Morphostructural Analysis Research Articles

Tectonic control on sedimentary dynamics in intraplate oceanic settings: A geomorphological image of the eastern Canary Basin and insights on its middle-upper Miocene to quaternary volcano-tectonic-sedimentary evolution

This paper integrates sedimentary, tectonic and volcanic geological processes inside a model of volcano-tectonic activity in oceanic intraplate domains related to rifted continental margins. The study case, the eastern Canary Basin (NE Atlantic), is one of the few places in the world where giant MDTs and Quaternary volcanic and hydrothermal edifices take place in intraplate domains. In this paper, we analyse how two structural systems (WNW-ESE and NNE-SSW) matching with the oceanic fabric control the location of volcanic systems, seafloor tectonic reliefs and subsequently the distribution of main sedimentary systems. Linear turbidite channels, debris flow lobes and the lateral continuity of structural and volcanic reliefs follow a WNW-ESE trend matching the tracks of the oceanic fracture zones. Furthermore, escarpments, anticline axes and volcanic ridges follow a NNE-SSW trend matching normal faults delimiting blocks of oceanic basement. The morpho-structural analysis of all the above geomorphological features shows evidence of a volcanic and tectonic activity from the middle–upper Miocene to the Lower–Middle Pleistocene spread over the whole of the eastern Canary Basin that reached the western Canary Islands. This reactivation changes the paradigm in the seamount province of Canary Islands reported inactive since Cretaceous. A tecto-sedimentary model is proposed for this period of time that can be applied in other intraplate domains of the world. A tectonic uplift in the study area with a thermal anomaly triggered volcanic and hydrothermal activity and the subsequent flank collapse and emplacement of mass transport deposits on the Western Canary Slope. Furthermore, this uplift reactivated the normal basement faults, both trending WNW-ESE and NNE-SSW, generating folds and faults that control the location of turbidite channels, escarpments, mass transport deposits and volcanic edifices.

The role of fault reactivation in the geomorphological evolution of coastal landforms on passive continental margins: Evidence from a tectonic estuary in southern Brazil

Coastal areas are unique, fast-changing environments shaped by the action of a wide range of climatic, anthropogenic and geological factors. Tectonic processes (e.g., subsidence, uplift, faulting and tilting) are major controls of landscape evolution and may be responsible for significant changes in river catchments, sea level and erosion rates on coastal zones. In continental passive margins, however, strong tectonic influence is typically attributed to early post-rift evolutionary stages, while changes in climate and/or sediment flux become increasingly dominant in the latest phases. However, there are key exceptions to this rule. We provide new results on an estuarine system formed due to reactivation of major structures crossing the southern edge of Serra do Mar escarpment, where Precambrian terrains, Cretaceous volcanic rocks and Neogene coastal deposits coexist. Morphostructural analysis revealed strong morphometric anomalies near Proterozoic fault zones marked by local subsidence and reactivation of oblique and normal faults, responsible for relevant changes in coastal landscape and tilting of the coastal plain towards the Atlantic Ocean. Despite major Late Holocene progradation along the southern Brazilian coast, local subsidence led to development and preservation of Babitonga Bay, an atypical tectonic estuary formed in the latest stages of passive margin evolution. Our findings imply that the common assumption of recent tectonic stability for intraplate passive margins is false and may lead to misinterpretation of similar coastal systems around the world.

Neotectonic vertical movements of Northern Sikhote-Alin and adjacent territories and its relationship with the characteristics of the stream network

Morphostructural analysis of the relief and the analysis of the self-similarity characteristics of stream network of the Northern Sikhote-Alin and adjacent territories were carried out. The relief of the studied territory has an inherited character; it was formed in several stages during the neotectonic stage. The most intense vertical movements occurred at the early phases of the neotectonic stage. At Pleistocene time the intensity of vertical movements decreased significantly. At this time, the modern erosion-denudation forms of relief was formed. At the final stages of neotectonic development (at the end of the Pleistocene — Holocene), there was a slight activation of vertical movements with a changes in the structural plan and the manifestation of NNE stretched structures in the relief, which was reflected in the features of the residual relief. The boundaries of areas with increased residual relief coincide with areas of increased seismicity in the region. A modification of the complex self-similarity parameter PRNS was proposed, the use application of which allowed us to improve the correlation of this parameter with the latest (youngest) movements detected by the morphostructural method. Zones of maximum PRNS values correlate with the areas of greatest relief increment, and zones of it’s minimum correlate with areas the smallest relief increment, or areas of most significant erosion. The results of the analysis of the characteristics of self-similarity of the stream network are mainly comparable with the manifestations of vertical tectonic movements at the final stages of neotectonic development.

GIS based integration of multi-spectral remote sensing and morphostructural analysis for delineating potential areas of hydrocarbon exploration in Western Vindhyan Basin, India

The Chambal Valley forms the western part of the Proterozoic Vindhyan Basin that has been less studied and poorly explored from the hydrocarbon perspective than its eastern counterpart—the Son Valley Vindhyans. In the present manuscript, attempts have been made to use remote sensing and GIS (geographic information system) based analysis to focus on the northern part of Chambal Valley to decipher its tectonics and structural configuration, its tectonic relation with the Son Valley Vindhyans, Bundelkhand Massif and Ganga Basin. This study also assumes significance as it attempts to delineate potential lead areas for hydrocarbon exploration in Chambal Valley. As part of the study, a detailed spectral analysis based on image data sets is carried out to identify areas of microseeps as proxies of potential hydrocarbon accumulations. Also, a neotectonics-based geomorphic analysis is carried out to delineate a fault network and geomorphic highs that act as aliases to subsurface faults and structural highs. The results are subsequently validated by available geophysical data and extensive fieldwork, and suggest four structural trends in the Chambal Valley as striking NE-SW, E-W, NW-SE and N–S, of which the NW-SE trend is the oldest, followed by the NE-SW, E-W and N–S trends. A GIS-based analysis of the E-W trends indicates that these are probably manifestations of the westward continuity of E-W-trending shear zones developed in Bundelkhand massif within the basement of the Chambal Valley. Further remote sensing studies of the shear zone network exposed in the Bundelkhand massif indicate the pattern to be replicated on a larger scale in the morphostructural fault layout in the adjacent Ganga Basin, implying these shear zones may be continuing in the basement of Ganga Basin and controlling structures developed later, and consequently the different petroleum system elements in the basin. A dip data based structural analysis of the Chambal Valley describes a regional synform attributed with an almost vertical NW-SE-trending axial trace. This axial trace may be in continuity with the NE-SW-trending synformal axis of the Son Valley with its trajectory sympathetic to the southern boundary of the Bundelkhand massif and the Central Indian Tectonic Zone (CITZ) – Aravalli Delhi Fold Belt (ADFB) geometry. Finally, based on the integration of the results of spectral and morphostructural analysis, a number of potential areas of hydrocarbon exploration are demarcated in the study area.

Integral assessment of the geodynamic conditions for the formation of the Black Sea basin and connection with the current regime of groundwater in its northwestern shelf

The paper has a multidisciplinary character connecting bathymetric, geophysical and geological information to innovatively reconstruct the geodynamic conditions of the Black Sea basin formation, their influence on the modern relief and groundwater regime within its northwestern shelf as a reference region. The major goal is the rationale of modern geodynamic settings for the Black Sea Basin against the back- ground of the processes of its closure under tangential compression conditions, as well as their relation- ship with the hydrogeological conditions of the shelf zone. As primary evidence, the author determined the spatial positions of the Constanta-Sinop and SubPontian Suture Zones, pinpointing absorption locations of the Earth's crust at subduction zones. The facts and arguments presented in this paper are well integrated into the scheme of the oncoming of the Pontides island arc to the Eurasian Plate and the gradual closure of the back-arc marginal Black Sea Basin with a crust of transitional-type crust. The specific feature of the study is an innovative approach to comprehensive analysis of data that are a result of geological and geophysical works within the Black Sea water area. In doing so, major attention is paid to the spatial morphostructural analysis and interpretation of newly integrated digital data array, as a result of bathymetric surveys, namely the EMODnet 2019—2022. The subject of analysis is the basic structural surfaces, including the Modern and on its margin consolidated basement. New justification is formulated on the confinement of gas seeps and mud volcanoes, within the Black Sea Basin, to the deep earth`s crust structures. The graphical correlation of the mentioned ones is performed as well as their spatial position in the structural-geodynamic model of the region is theoretically substantiated. A generalized geomorphological zoning of the northwestern shelf of the Black Sea with the identification of the Dobrogea, Odesa and Kalamit zone is proposed. Within the Odesa geomorphological region, an integrated geological and geomorphological analysis was carried out and, as a result, dividing the shelf into submarine groundwater discharge (SGD) zone of aquifer was substantiated. The study, carried out by the author is of crucial importance to understanding the tectonic and geo- dynamic characteristics of the Black Sea Basin as well as for forecasting SGD zones and fresh groundwater resources. It is recommended to set targeted prospecting works to assess fresh groundwater resources in order to meet the water needs of coastal communities.

НЕОТЕКТОНІКА ТА МОРФОСТРУКТУРНІ ОСОБЛИВОСТІ РЕЛЬЄФУ ПРАВОБЕРЕЖЖЯ СЕРЕДНЬОГО ПРИДНІПРОВ'Я

On the basis of a complex structural-morphometric analysis, methods of remote sensing of the Earth and spatial modeling, the evolution of different-scale morphostructures of the right bank of the Middle Dnieper region is analyzed. Based on the created structural-morphometric models, the features of tectogenesis and morphogenesis during the Neogene-Quaternary time were revealed. The regional and local structures are characterized and the amplitudes of the latest and modern crustal movements within them are determined. The complex relationship between endogenous and exogenous relief formation has been confirmed, and the role of glacial influence on relief formation has been characterized. The nature of the relationship between structural-tectonic processes and the development of dangerous geological processes has been determined. Geological and geomorphological field studies revealed the characteristic structural and tectonic features of block structures and their influence on individual factors of geomorphogenesis. Tectonic-geomorphological modeling, taking into account morphostructural analysis, illustrated the formation of relief of various types under conditions of variable rhythms of endogenous and exogenous processes.

Interdisciplinary geoscientific approach to radioactive waste repository site selection: the Březový potok site, southwestern Czech Republic

ABSTRACT Interpretation of the deep geological and tectonic setting is a key step for safety assessment of the potential sites for a deep geological repository of radioactive waste. However, the conventional geological mapping is difficult in the agricultural landscape with lacking rock outcrops. To address this task, we combined geological and hydrogeological mapping, morphostructural analysis and geophysical methods to construct a new geological map and a 3D model of the Březový potok site in the southwestern Czech Republic. They provide unique constraints for the understanding of the subsurface geological and tectonic architecture. The results are compared with the archive geological data and the usefulness of individual geophysical methods to detect the lithological contacts and tectonic zones is discussed. We present this multi-disciplinary research strategy as a workflow for detailed geological characterization, which can be successfully applied on other sites with similar geological environment.

Elevation modelling of an area of the Siverskyi Donets riverbed (near Haidary village, Chuguyevskiy district, Kharkiv region)

Formulation of the problem. The article represents the practical experience of the bottom echo sounding and processing of the data received for digital elevation modelling. The relevance and specificity of using sonar equipment to study the specificity of the morphology of the underwater relief of small hydrological features are covered. The domestic and foreign publications in this area are analysed, and therefore the conclusion of the issue being not studied enough in domestic sources is made. Methods. The analysis of literature sources on modelling the river network, visualization of relief models. The bathymetric survey data was used to compile a bathymetric map of the river and build a digital elevation model. The purpose of the article is sharing developer experience in making of digital elevation models of a section of the riverbed on the example of the Siverskyi Donets River (near Haidary village, Chuguevskiy district, Kharkiv region). Processing of measurement data received as a result of echo sounder surveys. Preservation and recording of general information received to expand the river bottom relief database. Provide an overview of the uses and applications of geoinformation technologies, determine the research prospects based on the developed digital elevation models. Results. The results of echo sounding and post-processing of the data received using specialized software are presented. The section of the Siverskyi Donets River in the area of the geographical educational and scientific station «Haidary» was chosen as the territory for the hydrographic research (Haidary village, Chuguevsky District, Kharkiv region). The field part of the research was conducted using the equipment of the material and technical basis of the Physical Geography and Cartography Department of the V. N. Karazin Kharkiv National University, for instance using the Lawrance Elite 7 TI chartplotter-echosounder with modern scanning modes CHIRP, DownScan, StrucureScan. Scientific novelty and practical significance. The specificity of creating and visualizing in the ReefMaster software package is covered in the article. A model of the bottom of the corresponding section of the Siverskyi Donets River and a depth map, which will allow the future analysis of the dynamics and the prediction of changes of the bed configuration, have been developed on the basis of the field work results. The advantages of using budget equipment and software for performing underwater relief studies of such hydrological objects are formulated. The novelty of the study is not only the use of the methodological foundations of digital modelling, but also the alternative classification approaches for describing the relief and conducting morphostructural analysis based on the GIS technologies.

Paleoúdolí Doubravník–Borač ve světle elektrické odporové tomografie (ERT), jeho 3D model a vazba na hydrogeologický rajon 2242 (Kuřimská kotlina), karpatská předhlubeň

There is a narrow depression of the relief between Doubravník and Borač villages situated on the contact between the Bohemian Massif and Carpathian Fordeep of the Western Carpathians. Depression is mainly filled with Lower Badenian marine sediments, to a lesser extent also with Quaternary sediments of alluvial cones, loess and slope (colluvial) deposits. Current reflections on origin of the depression oscillate between the idea of an abandoned pre-Badenian valley of the Svratka River after a depression caused by purely tectonic processes. Disadvantage of the existing assumptions is that they rely on a minimum of objective data, especially in terms of thickness of sediments and the shape of the buried relief. The aim of this study is to increase knowledge about the tectonic structure, extent and thickness of sediments. Morphostructural analysis, field research and especially geophysical measurements (ERT) on 13 profiles with lengths of 81 to 595 m and a depth range of up to 65 m were used for this purpose.The work confirmed that the studied area is probably a paleo-valley of the Svratka River, which is divided by faults into several segments. The most significant appears to be the tectonic zone in the area between Borač and Maňová. In the interpreted results of ERT measurements, it manifests itself in a rapid change in the thickness of calcareous clays as on the D05 profile, the bottom of the valley was found at about 285 m a. s. l., while from other profiles towards Borač it is certain that the bottom altitude is at least 30 m lower (and tertiary sediments width on the surface section is bigger).What is the position of the rock bottom of the depression at the site of the divide with the D14 profile could not be determined, but it is definitely situated at a depth greater than 310 m a. s. l. From the profiles led directly in Doubravník (D01, D02, D15) it is clear that the deepest part of the valley filled with Lower Badenian sediments is situated W of Doubravník church, but towards the north it turns to the east. The bottom was not found, but it is lower than 270 m a. s. l.Overall, it is possible to summarize that within the section between Doubravník and Borač, the deepest shape of the relief is formed by meandering depression. Its position is different within today’s shape of the relief depression. The situation is similar in the direct parts of the Svratka valley north and south of this area of interest (between Nedvědice and Doubravník and between Borač and Štěpánovice). Therefore, the hypothesis of a paleo-valley of the Svratka River seems to be very probable. The diversion of today’s flow of the Svratka River between Doubravník and Borač to the current valley was caused by horst uplift and the overall change in the slope of the area after Badenian regression. There are also some hydrogeological impacts of this study. It is clear, the groundwater source (well HBV-1) is not situated in the deepest part of the valley, where sandy layers can be assumed, similar to that in Nedvědice (north from the area of interest). Besides groundwater flow under Badenian clays into hydrogeological district 2242 – Kuřimská kotlina (south from the areaof interest) from more distant parts of the Svratka River drainage area can be supposed, as the bottom of the Tertiary paleo-valley between Doubravník and Borač is not raised above the level of the floodplain. Also a significant failure of the underlying rocks at the contact of the Svratka Crystalline complex and the Moravicum (crystalline complex) certainly allows an uninterrupted overflow of groundwater under the insulator of Badenian clays.3D model is disponible on https://geology.maps.arcgis.com/home/webscene/viewer.html?webscene=c2bbd5de2c1c4f13b34119add56501e7 (and other from the Czech Republic: www.geology.cz/3d).

Paleoúdolí Doubravník–Borač ve světle elektrické odporové tomografie (ERT), jeho 3D model a vazba na hydrogeologický rajon 2242 (Kuřimská kotlina)

There is a depression of the relief between Doubravnik and Borac villages, filled mainly with Lower Badenian sediments, to a lesser extent also with sediments of alluvial cones, loess and slope (colluvial) deposits. Current reflections on its origin oscillate between the idea of an abandoned pre-Badenian valley of the Svratka River after a depression caused by purely tectonic processes. Their disadvantage is that they rely on a minimum of objective data, especially in terms of thickness of sediments and the shape of the buried relief. The aim of this study is to increase knowledge about the tectonic structure, extent and thickness of sediments. Morphostructural analysis, field research and especially geophysical measurements (ERT) on 13 profiles with lengths of 81 to 595 m and a depth range of up to 70 m were used for this purpose. The work confirmed that the studied area is probably a paleo-valley of the Svratka River, which is divided by tectonic faults into several segments. The most significant appears to be the tectonic zone in the area between Borac and Maňova. In the interpreted results of ERT measurements, it manifests itself in a rapid change in the thickness of calcareous clays as on the D05 profile, the bottom of the valley was found at about 285 m a. s. l., while from other profiles towards Borac it is certain that the bottom altitude is at least 30 m lower. What is the position of the rock bottom of the depression at the site of the divide with the D14 profile could not be determined, but it is definitely situated at a depth greater than 310 m a. s. l. From the profiles led directly in Doubravnik (D01, D02, D15) it is clear that the deepest part of the valley filled with Lower Badenian sediments is situated W of the church, but towards the north it turns to the east. The bottom was not found, but it is lower than 270 m a. s. l. Overall, it is possible to summarize that within the section between Doubravnik and Borac, the deepest shape of the relief is formed by depression with curves. Its position is different within today's shape of the relief. The situation is similar in the direct parts of the Svratka valley north and south of this area of interest (between Nedvědice and Doubravnik and between Borac and Stěpanovice). Therefore, the hypothesis of a paleo-valley of the Svratka River seems to be very probable. The diversion of today's flow of the Svratka River between Doubravnik and Borac to the current valley was caused by horst uplift and the overall change in the slope of the area after Badenian regression. There are also some hydrogeological impacts of this study. It is clear, the groundwater source (well HBV-1) is not situated in the deepest part of the valley, where sandy layers can be assumed, similar to that in Nedvědice (north from the area of interest). Besides groundwater flow under Badenian clays into hydrogeological district 2242 – Kuřimska kotlina (south from the area of interest) from more distant parts of the Svratka River drainage area can be supposed, as the bottom of the Tertiary paleo-valley between Doubravnik and Borac is not raised above the level of the floodplain. Also a significant failure of the underlying rocks at the contact of the Svratka Crystalline complex and the Moravicum (crystalline complex) certainly allows an uninterrupted overflow of groundwater under the insulator of Badenian clays.

Geomorphic analysis and quaternary neotectonic deformation in the eastern Babors chain, Bejaia, Algeria

The Eastern Babors are part of the Maghrebides chain formed by the alpine orogeny. This section of the Tellian Atlas is marked by a typical relief subjected to both tectonic and erosive activity observed in its rugged morphology and deep valleys. The paper highlights the link between external dynamics and neotectonic processes through the analysis of geomorphic factors and a morphostructural assessment. These factors are extracted from a series of processing using a Digital Elevation Model (DEM) in a GIS environment to quantitatively and qualitatively assess the response and evolution of the catchments in a morpho-tectonic context that characterizes the study area. Thus, we relied on hypsometric curve analysis, hypsometric integral distribution, elongation ratio and asymmetry. The indices were complemented by longitudinal profiles and the channel steepness index allowing a closer observation of the rivers' response to tectonic processes affecting the region by analyzing knickpoint and their relation with the fault zone that marks this region. Also, the uplift rate was estimated using the relative tectonic uplift index. The geomorphic factors reveal a young relief exposed to intense external dynamics in an active tectonic context. This is correlated with the hypsometric curves and longitudinal profiles confirming streams in equilibrium, while the breaking points highlight tectonic processes. The analysis of the relative uplift factor and the channel steepness index indicate an overall tectonic uplift in the region, with some areas uplifted more than others, particularly in the central region of the study area. Moreover, the channel steepness values reveal a tectonicly active zone around the Kherrata fault. In addition, this study is based on a morphostructural analysis in order to determine the different tectonic phases and, in particular, to highlight the influence of the current phase in the relief evolution. The different results obtained in this study reveal a rugged relief, young and strongly incised by a drainage system that undergoes tectonic and neotectonic activity that influences the evolution of the drainage system and the relief. This evolution is particularly observed in the center of the region and indicates that this region is marked by various tectonically uplifted blocks.

Back analysis of a coastal cliff failure along the Forkastningsfjellet coastline, Svalbard: Implications for controlling and triggering factors

Based on a morphostructural analysis of a cliff coast segment of Forkastningsfjellet, back analysis of the August 12th, 2016 rock slide situated at 78°19′10”N/15°39′52″E was carried out. This rock slide comprises a volume of 175,000 m3, and indicates a partial reactivation at the front of the ~100 million m3 large postglacial Forkastningsfjellet rock slide. We studied the controlling and triggering factors of the reactivation using a 2-D limit-equilibrium calculations and a 3-D simulation with Scoops3D. Slope instability initiated along a pre-existing listric block fault that was inherited from the postglacial Forkastningsfjellet rock slide. The cause of the failure is attributed to a strength decrease and additional water pressures along the pre-existing sliding plane, possibly in combination with a degradation of the affected weak shales of the Rurikfjellet Formation, which build up a major part of the steep slope.Although the analysis suggests a structural control on the type and mechanism of slope failure, a significant impact of climate-related factors is inferred. Increasing temperatures and changing precipitation trends are reported from Svalbard. These are interpreted to foster permafrost degradation and reduce bonding forces in the thawing ice-filled fractures at the site. In addition, progressive weakening by more frequent frost and thaw cycles of the slaking shales and the introduction of additional water pressures to the rock mass are considered to contribute to the instability. The final trigger of the 2016 failure is attributed to a two-day rainfall that had preceded the event.The application of the Scoops3D software tool showed that it is capable of predicting the locations and affected volumes of landslides with reasonable accuracy, when the geological and structural setting is well established. Under such premises the tool can be used to support preliminary susceptibility assessments in study areas with comparable geological and morphostructural settings.

Chemical and morpho-structural characterization of atmospheric aerosol (PM10 and PM2.5) in a city of São Paulo state, Brazil.

To access the sources of air pollutants is crucial to control atmospheric pollution in urban areas, minimizing human exposure. Particulate matter is a pollutant of great concern making its chemical and morpho-structural characterization of enormous importance. The present work aims at the characterization of atmospheric PM10 and PM2.5. Data of the aerosol mass concentration was correlated by multivariate analysis with water-soluble ion fraction composition accessed by ion chromatography (IC), as well as with meteorological information and air mass backward trajectories. The gravimetric analysis presented average values 3 to 4 times higher than the guide values recommended by the World Health Organization (WHO). A morpho-structural analysis by SEM/FEG coupled to EDS was also carried out identifying the coarse fraction elements from minerals and from soil resuspension organic spherical particles that originated from combustion processes as well as Ti, associated with long-distance transportation. In the fine fraction, Zn with origin probably in tires and vehicle brakes was found. These origins were confirmed by the air masses' backward trajectories obtained by the HYSPLIT model (NOAA). This study contributes to a better understanding of the complex composition of the particulate material in the atmosphere of Araraquara City, resulting from the combination of local and long-distance sources, and serves as a basis for the comparison with future studies related to the air quality at this and other regions in Brazil and in the world.

Late Pleistocene–Holocene stress in the South American intraplate evidenced by tectonic instability in central Amazonia

Abstract Documenting neotectonic instabilities and determining the style and time of deformation in the vast and difficult to access central Amazonia region is challenging. We focus on these issues by investigating a large area of the Negro River drainage basin, applying morphostructural analysis based on synthetic aperture radar data. The digital elevation models of the C-band Shuttle Radar Topography Mission and the L-band Protection System of Amazonia were used as the database. We also used subsurface magnetic information from the Earth Magnetic Anomaly Grid global model to validate the morphostructures. The results revealed NW-oriented morphostructural lineaments bounding multiple depositional valley fills. These were extensively fragmented to form regularly distributed en échelon rectangular blocks commonly offset horizontally by several kilometers. Strike-slip faults and oblique, either normal or reverse, faults are present. These structures were reactivated along the main NE- and SW-oriented regional structural trends due to N-S-oriented horizontal compression and E-W-oriented horizontal extension in the late Pleistocene and Holocene. The extensive neotectonic faulting results from the interplay of plate motion and Andean uplifting since the late Pleistocene, combined with local stresses.

Stress–Strain State of the Earth’s Crust in the Central Caucasus

The Caucasus is a region of continental collision between Eurasia and Arabia and one of the Earth’s most seismically active and rapidly deformed continental regions. The wide range of deformation processes occurring in this relatively limited region makes the Caucasus as a whole and its central parts in particular a unique test area, the study of which can improve our understanding of the complexities of the stress–strain state, as well as the associated seismicity. During the instrumental period of observations, many strong earthquakes have been recorded here, e.g., the August 4, 1974 Bezhta earthquake (Mb = 5.4), the 1978 earthquake with a magnitude of 5.7, the February 23, 1981 Gavaz earthquake (Mb = 5), the October 12, 1992 Barisakho earthquake (Mb = 6.1), and the July 5, 2012 Zaqatala (Mb = 5.7). We have constructed the mechanisms of strong earthquakes and compared the results with the tectonic conditions of the studied region. Based on a morphostructural analysis of the modern relief of the central and eastern Greater Caucasus, a diagram of its morphostructural blocks has been compiled. The average earthquake mechanisms were constructed for the distinguished blocks, the prevailing types of slip in earthquake sources in each selected block were identified, and the fault kinematics were reconstructed. The solution was based on generally accepted tectonophysical theoretical views, with the wide application of modern structural–geomorphological methods, modern GIS technologies, and morphological analysis of the modern relief of this region. The modern tectonic stress field was reconstructed based on seismological data on earthquakes recorded during the entire instrumental period (1971–2019).

EARTH SCIENCES AND GEOMORPHOLOGY DEPARTMENT OF KYIV UNIVERSITY: A XXI CENTURY PERSPECTIVE

The historiographical article is devoted to the analysis of the 70-year history and development of the Kyiv University Earth Sciences and Geomorphology Department and the formation of its educational, scientific and applied area activities. The presented list of educational and research areas and description of their essential principles testifies not only to the existence of certain stages in the department history, but also to formation of trends in scientific preferences of the teaching and research staff. Over the course of the Department’s work many theoretical and practical aspects of Earth Sciences have been developed including general and theoretical geomorphology, geomorphological mapping and zoning, Quaternary sedimentology and palaeogeography, structural geomorphology and morphostructural analysis, engineering and anthropogenic geomorphology, palaeogeomorphology and ecology, scientific principles of remote and expeditionary relief research. Modern applied scientific and educational areas of the Department are geomorphology and nature tourism (geotourism), and soil science, land management and spatial planning. The development of scientific principles of nature tourism as a factor of sustainable development will not only spread the scientific worldview, understanding of the society laws and environmental ideas, but will also attract national and foreign investment, facilitate the development of territorial communities and tourism as a highly profitable sector of Ukraine's economy. Soil science, land management and spatial planning as areas of theoretical and applied geographical research are crucial to meet the current challenges of decentralization and land reform. It covers the development of multi-level spatial planning methodologies for sustainable spatial development, methods of scientific substantiation of urban projects, land management project planning, soil protection measures, engineering protection of the territory to create a favourable human habitat, preservation of landscape diversity and natural and cultural heritage. In recent years, the research interests of the Department have also included management of eco-projects and geoarchaeological studies, which were formed on multidisciplinary approaches and provide a thorough scientific and practical base for training of future professionals. Key words: Kyiv University Earth Sciences and Geomorphology Department; palaeogeomorphology; ecological geomorphology; morphostructural analysis; nature tourism; soil science; land management; spatial planning; eco-project management; geoarchaeology.

Late Quaternary displacements along the Zunduk fault according to ground-penetrating radar and morphostructural analysis (northwestern coast of Lake Baikal)

The article considers the results of GPR studies of the Zunduksky fault section activated between the Cape Oto-Khushun and the Zunduk River, activated in the late Quaternary. The aim of this work is to clarify the kinematic type, determine the vertical displacement amplitudes, and dip angles of the Zunduksky active fault activated in the late Quaternary, as well as determine the maximum magnitude of the earthquake that could occur as a result of the activation of the fault. The work was carried out by OKO-2 GPR with a shielded antenna AB-90 and ABDL-Triton. In addition to the main method, morphostructural analysis of the ledge was used. As a result of the work performed, it was found that the Zunduksky fault in the Late Quaternary was activated under tectonic extension with predominant fault displacement kinematics. The one-act vertical displacements along the seismic fracture change from SW to NE from 6.9 to 1.6 m. When the Late Quaternary ledge of the Zunduksky fault formed, the plastic component of the displacement had a certain value, the contribution of which is from 18 to 78 % of the total displacement. Paleo-earthquake magnitudes calculated from the maximum vertical displacement are Mw = 7.3 and Ms = 7.5.

ВОПРОСЫ МЕТОДОЛОГИИ ГЕОЛОГО-ГЕОМОРФОЛОГИЧЕСКИХ ИССЛЕДОВАНИЙ ДЛЯ ЦЕЛЕЙ МЕТАЛЛОГЕНИИ

The basic questions of the methodology of geological and geomorphological study (ore geomorphology, morphostructural analysis, morphotectonics, neotectonics) of ore-bearing territories are considered. The concepts of "geomorphologic systems organization element" as the smallest particle of matter preserving the structure and properties of a mineral, as well as "objectives", "objects" and "subjects" of morphostructural and morphotectonic studies for solving problems of metallogeny have been formulated. In areas with complex geological structure, it is recommended to carry out complex of morphostructural and morphotectonic works with repeated solution of direct and inverse problems: relief and geological environment, geological environment relief. This will make it possible to establish the totality of available deterministic and chronological relations between landforms and structural elements of the lithosphere. Along with the solution of traditional problems of ore geomorphology, it is proposed to use the developed original complex of morphostructural and morphotectonic studies.

Drilling Capability of Orthodontic Miniscrews: In Vitro Study.

The aims of this study were to assess the values and mechanical properties of insertion torque (IT) of steel miniscrews inserted in artificial bone blocks (Sawbones, Pacific Research Laboratories, Vashon, WA, USA) with different bone densities and to detect any scratches on the surface of the miniscrews after insertion. Forty self-drilling miniscrews (Leone S.p.A. ø 1.75 mm, L 8 mm) have been inserted into bone blocks that mimic different stability conditions (density: 20 PCF—pounds per cubic foot, 40 PCF, and 30 + 50 PCF with 2 mm and 4 mm of cortical bone). Before insertion and after removal, all miniscrews were inspected with a stereomicroscope 5x and a SEM to detect potential microscopic cracks. Using an electronic surgical motor (W&H Dentalwerk Bürmoos GmbH, Werner Bader Str. 1, 5111 Bürmoos, Austria), the maximum insertion torque value was registered. Stereomicroscope and SEM examination did not indicate any morphological and surface structural changes to the miniscrews, irrespective of the bone density they were inserted into. The findings showed that IT increased significantly with increasing bone density. In each artificial bone block, morphostructural analysis demonstrated the adequate mechanical properties of the self-drilling miniscrews. IT measurements indicated torque values between 6 and 10 Ncm for blocks with a density of 30 + 50 PCF, whereas the suggested values are between 5 and 10 Ncm.

Statistical analysis of the structural trends in the Galician Margin and their relationship with the Cenozoic evolution of the northwestern sector of the Iberian Margin

Statistical methods of crust surface analysis based on Digital Terrain Models (DTM) and applied to structural elements have become a useful tool in tectonic studies. This paper presents a DTM morphostructural analysis of the Galicia Margin and the Iberian and Biscay abyssal plains, which has identified about 5,800 lineaments. The highest number of lineaments are located in the Charcot and Coruña Highs, in the western sector of the Galicia Bank, in the marginal platforms zone and in the Galicia northern margin. The lineaments analysis shows that they have two dominant directions, E-W and NE-SW. In addition, two other relative maxima of NW-SE and N-S directions have been determined. The cumulative total length of the identified lineaments exceeds 45,000 km. The statistical parameters have a length mode of around 5,000 m, a length average of about 7,800 m and a log-normal distribution of the length frequency. The orientations determined from the analysis of the lineaments are a reflection of the crustal scale fault systems established from gravimetric and magnetic anomalies and multi-channel seismic profiles. These faults developed in the Galicia Margin during the Variscan and Alpine orogenies and were reactivated under the recent stress field.