Geological Layers Research Articles

MAES implementation in Greece: Geodiversity

The present study aims to support the Mapping and Assessment of Ecosystems and their Services (MAES) implementation in Greece, by synthesizing an indicator that could be used for abiotic attribute assessments and specifically for geodiversity. Such an indicator can be used not only for reporting obligations under EU initiatives but also for identifying “conservation hotspots”. Such areas, characterized by rich geodiversity, are important for supporting biodiversity and other ecosystem services. In addition, identification and mapping of threats to those areas, due to natural or anthropogenic processes, can be used for the introduction or reformation of protective environmental legislation. The geodiversity indicator has been compiled using geological, geomorphological, climatic, pedological and hydrological data layers, while threats to geodiversity have been produced by integrating the sub-indices of erosion, protection level, land degradation, mineral and/or ore extraction activity, and the concentration of wildfire ignition sites. Finally, a bivariate map highlights geodiversity “hotspots” in Greece, which were found to correspond in most cases with locations of rich geodiversity and poor protection from adverse natural or human induced processes, mainly due to the lack of protective legislation. The study's outcomes provide a baseline for scientifically informed decisions for conservation, management and spatial planning, while simultaneously complying with EU and national legislation and strategies for nature conservation and integrated development.

Enhancing the efficiency of geochemical quality assessment and prediction in Holocene aquifers in Central Vietnam

This study used 2-D electrical resistivity tomography (ERT), exploratory drilling, and physico-chemical analysis combined with machine learning models to analyze the geological and groundwater distributions in the Holocene aquifers in Central Vietnam. The dataset included 534 sets and nine features from 2019–2022, and the groundwater quality index (GWQI) was computed based on eight inorganic elements. The best parameter set for modeling the GWQI was found using the pattern search algorithm in R language. The prediction performance of the models was determined using the root mean square error and mean absolute error metrics. The study found that some research areas demonstrated organic pollution and alum contamination, and these pollutants were found in shallow geological layers close to the ground (within the second geological layer). The model performance varied by district, with Cubist outperforming other models with an R2 value of 0.900 for the Son Tra District and 0.992 for the Lien Chieu District.

A study of the influence of water level fluctuations on the geodynamic situation in the natural and technical geosystem of the Dniester HPP and PSPP cascade

Purpose. Statistical information for the period from 2016 to 2021 was used to analyze seismic activity. Objective. The aim of the study is to identify the relationship between changes in water level and local seismic activity in the region. Using HPP and Psing filtering, the hypocenters of earthquakes within a radius of 30 km from the seismic station with the NDNU index were selected, and using geographic information technology tools, the hypocenters of earthquakes were compared with the geological structure of the region. Methodology. Statistical information for the period from 2016 to 2021 was used to analyze seismic activity. Using filtering, the hypocenters of earthquakes within a radius of 30 km from the seismic station with the NDNU index were selected, and using geographic information technology tools, the hypocenters of earthquakes were compared with the geological structure of the region. Results. The studies revealed a correlation between seismic events and water level fluctuations in the reservoir. The paper also established the density of episodes concentrated in the reservoir operation area, as well as the magnitude and shallow depth, indicated the probability of activation of faults located in geological layers close to the ground surface. The stresses in the soils were assessed. Using the Coulomb-Mohr theory, the ultimate stresses leading to the destruction of structural ties were calculated approximately, and the optimal modes of operation of the reservoir were determined. Originality. The research in the article allows us to more accurately assess the effect of the stress gradient in the soils on the background seismicity in the reservoir operation area. Practical significance. The practical significance of this study is understanding the effect of the stress gradient on induction earthquakes. The described method, which is based on the principles of Coulomb's law and Mohr's theory, allows us to remotely study the behavior of the material under different loading conditions. This study and the development of a geomechanical model helps to better understand and predict earthquake behavior and determine safe loading zones. This has practical implications for the design and construction of structures, as well as for risk assessment and appropriate safety measures.

Application of cross-spectral analysis and fast Fourier transform to detect soil vibrations in the natural and technical geosystem of the Dniester PSPP

The main purpose of the study is to identify the relationship between changes in water level and soil deformation, where the cyclic change in loads on the reservoir bed is the stress deviator, i.e., the PSPP reservoir acts as an oscillator of transverse vibrations, and the soil extensometer performs the function of reading and recording these vibrations. Methodology. Solution of the problem requires recording the time series of water level fluctuations and extensometer sensor fluctuations on all depth horizons. It is also necessary to perform a fast Fourier transform for water level fluctuations separately and similarly to each extensometer sensor fluctuation. We need to separately calculate the signal power spectrum of all sensors in the soil, and compare the amplitude-frequency, phase-frequency components of the power spectra of water level oscillations and vertical oscillations of the extensometer sensors. Results. During the studies, it was found that the PSPP reservoir is a source of low-frequency vibrations in a wide spectral range. These vibrations have a very long wavelength, measured in tens of thousands of kilometers, which can propagate over long distances, both along the front of geological layers and in depth. Scientific innovation. The research in this article allows us to more accurately assess the frequency spectrum of vibrations and identify possible resonance phenomena that may occur in soils during the operation of a power facility. In addition, this study was conducted in a specific region, which makes it possible to obtain more accurate data on the impact of low-frequency vibrations on the geosystem in this region. Thus, this paper may be of interest to specialists in the field of geotechnics, geology, and energy. It can also be used in the planning and operation of other power facilities in similar conditions. Practical significance. Low-frequency waves can be detected by seismic instruments such as seismometers. The results of this study will help to correct the analysis and interpretation of seismograms, which is important for understanding the processes occurring in the hydroelectric power plant operation area.

Spectral Analysis of the Infinite-Dimensional Sonic Drillstring Dynamics

By deploying sonic drilling for soil structure fracturing in the presence of consolidated/ unconsolidated formations, this technique greatly reduces the friction on the drillstring and bit by using energetic resonance, a bit-bouncing high-frequency axial vibration. While resonance must be avoided, to our knowledge, drilling is the only application area where resonance is necessary to break up the rocks. The problem is that the machine’s tool can encounter several different geological layers with many varieties of density. Hence, keeping the resonance of the tool plays an important role in drill processes, especially in tunnel or infrastructure shoring. In this paper, we analyze the sonic drillstring dynamics as an infinite-dimensional system from another viewpoint using the frequency domain approach. From the operator theory in defining the adequate function spaces, we show the system well-posedness. The hydraulic produced axial force that should preserve the resonant drillstring mode is defined from the spectrum study of the constructed linear operator guided by the ratio control from the top to tip boundary magnitudes.

The quality of well waters in Poland – a study case

The aim of this study was to analyse the quality and compare the functional value of water from traditionally dug and drill wells located in west Poland. Basic physicochemical and microbiological (Escherichia coli in 100 ml, coliform bacteria in 100 ml, enterococci in 100 ml, total number of bacteria in 1 ml grown at 22 °C, total number of bacteria in 1 ml grown at 36 °C) were determination for the water samples. Additionally, some waters samples were analysed of the presence of heavy metals , TN (total nitrogen), TOC (total organic carbon) and NPOC (dissolved organic carbon). The conducted research has indicated that mineral and microbiological contamination occurs in the waters collected from the wells. This confirms that the wells were not sufficiently protected and that penetration of pollutants into the water occurs from their immediate surroundings, geological layers with which underground water resources come into contact.

Robust High-Throughput Proteomics Identification and Deamidation Quantitation of Extinct Species up to Pleistocene with Ultrahigh-Resolution MALDI-FTICR Mass Spectrometry.

Peptide mass fingerprinting (PMF) using MALDI-TOF mass spectrometry allows the identification of bone species based on their type I collagen sequence. In the archaeological or paleontological field, PMF is known as zooarchaeology mass spectrometry (ZooMS) and is widely implemented to find markers for most species, including the extinct ones. In addition to the identification of bone species, ZooMS enables dating estimation by measuring the deamidation value of specific peptides. Herein, we report several enhancements to the classical ZooMS technique, which reduces to 10-fold the required bone sample amount (down to the milligram scale) and achieves robust deamidation value calculation in a high-throughput manner. These improvements rely on a 96-well plate samples preparation, a careful optimization of collagen extraction and digestion to avoid spurious post-translational modification production, and PMF at high resolution using matrix-assisted laser desorption ionization Fourier transform ion cyclotron resonance (MALDI-FTICR) analysis. This method was applied to the identification of a hundred bones of herbivores from the Middle Paleolithic site of Caours (Somme, France) well dated from the Eemian Last Interglacial climatic optimum. The method gave reliable species identification to bones already identified by their osteomorphology, as well as to more challenging samples consisting of small or burned bone fragments. Deamidation values of bones originating from the same geological layers have a low standard deviation. The method can be applied to archaeological bone remains and offers a robust capacity to identify traditionally unidentifiable bone fragments, thus increasing the number of identified specimens and providing invaluable information in specific contexts.

Revealing the Extent of Submarine Permafrost and Gas Hydrates in the Canadian Arctic Beaufort Sea Using Seismic Reflection Indicators

AbstractThe Canadian Arctic Southern Beaufort Sea is characterized by prominent relict submarine permafrost and gas hydrate occurrences formed by subaerial exposure during extensive glaciations in Pliocene and Pleistocene. Submarine permafrost is still responding to the thermal change as a consequence of the marine transgression that followed the last glaciation. Submarine permafrost is still underexplored and is currently the focus of several research projects as its degradation releases greenhouse gases that contribute to climate change. In this study, seismic reflection indicators are used to investigate the presence of submarine permafrost and gas hydrates on the outer continental shelf where the base of permafrost is expected to cross‐cut geological layers. To address the challenges of marine seismic data collected in shallow water environments, we utilize a representative synthetic model to assess the data processing and the detection of submarine permafrost and gas hydrate by seismic data. The synthetic model allows us to minimize the misinterpretation of acquisition and processing artifacts. In the field data, we identify features along with characteristics arising from the top and base of submarine permafrost and the base of the gas hydrate stability zone. This work shows the distribution of the present submarine permafrost along the southern Canadian Beaufort Sea region and confirms its extension to the outer continental shelf. It supports the general shape suggested by previous works and previously published numerical models.

Water availability identification of underground river in the Gunung Sewu karst area using inverse model

The karst area is identified in the Gunung Kidul Regency, the so-called Gunung Sewu karst area, as one of the Geopark areas in Indonesia. Gunungkidul Regency has had moderate to high yearly rainfall for the last ten years. However, this region has a problem with a surface water shortage. It is due to the characteristics of the karst, which allows rainwater to penetrate the geological layers accumulating in the certain noose yielding abundant underground water reserves. The purpose of this study is to assess the underground river water availability and the hydrological characteristics in the karst region using Inverse Modeling. Inverse Modeling is a method to identify the features of the underground river by adjusting the hydrological variables as an input and output discharge as a control. The FJ Mock Model as a surface hydrological model is used to characterize the Karst region’s underground river. There were five models in total to be simulated. The conditions under the Mock model show consistent results compared to the stepwise model in terms of low discharge conditions; Coefficient Correlation, RMSE, and R2 values obtain 0.637, 17.29, and 0.407, respectively. In this case, estimating the low flow conditions is more accurate than the high-rate flow conditions. The results are closer to the stepwise model without the infiltration variable involved.

Why landfill deposits are a distinguishing feature of the Anthropocene

The Anthropocene is generally defined as a postulated new geological epoch, which, according to various authors, began in the 20th century. The postulated Anthropocene Epoch is characterized by a decrease in biodiversity, climate change, transformations of the Earth’s surface, exploitation of natural resources, and environmental pollution. Waste landfills influence some of these features (e.g. biodiversity and climate change, create new anthropostratigraphic geological layers); therefore, they should also be a matter of interest and research conducted in order to become considered as a subsequent postulate confirming the Anthropocene Epoch. This paper draws attention to the fact that environments created and dominated by human activity, such as waste landfills, may be used as an effective starting point to confirm the new Anthropocene Epoch. Waste landfills contribute significantly to geological, climatic, environmental, and ecological changes (modification).

Groundwater Assessment using Numerical Flow Model: A Case Study in Gash Sub-Basin-Kassala State, Sudan

The main objective of groundwater modelling in Gash River Sub-basin, is to investigate the effect of hydrologic, hydrogeological parameters and stresses on hydrodynamic behaviour through the implementation of a realistic three-dimensional groundwater flow model. Severe decline of water level due to uncontrollable heavy abstraction, exposes a water scarcity problem especially in summer seasons. The model was developed for four geological layers encompassing two aquifer zones. The improved three-dimensional visual MODFLOW Code was selected, implemented and run using WHS method to solve the finite difference equation using trail-and-error calibration procedure at Kassala Area. The transient model was successfully calibrated with acceptable results of model calibration criteria. The contour maps of the simulated heads were performed as potentiometric surface. The general flow direction of the groundwater is from southeast towards northwest part of the area and from Gash River course towards the east and west directions as detected from gradual decreasing of potential line’s values in those directions, confirming the aquifer recharge from Gash River. The similarity of potentiometric surface contour maps of the two aquifers confirm the aquifers hydraulic interactions. It is found that the increasing pumping rate caused considerable increase in drawdown as detected from pumping rate incremental scenarios. Moreover, incremental pumping rate scenarios also reflected increasing river leakage into the aquifer system due to disturbance of water balance due to water level decline. The components of water budgets were calculated and its percentage was performed for the hydrologic balance. The difference between inflow and outflow of the water balance shows a deficit in most stress periods of the model simulations. Calibration fitness was accomplished at most of the observation wells suggesting that the groundwater model is an accurate representation of the actual historic groundwater system and confirm the validity of the model to forecasting purposes. It was found that the model is more sensitive to hydraulic conductivity and least sensitive to specific yield (Sy). Hence, precaution should be revealed for hydraulic conductivity in forecasting model usage.

The Time of the Migrant

The Time of the Migrant

Cross-Correlation Analysis of the Stability of Heterogeneous Slopes

Geologic material properties of hillslopes are inherently heterogeneous, with complex layering structures due to geological deposition processes. Lacking detailed sampling of the properties’ spatial distribution has led to the stochastic representation of the properties to address uncertainty in the hillslope stability evaluation. This study treats the spatial distributions of the shear strength parameters, the cohesion (c), and the internal friction angle (φ), in a synthetic two-dimensional slope as stochastic random fields characterized by their means, variances, and correlation scales. This study then evaluates the cross-correlation between these parameters and the factor of safety (FS) using unconditional Monte Carlo simulation (MCS). Different from classical sensitivity analyses, the cross-correlation analysis of FS and the stochastic parameter fields stresses the importance of the orientation of the large-scale geological layering, the correlation between the geological media’s cohesion, and the internal friction angle at the local scale on the probability and uncertainty of failure of the heterogeneous hillslope. The analysis further guides the field sampling strategy to reduce uncertainty in the slope stability analysis due to unknown heterogeneity. More importantly, it suggests the location of stability reinforcement measures. The results of this study provide cost-effective tools for geoengineers to deal with field slope stability analysis under uncertainty.

A new Trapa from the middle Miocene of Zhangpu, Fujian, southeastern China

The Zhangpu biota from the middle Miocene, located in the Fotan Group of Fujian, southeastern China, is renowned for being an ancient megathermal seasonal rainforest ecosystem. This paper presents the description of a new species of Trapa (Trapoideae, Lythraceae) based on the examination of well-preserved fossil fruits from the Fotan Group, adding to knowledge of the freshwater plant diversity within the Zhangpu biota. Trapa haominiae n. sp. has medium-sized fruits with four horns that are more or less similar in form and size. The horns are expanded nearly horizontally or slightly upward pointing, with a spiny, harpoon-like apex bearing retrorsely barbed spines. Trapa haominiae is among the earliest, unequivocal fossil record of Trapa in the world. The fruit morphology of T. haominiae confirms a close relationship between Trapa and Hemitrapa. The discovery of the present fossil, along with horned fruits of Hemitrapa zhangpuensis, and the pollen grains of Sporotrapoidites weiheensis and S. erdtmanii from the same geological layer, indicates that the Trapoideae were important components of the freshwater ecosystem in Zhangpu during the middle Miocene.

Building a geospatial model to identify potential geothermal sites in Ayrobera: Afar depression, NE Ethiopia

Ethiopia has a long-term plan to maximize its power generation to support its growing economy by diversifying its energy sources. Geothermal is an important alternative energy source as the country has a vast potential within the Ethiopian Rift. Several high-temperature geothermal sites that can be utilized for power generation have been identified in the Main Ethiopian Rift and the Afar Depression, using geoscientific investigations at different times. Locating a potential site for geothermal development is a complex process involving decision-making and is prone to human error. Various geospatial datasets can be integrated using geographic information systems to identify potential areas for geothermal development. This technique would facilitate informed decision-making, thus lowering the risk of drilling unsuccessful wells. In this paper, we have used geospatial modeling for potential site identification in the Ayrobera geothermal field, located in the Afar Depression in NE Ethiopia. Weighted Overlay Analysis using the Analytical Hierarchy Process was performed using geospatial datasets as the inputs, including geological, temperature, and geophysical data layers, to determine the most suitable potential geothermal sites. This process yielded a final suitability map, showing the Highly Suitable, Suitable, Less Suitable, and Unsuitable zones. The Highly Suitable and Suitable areas were located near the faults and fumaroles. The Less Suitable and Unsuitable regions were located in the central and northern portions of the study area, far away from surface manifestations and faults.

Evaluation of underground blast-induced ground motions through near-surface low-velocity geological layers

Surface ground motion produced by underground blasts is significantly influenced by near-surface geological conditions. However, near-surface low-propagation velocity layers were always ignored in past analyses of ground motions due to their thin thickness. With the rising concern about surface ground motions produced by the ascendant scale and frequentness of underground excavation and mining, close attention is gradually paid to ground blast vibrations. Therefore, systemic experiments were conducted and took seven months in an underground mine to clarify the variation of motion from underground rock to surface ground. The attenuation of surface ground peak particle velocities (PPVs) is compared to that in underground rock, and horizontal amplitudes are compared to vertical amplitudes. Differences between bedrock and surface ground vibrations are analyzed to illustrate the site effect of near-surface lower-propagation velocity layers. One-dimensional site response analysis is employed to quantify the influence of different geological profiles on surface ground vibrations. The experimental data and site response analysis allowed the following conclusions: (1) geological site effects mainly produce decreasing dominant frequency (DF) of surface ground vibrations; (2) the site amplification effect of blast vibration needs to be characterized by peak particle displacement (PPD); (3) shear waves (S-waves) begin to dominate and surface Rayleigh waves (R-waves) develop as blast-induced ground vibrations travel upward through rock and lower-velocity layers to the surface. The comparison of response relative displacement to a critical value is best to assess the potential for cracking on surface structures.

VES Geoelectrical Method for Identification of Aquifer Depth in Coastal Area of North Lombok Regency, Indonesia: Implications for the Sustainable Utilization of Water Resources

Measurement of the resistivity value distribution of subsurface rocks has been carried out in Mumbul Sari Village, Bayan District, North Lombok, which is one of the drought-prone areas in NTB Province, Indonesia. This research was conducted to identify the presence of groundwater aquifer layers in the study area based on the distribution of resistivity values. Data collection was carried out at two measurement points, namely the MBLS-1 Point with a track length of 700 m and the MBLS-2 Point with a length of 750 m. Data processing was carried out using IP2WIN Software to obtain a one-dimensional subsurface cross-sectional model, then interpreted using a resistivity log to make it easier to draw information on the subsurface point of measurement. Based on the distribution of resistivity values, it is known that the geological layers in the study area consist of pumice tuff, silty silt, sandy silt, and lava. The inversion results from the IP2WIN software show that the depth of the aquifer zone at Point MBLS-1 is 15.6 – 70.2 m with a resistivity value of 90.3 Ωm and a thickness of 54.5 m, while at Point MBLS-2 it is located at a depth of 21.9 – 86.1 m with a resistivity value of 112 Ωm and a thickness 64.3m. The aquifer zone at both measurement points is interpreted as a sandy silt layer. Groundwater drilling is recommended at the MBLS-1 point to a depth of 70 m and at the MBLS-2 point to a depth of 86 m. The geological structure that forms the boundary of the aquifer zone is a layer of compact and hard lava, so for groundwater utilization in the study area, it is recommended to use drilled wells to a depth of 70 – 86 m which is the lower limit of the aquifer layer.

Physics-driven self-supervised learning system for seismic velocity inversion

Seismic velocity inversion plays a vital role in various applied seismology processes. A series of deep learning methods have been developed that rely purely on manually provided labels for supervision; however, their performances depend heavily on using large training data sets with corresponding velocity models. Because no physical laws are used in the training phase, it is usually challenging to generalize trained neural networks to a new data domain. To mitigate these issues, we have embedded a seismic forward modeling step at the end of a network to remap the inversion result back to seismic data and thus train the neural network through self-supervised loss, i.e., the misfit between the network input and output. As a result, we eliminate the need for many labeled velocity models, and physical laws are introduced when back-propagating gradients through the seismic forward modeling step. We verify the effectiveness of our approach through comprehensive experiments on synthetic data sets, where self-supervised learning outperforms the fully supervised approach, which accesses much more labeled data. The superior performance is even more significant when compared with a new data domain that has velocity models with faults and more geologic layers. Finally, in case of unknown and more complex data types, we develop a network-constrained full-waveform inversion (FWI) method. This method refines the initial prediction of the network by iteratively optimizing network parameters other than the velocity model, as found with the conventional FWI method, and demonstrates clear advantages in terms of interface and velocity accuracy. With these measures (self-supervised learning and network-constrained FWI), our physics-driven self-supervised learning system successfully mitigates issues such as the dependence on large labeled data sets, the absence of physical laws, and the difficulty in adapting to new data domains.

Application of 2-D imaging survey for ascertaining the cause(s) of road failures along Sapele/Agbor road in Delta State, Nigeria

Surveying involving 2-D imaging dipole–dipole geophysical technique was carried out along Sapele-Agbor Highway situated in Southern, Nigeria to determine the primary causes for Highway pavement failure. Twelve profiles spreading over 100 meters were in each cases conducted on road surface sections along the stable (control) and unstable portions of the road. Data were gathered together along the various profile employing ABEM Terra meter SAS 1000. The field data were processed and inverted utilizing Dipro software. This was done by specifying and locating the geoelectric arrangement within the surface, sub-base and sub grade soil to obtain the confirming cause(s) of the road associated with pavement failure. Geoelectric sections identified four geologic layers embracing the topsoil, clayey, laterite and sand. The sections failure is due to disparity of the material used for road model (construction) as some comprises of clay materials. The results show the presence of low resistivity values at several subdivisions of the 12 profiles. Resistivity values varying from 21.60 Ωm – 1026.0 Ωm to a depth of 14.92 m from the surface was observed along Okpara Water side, Aghalokpe and Otumara. In Igun, Eku and Obiaruku resistivity values ranges from 10.5 Ωm – 500.0 Ωm to a depth of 5.5 m from the topsoil, 22 m from sub grade and 9.8 m - 50 m were observed along the four profiles. Urhomehe, Urhonigbe, Abavo and Agbor indicate resistivity ranging from 59.25 Ωm – 1467.50 Ωm for stable and unstable sections of the road with depth up to 15.0 m for some profiles. Low resistivity values, not greater than 199 Ωm observed in some distinctive regions of 12 profiles comprises of expansive, compressible, collapsible and sandy clay materials which have the capacity of absorbing water. These make the roads swell and collapse leading to road failure under stress and strain. Many stable portions of the road are characterized with high resistivity value greater than 199 Ωm, mostly laterite materials. Competent fill soil should replace low resistivity soil to a depth of 5 m – 7m from the surface of the road. Good drainage system is also recommended within the unstable road sections.

Groundwater flow modeling and hydraulic assessment of Al-Ruhbah region, Iraq

Abstract Al-Ruhbah region is located in the southwest of Najaf Governorate. A numerical model was created to simulate groundwater flow and analyze the water quality of the groundwater, by developing a conceptual model within the groundwater modeling system software. Nineteen wells were used, 15 for pumping and four for observation. A three-dimensional model was built based on the cross-sections indicating the geologic layers of the study area, which were composed of five layers. When a distance of 1,000 m between the wells was adopted, 135 wells can be operated simultaneously. These wells were hypothetically operated at 6, 12, and 18 h intervals, with a discharge of 200, 430, and 650 m3/day, respectively, and the maximum drawdowns of 12.5, 15, and 21 m were achieved. Water was also extracted from five wells in the study area to evaluate the quality of water for irrigation purposes and to characterize the type of water in these wells based on the Food and Agriculture Organization and Iraqi standards. The results of the laboratory tests revealed that the water suffers from different salinity concentrations, so for a large part of the study area, the water is suitable for some plants that can withstand high salt ranges between 3,000 and7,500 µc/cm.