method, corrected K1/K2 tides at three GPS stations are much closer to the modeled K1/K2 tides from FES2014, which is one of the most accurate tide models. Furthermore, the proposed method can be easily applied to other areas to correct GPS-system errors because their smooth nature is valid for global tidal signals.

How reproducible and reliable is geophysical research?

Geophysical research frequently makes use of agreed-upon methodologies, formally published software, and bespoke code to process and analyse data. The reliability and repeatability of these methods is vital in maintaining the integrity of research findings and thereby avoiding the dissemination of unreliable results. In recent years there has been increased attention on aspects of reproducibility, which includes data availability, across scientific disciplines. This review considers aspects of reproducibility of geophysical studies relating to their publication in peer reviewed journals. For 100 geophysics journals it considers the extent to which reproducibility in geophysics is the focus of published literature. For 20 geophysical journals it considers a) journal policies on the requirements for providing code, software, and data for submission; and b) the availability of data and software associated for 200 published journal articles. The findings show that: 1) between 1991 and 2021 there were 72 articles with reproducibility in the title and 417 with reliability, with an overall increase in the number of articles with reproducibility or reliability as the subject over the same period; 2) while 60% of journals have a definition of research data, only 20% of journals have a requirement for a data availability statement; and 3) despite ~86% of sampled journal articles including a data availability statement, only 54% of articles have the original data accessible via data repositories or web servers, and only 49% of articles name software used. It is suggested that despite journals and authors working towards improving the availability of data and software, frequently they are not identified, or easily accessible, therefore limiting the possibility of reproducing studies.

Partitioning of Fe2+ and Fe3+ between bridgmanite and silicate melt: Implications for redox evolution of the Earth's mantle

Crystallization of deep magma oceans would have created the chemical heterogeneity of the Earth's mantle. Previous geophysical studies have suggested a possible existence of the Fe3+-rich lower mantle relative to the upper mantle because the seismic profile of the Earth's lower mantle is well explained by the presence of Fe3+-rich bridgmanite. Such a contrasting distribution of Fe3+/ΣFe ratios between the upper mantle and the lower mantle could have triggered the gradual oxidation of the upper mantle by upwelling Fe3+-rich lower mantle in the early Archean around 3 billion years ago (Ga). However, whether Fe3+-rich lower mantle and Fe3+-poor upper mantle could have been formed or not in the early Earth is still poorly understood. Here we report experimental constraints on the partitioning of Fe2+ and Fe3+ between bridgmanite and silicate melt at 23–27 GPa to investigate the solid-liquid fractionation of Fe2+ and Fe3+ in the deep magma ocean. Our results show negligible fractionation of Fe2+ and Fe3+ between bridgmanite and silicate melt at the uppermost lower mantle conditions, suggesting that preferential incorporation of Fe3+ into bridgmanite during magma ocean crystallization is unlikely. If the lower mantle had become enriched in Fe3+ during the formation of the Earth, another mechanism, such as the redox disproportionation of Fe2+, may have played a more important role in controlling the Fe3+/ΣFe ratio of the mantle.

Deep TDEM Study for Structural and Mining Purposes: A Case Study of the Barbastro Saline-Evaporitic Formation, Spain

The objective of this study was to obtain the deep subsurface structure of a saline-evaporitic formation affected by an anticlinal structure, defining the position and thickness for its future exploitation (potassium salts). To improve this knowledge, geophysical methods can be applied to establish detailed information on geological structures at depth. This work analyzes the results of a deep time domain electromagnetic (TDEM) survey acquired over the southern flank of the Barbastro-Balaguer Anticline present in the Ebro Basin in the vicinity of Graus (Huesca, Spain), that controls the geometry of the Barbastro saline-evaporitic formation, of interest from the mining point of view. A deep time domain electromagnetic system (TDEM) is used, providing a penetration capability down to 3.0 km depth. A parametric constrained inversion over a lithological known borehole (Monzón-1) is used to obtain a resistivity model and then applied to the rest of the survey points. The applied methodology contributes to improving the geological knowledge, revealing a new detailed geological structure of the Barbastro saline-evaporitic formation affected by the Barbastro-Balaguer Anticline. The survey shows that the Barbastro saline-evaporitic formation presents a structure with a ramp hanging wall and close to flat footwall, generally dipping to the SW, with a decreasing thickness from 1103 m to 601 m, in concordance with the previous accepted geological structural model. The new geophysical study provides essential data, allowing design and drilling optimization in future mining exploitations.

Exploratory Mapping of the Geothermal Anomalies in the Neoproterozoic Arabian Shield, Saudi Arabia, Using Magnetic Data

In this paper, certain areas of the Kingdom of Saudi Arabia (KSA) are assessed in order to map potential geothermal energy zones. To evaluate high-resolution aerial magnetic data, spectral depth analysis using a modified centroid approach was used. The calculated geothermal parameters were gridded in order to delineate the regions characterised by a shallow Curie point depth (CPD) and a high geothermal gradient (GG) as well as a high heat flow (HF). The CPD, GG and HF calculated from the analysed data varied in the ranges of 6.0–15.0 km, 40.0–100.0 °C/km and 90.0–270.0 mW/m2, respectively. The obtained results show the concurrence of the positions of shallow CPD (<8.0 km), high GG (>83.5 °C/km) and high HF (>211.0 mW/m2). The geothermal systems that are oriented in the E–W direction are related to the Red Sea tectonics, the tectonic opening of the Red Sea/Gulf of the Suez Rift, hot subterranean anomalies and high enthalpy from radioactive granites. Likewise, the geologic structures (fractures and faults) related to the Red Sea tectonics serve as channels for the movement of hydrothermal fluids and the deposition of associated minerals. All in all, another geophysical study involving deep boreholes, and seismic, magnetotelluric, electromagnetic and geochemical data should be conducted to evaluate and estimate precisely the economic reserves of geothermal resources.

High resolution multi-methodological geophysical investigations to enhance the knowledge of Tusculum archaeological site (Roma, Italy)

To better understand the location and help in the conservation of buried structures in the ancient site of Tusculum, in Central Italy, archaeological and multi-methodological geophysical studies were developed in the recent last years. These studies included geophysical surveys, which were combined with topographical survey and direct archaeological excavations. Tusculum is one of the largest Roman archaeological sites in the Alban Hills, located in the Latium region (Italy), about 25 km South-East of Rome. This settlement was inhabited since pre-Roman times, up to the middle ages. The objective of the Tusculum Project is to verify the town-planning of Tusculum and to obtain information about the location, shape, depth and size of the hypothesised buried buildings. With these aims, multi-methodological geophysical surveys have been carried out in the time range 2016–2019 to locate the archaeological remains in different portions of the studied area and to verify the orientation of the underground aqueduct system. GPR and gradiometric surveys were carried out to investigate the archaeological remains, while ERT surveys, were employed to find evidence of undiscovered parts of the underground aqueduct system. These results, along with geological studies and historic evidence, are being examined by archaeologist to understand the limits of the town and how water was supplied to such a large, populated settlement. The obtained results show very good correspondence between the buried architecture, the geophysical anomalies and the archaeological excavations. A number of unexpected buried buildings were discovered, which were excavated in 2017 and 2018, which showed remains of buried public thermal bath and a large church with surrounding funerary area built in the Middle Ages.

Results of geophysical research on the Zmiyinyy island

The article presents the results of geophysical observations by the Dnepropetrovsk geophysical expedition «Dneprogeofizika» on Zmiyinyy Island, which performed a full cycle of work from prospecting and surveying studies to providing the island with drinking water.
 In structural and tectonic conditions, the island is considered as the Zmiyinyy insular block of the Danubian horst megablock. The geodynamics of the region is determined by the position and inclination of the collision sutures within the zone of interaction between the Eurasian and African lithospheric plates. Comprehensive geological and geophysical studies included magnetic prospecting, gravity prospecting and electric sounding (Dipole-axial sounding induced polarization DAS-IP) with geological routes along all rock outcrops on the Zmiyinyy island. Detailed integrated geophysical studies were: gravimetric observations over a network of 20×10 m, magnetometric — 10×5 m and electrometric (DAS-IP) — 40×5 m. For the first time on the island, gravimetric stations were set up, which will later become a support for gravimetric surveys. According to the results of magnetic field survey and DAZ-OP electrical exploration observations, an anomalous area was identified, which is perspective for archaeological research. Based on a comprehensive interpretation of geological and geophysical materials, a well was drilled to a depth of 120 m, which confirmed the constructed predictive stratigraphic section of about. Zmiyinyy. Based on the results of the search for sources of drinking water, three wells were drilled, with a fresh water flow rate of up to 10 m3 per day (each). Subsequently, fresh water with minor purification is used as drinking water.

Concerning the discussion about the Bug series of the Middle Bug (Ukrainian shield)

The materials of several articles and reports published in 2022 by the authors of this work and V.P. Kirilyuk (Kirilyuk, 2022 a,b), who discussed the structure and stratigraphy of the Вug area granulite complex of the Ukrainian Shield. The authors, relying on their geological, geophysical and geochemical studies, isotopic geochronology data, as well as on the world experience in studying the Early Precambrian complexes of the Canadian and Australian shields, argue that during 3.8—1.7 Ga, the Bug area granulite complex underwent at least a threefold structural metamorphic processing. Its modern structural plan, as well as, to a large extent, the composition and structural and textural features of metamorphic rocks, are of Early Proterozoic age. Therefore, its division into suites of primary sedimentary-volcanogenic rocks and their vertical distribution by age does not make sense. Only a division into two series is possible — the Dniester-Bug and the Bug, between which there is a tectonic contact. Contrary to this, V.P. Kirilyuk, relying on the experience of his stratigenic-metamorphogenic studies and the authority of the well-known school of L.I. Salopa, E.M. Lazko et al., defends the point of view on the stratigenic nature of the Bug area granulite complex, in which the primacy and stability of the position of strata-formations relative to each other were preserved throughout the entire time. According to V.P. Kirilyuk, there are no breaks and disagreements between the suites, so he proposes to abandon the identification of the early Precambrian USh Bug Group. And the seven suites identified by him, the youngest of which is 3.8 billion years old, are proposed to be attributed to a single Dniester-Bug series. The authors of both alternative points of view apply to the National Stratigraphic Committee of Ukraine with a proposal to revise the stratigraphic scheme of the Early Precambrian of the USh.