The results of a complex study of the Turchu limestone hollow (polje). Western Georgia, Caucasus

Based on the complex studies (geographical-geological, karst-speleological, and geophysical studies), conducted by the authors in the study area, karst forms such as sinkholes and ponors were identified, the width (2-17 m) of the Quaternary deposits located on the limestones were determined, the average and maximum discharges of the streams flowing on the bottom of the hollow were calculated. Studies have also shown that relatively heavy rains and snowmelt periodically flood the relatively low, western part of the hollow and create a temporary lake that soon dries up through the ponors at the bottom of the hollow, where the water stream are discharged. The closed shape of the Turchu hollow the limestone bottom covered with Quaternary deposits and the events described above indicate the corrosive origin of the hollow, which has been practically confirmed by our georadiological and electrometric studies. It is notable that the role of tectonic movements in the origin of the hollow along with the corrosive processes, which had a periodic character, and together with the uplifting of the area caused the lowering of the levels of underground waters and, consequently, the activation of karst processes.

Geotourism interesting locality with Remediation of the bedrock and restoration of Spiš Castle - UNESCO heritage site

Understanding the structure of the geological subsoil should be the first stage in the construction of any major building. Therefore, if the problem of rescue and restoration of various historical buildings is currently being addressed, it is necessary to study their subsoil in detail. Among the important historical buildings that have been preserved in Slovakia are numerous castles and chateaux. Nowadays, many of these buildings need to be extensively restored to prevent their gradual devastation. The issue of rehabilitation of some buildings has been addressed for several decades. The reasons for the rehabilitation of these buildings have varied. In the case of the ruins of Strečnian Castle and its subsoil, it was primarily the safety of traffic on the adjacent important road. In the case of Spiš Castle, it is a monument of world importance. It is one of the largest castle complexes in Europe. The beginnings of the construction of this complex date back to the 11th century. Its current state is due, among other factors, to the instability of its geological subsoil. For this reason, the stabilisation of the travertine body, which has been severely damaged, particularly by tectonics and karst processes, has already been addressed in the past. The solution of this problem in the past has already produced positive results, but due to exogenous processes and, hypothetically and certainly, seismicity, the bedrock may move again in the future. For this reason it is necessary to pay attention to continuous monitoring of the movement of its rock blocks. As far as the castle itself is concerned, its current state is mainly due to the fire at the end of the 18th century, followed by its rapid devastation. In view of the world importance of the castle, the restoration of the site may therefore also take other directions. One possibility is, for example, its reconstruction according to contemporary records, which would bring its final appearance even closer to its original grandeur.

Tectonic control on groundwater flow in a karst polje of southern Italy

<p>In the last decades, climate changes are affecting the freshwater resources quality and quantity around the globe, reducing their availability. On Earth, glaciers and ice cap occupy 68,7%, but they are not easily usable for human purposes; groundwater stands for 30,1%, while surface waters represent the remaining 1,2%. Therefore, groundwater resource is by far the most important natural tank to be preserved.</p><p>In karst, scientists are still working on developing new methods to understand the true groundwater hydrological behavior, due to subsoil anisotropy in both space and time. This requires a deep knowledge about discontinuity systems in the carbonates, and to improve our comprehension of karst processes, as basic elements for modelling.</p><p>The possibility to collect data directly from the subsoil, thanks to speleological explorations, is a precious chance for hydrogeology, and in general, for the environmental sciences. In this contribution we take advantage from a variety of speleological data, plus traditional geological surveys, to study groundwater flow in the karst of Apulia. Many karst processes, indeed, affect the Cretaceous limestones belonging to the Apulia carbonate platform, where the deepest cave in the region opens in the Canale di Pirro polje (altitude 300m a.s.l.). This latter is a W-E elongated tectonic-karst valley, representing one of the most significant karst landforms in this sector of Apulia. The cave reaches groundwater at a depth of -260m from the ground surface, whilst additional 60m below the water table have been explored by diving the flooded channels (total depth of the cave 320m).</p><p>We deal here with characterization of water flow direction into the fractured and karst aquifer, using a combined approach consisting of analysis of: i) primary and secondary discontinuities, ii) shape, size and orientation of karst conduits, and iii) geometry of the intersections between fractures and karst features.</p><p>The discontinuities have been analyzed with classical geological survey at the surface, and a semi-automatic extraction of their statistical properties, using the FracPaQ software. To characterize the water flow into the karst channels, we started from collection of available speleological maps of caves in the study area, in order to assess their main directions of development . From this analysis, some preliminary links were summarized: on the polje ridges, the prevailing discontinuity systems were well correlated with cave development, and, in turn, with the main regional tectonic directions (respectively, the SW-NE anti-Apennine, and the NW-SE Apennine systems). At the polje bottom, on the other hand, direction of cave segments and discontinuities are about similar, following the Canale di Pirro polje main elongation (W-E).</p><p>This first comparison among data from different sources eventually points out that water flows underground following the main structural lineations. These data, together with results of the groundwater flow model, confirm the key role of geo-structural control on karst development, and the possibility of variations at the local scale, as observed at the polje bottom. In karst, the integrated approach of geo-structural discontinuities and karst features and geometry is therefore a fundamental tool to gain insights into the understanding of the main groundwater flow directions.</p>

The Origin of Terraces in Buried Valleys in the Northwest of the East European Plain

—The paper considers the origin of terraces that often complicate the slopes of abnormally deep buried valleys in the northwest of the East European Plain. The Izborsk–Maly valley (Pskov Region, Russia), which is half filled with Quaternary sediments, was chosen as the object of study. Since the upper part of the valley remains unfilled, it is possible to study in detail both geologic and geomorphologic structures of its terraced slopes being of particular interest in the context of the origin of buried valleys and the role of substrate in it. The four denudation-terrace levels that have been identified on the slopes of the Izborsk–Maly valley at absolute elevations of 53, 56–58, 70–72, and 75–77 m formed during the destruction of the preglacial karst landscape under the influence of Pleistocene glaciations. The formation of the terraces was probably linked with several stages of overdeepening of the valley and its expansion by the glacial erosion processes, which corresponded to at least two stages of the ice sheet advance in this area. The last stage may have been the beginning of the Late Valdai (Weichselian) glaciation or the activation of the edge of an ice sheet during its Luga phase (~15.7 cal kyr BP). Results of the study suggest that the Izborsk–Maly valley formed in subglacial conditions. The degree of glacial erosion was determined primarily by the coherence of Devonian carbonate-terrigenous rocks hosting the valley and the degree of the area transformation by karst processes. The cirque shape of slopes is the evidence of karst processes expression in pre-glacial time. Analysis of literature data shows that the origin of denudation terraces in the buried valleys in the northwest of the East European Plain has been paid little attention. The obtained data contribute to the study of this problem and provide insights into the origin of buried valleys.

METHODOLOGICAL PRINCIPLES OF GEOPHYSICAL STUDIES OF KARST DANGEROUS TERRITORIES

The article is devoted to the analysis of the methodological principles of applying geophysical research methods in the study of karst-hazardous territories. The tasks that are posed in specialized studies of karst and geophysical methods for their solution are given. Four stages of specialized studies of karst-hazardous territories are identified: reconnaissance-methodological, prospecting, reconnaissance and monitoring. The set of geophysical methods for the development of these stages are determined. It is noted that a rational set of geophysical methods in the study of karst processes is determined for each individual natural environment (individual site). The possibility of performing field research by a separate geophysical method in this area, the presence of differentiation in rocks according to their physical properties which are used by a specific geophysical method and economic efficiency of the application of this geophysical method were taken into account. As an example, some results of geophysical studies carried out in the framework of the Lyubensky field of native sulfur are given.

Structural and Geomorphological Zoning of the Vladimir-Nizhniy Novgorod Area and its Environmental Geological Significance

The cyclic relief, neotectonic structures, geodynamically active zones (GdAZ) and exogenous geological processes have been investigated in the Vladimir-Nizhny Novgorod region. For the first time, six leveling surfaces were identified in the relief and the structure of four river terraces was considered. The analysis of obtained data made it possible to identify neotectonic structures of different types and classify them into three neotectonic regions. The boundaries of these areas are GdAZ, which are considered as crossing, superimposed and shear structures. Based on the cycling of relief formation, the total for the latest stage and stepwise amplitudes and rates of deformations are calculated. An increase in the rates of uplifts from the Miocene to the present is characteristic. Intensive development of suffusion-karst processes tends to specific types of relief and zones of disturbances, which are considered dangerous and environmentally significant for the territories of important engineering facilities

ОЦІНКА ВПЛИВУ ФАКТОРІВ УРБАНІЗАЦІЇ НА НЕБЕЗПЕКУ АКТИВІЗАЦІЇ КАР-СТОВИХ ПРОЦЕСІВ У РЕГІОНАХ УКРАЇНИ

The article presents the analysis of the exogenous geological process activation hazards, namely karst, in the conditions of urbanization processes. The scale of geoecological problems is shown to be directly or indirectly determined by the scale of urbanization. The relevance of the research is associated with the study of the nature of changes in the expansion of karst rocks in regions with different levels of urbanization in the period 2001 – 2020. The main aim is to analyze the hazards of karst development in relation with the factors of urbanization processes in the regions of Ukraine based on the indicator method. The particular characteristics of the impact of urbanized territories on the initiation of natural disasters and geological hazards have been determined. The urbogenic load of the regions was assessed using determined and calculated earlier indicators of ecological and ecological-demographic urbanization. The assessment of the dependence between the hazard indicator of the spread of karst rocks and the indicator of ecological urbanization in the regional context has been carried out. It is shown that in the third part of the regions, the growing hazard levels of karst processes practically coincide with the growth of the ecological urbanization index. A nearly doubling of the area of karst terrains was noted during 2001 – 2020 in all administrative regions. The coefficient of expansion of karst territories for the specified period has been calculated. Four groups of regions were identified according to the increase in karst areas in comparison with the hazards of karst processes and the index of ecological-demographic urbanization. Expansion of open karst areas in the Transcarpathian, Odessa, Rivne, Kherson, Chernivtsi regions was noted. For this group of regions, a tendency to increase the areas of surface karst in accordance with an increase in the values of urbanization indicators has been established. This is due to the exploitation of natural territorial resources, changes in the nature of land use, depletion of vegetation cover, anthropogenic loads on the ground, and imbalances in the interaction of surface and underground waters in urbanized areas. Thus, the Ukraine’s regions with different urbogenic load are differentiated depending on the territorial indicator of the danger of karst terrains, as well as the dynamics of changes in the areas of karst rocks.