Geophysical Surveys Research Articles

Delineation of LNAPL plumes in a clay-rich site in Gyeongsangnam-do Province, South Korea: integration of geophysical survey data with borehole data and soil sampling information.

To effectively delineate the spatial distribution of oil contaminant plumes, geophysical methods indirectly measure the physical properties of the subsurface and can provide spatial information and images on a large scale, as opposed to traditional direct methods such as borehole drilling, sampling, and chemical analysis, which are time-consuming and costly. However, interpreting geophysical responses over non-aqueous phase liquid (NAPL)-contaminated sites is not straightforward due to inconsistent responses from biodegraded oil contaminants. In this study, we performed multi-geophysical surveys including seismic refraction, ground-penetrating radar, electrical resistivity tomography (ERT), and induced polarization (IP) surveys, to locate NAPL-contaminated zones in a clay-rich site. To reduce ambiguity in discriminating between oil contaminants and clay layers, we first figure out the geological structure of the site by interpreting geophysical data incorporating with borehole data. The ERT data highlighted the heavily contaminated regions in the unsaturated zone but were less distinctive below groundwater levels. Conversely, IP responses revealed potential hotspots within the clay layers, extending beneath the groundwater. Considering the 3D geological model, NAPL-contaminated zones are properly delineated through interpretation of ERT and IP data together with borehole data, and the contaminant source zone was properly estimated within the site.

Unveiling a hidden fortification system at “Faraglioni” Middle Bronze Age Village of Ustica Island (Palermo, Italy) through ERT and GPR prospections

We carried out a geophysical research project in the Middle Bronze Age village of Ustica (Palermo, Sicily, Italy), named “Faraglioni Village” after the stack formations which detach from the coast north of the archaeological site. The investigation, which comprised Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) techniques, allowed us to discover the buried foundations of an outwork fortification system never evidenced by previous archaeological studies, only hypothesised from the observation of aerial photography and partially outcropping boulders, which align roughly parallel to the main defensive wall of the Village.Our geophysical prospection involved the entire 250 m-long arc of the outward village defensive wall, with the acquisition of eleven ERT profiles and 27 GPR scans. The techniques were selected based on both favourable logistics and methods applicability: ERT sections allowed us to trace a series of high-resistivity anomalies arranged to form an arc-shaped structure along the perimeter of the defensive wall. GPR investigation was localised in the most accommodating patch of terrain of the site, with the effort of intercepting clear enough sections of the target, to determine more accurately its shape, depth, and overall dimensions. Our discovery paves the way for new investigations, mainly aimed at defining the timing of construction of the fortification system, as well as the function of the remains of other architectural structures identified close to the wall, which could represent the target of further geophysical investigations.

Characterization of seepage in an earthfill dam by the integration of geophysical surveys and geotechnical data

Seepage is a common phenomenon in earthfill dams, and one that typically warrants episodic assessment and monitoring by regulatory agencies. Geophysical surveys provide a convenient, cost-effective, and convenient means for assessing seepage, but only if they are applied in effective combinations and if the data are analyzed properly. In the present study, a self-potential survey of streaming potential and a 2D electrical resistivity tomography survey were notably successful in detecting seepage under the embankment of the nearly 90-year-old Standing Rock Dam No. 1 in South Dakota, USA. Self-potential (SP) measurements show a localized negative anomaly of up to 27 mV on the upstream side of the dam, which we interpret to be the inlet or recharge zone for seepage, and a positive anomaly of up to 20 mV on the downstream side, which we interpret to be the outlet or discharge zone. The spatial correlation between our resistivity models, SP data, and topography was excellent. Water-saturated, conductive deposits in the dam's embankment match a negative SP amplitude in the inlet or recharge area. Similarly, water-saturated electrically conductive sediments are characterized by a positive SP amplitude in the discharge area where surface seepage occurs in a topographic low. Six years of water-level measurements in the existing piezometers interpreted relative to the properties and spatial distribution of coarser-grained alluvium (sand and gravel) underneath the dam's embankment fill, suggest that most seepage occurs under the dam. Our approach to assessing seepage in this project should be widely applicable to earthfill dams worldwide, and our modeled results constitute a valuable case study.

3‐D geophysical modeling of a buried, simple impact crater: Holleford impact structure, Ontario, Canada

AbstractHolleford Crater is a deeply buried, 2.35 km diameter late Proterozoic‐early Cambrian (550 ± 50 Ma) simple impact crater located in southeastern Ontario, Canada. Exploration drilling in the 1950–60s indicated a >450 m deep, simple impact structure with an infill stratigraphy of Cambro‐Ordovician clastic and carbonate sediments and a −2.2 mGal gravity anomaly. We conducted new ground‐based geophysical surveys (magnetics, gravity) and potential field modeling to better resolve the buried impact structure depth, subsurface geometry, and postimpact modification. Geophysical surveys reveal a well‐defined ~3 mGal Bouguer gravity low and <20 nT residual magnetic anomaly over the crater basin. The lack of a well‐defined magnetic anomaly is due to the low magnetic contrast between Mesoproterozoic metasedimentary target rocks and Paleozoic infill sediments. The modeled basement surface shows a deeply buried (>400 m), eroded simple impact structure with a rim‐to‐rim diameter (D) of 1.8–2 km, a residual rim height of about 30 m and a true depth (dt) >400 m. The modeled diameter is smaller than the previous estimate (2.35 km) based on the surface outcrop pattern of Paleozoic strata, which overestimates the buried impact structure dimensions. The modeled basement surface identifies a rim breach and a possible fluvial outflow channel in the southeast impact structure rim. The channel is up to 150 m deep and 400 m in width and has morphology similar to outlet channels produced by fluvial rim dissection of terrestrial impact structures and “tadpole craters” on Mars.

On the hydrothermal nature of cherts in the Artinskian stage deposits of the Cis-Urals

Relevance. The results of paleontological, geophysical, and mineragraphic studies of flints in Artinskian stage deposits in the Cis-Urals are presented. Purpose of the work. Reef organogenic structures with silicified limestones and flints, silicified sandstones and injections of flints into them have been studied. The goal is to show the hydrothermal nature of chert injections into reefs and sandstones. Research methods. Geophysical electrical prospecting studies of reef limestones with the aim of identifying areas of silicification, geological and paleontological mapping of reefs, biostromes, bioherms, sandstones, areas of accumulation of nodules and flint nodules, study of polished sections of silicified rocks, production of thin sections and their mineragraphic study. Results of the work. Paleontological mapping of the reef structure made it possible to establish the different species composition, size, and preservation of biota in the coastal, summit and outer parts of the reef. Mineragraphic studies have established the high-temperature hydrothermal nature of chert in all types of sediments. Hydrothermal injections of chert into sandstone layers occur by diffusion with the formation of siliceous nodules and Lysigang rings in sandstones. Intensive penetration of silicon hydrotherms into sandstone layers forms areas of silicification in them in the form of laccoliths tens of meters in size. Various degrees of development of flint hydrotherms by marine fauna have been established. Flints may include small specimens of small fauna, be rich in well-preserved fauna, or include layers of biota overlain by layers of flints covered with new colonies of microorganisms. Sometimes cherts contain only fragments of faunal shells caught in the hot gel of cherts. Conclusions. Hydrotherms of siliceous composition in loose marine sediments could be a condition for the development of biota and the basis for reef structures. Increased values of electrical resistivity of flints and silicified limestones allow electrical prospecting to explore the internal structure of reefs. It has been suggested that in the Carboniferous and Early Permian in the Cis-Urals there was a hydrothermal belt extending from Kungur to Sterlitamak.

SEISMICITY of YAKUTIA in 2018–2019

According to the information received from 20 stationary digital seismic stations of the Yakutia Branch of Geophysical Survey of the Russian Academy of Sciences, two-year (2018–2019) seismic monitoring of the territory of the Republic of Sakha (Yakutia) was carried out. During this time interval, more than 730 earthquakes with an energy class of KR≥7.2 (magnitude M≥1.8) were registered. During the previous two years, their number was 801. Manifestations of seismicity fixed the spatial position of the contact zones and their constituent blocks of known lithospheric plates: the Eurasian and North American plates in the northeastern and arctic regions, as well as the Eurasian and Amur plates – in the southern areas of Yakutia. The epicentral fields traced individual relief lineaments and identified active boundary structures combined into two large-scale seismic belts – BaikalStanovoy and Arctic-Asian. Their outlines are seen as bands of earthquake epicenters, elongated from the Olekma River to the Sea of Okhotsk in the south and as ensembles of separate groups and chains of earthquakes between the Laptev and Okhotsk Seas in the northeast and in the Arctic. Significant seismic activity has been detected in the northeast of the region – in the Olekminsk region and the Aldan Highlands (South Yakutia), as well as in the Yano-Oymyakon Highlands, the Chersky Ridge and the Laptev Sea. A map of epicenters was constructed for the entire territory of the region, where 12 districts were identified and an analysis of the seismotectonic situation in each of them was given. The map of Arctic earthquakes in the Lena River delta is considered separately. It is compiled according to the processing of digital seismograms obtained at 25 autonomous field stations installed in accordance with the Russian-German project "Seismicity and Neotectonics of the Laptev Sea Region" (SIOLA). In this area during 2016–2019 more than 2 thousand shocks of small energy classes KR≥7.2–10.7 (M≥1.8–3.7) were recorded within the depth interval of 1–36 km of the Earth's crust. The characteristics of the most seismically active local tectonic structures developed in this region are given.

SEISMICITY of KAMCHATKA and COMMANDERISLANDS in 2018–2019

The seismicity review of Kamchatka and surrounding territories for 2018–2019 is given. In the Kamchatka earthquake catalogue, the minimum local magnitude of completeness is MLmin=3.8, and for the Kamchatka seismically active region (latitude = 50.5–56.5° N, longitude = 156.5–167° E) MLmin=3.7, and for earthquakes with h≥350 km under the Okhotsk sea MLmin=3.8. The Kamchatka earthquake catalogue for 2018–2019, published in the Appendix to this article, includes 3646 events with ML≥3.5; 228 earthquakes with ML=3.65–7.3 were felt in Kamchatka and surrounding areas with seismic intensity I of 1–2 to 6–7 according to the Seismic Intensity Scale-2017 (Russian state standard). For 134 events with ML≥5.0 that occurred in 2018–2019 within the area of responsibility of Кamchatka branch of Geophysical Survey RAS, an attempt to calculate the seismic moment tensor (SMT) was made. The SMT and depth h of the equivalent point source were calculated for 67 earthquakes in 2018 with a range of ML=5.0–7.3, and for 67 events in 2019 with a range of ML=5.0–6.45. The level of seismicity according to the "SOUS'09" scale in 2018 corresponded to the “background increased”, but within the assessment accuracy – “high”; for 2019 it was the “background average”. On December 20, 2018, there was a strong earthquake with Mw=7.3, named “the Angular Uplift earthquake”. This earthquake was the strongest intraplate event, which belongs to the region south of the junction zone of the Kamchatka and Aleutian trenches The earthquake was accompanied by a large number of aftershocks.

SEISMICITY of the AMUR and PRIMORYE, SAKHALIN and the KURIL-OKHOTSK REGION in 2018-2019

A review of the Amur and Primorye, Sakhalin, and the Kuril-Okhotsk region seismicity for 20182019 is presented on the basis of data from the regional network of stationary seismic stations of the Sakhalin branch of the Geophysical Survey RAS with the involvement of data from adjacent seismological Russian and foreign agencies, as well as ten stations of the local network operating in the south Sakhalin. Parameters of 4989 seismic events have been determined, 193 of them are explosions. Focal mechanisms were calculated for 88 earthquakes. 116 earthquakes have shown a macroseismic effect. A map of the epicenters is presented, the distribution of the number N of crustal and deep-focus earthquakes by a magnitude, a total seismic energy ∑E for seismically active regions of three regions are given, in comparison with the average parameters N and ∑E for 20012017. For each region, an analysis of the parameters of the seismic regime in 20182019 is given in comparison with long-term averages, the maximum and significant seismic events are described. The seismicity of the Priamurye and Primorye, Sakhalin, and the Kuril-Okhotsk region in 20182019 can be characterized as a moderate one.

Integrated geomorphological analysis of a Mediterranean temporary pond priority habitat: the Lago del Capraro doline (Salento peninsula, Italy)

The Lago del Capraro doline (Salento peninsula, southern Italy), a valuable Mediterranean Temporary Pond (MTP), has been investigated aiming to define its geomorphological features and to collect data about the local hydraulic regime. At the bottom of the Lago del Capraro doline, in fact, a small temporary pond appears soon after major precipitation events as that one of autumn 2013. The morphological survey shows that this solution doline is placed on a karst plain surface stretching at about 70 m of altitude; the doline has an elliptical shape with the major axis 130 m long whereas the length of the minor axis is about 100 m. It shows a flat bottom, placed at about 65 m above m.s.l., due to the presence of a colluvial sandy clays filling, bordered by steep limestone slopes about 5 m high. Geophysical surveys and a cone dynamic penetrometer test allowed a detailed geological model to be realized. In particular, ERT and seismic refraction models revealed the geometry and the thickness of doline filling deposits as well as the preferential infiltration zones of surface waters. Interestingly, the cone penetrometer test reveals that resistance decreases downward in the filling lower part, most likely because of the active solution process at the doline bottom. The results of this study suggest an increase of surface water infiltration at doline bottom in the next future so that the development of a pond will be an increasingly rare event, partly compensated by the clustering of rainy periods during autumn months as expected in the future by climate models.

Optimal set of geological exploration works and development directions in the Sea of Okhotsk

Background. The optimal complex and directions of further geological exploration in the waters of the Sea of Okhotsk are considered. All the promising areas recommended for licensing occupy significant territories and require a step-by-step study, including at the regional and zonal levels.Aim. Obtaining new full-fledged information through regional geophysical surveys in order to assess new promising areas of the Sea of Okhotsk.Materials and methods. Systematization of data and statistical generalization, partial borrowing of materials from field data, reference literature and published materials.Results. As a result of the research, recommendations are given to reduce geological risks, assessment of promising sites, comparative characteristics of resource assessments of the research area. The significant potential of the Okhotsk Sea area may be associated with the lower (Eocene) structural floor. However, these estimates are based on encouraging, but far from complete geochemical information about the potential of the oil and gas mother strata.Conclusion. It is necessary to carry out an audit of the existing seismic data from the point of view of vertical resolution and establish the current seismic study. Taking into account this information, design and perform additional volumes of 2D seismic exploration sufficient to solve the set geological tasks, the main of which is the construction of a detailed structural framework of the sedimentary cover. The second most important geological task is a large-scale study of the geochemical properties of the organic matter of the rocks of the Eocene part of the section (in outcrops, wells), establishing changes in these properties depending on the paleogeographic situation for their more correct extrapolation to the water area.

Недеструктивно археологическо проучване в местността „Долната чатма“ при село Велино, Шуменско

In the late autumn of 2022, a non-destructive archaeological survey was carried out in the territory of Velino village, Shumen municipality. The survey went through several stages: 1) collection of preliminary information on the names of localities and toponyms in the area of the survey; 2) conducting a field survey during which accumulations of large unprocessed stones and a relatively large concentration of fragmented Old Bulgarian household ceramics were registered; 3) aerial photogrammetric survey of the terrain, as a result of which a digital elevation model and an ortho-photo plan of the area designated for study were produced. The contours of linear structures of artificial origin were clearly visible; 4) geophysical survey in four zones, which confirmed the proposals for the presence of anomalous zones; 5) vertical electric sounding with the aim of studying the stratigraphy of the object during which it was established that the structures probably develop at a depth of 0.80-1.00 m from the contemporary terrain. The results of the non-destructive archaeological survey in Dolnata Chatma locality, near the village of Velino, Shumen region show that linear stone structures develop on the flat terrace east of the village, probably part of a presumed archaeological object. At this stage, its scope, chronology and character are not clarified, and this remains a task for the team in future exploratory and subsequently regular archaeological surveys.

Developing a conceptual model of groundwater – Surface water interactions in a drought sensitive lowland catchment using multi-proxy data

Frequencies and intensities of droughts have increased due to climate change, providing an urgent impetus to improve understanding of ecohydrological fluxes in drought-sensitive areas where water and food security are threatened. We used a multi-proxy approach for assessing the effects of landuse and catchment properties on recharge and groundwater – surface water interactions during a prolonged drought starting in summer 2018 in a 66 km2 lowland, mixed landuse catchment (Demnitzer Mill Creek, Germany). We used water table monitoring, water stable isotopes, tritium isotopes, hydrogeochemical tracers, streamflow observations and geophysical investigations to characterise the spatial and temporal patterns of groundwater recharge in a shallow, unconfined aquifer system. Long-term groundwater levels showed a declining trend since 2011, which accelerated after 2018 resulting in increasingly intermittent streamflow. Geophysical surveys and groundwater monitoring indicated that shallow water tables (typically < 3 m deep) in low to moderate permeability surficial deposits are generally recharged during winter, leading to higher groundwater – surface water connectivity in riparian alluvial aquifers, which is the first order control on streamflow generation. This was supported by similar geochemical characteristics of groundwater and streamflow. Water stable isotopes indicated a high damping in groundwater with a bias towards winter precipitation and direct recharge. Groundwater age estimates using tritium showed high uncertainty but indicated that shallow groundwater was < 10 years old and generally similar to streamflow. Such multi-proxy approaches help understand changes in groundwater recharge and stream-aquifer interactions during droughts and contribute to the development of sustainable land and water management strategies for groundwater systems that are sensitive to climate change.

Factors influencing the creation of high-impact oil and gas geophysical seismic cutlines in an ecologically-sensitive landscape in northeastern British Columbia, Canada

Oil and gas (OG) resource extraction has adverse impacts on landscapes despite the socio-economic benefits that trickle down to society. Whereas many recent studies have focused on direct landscape change from OG activities, this study focuses on factors associated with the creation of high-impact OG seismic cutlines, geophysical survey paths that have widths of more than 5.5 m. Using geographic information systems and a spatially-explicit logistic regression framework, we model the relationship between high-impact seismic cutlines and associated explanatory variables (e.g., seismic cutline type, land ownership type, etc.) by drawing on political ecology perspectives. The study finds that mechanically-cut seismic cutlines are 514.34 times significantly more likely to be high-impact seismic cutlines as compared to hand-cut seismic cutlines. We find that seismic cutlines found on private land are 0.05 times significantly less likely to be high-impact type as compared to those found on crown (public) land. These findings suggest that societal land use decisions and preferences are likely to influence the creation of spaces for different levels of OG land user–environment interactions. Thus, land use managers are presented with unique land use challenges that require environmental management strategies for dealing with the impacts of OG activities on the environment.

Application of Electrical Resistivity Method to Decipher Groundwater Occurrence Status at Isikuku, Southern Nigeria

Electrical resistivity method is a type of geophysical survey employed for groundwater investigation, conducted in Isikuku Community in Benin City, Edo state with the aim of delineating groundwater occurrence. Schlumberger electrode array configuration was employed in this study. Six (6) VES points were surveyed with linearised inversion technique used for the interpretation of sounding taken at various locations in the area. The data collected were interpreted by curved matching and computer iteration using Interpex Ix1D v 2 software. From the geoelectric section, VES 1 possess the AK curve with four layers ρ1˂ρ2˂ρ3˃ρ4, VES 2 possess the KQ curve with four layers ρ1˂ρ2˃ρ3˃ρ4, VES 3 possess the A curve with three layers ρ1˂ρ2˂ρ3, VES 4 possess the AK curve with four layers ρ1˂ρ2˂ρ3˃ρ4, VES 5 possess the A curve with three layers ρ1˂ρ2˂ρ3, VES 6 possess the K curve with three layers ρ1˂ρ2˃ρ3. Geo-electrical layers identified in the study area included topsoil, sandy clay, clay basement and sandstone. The VES study revealed the layer which constitute the productive water-bearing zones referred to as good groundwater potential aquifers. The analysis of the interpretation of the field data showed that the area under investigation delineated four layers earth in each of the vertical electrical sounding point. Generally, the geoelectric survey conducted in the study area revealed the subsurface lithologies: Clay, Clayey Sandstone, Sand stone, Coarse Sand, Lateritic soil and Top soil. Thus, vertical electrical sounding techniques employed in this study has proved useful and successful in delineating subsurface lithology in the study area.

A Numerical Output Technique for Voxler’s ObliqueImages and Its Application

In geophysical surveys, there will be no measured data at some location where it is inaccessible for placement of survey points or lines. The interpolation data of those locations can be obtained and displayed by using three-dimensional (3D) mapping platform. Based on the study of the file format of ObliqueImage output in Voxler platform, this paper presents a technique for extracting spatial coordinates and physical parameter values of each point in the ObliqueImage. This numerical output technique is used to map the profiled slice across the tunnel axis where boreholes can not be arranged in the electromagnetic wave CT investigation section in a dedicated karst survey of an underwater tunnel in Wuhan, rendering the karst development on the profile across the tunnel axis; after further extension, the point cloud data of bedrock surface and karst caves for building 3D geological model are extracted from isosurface files, which provides data basis for tunnel design and construction digitization.

Marine Geophysical Survey of a Medieval Shipwreck in Shallow Waters Using an Autonomous Surface Vehicle: A Case Study from Avaldsnes, Norway

This study demonstrates the successful use of a single-channel chirp system mounted on an Autonomous Surface Vehicle (ASV) for detecting and mapping a partly buried medieval ship found in water approximately one meter (m) deep in a dynamic, intertidal environment at Avaldsnes, south-western Norway. The ASV's fast mobilization and access to areas otherwise difficult to reach, makes it an efficient, low-cost, and non-invasive platform for examining the seafloor and subsurface with high-resolution seismic data, acquired in a dense grid. Line spacing of 0.25 m allowed for the generation of a detailed 3D data cube, enabling effective interpretation of both acoustic vertical sections and horizontal amplitude maps. This approach empowered accurate identification of the outline of the wooden hull and provided information about ship dimensions and maximum burial depth. Structural elements observed in the geophysical datasets, including the keelson, raiders, and maststep, corroborates with findings from previous diving investigations and photogrammetry documentation. Moreover, the geophysical survey offers valuable additional knowledge of the buried ship remains, revealing a slight tilt of the keel and a substantial object buried in close proximity to the stern, probably the rudder or another wreck-related artefact.

Engineering geological conditions for the construction of a photovoltaic power plant on coal tailings

Photovoltaic power plants have recently become increasingly common to reduce carbon emissions into the atmosphere. Non-fertile lands occupied by industrial waste are very suitable for their construction. The present study concerns the design and construction of a photovoltaic park on the territory of a reclaimed coal tailings dump “Suhoto Dere” near the TPP “Bobov Dol”. The study includes collection, processing and analysis of archival materials, site mapping, drilling of exploration boreholes, dynamic penetration tests, geophysical electrical resistivity survey, laboratory testing of soil samples to determine physical and mechanical properties; chemical analysis of soil samples to assess soil aggressiveness to concrete and steel. Based on the obtained data, an assessment of the suitability of the site is made and recommendations are given to prevent the occurrence of adverse phenomena and processes.

Heat Flow Prediction in Songliao Basin Based on Deep Neural Network

The heat flow is the key data for accurately predicting the contribution of underground heat, but due to the high cost of measurement, the spatial difference is huge, and the heat flow information in some areas is little known. This paper uses deep neural network technology to perform machine learning on a large number of relevant geological and geophysical features and heat flow measurements on a global scale. In addition, the model uncertainty quantification process is introduced, and the reliability of the prediction results is discussed based on the global sensitivity analysis and correlation calculation of the deep learning method. Finally, for the distribution map of heat flow and absolute difference in the Songliao Basin in the study area, the measured data error is less than 11%, and the predicted absolute difference is less than ±20 mW/m2. The results prove the accuracy of the method and the abnormal high heat flow in the central region of the basin. The existence of, further combined with the results of geophysical surveys, provides evidence for the analysis of regional thermal causes.

Defining of prospective areas for the localization of groundwater in fractured massifs (on the example of the Municipality of Brezovo, Plovdiv Region)

The northern part of the Municipality of Brezovo falls within the range of a fractured massif, which predetermines the presence of springs with a limited flow rate, insufficient for water supply for the villages there, which necessitates the localization of suitable locations for boreholes drilling. After a complex assessment of the geological-hydrogeological and tectonic conditions and field surveys, favorable sections were determined with prerequisites for the presence of probable water-saturated fractured zones. As a result of geophysical surveys carried out using the SP method, in the area of the villages of Svezhen, Chehlare and Rozovets, deep water-bearing zones were delineated, which were convincingly confirmed during the subsequent exploratory drilling.

THE ZABAIKALIAN PARAMETRIC BOREHOLE: A FIRST EVIDENCE ABOUT DEEP STRUCTURE OF THE BORSHCHOVOCHNY METAMORPHIC CORE COMPLEX

The Zabaikalian parametric borehole drilled out a metamorphic core complex on the reference geological and geophysical profile within the Central Asian fold belt, south of the Mongol-Okhotsk suture zone. In the section of the borehole drilled to a depth of 2600 m, a set of geophysical, geological and laboratory-analytical studies identified three main structural elements of metamorphic core complexes: the upper plate, detachment, and the lower plate. The upper plate (weakly metamorphosed rocks) is represented by serpentinite melange, which is separated from the underlying rocks of the lower plate by a zone of chlorite breccias (detachment). The lower plate, which is part of the crystalline basement complex, includes rocks of granite-schist and granite-plagiogneiss subcomplexes. The granite-schist subcomplex is composed of mafic and intermediate schist with amphibolites and quartzites. Biotite granite is widespread in the section; it forms layered veins with signs of synkinematic formations. According to preliminary estimates, the age of biotite granite is about 130 Ma. The schist is characterized by mylonite structure at intervals of interbedding with biotite granite veins. In accordance with data of geophysical surveys in the borehole and the petrophysical characteristics of cored rocks, the mylonite zone is the provenance of a series of inclined reflectors on the seismic reflection-CDP section, which can be traced to a depth of at least 10 km. The granite-plagiogneiss subcomplex is represented by plagiogneiss, leucogranites, and gneissic granites. In the Zabaikalian parametric borehole, a detailed section of the orshchovochny metamorphic core complex, fully characterized by core samples, of the was obtained, which should be considered as a reference for studying these structures. The investigation of this section will answer later many questions about the formation and evolution of the Central Asian fold belt.