Deep electromagnetic (MT and AMT) sounding of the suture zones of the Ukrainian shield

Antsiferov, A. V.; Sheremet, E.; Nikolaev, Yu. I.; Nikolaev, I.Yu.; Setaya, L.D.; Antsiferov, V. A.; Omelchenko, A.

doi:10.1134/s1069351311010010

Cited by 4 publications

(4 citation statements)

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“…Anomalous feature of the suture was studied in various papers (e.g. [Antsiferov et al,2011;Shirkov et al, 2017]) and its nature might be associated with the tectonomagmatic activation and fluid transport in the crust and mantle.…”

Section: Modeling Resultsmentioning

confidence: 99%

Geodynamics

Kováčiková¹,

Logvinov²,

Tarasov³

2022

JGD

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The purpose of the work is to study the features of seismotectonics of the junction zone of the Oash and Transcarpathian faults in the Ukrainian Transcarpathians. The research methodology combines a complex analysis of geological-tectonic, seismological, geomorphological and geodetic data on the studied area. For the clarification of coordinates and depths of local earthquake foci we applied methods of their hypocenters specification, using a calculated seismological hodograph and kinematic corrections. Geological and geophysical data, in particular on regional profiles, were used to link seismic events to specific geological structures. It was established that a number of seismic events were recorded at depths of 40-52 km in the studied zone, in its northeastern part. They occurred simultaneously with traditional deep localization of seismic sources in the crust of the Transcarpathian depression (0-27 km deep), including at the depths of the sole of thrust sedimentary strata / roof of the pre-Neogene basement of the Transcarpathian depression (2-3 km deep) in the southwestern part of the studied area. Since these earthquakes are spatially localized to the northeast of the zone where the Transcarpathian deep fault is traced by geological and geomorphological data on the surface, they indicate the subduction of the crustal structures of the Transcarpathian trough in this direction under the thrusts of the Folded Carpathians. This is also evidenced by the corresponding slope of the seismofocal zone at the intersection of the Transcarpathian Deep Fault at greater (15-30 km) depths. These and other features of local seismotectonics reflect the so-called "crocodile" tectonics in the Ukrainian Carpathians. The features encompass the reverse, south-west slope of the seismofocal zone at shallower (0-12 km) depths, as well as the features of the relief of the Carpathians in the studied seismogenic zone. They fully correspond to the characteristics of the "alpine" and "terrain" geodynamics of the region, i.e. compression and displacement in the northeastern and eastern directions, respectively. For the first time, the research established the presence of relatively deeper (30-55 km) seismic activity in the earth's crust of the Ukrainian Transcarpathians – in the zone of subduction of the Moho border under the Carpathians in the area of junction of the Transcarpathian and Oash deep faults. Additionally, the geodynamic and tectonophysical justification for its presence was given in terms of combination of "alpine", terrane and asthenolitic geodynamics of the region. Taking into account the features of seismotectonics of the Oash and Transcarpathian faults junction zone will contribute to clarifying the assessment of the characteristics and peculiarities of the spatial distribution of natural geoecological, in particular, seismotectonic risks and hazards in the central part of the Ukrainian Transcarpathians.

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Section: Modeling Resultsmentioning

confidence: 99%

Geodynamics

Kováčiková¹,

Logvinov²,

Tarasov³

2022

JGD

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“…For the core, the value of the gravitational effect was de fined as 367,131.8 mGal. The gravitational effects from the up per and lower mantle were calculated using the data obtained from the five reference models (AK135, IASP91, PREM, PEMA, PEMC), adding the values for the crust at the point of calculation according to the data on the density of the crust of the Ukrainian Shield given by Svistun, et al [10], Kurlov, et al [13], Azarov, et al [14,15], Antsiferov, et al [16,17]. By com parison of the total amount with the value of 981,658.94 mGal, it was found that the value of the total gravity field calculated using the AK135 model has the smallest deviation.…”

Section: Introductionmentioning

confidence: 99%

“…The AdamsWilliamson equation (10) for the first iteration step requires initial density parameters ρ 0 . The initial densities at the 50 km level were provided by Kurlov, et al [13], Azarov, et al [14,15], Antsiferov, et al [16,17].…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional density model of the mantle beneath the Ukrainian shield

Shumlianska,

Pigulevskiy,

Vilarrasa

2024

Nauk. visn. nat. hirn. univ.

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Purpose. Mantle density models are key tools for understanding the fundamental geological and physical processes occurring within the Earth and are essential to our scientific and applied understanding of the planet. Methodology. The tasks were solved by a complex research method, including analysis and generalization of literary and patent sources, analytical, experimental studies, using computer and mathematical modelling methods. Findings. One-dimensional models simplify the mantle density distribution by assuming that it is uniform only in the vertical direction. This limitation does not allow for horizontal variations in mantle density, which may be important on a regional scale. 3D models are more complex and require more data and computational resources, so their use may be limited. In this study, we present a quasi-three-dimensional model of mantle density beneath the Ukrainian Shield. This 3D model is obtained using a basic set of one-dimensional seismic tomographic velocity models calculated for 21 mantle domains in the depth range from 50 to 2,600 km. The process of converting the P-wave velocity model into a density model includes the following stages: 1) determining seismic boundaries in the mantle based on P-wave velocity curves for each mantle domain; 2) creating a synthetic mantle model beneath the Ukrainian Shield for the P,S-wave velocity curves; 3) solving the Adams-Williamson equation for each domain, considering polynomial corrections to extract heterogeneities during its solution; 4) analysing existing models by comparing the calculated gravitational potential at the central point of the Ukrainian Shield as the standard reference for selecting one of 5 reference models. Here, we focus on the final stages of constructing the mantle density model by: 1) balancing the mass of the upper and lower mantle for each domain when determining density using the Adams-Williamson equation and introducing polynomial corrections; 2) calculating densities for each of the 21 mantle domains and their 3D integration. Originality. The obtained mantle-density model of the Ukrainian Shield aligns well with the division of the mantle into three main layers: lithosphere, upper mantle, and lower mantle. Each of the mantle’s structural layers has its representation pattern in density heterogeneities. Anomalies of decreased density in the lithosphere of the Ukrainian Shield correlate with thermal anomalies, whereas anomalies of increased density correspond to tectonic zones dividing its megablocks. Practical value. Regions of increased density gradient are associated with mantle thrust faults, which in some cases can be boundaries between different petrological formations and serve as channels for magma ascent into the Earth’s crust at certain stages of geological development of the Ukrainian shield and, in turn, be sources of minerals.

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“…1. The region of the central part (49°15'-50°40' N × 28°45'-30° W) of the 3D geoelectric model area of the Zvizdal-Zaliska and Brusyliv FZ of the USH on the scheme of megablocks and fault zones of the USH (inset) according to data [Gintov et al, 2018] and the geological-tectonic map of the surface of the crystalline basement according to [State ..., 2003[State ..., , 2005]: 1 -deep and main faults (a), other tectonic disturbances (б); 2 -observation points of MTZ and MVP: in red according to data [Nikolaev et al, 2019, 2020, Ilyenko, 2020, in yellow and blue [Antsiferov et al, 2009]; 3 -tippers for a period of 100 s (observed in black, model calculated in red); 4 -profiles (I -Radomyshl-Fastiv [Nikolaev et al, 2019]), II -Korninsky [Ilienko et al, 2020] and III -Shirmivka-Logvin [Ilienko et al, 2019]). USH megablocks: П -Podil, Р -Rosyn, В -Volyn.…”

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confidence: 99%

Three-dimensional geoelectrical model of the central part of the Zvizdal-Zaliska and Brusyliv fault zones of the Ukrainian Shield

Burakhovych

Ilienko

Kushnir

2023

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To study the deep structure of the geoelectrically complex junction zone of three megablocks of the western part of the Ukrainian Shield (Volyn', Podil, and Ros'), a three-dimensional model of the central part of the Zvizdal-Zaliska and Brusyliv fault zones was created. It is based on modern experimental observations of the Earth's natural low-frequency electromagnetic field in a wide range of periods. Synchronous experimental data of deep magnetotelluric sounding and magnetovariational profiling, obtained by the Institutes of the National Academy of Sciences of Ukraine in 2009—2019, were analyzed. The main issues of the geoelectrical modeling methodology using the Mtd3fwd software complex were considered, such as model elements, stages, alternative models, examples of calculations and comparison of observations, errors, etc. The constructed model analysis showed that of the large number of near-surface anomalies with low resistivity (5 to 100 Ohm · m), most sink to 500 m and only a few reach a depth of 1 km and are followed up to 11 km. It was established that there are connections between conductivity and structural features of the Zvizdal-Zaliska, Brusyliv, Nemyriv fault zones, the Samgorod fault and the Kocheriv synclinorium. Most of the isolated conductors appear in a mosaic pattern along the extended fault zones and form interspersed chains of high and low resistivity. Regional anomalies were confirmed and detailed both in the deep part of the crust and in the upper mantle; part of the Zvizdal-Zaliska fault zone appeared at depths of 15—30 km as a contact zone of abnormally high and low resistivities. Anomalies are confined to elongated zones of metasomatization and graphitized rock areas, some of the surface anomalies correspond to areas of the weathering crust. Most of the anomalies coincide with ore occurrences, ore-bearing fields and mineral deposits. The conducted geological-geoelectrical analysis of the model made it possible for the first time to identify two promising areas for further study that meet the geoelectrical criteria for the mineral search: along the Zvizdal-Zaliska fault zone between the Samgorod and Unava faults; along the Samgorod fault in the area of its intersection with the Kocheriv and Taboriv faults.

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Deep electromagnetic (MT and AMT) sounding of the suture zones of the Ukrainian shield

Cited by 4 publications

References 1 publication

Geodynamics

Geodynamics

Three-dimensional density model of the mantle beneath the Ukrainian shield

Three-dimensional geoelectrical model of the central part of the Zvizdal-Zaliska and Brusyliv fault zones of the Ukrainian Shield

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