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The dissolution of CO2 in seawater in the form of bicarbonate ions is an attractive alternative to storage in geological formations, on the condition that the storage is stable over long periods and does not harm the marine environment. In this work, we focus on the long-term chemical stability of CO2 absorbed in seawater as bicarbonate by monitoring the physico-chemical properties of the solutions (pH, dissolved inorganic carbon and alkalinity) in six different sets of experiments on both natural and artificial seawater lasting up to three months. The bicarbonate treatment of natural seawater consists of mixing it with pre-equilibrated solutions obtained from the reaction of CO2 and Ca(OH)2, with the same pH as natural seawater. This was achieved with a pilot plant working with tons of seawater, while small-scale laboratory experiments were carried out by adding sodium bicarbonate to artificial seawater solutions. If the increase in the overall carbon concentration in the final mixture does not exceed a critical threshold (about 1000–1500 μmol/L), the resulting bicarbonate-rich solutions are found to be stable for over three months. [ABSTRACT FROM AUTHOR]

Despite the elevated heat flow known in the Western part of the South Slave Region (Northwest Territories, Canada), a continuous and equilibrium geothermal gradient was never measured in boreholes below the communities where geothermal energy could be developed. This paper aims to predict the geothermal gradient and assess the Earth's natural heat flow below the communities of Fort Providence, Kakisa, Hay River, and Enterprise. Temperatures from drill-stem tests and bottom well logs were corrected for drilling disturbance and paleoclimate. The thermal conductivity and heat generation rate of the geological formations were determined from the literature and with new laboratory measurements. Original 1D models were developed to evaluate subsurface temperature through the sedimentary formations based on a thermostratigraphic assessment. The results indicate a geothermal gradient that varies from 44.1 ± 10.6 °C km−1 to 59.1 ± 14.9 °C km−1 and heat flow that varies from 105.5 mW m−2 to 160.2 mW m−2 below the communities. These estimates were in agreement with the equilibrium geothermal gradients measured in Cameron Hills, south of the four communities, and were used to verify our predictions. The highest geothermal gradient (59.1 ± 14.9 °C km−1) was estimated at Hay River, which, therefore, has the most favorable geological conditions for geothermal development. [ABSTRACT FROM AUTHOR]

This work aims to explore the Lower Silurian shale gas and tight sandstone gas accumulation conditions in the Gongtan Syncline, southeastern Sichuan Basin. The sedimentary environment, organic geochemical characteristics, reservoir characteristics, gas content, and preservation conditions of the reservoir were comprehensively analyzed. The results show that the Wufeng–Longmaxi Formation shale formed in a deep-water shelf characterized by a large thickness (50–70 m), appropriate total organic carbon content (0.5–5.47%), high maturity (2.38%), high brittle mineral content (67.10%), and large gas content (0.71–1.64 m3/t), and the formations show the good resource potential of the shale gas. The Xintan Formation formed in a lower shore phase, and the tight sandstone is locally developed with a small thickness. The Xiaoheba Formation formed in an upper-middle shore phase, and the tight sandstone is stably distributed with large thicknesses. The porosity and permeability of the two sets of sandstone are small and some natural fractures are developed in the sandstone, but the fracture filling degree is higher. The results of well logging show that there are abnormally high values of total hydrocarbon in both the Xintan Formation and Xiaoheba Formation; this indicates that tight sandstone gas is developed in the Lower Silurian strata. A comprehensive study indicates that the Lower Silurian of the Gongtan Syncline has the geological conditions for the formation of shale gas and tight sandstone gas, which are the "Two gases" with good co-exploration prospects. [ABSTRACT FROM AUTHOR]

Assessment of the current state of the near-surface part of the geological environment and understanding of its layered structure play an important role in various scientific and applied fields. The presented work is devoted to the application of phasometric modifications of geoelectric control methods to solve the problem of the detailed complex study of the underground layers of the environment in the process of drilling operations with the use of special equipment. These studies are based on the analysis of variations in phase parameters and characteristics of an artificially excited multiphase electric field to assess poorly distinguishable details and changes in the layered structure of the medium. The proposed method has increased accuracy, sensitivity and noise proofness of measurements, which allows for extracting detailed information about the heterogeneity, composition and stratification of underground geological formations not only in the zone where the drill makes contact with the medium, but also in the entire control zone. This paper considers practical mathematical models of phase images for basic scenarios of drill penetration between the layers of the near-surface part of the geological medium with different characteristics, obtained by means of approximation apparatus based on continuous piecewise linear functions, and also suggests the use of modern machine learning methods for intelligent analysis of its structure. Studying the phase shifts in electrical signals during drilling highlights their value for understanding the dynamics of soil response to the process. The observed signal changes during the drilling cycle reveal in detail the heterogeneity in soil structure and its response to changes caused by drilling. The stability of phase shifts at the last stages of the process indicates a quasi-equilibrium state. The results make a significant contribution to geotechnical science by offering an improved approach to monitoring a layered structure without the need for deep drilling. [ABSTRACT FROM AUTHOR]

In order to scientifically and rationally evaluate the susceptibility to landslide hazards in Tekes County, Yili State. This paper takes Tekes County in Xinjiang as an example, on the basis of a comprehensive analysis of the regional geological environment conditions and the distribution pattern and formation conditions of geological disasters, using the data of geological disaster points (landslide center points), and through the correlation matrix calculation of the evaluation factors, the nine evaluation factors with larger absolute values of correlation coefficients were determined to construct the evaluation system of the susceptibility to landslide geological hazards in Tekesi County. Combining the information quantity method and the entropy value method, using the weights determined by the entropy value method, the information quantity method is used to calculate the information quantity value of each factor within the factor, calculate the susceptibility index of landslide geological disasters within the territory of Tekes County, and then carry out the landslide susceptibility evaluation. The susceptibility of landslide disasters was evaluated by ArcGIS. The results show that the landslide disaster susceptibility level in Tekes County can be divided into four levels: high susceptibility, medium susceptibility, low susceptibility, and not susceptible, with areas of 491.3276 km2, 1181.5171 km2, 1674.7609 km2 and 5295.2976 km2 accounting for 5.68%, 13.67%, 19.38% and 61.27% of the total area of Tex County, respectively. The AUC number obtained by the success curve method (ROC) is 0.8736, reflecting the evaluation accuracy of 87.36%, indicating that the model method used in this paper is effective. The results are expected to provide practical data support for landslide disaster control in Tekes County and provide a reference for geological disaster monitoring, early warning and engineering prevention and control deployment in Yili Valley. [ABSTRACT FROM AUTHOR]

Geothermal energy, recognized as a clean energy source, has attracted widespread attention for its extraction. However, it is located in deep and complex geological formations, presenting a significant challenge to the drilling operations of existing Polycrystalline Diamond Compact (PDC) drill bits. To further understand the rock-breaking mechanism of PDC cutters in deep geological formations and improve rock-breaking efficiency, a finite element model employing the cohesive zone method was developed for a saddle-shaped PDC cutter (SC). This model was validated against experimental simulations, proving its capability to capture real rock crack initiation during the simulation process accurately. By analyzing the formation of cracks under cutting forces, the SC's rock-breaking mechanism was explored and compared with conventional cutters (CCs), clarifying its advantages. Additionally, the model analyzed the effects of different confined pressures, back rake angles, and structural parameters on crack formation in SC rock-breaking, highlighting directions for structural optimization. Full-scale drill bit rock-breaking simulations were conducted to verify the effectiveness and optimization of single cutter usage. The results indicated that the total number of cracks and the generation of tensile cracks determine the rock-breaking efficiency of the cutter. A lower total number of cracks and a higher proportion of tensile cracks lead to better rock-breaking performances. Due to its unique ridged and curved structure, the SC can generate concentrated and tensile stresses on the rock more effectively, resulting in fewer total cracks and a higher proportion of tensile cracks. The increase in confined pressure suppresses the generation of tensile cracks during rock-breaking, dispersing the rock-breaking energy, increasing the total number of cracks, and reducing rock-breaking efficiency. However, under the same conditions, using SC can effectively address these issues and enhance efficiency. For deep formation drilling, a back rake angle range of 15° to 20° is recommended for SC. The arc radius significantly impacts the SC's tensile cracks and total number of cracks, with a recommended arc radius range of 50 mm to 60 mm, and the SC structure could be modified from an arc to a straight line and back to an arc. The results contribute to enhancing the efficiency of deep drilling and theoretical research on drill bits. [ABSTRACT FROM AUTHOR]

The Taoudéni Basin, spanning 20% of Burkina Faso, holds vital aquifers for the Sahel's water security and development. However, limited understanding of these aquifers' hydrodynamics, including the flow patterns, mineralization processes, and renewal rates, hinders sustainable management practices in this arid region. Therefore, this study aims to investigate the aquifer hydrodynamics, mineralization processes and groundwater renewal in the transboundary Taoudéni Basin. Through a combination of hydrogeochemical and isotopic analyses, alongside existing data, this study examines 347 physicochemical samples, 149 stable isotope samples, and 71 tritium samples collected from 2013 to 2022. The findings reveal mineralization and stable isotopes (δ18O, δ2H) spatially aligned with the groundwater flow direction, validating this and indicating potentially multiple independent aquifers. The predominant mineralization mechanisms involve silicate hydrolysis and carbonate dissolution, supplemented by minor processes like evaporitic dissolution and cation exchange. The anthropogenic influence suggests potential groundwater recharge with potential pollution in the "SAC1", "SAC2", "GFR", "GGQ", and "GKS" geological formations. The stable isotopes (δ18O, δ2H) indicate recharge occurred over 4.5 kyr B.P., while tritium (3H) analysis confirms the presence of old, mixed waters, indicating slow renewal. Overall, this study highlights the minimal recent recharge and limited renewal rates, questions tritium's efficacy for old water detection, and emphasizes the need for sustainable management. [ABSTRACT FROM AUTHOR]

Karst regions are characterized by unique geological formations that pose challenges to soil fertility and plant nutrition. In this study, we investigated the distribution and interactions of selenium (Se) in soils of Zheng'an County, a representative karst region in subtropical China. The results showed that the Se enrichment in the soils of Zheng'an County was high, with total contents ranging from 0.49 to 3.87 mg/kg and an average of 1.22 mg/kg, making the area Se-rich. Despite the abundance of Se, the effective percentage of Se uptake by plants was relatively low due to the generally moderately acidic nature of the soils in the region (pH: 5.98–6.60), which encourages the conversion of the available Se into forms that are not readily accessible. In addition, the high organic matter (OM) content (21.92–127.66 g/kg) promoted Se retention by interacting with Ca2+ in carbonate rocks. In addition, the clay content (50.73% to 76.19%) enhanced Se adsorption and limited Se availability. In conclusion, this study provides a basis for soil management and ecological restoration strategies in karst landscapes, highlights new insights into the dynamics of Se, and calls for further research to elucidate the Se availability mechanism and improve the efficiency of Se uptake by plants. Meanwhile, this study provides the first systematic study of Se transport and transformation, as well as Se-enriched Gastrodia elata in karst regions, and provides a preliminary understanding of the geochemical behavior of Se in karst regions. [ABSTRACT FROM AUTHOR]

The stability of rock cliffs is a longstanding issue and is of practical significance. This case study demonstrates the application and use of advanced 3D modeling techniques, concentrating on the geological formations of the Xrobb l-Ġħaġin peninsula on the south-east coast of Malta, where the Xrobb l-Ġħaġin Neolithic site is located. In order to utilize a static and dynamic analysis of the investigated scenario, a 3D finite element model (FEM) of the geological formation in which the monument is set had to be created. To this end, 3D scanning, unmanned aerial vehicles (UAVs), and oblique photogrammetry were first used with state-of-the-art commercial packages for mesh reconstruction. As a result, a geometric and finite element model (FEM) was created, suitable for both static and dynamic analysis. In the second stage, a parametric investigation of the material properties of the structural system of the geological substrate was sought. The structural response of the system was evaluated for different loading scenarios assuming nonlinear finite element analysis. Collapse case scenarios were investigated for standard and weakened materials, predicting which components would collapse first and under which case of weakened materials the collapse occurs. Among other aspects, the main novelty of this paper lies in the integrated approach and multidisciplinary paradigm that supplement the available historical knowledge for this specific cultural heritage Neolithic site towards its conservation. [ABSTRACT FROM AUTHOR]

Tunnel boring machine (TBM) tunnel construction in composite strata relies heavily on understanding the rock-breaking characteristics of TBM cutters and optimizing cutter spacing and penetration. Utilizing a full-scale rock rotary cutting machine (RCM), this study conducted rock-breaking tests with disc cutters under varying rolling radii. An analysis of rock debris shape and cutter behavior provided insights into rock-breaking mechanisms. Two main types of rock fragments were identified, with both shear and compression failure observed during cutter–rock interactions. The influence of the rolling radius and cutter spacing on cutter forces was analyzed, along with numerical modeling using the particle flow method. Optimal cutter selection in soft–hard composite strata should prioritize cutter force, with the greatest force required in hard rock. Cutter force increases with penetration, while the force difference between cutters decreases with reduced cutter spacing. These findings offer practical guidance for efficient rock-breaking in composite geological formations during tunnel construction. [ABSTRACT FROM AUTHOR]

Over the past three decades, Sri Lanka has observed a substantial rise in landslide occurrences linked to intensified rainfall. However, the lack of comprehensive landslide inventories has hampered the development of effective risk analysis and simulation systems, requiring Sri Lanka to rely heavily on foreign-developed models, despite the difficulty of fully examining the similarities between the characteristics of landslides in Sri Lanka and the areas where the model has been developed. Satellite images have become readily available in recent years and have provided information about the Earth's surface conditions over the past few decades. Thus, this study verifies the utility of satellite images as a cost-effective remote-sensing method to clarify the commonalities and differences in the characteristics of landslides in two regions Ikawa, Japan, and Sabaragamuwa, Sri Lanka, which exhibit different geological formations despite similar annual rainfall. Using Google Earth satellite images from 2013 to 2023, we evaluated land-slide density, types, and geometry. The findings reveal that Ikawa exhibits a higher landslide density and experiences multiple-type landslides. In contrast, both areas have similar initiation areas; however, Sabaragamuwa predominantly experiences single landslides that are widespread and mobile. The findings also reveal that various characteristics of landslides are mainly influenced by varied topography. Here, we confirmed that even in areas where comprehensive information on landslides is conventionally lacking, we can understand the characteristics of landslides by comparing landslide geometry between sites using satellite imagery. [ABSTRACT FROM AUTHOR]

Featured Application: This study emphasizes the importance of comprehensive monitoring, calibration, and optimization of storage strategies in a saline aquifer. It also highlights the need to manage geomechanical risks and uncertainties. By understanding these risks and employing suitable monitoring techniques, the integrity and safety of GCS can be ensured, contributing to the reduction of CO2 emissions. Geological Carbon Storage (GCS) involves storing CO2 emissions in geological formations, where safe containment is challenged by structural and stratigraphic trapping and caprock integrity. This study investigates flow and geomechanical responses to CO2 injection based on a Brazilian offshore reservoir model, highlighting the critical interplay between rock properties, injection rates, pressure changes, and ground displacements. The findings indicate centimeter-scale ground uplift and question the conventional selection of the wellhead as a monitoring site, as it might not be optimal due to the reservoir's complexity and the nature of the injection process. This study addresses the importance of comprehensive sensitivity analyses on geomechanical properties and injection rates for advancing GCS by improving monitoring strategies and risk management. Furthermore, this study explores the geomechanical effects of modeling flow in the caprock, highlighting the role of pressure dissipation within the caprock. These insights are vital for advancing the design of monitoring strategies, enhancing the predictive accuracy of models, and effectively managing geomechanical risks, thus ensuring the success of GCS initiatives. [ABSTRACT FROM AUTHOR]

Currently, the production of radioactive waste from nuclear industries is increasing, leading to the development of reliable containment strategies. The deep geological repository (DGR) concept has emerged as a suitable storage solution, involving the underground emplacement of nuclear waste within stable geological formations. Bentonite clay, known for its exceptional properties, serves as a critical artificial barrier in the DGR system. Recent studies have suggested the stability of bentonite within DGR relevant conditions, indicating its potential to enhance the long-term safety performance of the repository. On the other hand, due to its high resistance to corrosion, copper is one of the most studied reference materials for canisters. This review provides a comprehensive perspective on the influence of nuclear waste conditions on the characteristics and properties of DGR engineered barriers. This paper outlines how evolving physico-chemical parameters (e.g., temperature, radiation) in a nuclear repository may impact these barriers over the lifespan of a repository and emphasizes the significance of understanding the impact of microbial processes, especially in the event of radionuclide leakage (e.g., U, Se) or canister corrosion. Therefore, this review aims to address the long-term safety of future DGRs, which is critical given the complexity of such future systems. [ABSTRACT FROM AUTHOR]

Carbon capture and storage technologies play a crucial role in mitigating climate change by capturing and storing carbon dioxide emissions underground. Saline aquifers, among other geological formations, hold promise for long-term CO2 storage. However, accurately assessing their storage capacity and CO2 behavior underground necessitates advanced numerical simulation and modeling techniques. In this study, we introduce an approach based on a solubility thermodynamic model that leverages cubic equations of state offline from the simulator. This approach enables the precise prediction of CO2–brine equilibrium properties and facilitates the conversion of compositional data into black oil PVT data suitable for black oil simulations. By incorporating industry-scale saline aquifer properties, we simulate a carbon storage scheme using the black oil model technique, significantly reducing computation time by at least four times while preserving the essential physical phenomena observed in underground carbon storage operations. A comparative analysis between black oil and compositional simulations reveals consistent results for reservoir pressure, CO2 saturation distributions, and mass fraction of trapping mechanisms, with differences of less than 4%. This validation underscores the reliability and efficiency of integrating the black oil model technique into carbon storage simulations in saline aquifer formations, offering tangible benefits to industry operators and regulators by striking a balance between accuracy and efficiency. The capability of this approach to extend to temperatures of up to 300 °C and pressures of up to 600 bars broadens its applicability beyond conventional CCS applications, serving as a valuable tool for optimizing decision-making processes in CCS projects, particularly in scenarios where profitability may be marginal. [ABSTRACT FROM AUTHOR]

The growth of the geothermal industry demands the constant search of techniques with the aim of reducing exploration efforts whilst minimizing subsurface uncertainty. The exploration of geothermal resources is fundamental from the exploitation point of view, especially in those regions where this energy is not as widespread as the rest of renewable sources. This research shows how geoelectrical methods can contribute to the investigation and characterization of medium–low enthalpy geothermal resources until about 800 m of depth. A 2000 m long electrical-resistivity tomography profile was performed in a region of Southern Spain with previous evidence of moderate geothermal potential. Results of this geophysical campaign (together with a preliminary geological characterization) allowed for the obtainment of a 2D profile and a pseudo-3D model with extensive information about the subsoil in terms of geological composition and formations. The interpretation of geophysical results denotes the existence of a potential formation constituted by carbonate materials with thickness greater than 300 m, crossing different fractures. Once the ideal location for the geothermal exploitation is defined, the research evaluates the contribution of the possible energy source, deducing that the energy extraction in the potential fracturing area would be double that of the one in the vicinity of the site. [ABSTRACT FROM AUTHOR]

Geological hazards in Xinxian County, Xinyang City, Henan Province, are characterized by their small scale, wide distribution, and significant influence from regional tectonics. This study focuses on collapses and landslide hazards within the area, selecting twelve evaluation factors: aspect, slope shape, normalized difference vegetation index (NDVI), topographic relief, distance from geological structure, slope, distance from roads, land use cover type, area of land change (2012–2022), average annual rainfall (2012–2022), and river network density. Utilizing data from historical disaster sites across the region, the information quantity method and hierarchical analysis method are employed to ascertain the information quantity and weight of each factor. Subsequently, a random forest model is applied to perform susceptibility zoning of geological hazards in Xinxian County and to examine the characteristics of these geological disasters. The results show that in the study area, the primary factors influencing the development of geohazards are the distance from roads, rock groups, and distance from geological structure areas. A comparison of the susceptibility results obtained through two methods, the analytic hierarchy process information quantity method and the random forests model, reveals that the former exhibits a higher accuracy. This model categorizes the geohazard susceptibility in the study area into four levels: low, medium, high, and very high. Notably, the areas of very high and high susceptibility together cover 559.17 km2, constituting 35.99% of the study area's total area, and encompass 57 disaster sites, which represent 72.15% of all disaster sites. Geological hazards in Xinxian County frequently manifest on steep canyon inclines, along the curved and concave banks of mountain rivers, within watershed regions, on gully inclines, atop steep cliffs, and on artificially created slopes, among other sites. Areas with very high and high vulnerability to these hazards are mainly concentrated near the county's geological formations. The gneiss formations are widely exposed in Xinxian County, and the gneisses' strength is significantly changed under weathering, which makes the properties of the different degrees of weathering of the rock and soil bodies play a decisive role in the stability of the slopes. This paper provides a basis for evaluating and preventing geologic hazards in the Dabie mountainous area of the South Henan Province, and the spatial planning of the national territory. [ABSTRACT FROM AUTHOR]

In gripper tunnel boring machine (TBM) tunneling through complex geological formations, the safe and efficient recovery from large-scale collapses remains a formidable challenge. In this study, we investigate the causes of a 1246 m3 collapse that occurred during the gripper TBM tunneling in the diversion tunnel in Xinjiang, China. Various techniques including TSP seismic waves, CFC advanced water exploration, laboratory point load tests and packer permeability tests were employed for thorough research. The examination discloses that the water softening in biotite-quartz schist in fractured zones contributes significantly to the loosening and dislocation of rock layers along joints. The gripper TBM's cutterhead exacerbates this process through cutting action and vibrations, causing large-scale instability and eventual rock mass collapse. To tackle this engineering problem, we propose a three-step treatment scheme comprising "Reinforcement-Backfill-Re-excavation". Furthermore, we propose a technique to handle TBM collapses by creating a "protective shell" within the cavity. The safety and feasibility of these proposed solutions were thoroughly validated through numerical simulations. Also, we utilized the Hoek-Brown theory and Rostami prediction formula to establish recommended values for the total thrust and total torque of the TBM during the collapsed section. The proposed treatment scheme and estimated parameters were successfully applied, resulting in a comprehensive solution from collapse handling to tunneling. This study offers valuable details on effectively managing large-scale collapses in gripper TBM tunneling, which can be useful for similar tunnel engineering and improve safety and efficiency. [ABSTRACT FROM AUTHOR]

The increasing use of finite element analysis in modern infrastructure design emphasizes the importance of determining soil stiffness at small strains. This is usually represented by the normalized shear modulus degradation curve, which is crucial for accurate design. In the absence of specific measurements on the local soil, engineers often rely on empirical correlations and assume comparable behavior of soils with similar intrinsic properties. However, the application of this approach leads to uncertainties, especially for unique geological formations such as the soft cohesive soils of the Ljubljana Marsh. The main objective of this study was to determine the small strain shear modulus of Ljubljana Marsh soil with a plasticity index between 11 and 35%. Isotropic and anisotropic stress conditions were investigated as part of an extensive laboratory test program that included 45 bender element and 89 resonant column tests on 20 soil samples. By emphasizing the importance of measuring soil stiffness at small strains, this study not only provides reliable data for the development of the built environment in the Ljubljana Marsh and similar areas, but also underlines its necessity. [ABSTRACT FROM AUTHOR]

Accurate identification and understanding of various metallic minerals are crucial for deciphering geological formations, structures, and ages. Giving their pivotal role as essential natural resources, a microscopic exploration of metallic minerals becomes imperative. Traditional analytical methods, while helpful, exhibit certain limitations. However, terahertz time-domain spectroscopy, distinguished by its high signal-to-noise ratio, expansive frequency band, and low incident wave energy, is a promising complement to conventional techniques in characterizing metallic minerals. This study employs terahertz time-domain spectroscopy to examine samples of Stibnite, Sphalerite, Galena, and Pyrite originating from diverse geological conditions. The vibrations of molecules within these metallic minerals induce discernible changes in the terahertz spectra. Our findings untiate the extensive potential of terahertz time-domain spectroscopy in the characterization of metallic minerals, affirming its considerable practical value in mineral resource exploration. [ABSTRACT FROM AUTHOR]

Tabular Middle Atlas of Morocco holds the main water reservoir that serves many cities across Morocco. Dolomite and limestone are the most dominant geologic formations in this region in which water resources are contained. The recent studies conducted to evaluate the quality of this water suggest that it is very vulnerable to pollutants resulting from both anthropogenic and natural phenomenon. High and very high-resolution satellite imagery have been used in an attempt to gain a better understanding of this karstic system and suggest a strategy for its protection in order to reduce the impact of these phenomenon. Based on the surface reflectance of land cover benchmarks, the karstic system has been horizontally delineated, as well as regions with intense human activities. Using band combination in the portion of the infrared, shortwave infrared, and visible parts of the electromagnetic spectrum, we identified bare lands which have been interpreted as carbonate rocks, clay minerals, uncultivated fields, basalts rocks, and built-up areas. Other classes such as water and vegetation have been identified. Carbonate rocks have been identified as areas with a high rate of water infiltration through their fracture system. Using a Sobel operator filter, these fractures have been mapped and their results have revealed new and existing faults in two major fracture directions, NE-SW and NW-SE, where NE-SW is the preferable pathway for surface water infiltration towards the groundwater reservoir, while the NW-SE direction drains groundwater from the Cause to the basin of Saiss. Over time, the infiltration of surface water through fractures has contributed to a gradual erosion of the carbonate rocks, which in turn developed karst landforms. This karst system is vulnerable due to the flow of pollutants in areas with shallow sinkholes. Using GDEM imagery, we extracted karst depressions, and their analysis shows that they are distributed along the fracture system and many of them were located on curvilinear or linear axes along the NE-SW fracture direction. We found also dolines scattered in areas with a high intensity of fractures. This distribution has been validated by both on-the-ground measurements and very high-resolution satellite images, and depressions of different forms and shapes dominated by dolines, poljes, lapiez, and avens have been identified. We also found many water springs with a highly important water output, such as the Ain Maarrouf water spring. The aim of this study is to enhance the understanding of the hydrogeological system of TMA, to improve the existence of the fracture database in the Cause of Agourai, and to establish a new morpho-structural picture of the Ain Maarrouf water spring. [ABSTRACT FROM AUTHOR]

The utilization of geological formations, distinguished by natural porosity and permeability and protected by low-permeability caprock, has emerged as an effective strategy for carbon dioxide (CO2) storage. This method significantly contributes to mitigating anthropogenic greenhouse gas emissions and addressing the challenges of climate change. Recent research has unveiled the potential of CO2 to enhance geothermal heat energy extraction in geothermal reservoirs by acting as a subsurface heat exchange fluid. This review paper explores the viability of CO2 in augmenting geothermal heat energy extraction, comparing it to conventional water-based geothermal systems. Special emphasis is placed on CO2 plume geothermal (CPG) systems, characterized by rapid deployment and long-term utilization of geothermal energy resources. With the overarching objective of establishing net-zero energy communities, the analysis of such systems offers a comprehensive understanding of their features, providing a fresh perspective on extracted energy within the context of energy supply in integrated, sustainable energy in built systems. Notably, these systems demonstrate efficacy in meeting the power requirements of an energy community, spanning both distinct heating and electricity needs. However, the key challenge lies in selecting suitable locations. This scientific review aims to comprehend the characteristics of CPG under specific temperature and pressure conditions while optimizing subsurface permeability. This insight is pivotal for identifying future locations for CPG operations with the intent of powering small energy communities. [ABSTRACT FROM AUTHOR]

The rational structural design of polycrystalline diamond compact (PDC) cutters effectively enhances the performance of drill bits in rock fragmentation and extends their service life. Inspired by bionics, a bionic PDC cutter was designed, taking the mole claw toe, shark tooth, and microscopic biomaterial structures as the bionic prototypes. To verify its rock-breaking effectiveness, the finite element method was employed to compare the rock-breaking processes of the bionic cutter, triangular prism cutter, and axe cutter. The study also investigated the influence of different back rake angles, cutting depths, arc radii, and hydrostatic pressures on rock breaking using the bionic cutter. Prior to this, the accuracy of the finite element model was validated through laboratory tests. Subsequently, a drill bit incorporating all three types of cutters was constructed, and simulations of rock breaking were conducted on a full-sized drill bit. The results demonstrate that the bionic cutter exhibits superior load concentration on the rock compared to the triangular prism cutter and the axe cutter. Additionally, its arc structure facilitates the "shoveling" of the rock, making it more susceptible to breakage under tensile stress. As a result, the efficiency of the bionic cutter surpasses that of the triangular prism and axe cutters. Similarly, it exhibits minimal fluctuations and values in cutting force. As the back rake angle and cutting depth increase, the MSE and cutting force of all three cutters also increase. However, the bionic cutter consistently maintains the lowest MSE and cutting force, confirming the superiority of its bionic structural design. The MSE and cutting force of the bionic cutter fluctuate with the increase of the arc radius, and the optimal arc radius falls within the simulation range, between 21 mm and 23 mm. Compared to the other two types of cutters, bionic cutters possess a unique structure that allows for better release of internal stress within the rock, thereby ensuring higher efficiency in rock-breaking, particularly in deep geological formations. The rock breaking simulation results of full-sized drill bits show that the use of a bionic cutter can improve the drill bit's ability to penetrate the formation, reduce the possibility of drill bit bounce during the rock breaking process, prevent the occurrence of stick-slip, improve the drilling stability, effectively improve the efficiency and service life of the drill bit during the rock breaking process, and reduce the drilling cost. It is concluded that the research results of bionic PDC cutters are helpful to the development of high-performance drill bits and the reduction of drilling costs. [ABSTRACT FROM AUTHOR]

Demantoid is the green variety of andradite [Ca3Fe2(SiO4)3], an exceptionally rare and precious gemstone worldwide. In recent years, a small amount of gem-quality demantoid has been found in Pakistan. This research focuses on nine demantoids sourced from Muslim Bagh, Baluchistan, Pakistan, presenting a comprehensive analysis of the spectral characteristics and inclusions of Pakistani demantoid using classical gemological methods, energy dispersive X-ray fluorescence (EDXRF) chemical analyses, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and ultraviolet and visible (UV-vis) spectroscopy. The results show that the content of Cr and V in most samples is lower than the detection line of EDXRF, with only one sample containing a Cr2O3 content of 0.032%. The extremely low Cr content sets Pakistani demantoid apart from demantoid of the serpentinite type found in other regions. Notably, the UV-vis spectrum reveals characteristic absorption at 443 nm due to Fe3+, while a further contribution from Cr3+ would be highly likely, and weak absorption at 550 nm caused by Fe3+. This suggests that iron (Fe) is the primary chromogenic element of Pakistani demantoid, but the role of Cr3+ cannot be ignored. The FTIR spectrum of Pakistani demantoid displays the absorption peaks associated with [SiO4]4− groups at 937 cm−1, 848 cm−1, and 817 cm−1, while the absorption peaks resulting from trivalent cations appear at 481 cm−1 and 442 cm−1, which are the characteristic FTIR spectra of demantoid. Raman spectroscopy further reveals absorption peaks are displayed near 994 cm−1, 843 cm−1, 818 cm−1, associated with (Si–O)Str vibrations (Si–O stretching vibration), and absorption peaks are displayed near 350 cm−1 and 310 cm−1, related to the rotation of SiO4–R(SiO4)4−, and the peaks near 514 cm−1 and 494 cm−1 are related to (Si–O)bend vibrations (Si–O bending vibration). Additionally, related absorption peaks near 168 cm−1 are attributed to the translation of SiO4–T(SiO4)4−, and absorption peaks near 234 cm−1 are associated with the translation of X2+–T(X2+) (X2+ represents divalent ions). The common dark opaque inclusions found in Pakistani demantoid consist of a combination of magnetite and hematite. Additionally, some samples of Pakistani demantoid display inclusions of calcite. This unique combination of inclusions differentiates Pakistani demantoid from demantoids sourced from other regions. It signifies that Pakistani demantoid has a distinctive geological origin resulting from the interplay of serpentinization and skarnization processes. This geological formation distinguishes it from demantoids solely hosted in serpentinite or skarn environments in other origins. The identification of these characteristics holds significant importance for accurately determining the origin of Pakistani demantoid. [ABSTRACT FROM AUTHOR]

Stratigraphic identification from wire-line logs and core samples is a common method for lithology classification. This traditional approach is considered superior, despite its significant financial cost. Artificial neural networks and machine learning offer alternative, cost-effective means for automated data interpretation, allowing geoscientists to extract insights from data. At the same time, supervised and semi-supervised learning techniques are commonly employed, requiring a sufficient amount of labeled data to be generated through manual interpretation. Typically, there are abundant unlabeled geophysical data while labeled data are scarcer. Supervised and semi-supervised techniques partially address the cost issue. An underutilized class of machine-learning-based methods, unsupervised data clustering, can perform consonant classification by grouping similar data without requiring known results, presenting an even more cost-effective solution. In this study, we examine a state-of-the-art unsupervised data clustering algorithm called piecemeal clustering to identify lithofacies from wire-line logs, effectively addressing these challenges. The piecemeal clustering algorithm groups similar wire-log signatures into clusters, determines the number of clusters present in the data, and assigns each signature to one of the clusters, each of which represents a lithofacies. To evaluate the performance, we tested the algorithm on publicly released data from ten wells drilled in the Hugoton and Panoma fields of southwest Kansas and northwest Oklahoma, respectively. The data consist of two major groups: marine and non-marine facies. The study herein is centered around addressing two fundamental research questions regarding the accuracy and practicality of the piecemeal clustering algorithm. The algorithm successfully identified nine distinct clusters in our dataset, aligning with the cluster count observed in previously published works employing the same data. Regarding mapping accuracy, the results were notable, with success rates of 81.90% and 45.20% with and without considering adjacent facies, respectively. Further detailed analysis of the results was conducted for individual types of facies and independently for each well. These findings suggest the algorithm's precision in characterizing the geological formations. To assess its performance, a comprehensive comparative analysis was conducted, encompassing other data clustering algorithms, as well as supervised and semi-supervised machine learning techniques. Notably, the piecemeal clustering algorithm outperformed alternative data clustering methods. Furthermore, despite its unsupervised nature, the algorithm demonstrated competitiveness by yielding results comparable to, or even surpassing, those obtained through supervised and semi-supervised techniques. [ABSTRACT FROM AUTHOR]

Capturing and storing CO2 (CCS) was once regarded as a significant, urgent, and necessary option for reducing the emissions of CO2 from coal and oil and gas industries and mitigating the serious impacts of CO2 on the atmosphere and the environment. This recognition came about as a result of extensive research conducted in the past. The CCS cycle comes to a close with the last phase of CO2 storage, which is accomplished primarily by the adsorption of CO2 in the ocean and injection of CO2 subsurface reservoir formation, in addition to the formation of limestone via the process of CO2 reactivity with reservoir formation minerals through injectivities. CCS is the last stage in the carbon capture and storage (CCS) cycle and is accomplished chiefly via oceanic and subterranean geological sequestration, as well as mineral carbonation. The injection of supercritical CO2 into geological formations disrupts the sub-surface's existing physical and chemical conditions; changes can occur in the pore fluid pressure, temperature state, chemical reactivity, and stress distribution of the reservoir rock. This paper aims at advancing our current knowledge in CO2 injection and storage systems, particularly CO2 storage methods and the challenges encountered during the implementation of each method and analyses on how key uncertainties in CCS can be reduced. CCS sites are essentially unified systems; yet, given the scientific context, these storage systems are typically split during scientific investigations based on the physics and spatial scales involved. Separating the physics by using the chosen system as a boundary condition is a strategy that works effectively for a wide variety of physical applications. Unfortunately, the separation technique does not accurately capture the behaviour of the larger important system in the case of water and gas flow in porous media. This is due to the complexity of geological subsurface systems, which prevents the approach from being able to effectively capture the behaviour of the larger relevant system. This consequently gives rise to different CCS technology with different applications, costs and social and environmental impacts. The findings of this study can help improve the ability to select a suitable CCS application method and can further improve the efficiency of greenhouse gas emissions and their environmental impact, promoting the process sustainability and helping to tackle some of the most important issues that human being is currently accounting global climate change. Though this technology has already had large-scale development for the last decade, some issues and uncertainties are identified. Special attention was focused on the basic findings achieved in CO2 storage operational projects to date. The study has demonstrated that though a number of CCS technologies have been researched and implemented to date, choosing a suitable and acceptable CCS technology is still daunting in terms of its technological application, cost effectiveness and socio-environmental acceptance. [ABSTRACT FROM AUTHOR]

In order to assess the influencing factors of the presence of mercury in a river within the Savanna biome (Cerrado), we surveyed total mercury (THg) in bottom sediment from 50 lakes along 750 km of the Middle Araguaia floodplain. The sampling sites included non-urban and urban surroundings over three distinct geomorphologies. We measured water physicochemical parameters at each site and tested statistically if land use nested within the geological formation influenced the THg concentration in bottom sediments and related water parameters. Multivariate results indicate that the interaction between geological groups and land use is statistically significant (p < 0.05). Nested ANOVA and Tukey HSD tests confirmed that the geological formation with its nested land use influences the THg, pH, DO, conductivity, and TDS (p < 0.05). THg was significantly lower in Quaternary terrains (p < 0.05) and differed significantly between non-urban and urban areas in Neoproterozoic terrains (p = 0.02). The spatial projections of the THg eigenvector on the main axes with the scoring factors of the Neoproterozoic/Paleoproterozoic terrains, and urban/non-urban, confirmed the spatial correlations. These results indicate that the association of land use and geology could be the main driver of THg in the bottom sediments of lakes from the Middle Araguaia floodplain. [ABSTRACT FROM AUTHOR]

The Chure Hills, already vulnerable due to their fragile nature, face increased landslide risk, prompting the need for reliable susceptibility assessment. This study uses Poisson regression modeling to assess landslide susceptibility in two highly susceptible districts of the Chure region. Variance inflation factor (VIF) tests were conducted to ensure robustness, indicating no multicollinearity among the variables. Subsequently, Poisson regression analysis identified eight significant variables, among which geology, lineament density, elevation, relief, slope, rainfall, solar radiance, and land cover types emerged as important factors associated with landslide count. The analysis revealed that higher lineament density and slope were associated with lower landslide counts, indicating potential stabilizing geological and topographical influences. The categorical variable, namely geology, revealed that middle Siwalik, upper Siwalik, and quaternary geological formations were associated with lower landslide counts than lower Siwalik. Land cover types, including areas under forest, shrubland, grassland, agricultural land, water bodies, and bare ground, had a substantial significant positive association with landslide count. The generated susceptibility map that exhibited a substantial portion (23.32% in Dang and 5.22% in Surkhet) of the study area fell within the very-high-susceptibility categories, indicating pronounced landslide susceptibility in the Dang and Surkhet districts of the Chure hills. This study offers valuable insights into landslide vulnerability in the Chure region, serving as a foundation for informed decision-making, disaster risk reduction strategies, and sustainable land-use and developmental policy planning. [ABSTRACT FROM AUTHOR]

Long-runout landslides occur frequently in the sandstone and mudstone mountainous areas in southwestern China under heavy rainfall conditions. This has been a key issue in the field of disaster prevention and reduction. Considering the Niuerwan landslide in Wulong, Chongqing, on 13 July 2020, as an example, we employed technical methodologies, including unmanned aerial vehicle (UAV) images, field investigation, geological condition analysis (including geomorphology and topography, stratigraphic structure and formation lithology, etc.), interferometric synthetic aperture radar (InSAR) monitoring and Particle Flow Code 3D (PFC3D) simulations to study failure mechanism and a long-runout motion model of flow-like landslides induced by the heavy rainfall. The results showed that (1) the large differences between the upper and lower strata are the root cause of the instability and long-runout fluidization movement; (2) heavy rainfall is the key driving factor of slope instability and deep-seated landslides, leading to long-distance movement of the upper saturated residual soil; (3) the long-runout fluidization model of bedding landslides is mainly divided into the overall sliding in the lower layer, the mixing of coarse and fine particles in the middle layer, and saturation fluidization in the upper layer; and (4) the long-runout fluidization process of bedding landslides is composed of three stages: overall instability, mixed acceleration, and fluidization accumulation. In view of these findings, in the risk evaluation and prediction of long-runout fluidization landslides in sandstone and mudstone mountainous areas, this particular disaster model can be used to provide quantitative references for disaster prevention and mitigation. [ABSTRACT FROM AUTHOR]

With the widespread recognition of underground salt cavern compressed air storage at home and abroad, how to choose and evaluate salt cavern resources has become a key issue in the construction of gas storage. This paper discussed the condition of building power plants, the collection of regional data and salt plant data, and the analysis of stability and tightness. Comprehensive analysis and evaluation methods were put forward from four aspects, including ground comprehensive conditions, regional geological conditions and formation lithology, salt mine characteristics, stability, and tightness of salt caverns. The limit equilibrium theory was applied to establish the limit equilibrium failure mode of salt caverns under operating pressure, and the stability coefficient calculation method of the target salt cavern was determined by combining the mechanical characteristics. Based on the physical and mechanical properties of salt rocks, it was found that salt rocks with enough thickness around the salt cavity could be used as sealing rings to ensure the tightness of the salt cavern. Combined with the field water sealing test, the tightness of the target salt cavern is verified. This method has been applied to the salt cavern screening and evaluation of a 300 MW compressed air energy storage power plant project in Yingcheng, Hubei Province, and remarkable results have been obtained, indicating the rationality of the method. [ABSTRACT FROM AUTHOR]

The development of cost-effective methods for estimating hydraulic conductivity profiles has been an ongoing effort in the field of engineering practice, which can be used to increase availability to clarify the hydrogeological complexity of fractured rock aquifers for the aid of solving groundwater-related problems. A new methodology is presented, which combines electrical well logs, fluid conductivity logs, double-packer hydraulic tests, Archie's law, and the Kozeny–Carman-Bear equation to investigate relations between formation factor (F) and hydraulic conductivity (K). Available geophysical and hydraulic test data measured from 88 boreholes in fractured rock formations in Taiwan were collected to perform the correlation studies. The correlation investigation outcomes indicate that the established F-K relations have the potential to serve as the transformation function for estimating hydraulic conductivity through the geological directly. To improve F-K relations in response to the effect of clay mineralogy, two proposed clustering techniques (the natural gamma ray threshold method and the modified Archie's law method) successfully play an important role in filtering clayed data. The prevalence of clay content in most of Taiwan's fractured rock formations has been found, which implies that careful consideration of clay-related issues in complex geologic formations is essential while applying Archie's law theory. Finally, the predictive models for estimating hydraulic conductivity have been developed for three types of lithology (sandstone, schist, and slate). [ABSTRACT FROM AUTHOR]

Claystone is potentially the main rock formation for the deep geological disposal of high-level radioactive nuclear waste. A major factor that affects the deformation of the host medium is effective stress. Therefore, studying the effective stress principle of claystone is essential for a stability analysis of waste disposal facilities. Consolidated drained (CD) tests were carried out on claystone samples to study their effective stress principle in this paper. Firstly, two samples were saturated under a specified confining pressure and pore pressure for about one month. Secondly, the confining pressure and pore pressure were increased to a specified value simultaneously and then reverted to the previous stress state (the deformations of the samples were recorded during the whole process). Different incremental combinations of the confining pressure and pore pressure were tried at this step. Finally, the effective stress coefficients of the samples were obtained through a back analysis. Furthermore, some potential influencing factors (the neutral stress and loading rate) of the effective stress coefficient were also studied through additional tests. Some interesting results are worth mentioning: (1) the effective stress coefficient of claystone is close to one; (2) the neutral stress and loading rate may have little effect on the effective stress coefficient of claystone. [ABSTRACT FROM AUTHOR]

Lithological mapping is a crucial tool for exploring minerals, reconstructing geological formations, and interpreting geological evolution. The study aimed to investigate the application of the back propagation neural network (BPNN) and particle swarm optimization (PSO) algorithm in lithological mapping. The study area is the Beiliutumiao map-sheet (No. K49E011021) in Inner Mongolia, China. This area was divided into two parts, with the left side used for training and the right side used for validation. Fifteen geological relevant factors, including geochemistry (1:200,000-scale) and geophysics (1:50,000-scale), were used as predictor variables. Taking one lithology as an example, the lithological binary mapping method was introduced in detail, and then the complete lithology was mapped. The model was compared with commonly used spatial data mining methods using the E-measure, S-measure, and Weighted F-measure values. In diorite testing, the accuracy and kappa of the optimized model were 92.11% and 0.81, respectively. The validation results showed that our method outperformed the traditional BPNN and weights-of-evidence approaches. In the extension of the complete lithological mapping, the accuracy, recall, and F1-score were 82.66%, 74.54%, and 0.76, respectively. Thus, the proposed method is useful for predicting the distribution of one lithology and completing the whole lithological mapping at a fine scale. In addition, the trained network can be extended to an adjacent area with similar lithological features. [ABSTRACT FROM AUTHOR]

Drilling-fluid loss has always been one of the challenging issues in the field of drilling engineering. This article addresses the limitations of a single fluid-loss pressure mechanism model and the challenges in predicting positive drilling-fluid-loss pressure. By categorizing fluid losses of various types encountered during drilling, different geological formations associated with distinct mechanisms are considered. The actual drilling-fluid density in the wellbore at the time of fluid-loss occurrence is taken as a reference value for calculating the positive drilling-fluid-loss pressure of the already drilled well. Building upon this foundation, a combined model utilizing the Sparrow Search Algorithm (SSA) and Long Short-Term Memory (LSTM) neural network is constructed. This model effectively explores the intricate nonlinear relationship between well logging, logging engineering data, and fluid-loss pressure. By utilizing both data from the already drilled wells and upper formation data from ongoing drilling, precise prediction of positive drilling formation fluid-loss pressure can be achieved. Case studies demonstrate that the approach established in this paper, incorporating upper formation data, reduces the average absolute percentage error of fluid-loss pressure prediction to 2.4% and decreases the root mean square error to 0.0405. Through the synergy of mechanistic models and data-driven techniques, not only has the accuracy of predicting positive drilling formation fluid-loss pressure has been enhanced, but also valuable insights have been provided for preventing and mitigating fluid losses during drilling operations. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) dissolution is the secondary trapping mechanism enhancing the long-term security of CO2 in confined geological formations. CO2 injected into a randomly multilayered formation will preferentially migrate along high permeability layers, increasing CO2 dissolution efficiency. In this study, sequential Gaussian simulation is adopted to construct the stratified saline formations, and two-phase flow based on MRST is established to illustrate the spatial mobility and distribution of CO2 migration. The results show that gravity index G and permeability heterogeneity σ Y 2 are the two predominant factors controlling the spatial mobility and distribution of CO2 transports. The CO2 migration shows a totally different spatial mobility under different gravity index and heterogeneity. When the permeability discrepancy is relatively larger, CO2 preferentially migrates along the horizontal layer without accompanying the vertical migration. For the formation controlled by gravity index, CO2 migration is governed by supercritical gaseous characteristics. For the medium gravity index, the upward and lateral flow characteristics of the CO2 plume is determined by gravity index and heterogeneity. When the gravity index is smaller, permeability heterogeneity is the key factor influencing CO2 plume characteristics. Permeability heterogeneity is the decisive factor in determining final CO2 dissolution efficiency. This investigation of CO2 mobility in randomly multilayered reservoirs provides an effective reference for CO2 storage. [ABSTRACT FROM AUTHOR]

This work is devoted to the modeling of fracture networks. The main attention is focused on the fractal features of the fracture systems in geological formations and reservoirs. Two new kinds of fracture network models are introduced. The first is based on the Bernoulli percolation of straight slots in regular lattices. The second explores the site percolation in scale-free networks embedded in the two- and three-dimensional lattices. The key attributes of the model fracture networks are sketched. Surprisingly, we found that the number of effective spatial degrees of freedom of the scale-free fracture network models is determined by the network embedding dimension and does not depend on the degree distribution. The effects of degree distribution on the other fractal features of the model fracture networks are scrutinized. [ABSTRACT FROM AUTHOR]

Raster logs are scanned representations of the analog data recorded in subsurface drilling. Geologists rely on these images to interpret well-log curves and deduce the physical properties of geological formations. Scanned images contain various artifacts, including hand-written texts, brightness variability, scan defects, etc. The manual effort involved in reading the data is substantial. To mitigate this, unsupervised computer vision techniques are employed to extract and interpret the curves digitally. Existing algorithms predominantly require manual intervention, resulting in slow processing times, and are erroneous. This research aims to address these challenges by proposing VeerNet, a deep neural network architecture designed to semantically segment the raster images from the background grid to classify and digitize (i.e., extracting the analytic formulation of the written curve) the well-log data. The proposed approach is based on a modified UNet-inspired architecture leveraging an attention-augmented read–process–write strategy to balance retaining key signals while dealing with the different input–output sizes. The reported results show that the proposed architecture efficiently classifies and digitizes the curves with an overall F1 score of 35% and Intersection over Union of 30%, achieving 97% recall and 0.11 Mean Absolute Error when compared with real data on binary segmentation of multiple curves. Finally, we analyzed VeerNet's ability in predicting Gamma-ray values, achieving a Pearson coefficient score of 0.62 when compared to measured data. [ABSTRACT FROM AUTHOR]

In this paper, we present a systematic GIS-based approach for producing updated, upscaled, unified and reevaluated maps for the Ionian Islands of Greece, which is an area of great geological interest. In particular, Cephalonia and Lefkada are two islands with an increased and intense seismicity. Therefore, a common GIS geodatabase was produced for handling the geoinformation of the area. New upscaled (scale 1:50,000) geotechnical and seismotectonic maps of these islands were produced based on older ones. On the other hand, the corresponding maps of the islands, based on the categories of the Greek antiseismic code and Eurocode 8, were produced in an effort to correlate them. Beyond that, all the available isoseismal maps of the earthquakes that hit the Ionian Islands were gathered in an effort to evaluate them and to find possible correlations with the other types of maps. Based on the correlation results, the consideration of the Vs30 parameter in the Greek antiseismic code is proposed for a better categorization of the geological formations. [ABSTRACT FROM AUTHOR]

Understanding hydrological and hydrochemical processes is crucial for the effective management and protection of groundwater resources. This study conducted a comprehensive investigation into hydrochemical processes and variations in groundwater quality across five distinct aquifers in Phra Nakhon Si Ayutthaya, Thailand: Bangkok (BKK), Phra Pradaeng (PPD), Nakhon Luang (NKL), Nonthaburi (NTB), and Sam Khok (SK). Utilizing various diagrams, the findings revealed that high levels of sodium and salinity in shallow aquifers (BKK and PPD) were found which can impede soil permeability and have potential consequences on crop yields. The presence of four distinct types of groundwater—Na-Cl, Na-HCO3, Ca-Cl, and Ca-HCO3—suggests the influence of rock weathering, mineral dissolution, and ion exchange reactions with the surrounding geological formations, controlling the chemistry in the groundwater basin. The research also highlights concerns regarding groundwater quality, particularly elevated concentrations of heavy metals (e.g., Zn, Hg, Pd, Fe, and Mn) exceeding safe drinking water guidelines established by the World Health Organization (WHO) in certain samples. The evaluation of water suitability for consumption and irrigation using the Water Quality Index (WQI) and Wilcox diagram reveals a predominance of "poor" or "unsuitable" categorizations. Untreated sewage discharge and fertilizer usage were identified as the primary anthropogenic activities affecting hydrochemical processes in groundwater. These findings emphasize the need for continuous monitoring, appropriate management, and remediation efforts to mitigate potential hazards. [ABSTRACT FROM AUTHOR]

To study the evolution of geological hazard sources of waste dump slopes under rainfall conditions, a physical model of a rainfall-affected slope was designed. The apparent resistivity of the slope rock and soil mass at different rainfall times was measured via the high-density resistivity method, and the formation process of internal disaster sources of the rainfall-affected slope was obtained. The variation characteristics of the resistivity of the rain-affected slope were analyzed when it had a weak surface and crack development. Based on the three-water model and Maxwell conductivity formula, the evolution process of geological hazard sources of the rainfall-affected slope was summarized. A resistivity response mechanism equation for rainfall-induced slope hazard sources was derived and compared to the Archie formula, verifying the model rationality. The test results showed that the behavior of the rainfall-affected slope conforms to the saturated–unsaturated dynamic cycle process. The apparent resistivity was positively correlated with the development of slope pores and cracks and negatively correlated with the water content in the slope. The apparent resistivity increased during fracture development and decreased during water seepage. In the slope failure and disaster process, the apparent resistivity varies under the coupling effect of crack development and water seepage. During the formation of geological hazard sources, the apparent resistivity abruptly changes and fluctuates. Therefore, according to the abrupt changes and abnormal fluctuations in the apparent resistivity detected, the development of geological hazard sources of slopes can be determined. [ABSTRACT FROM AUTHOR]

Carbon capture utilization and storage (CCUS) technologies are regarded as an economically feasible way to minimize greenhouse gas emissions. In this paper, various aspects of CCUS are reviewed and discussed, including the use of geological sequestration, ocean sequestration and various mineral carbon mineralization with its accelerated carbonization methods. By chemically reacting CO2 with calcium or magnesium-containing minerals, mineral carbonation technology creates stable carbonate compounds that do not require ongoing liability or monitoring. In addition, using industrial waste residues as a source of carbonate minerals appears as an option because they are less expensive and easily accessible close to CO2 emitters and have higher reactivity than natural minerals. Among those geological formations for CO2 storage, carbon microbubbles sequestration provides the economic leak-free option of carbon capture and storage. This paper first presents the advantages and disadvantages of various ways of storing carbon dioxide; then, it proposes a new method of injecting carbon dioxide and industrial waste into underground cavities. [ABSTRACT FROM AUTHOR]

Button cutters are commonly used in hard rock drilling because the inserted carbide buttons provide exceptional wear resistance, impact resistance, and high strength in challenging geological formations. One of the most pressing issues in designing a button cutter is to study the rock breaking mechanisms of carbide buttons. In this study, the three-dimensional discrete element method (DEM) was employed to investigate the rock breaking mechanism and cutting performance of five widely used carbide buttons, i.e., spherical, saddle, wedge, conical, and parabolic buttons. The simulation results were compared with laboratory tests to reveal the rock indentation process. The crack propagation pattern, energy dissipation, and damage evolution associated with the force–penetration depth curve were investigated. Tensile damage was the primary determinant for crack propagation and coalescence. By systematically exploring the penetration index, specific energy, and crack propagation characteristics, the conical button had a high rock breaking efficiency when the penetration depth was low, and the saddle button had a high rock breaking efficiency when the penetration depth was high. The findings can provide references for the design of a button cutter. [ABSTRACT FROM AUTHOR]

Major concerns of carbon dioxide (CO2) sequestration in subsurface formations are knowledge of the well injectivity and gas storage capacity of the formation, the CO2 pressure and saturation plume extensions during and after injection, and the risks associated with CO2 leakage and fault reactivation. Saline reservoirs are considered as one of the target formations for CO2 sequestration through structural, residual, dissolution, and mineral trapping mechanisms. The boundary condition of the saline reservoir dictates the pressure and saturation plume extension of the injected supercritical CO2 that could expand over large distances. This can lead to sources of risk, e.g., leakage and/or fault reactivation due to presence of wells, thief zones, and geological discontinuities. Therefore, there is a critical need to develop a model that describes how risk-related performance metrics (i.e., the CO2 saturation plume size, the pressure differential plume area, and the pressure differential at specific locations) vary as a function of the size of injection, time following injection, injection operations, and geologic environment. In this study, a systematic reservoir modeling studies of anthropogenic CO2 sequestration in Citronelle dome, Alabama, was performed where all relevant scenarios and conditions to address the questions of the saturation and pressure plume size in the area of review (AoR) and post-injection site care (PISC) are considered. The objective for this study was firstly to systematically simulate CO2 sequestration, i.e., saturation dynamics, and pressure behavior over a range of operational and geological conditions and to derive conclusions about the factors influencing saturation and pressure plume size, post-injection behavior, and the risk associated with them, by developing third-generation reduced order models (ROMs) for reservoir behavior. Finally, to assess the uncertainty associated with our studies, Latin Hypercube Sampling (LHS) together with an experimental design technique, i.e., Plackett–Burman design, was used. Application of Pareto charts and respond surfaces enabled us to determine the most important parameters impacting saturation and pressure plume sizes and to quantify the auto- and cross-correlation among different parameters in both history-matched and upscaled models. [ABSTRACT FROM AUTHOR]

The article presents data on the analysis of U accumulation in recent sediments of lakes in the territory of the Southeast Fennoscandia. The research was carried out in the study area of the Republic of Karelia. It has been established that the content of U in sediments varies from 0.1 to 42.3 mg/kg (median is 0.91 mg/kg). In general, the studied sediments of the region had low concentrations of U in comparison with the average content of this element in the upper part of the Earth's crust. In some areas associated with deposits or ore occurrences of U, an increased content of U in lake sediments was revealed. The highest U accumulation level was found in the lake sediments, which are under the influence of the North Onega ore-geochemical region, where V deposits and ore occurrences that contain U, Fe, Mo and Cu are widespread. In the sediments of some studied lakes, Th anomalies were found, which often accompany U in ore geological formations. The analysis of uranium fractions in the sediments of some lakes in Karelia revealed the key role of the mineral (insoluble) phase in the accumulation of U, up to 64–68% of the total U content. The share of the organic fraction in the accumulation of U in the studied sediments of the lakes is small and ranges from 7 to 15% with respect to the total concentration of the metal. [ABSTRACT FROM AUTHOR]

The Kashmir Valley is immensely susceptible to soil erosion due to its diverse topography and unstable geological formations in the Himalayan region. The present study helps in assessing the spatial distribution and prioritizing soil erosion zones in the Central Kashmir region covering the Sindh and Dachigam catchments. The study implemented the GIS-based analytic hierarchy process (AHP) and weighted sum method (WSM) using datasets of precipitation, geological map, soil map, and satellite imagery and derived eleven factors (topographical derivatives, LULC, soil, drainage, rainfall, lithology, wetness index and greenness of an area). The ratings and weightage were proven to be unbiased and reliable based on the observed value of the consistency ratio (CR) (i.e., 0.07). The study depicts 41% of the total area to be extremely vulnerable to soil erosion. The slope varies from 0–62° with mean of 22.12°, indicating 467.99 km2 (26%) and 281.12 km2 (15%) of the area under high and very high susceptible zones, respectively. The NDVI and NDWI maps indicate soil erosion severity covering an area of 40% and 38%, respectively, in highly susceptible zones. High drainage density and curvature zones were observed in 18.33% and 22.64% of the study area, respectively. The study will assist in the planning and implementation of conservation measures. [ABSTRACT FROM AUTHOR]

The main objective of this study was to investigate the stability of the Acropolis Hill, Greece, by developing a Rock Instability Model (RIM) based on fuzzy logic and remote sensing techniques. RIM aimed to identify locations on the rock formations of the Acropolis Hill that will potentially have instability issues due to the action of geomorphological factors, weathering and erosive processes. Six factors including lithology, slope angle, density of discontinuities, density of faults, density of surface runoff elements, and the orientation of the stratigraphy of the geological formations in relation to the orientation of the slope were considered as the most appropriate for implementing the proposed novel approach, with each variable classified and weighted by a fuzzy simple additive weighting method. Lithology and slope angle were considered the most significant variables that contributed to the overall stability of the Acropolis Hill. The outcomes of the RIM model were verified by remote sensing data and field observation, showing an agreement and high accuracy. From the satellite data analysis, it was concluded that for the entire Acropolis Hill, minor displacement rates were recorded, probably because of the extensive mitigation measures and consolidation works established in the recent past. Overall, the study highlighted the ability of the proposed methodology to be used as an alternative investigation tool in rock instability-related assessments valuable to land use planning and development, helping reduce the anticipated losses in highly susceptible zones. [ABSTRACT FROM AUTHOR]

Geology usually deals with rocks formed long ago, which are static and stable over the span of human lifetime. This study aims to analyze anthropogenic influence on the formation of geological features in the southeastern Mediterranean. Tel Dor, along Israel's northern coast, was chosen due to the continuous presence of humans in the area for over 4000 years and the protective environment of its natural bays that preserve geomorphological changes. This allows for the examination of whether and how humans affect their (geological) environment. Three rocky platforms were chosen in the shallow waters of the South Bay adjacent to the Tel, and four cores were extracted. Results show the extent of the direct and indirect anthropological influences on the landscape. The presence of building stones consisting of dolomite, which is not found along the Carmel coast, is an example of direct influence (importation). The evolution of a biological and non-biological reef upon the sturdy base of the port constructions is an indirect influence. The formation of a non-biological reef upon an archaeological feature is a unique process. It would not have consolidated without the presence of anthropogenic activity. This study shows how human interference in the coastal area can trigger a chain reaction of geological processes lasting more than 2000 years. [ABSTRACT FROM AUTHOR]

Over the past several decades, the international community has been actively engaged in developing a safe method for isolating spent nuclear fuel, high and intermediate level radioactive wase of different degrees of heat generation in deep geological formations on the basis of regulatory requirements existing in each individual country (for example, in the Russian Federation-NP-055-14). Such a storage facility should be equipped with an engineered safety barrier system that combines a range of materials capable of ensuring the safe localization of environmentally and health-threatening nuclear power generation industry and the nuclear industry waste products, in particular. On the basis of the international experience discussed in this article on the design and operation of such facilities, the most universal material in terms of the functions performed as a component of the engineered barrier system is cement and the cement-based product mixed with various components—concrete. Furthermore, due to the possible mutual influence of buffer materials and their transformation over time at interfaces, this work considers the impact of cement-based barriers on other components of engineered barrier systems, the information on which has been accumulated as a result of both analytical laboratory tests and in situ radioactive waste disposal facilities under construction. [ABSTRACT FROM AUTHOR]

Water scarcity affects all continents, with approximately 1.2 billion people living in areas where water is physically lacking. This scarcity is more accentuated in countries with an arid climate, and its impact becomes more threatening when the economy depends mainly on it. The Kingdom of Morocco, with its agricultural vocation, is one of them, especially in its southern regions. Therefore, mapping areas with high groundwater potential based on available geospatial data allows for optimizing the choice of a future well in such areas. Geometric average and fractal models were used to assess and delineate potential groundwater areas in the Tissent basin, Southeast Morocco. Eight factors, including topography, geology, hydrology, and hydrogeology, influencing the distribution of water resources was used. The formation permeability factor presents the most significant impact among the others, although it is directly related to most of them. The areas located in the central and downstream part of the basin are characterized by a high water potentiality due to increased geological formations' permeability near the drainage system, which constitutes a recharge zone, and a low slope allowing a prolonged water-formation contact time favoring a gradual infiltration of the water towards the deep aquifers. The groundwater potential map has been edited and validated by comparing it with data from 52 wells scattered throughout the basin. The favorable potential sectors cover 15.81% of the basin's total area. The moderate ones account for 21.36% while the unfavorable areas cover 62.83%. These results aim to provide policymakers and managers with a guide map for groundwater research and reduce hydrogeological investigation costs. [ABSTRACT FROM AUTHOR]

Simple Summary: The Upper Jurassic deposits of the Lastres Formation crop out on the Asturian coast (northwest of the Iberian Peninsula), in the so-called "The Dinosaur Coast". This formation presents a high abundance of dinosaur remains and other vertebrates. Despite the deep knowledge about its fauna and environment, practically nothing is known about the plant communities that formed the landscape of the region at the end of the Jurassic. We present here the first palynological data of the Lastres Fm., identifying a rich and abundant palynological assemblage formed by more than 60 different taxa. The presence of some taxa with biostratigraphic value suggests a Kimmeridgian-Tithonian age for this formation. On the other hand, the botanical affinities of the taxa found indicate that the vegetation of the "The Dinosaur Coast" of Asturias would not be homogeneous, but would be formed by a mosaic of different plant communities that would adapt to the variety of environments present in the region. The presence of forest areas probably represented a protected environment as well as a food source for herbivorous dinosaurs. Analysis of charcoalified wood remains suggests that palaeofires were relatively recurrent in the study area. Abundant fossils of vertebrates (mainly footprints and bones of dinosaurs) and numerous invertebrates occur in the Upper Jurassic deposits of the Lastres Formation in the Asturias region, North of Spain. However, no palynological study has been published from this geological formation; therefore, much palaeoenvironmental and palaeoecological information is still unknown. In this study, a total of 62 morphospecies, belonging to 49 different morphogenera were identified, including pollen, spores, algae remains, fungi spores, dinoflagellates, foraminifera, and scolecodonts from four different locations on the Asturian coast. Spores are the dominant group of palynomorphs, both in diversity and abundance, contrasting with the minor diversity of pollen grains. The age of some key taxa indicates that the palynological assemblage cannot be older than the Kimmeridgian, suggesting a Kimmeridgian-Tithonian age. The botanical and environmental affinities of the pollen and spores indicate the presence of different plant assemblages, including plant communities from humid areas such as the margin of rivers and small freshwater ponds that were dominated by bryophytes and ferns, and a coastal plant community that would inhabit arid areas and would be dominated by gymnosperms and some pteridophytes. The SEM analyses of wood remains show the abundance of charcoalified remains suggesting that wildfires were usual in "The Dinosaur Coast" of Asturias during the Kimmeridgian. [ABSTRACT FROM AUTHOR]

This research assessed stress regimes and fields in eastern Iran using fault-slip data and the tectonic events associated with these changes. Our stress analysis of the brittle structures in the Shekarab Mountains revealed significant changes in stress regimes from the late Cretaceous to the Quaternary. Reconstructing stress fields using the age and sense of fault movements showed that during the late Cretaceous, the direction of the maximum horizontal stress axes (σ1) under a compressional stress regime was ~N290°. This stress regime led to the uplifting of ophiolites and peridotites in eastern Iran. During the Eocene, the σ1 direction was NE-SW. The late Eocene and Oligocene stress states showed two distinct transpression and transtension stress regimes. This transition from transpression to transtension in the eastern Shekarab Mountains was the consequence of regional variations in stress regimes. The Quaternary stress state indicates that the tectonic regime in the Quaternary is strike-slip and the σ1 direction is ~N046°, which coincides with the current convergence direction of the Arabia–Eurasia plates. Our paleostress analysis revealed that four distinct stress regimes have been recognized in the area, including compressional, transtensional, transpressional, and strike-slip regimes. Our findings indicated that the diversity of the tectonic regimes was responsible for the formation of a variety of geological structures, including folds with different axes, faults with different mechanisms, and the current configuration of the Sistan suture zone. [ABSTRACT FROM AUTHOR]