Arabian Journal of Geosciences最新文献

The geospatial techniques are being used in this research to determine the depths, trends, water levels, and likely groundwater zones in the Deori Tehsil. In the research area, topography maps of India and water quality analysis are used to define physical parameters for the inverse distance weighting (IDW) interpolation method. The soil slopes from 150 to 300 m at this point. With the branches of Navegaon Mountain and Chichgarh Hills to the south of it, it is situated 302 m above sea level. The study shows that the pre-monsoon water levels in the deeper aquifer range from 5.7 to 14.85 mbgl in May 2021, and the post-monsoon water levels in the deeper aquifer range from 0.2 to 2.5 mbgl in November 2021. This study region has the highest drinkable water quality (41.27%), followed by excellent water (17.46%) and good water (23.81%). This is because there is not much urbanization in the area, the water quality is excellent, and there is developed agricultural land nearby. There, the quality of the water appears to have declined. It has a capacity of 30.16% for bad water, 7.94% for unsuitable water, and 20.63% for extremely poor water, all of which are good for drinking and farming.

Food insecurity is a major issue in many parts of the world, driven by conflict, economic instability, environmental challenges, and poor governance processes. Understanding the impact of future rainfall extremes on areas already experiencing food insecurity is crucial. This study investigates how food insecurity hotspots (FIH), food crisis frequency, and duration will change in the near future (2021–2050) and far future (2071–2100) under Shared Socioeconomic Pathways scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5). The study utilizes precipitation data from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and FIH data from the NASA Socioeconomic Data and Applications Center (SEDAC). To calculate future exposure and vulnerability to FIH, as well as food crisis frequency and duration, weighted sum models were used. The results indicate that arid and semi-arid areas in northeastern Kenya, most of Somalia, zones in southeastern Ethiopia, most of Djibouti, and central and northern Sudan are highly vulnerable to future extreme rainfall events, an increase in FIH cases, and longer food crisis frequency and duration in the near future (2021–2050) and far future (2071–2100) under all scenarios. On the other hand, most districts in Uganda, southern and southwestern South Sudan, counties in western Kenya, and the majority of zones in western Ethiopia are projected to have very few FIH cases, low food crisis frequency, and duration in both the near and far future under all scenarios. These findings are crucial for early warning systems, humanitarian responses, and food security interventions. We recommend harnessing projected increases in rainfall for water harvesting in Kenya, as well as promoting cash and food crop production in central and western Ethiopia, central and northern Uganda, and most of South Sudan.

This paper presents an integrated approach involving geophysical and remote sensing datasets in the identification of regions that have undergone hydrothermal alteration in the gold-hosted site of the Ife–Ilesa schist belt. Geophysical methods employed include the aeromagnetic and aeroradiometric data, while the remote sensing involved Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Derivatives such as analytic signal, total horizontal derivative, tilt derivative of the total horizontal derivative, and 3-D Euler deconvolution were applied on the aeromagnetic data for the mapping and delineation of structures guiding migration of hydrothermal and mineralizing fluids in the study area. Radiometric analyses involving K/eTh, Ideal K anomalies deviation (Kd), and F-parameter, including principal component analyses on ASTER to isolate Potassic, Argillic, Propylitic, and Phyllic alteration zones were performed to delineate hydrothermally altered zones. The lineament map showed that the study area is geodynamically active as evident by the presence of deep-seated intersecting structures with depths ranging from 189 to 899 m, principally trending NE–SW, which is an impression of the Pan–African orogeny. The fuzzy gamma operator 0.9 was thereafter used in the integration of aeroradiometric and ASTER data for the hydrothermal alteration map production. Subsequently, five classes ranging from background to very high alteration anomalies were derived using the concentration–area (C–A) fractal model from the hydrothermal alteration map. These classes reveal the pervasive styles of alteration in the study area. The study further revealed the close association of structures, granitoids, hydrothermal alteration, and orogenic gold deposits. Also, the flurry of mining activities in the southern flank of the study coincides with most of the hydrothermally mapped areas with the Prediction–area (P–A) plot showing 78% occurrence of orogenic gold deposits in 22% of the total area explored. This translates to high potential of orogenic gold mineralization in the study area. The study therefore concluded based on the validation result that hydrothermal alteration mapping is important in the mapping of orogenic gold deposit. Hence, unexplored areas particularly in the western and eastern flank of the study area where there are strong indications of hydrothermal alteration have good prospect for gold mineralization.

The study presents a review of the Geology of the Senegalo-Mauritanian (S-M) sedimentary basin with a glance on stratigraphy, tectonic evolution, and integrated petroleum systems. The S-M basin is a typical Mesozoic-Cenozoic passive margin which opened westward from the Northwest African craton into the Atlantic Ocean. The basin overlies a Paleozoic sequence which represents part of the Taoudeni basin. Rifting and tectonic movements associated with the breakup of Gondwana and the formation of the Atlantic Ocean began in the Triassic and have led to a subdivision of the basin into three stages: pre-rift (Proterozoic-Paleozoic), syn-rift (Late Triassic-Middle Jurassic), and post-rift (Middle Jurassic-Present). Pre-rifting phase, made of sediments deposited between the Precambrian and Devonian, is mainly continental detrital rocks. The main deposits of the syn-rift stage are Triassic evaporites and Jurassic volcanic intrusion from the Central Atlantic Magmatic Province (CAMP). The post-rift segment consists of an Upper Jurassic-Lower Cretaceous carbonate platform overlain by a predominantly progradation and transgressive Cretaceous-Tertiary clastic sequence, up to 12,000 m thick in places. The S-M basin exhibits oil and gas potential. Indeed a total of three petroleum systems exist in the basin: the Lower Paleozoic Petroleum System (LPPS), the Subsalt Petroleum System (SSPS), and the Cretaceous-Tertiary Petroleum System (CTPS). Previous source rock analyses have shown a good quantity of total organic content (TOC) and type I kerogen; type I, II, and III for the LPPS and CTPS, respectively. The main reservoirs comprised fractured sandstone of Cambrian to Ordovician and Devonian, with good porosity up to 20%, karstified Oligocene limestone, and Maastrichtian and Miocene sandstones. The primary seals include the Upper Cretaceous and Tertiary marine mudstone and shale for these petroleum systems. Both stratigraphic and structural traps were derived from seismic profiles and included growth faults, slope truncation, turbidite-related traps, salt-related structures, carbonate bank deposits, and structures related to volcanism. Preserved extensional structures before the rifting and especially normal faults along the Paleozoic section have served as migration pathways for hydrocarbon in the Southern sub-basin.

This study focused on assessing and analyzing meteorological characteristics based on rainfall and temperature data from eight stations in Australia over the past three decades (1991–2000, 2001–2010, and 2011–2020). A Mann–Kendall test, followed by Sen’s slope analysis, was conducted to evaluate the spatial and temporal patterns of the most common indicators of climate change. Several drought indices were used to monitor and detect drought occurrences in the study area. It was found that from 2011 to 2020, most stations recorded negative rainfall trends, with no significant trends overall. Northern Australia saw slight rainfall increases, the northeast had notable increases, and the southwest and southeast showed drying trends. Minimum temperatures increased in northern and northeastern Australia, with significant positive trends at some stations. Maximum temperatures showed slight increases, with several stations having significant positive trends. PET values were higher at stations with low rainfall and high temperatures. The results of the drought indices show a normal drought cycle that recurs every ten years. Additionally, the driest conditions were recorded in the most recent decade, with extreme dryness noted in 2011–2020 compared to previous decades, highlighting the complex and changing climate patterns in Australia with varying regional impacts.

Potential zones of gold mineralization in Mwanza, Malawi, were mapped by employing an integrated analysis of satellite imagery and aeromagnetic data. PRISMA hyperspectral imagery satellite was used to map hydrothermal alteration minerals by employing linear spectral unmixing (LSU), spectral angle mapper (SAM), and spectral information divergence (SID) mapping techniques. Aeromagnetic data was used to map the structures using the Centre for Exploration Target (CET grid and porphyry analysis) and depth estimation using spectral analysis. The evaluation of LSU, SID, and SAM effectiveness showed an overall accuracy (OA) of 86.288% and a Kappa coefficient (ҡ) of 0.825, an OA of 82.042% and ҡ of 0.770, and an OA of 80.675% and ҡ of 0.753, respectively. The mineral maps revealed that the alteration zones mainly consist of kaolinite, indicating the potassic and argillic alteration types. About six zones that showed potential for mineralization were identified from the integrated analysis. The structures in the area were found to trend NE-SW dominantly, and the depth range to basement complex rocks, which host potential mineralization veins, was found to be 90.33–1416.40 m. Limited chemical data of quartz veins shows an average of 0.2 ppm gold anomalies from the identified zones. The suspected gold-bearing quartz veins have been observed to be in association with the gneisses and migmatites that make up the basement complex rocks in the area. A comprehensive study encompassing geological and geochemical surveys and analyses is required to ascertain its complete gold potential.

This research focuses on the technical and economic assessment of construction and demolition wastes (C&DW) as filling material for gabions executed for lining works of a river in the city of São Paulo, Brazil. Laboratory tests were performed on C&DW and natural rock to determine the durability, compressive strength, and water absorption necessary for gabion designs. In addition, an economic assessment was performed to estimate the costs of using C&DW to substitute rocks for gabion filling. The results showed that the studied C&DW complies with the technical standards and can be used as gabion-filling material, thus promoting a circular economy. However, due to the hydraulic efforts, a layer of shotcrete must be applied on the gabion surface. The economic assessment highlighted the economic advantages and low costs of substituting rocks for C&DW in gabions filling, even considering the need for a shotcrete layer.

Salinity affects greatly cultivated land by reducing its fertility; also it can lead to potential damages to substructures or even conduct to a collapse in the long run by changing soil geotechnical properties. Electrokinetic technology (EKR) is a promising technique for removing salinity from low-permeability soils. For these, it is essential to study the parameters that govern electro osmotic permeability in order to predict effectiveness and optimize electrokinetic treatment. This work concerns the application of the (EKR) method on the saline-sodic soil of the Bordjias plain located in the south-western region of Mostaganem (Algeria). Due to the semi-arid climate prevailing in this region, vast tracts of land are currently being lost due to salinization. The efficiency of this method is studied by the variation of the electric voltage gradient (0.375, 0.50, and 0.625 V/cm) surface and the electrode materials (brass and copper) on electro-osmotic permeability and electrical energy consumption. The results showed that increasing the electric voltage gradient had no effect on the intensity of electrolysis reactions, which did not change beyond a specific limit, and did not increase the electroosmotic flow; but it generated more electric current than the admissible current for copper electrodes, causing corrosion, unlike brass electrodes, which resisted significantly. For the same electric voltage gradient, brass electrodes resisted longer and resulted in a higher flow rate than copper. Maximum electroosmotic flow was recorded at 0.5 (V/cm) voltage gradient for both material electrodes, but the highest volume of flow evacuated was recorded for EKB2 (brass) (GR2) tests. The coefficient of electroosmotic permeability is inversely proportional to the electrical gradient in contrast to the electrical energy consumption which is also influenced by the type of electrode material used. This implies that an increased voltage gradient results in higher current and energy consumption. The study revealed no significant difference in energy consumption between brass and copper materials in terms of value; however, the Brass exhibits greater durability compared to copper materials. The conducted tests lead to the conclusion that the efficiency of the process can be achieved at a lower applied voltage, using a brass electrode for soils with high salinity concentrations. Consequently, an appropriate electric voltage gradient needs to be determined to achieve efficient electroosmotic treatment while effectively reducing the corresponding energy consumption.

Developing a geophysical test site (GTS) to a full target requires a lot of work in sequential order. This article presents the construction procedures and requirements for developing a GTS, field measurements, geophysical response analyses, and site descriptions. A GTS is an experimental site that contains several targets of known properties, materials, and parameters, buried at different locations, depths, and orientations. The 55 m × 55 m multi-purpose GTS was developed within the Ahmadu Bello University Geophysics Test Site (ABUGTS). The site was developed on a lateritic-clay soil within a shallow depth of 0.6–3 m to study the geophysical signature of various burial scenarios and replicate situations usually encountered in geophysical surveys, engineering, and environmental investigations. A pre-buried investigation with integrated geophysical methods was conducted to provide adequate information about the site condition. The integrated geophysical methods were also explored on a few buried targets for test runs alongside a laboratory test to determine the electrical and magnetic properties of the buried targets. The pre-burial study indicates that the site’s electrical resistivity (ER) values decrease significantly from 1081 Ωm to 47 Ωm with depth due to the regional groundwater effect. The post-burial investigations show positive results, corresponding to the laboratory results. The post-burial results show that the subsurface resistivity of the burial terrain decreases from 200 to 0.1 Ωm due to the influence of the buried metallic target and increases from 1081 to 110,000 Ωm due to the influence of the buried non-metallic target, while the total magnetic intensity of the site increases from 44,500 to 48,000 nT. Seismic result shows distortion in subsoil layers after the buried target, confirming a significant influence of the natural geophysical signature of the site by buried targets. The implications of the GTS on economic growth and educational activities were discussed. Geophysicists, researchers, and institutions can now take advantage of the site to explore the existing and new geophysical techniques routinely employed in geophysical investigations. Geophysical equipment manufacturers and individuals can also use the site for instrument configurations. The site can provide an experimental site to appreciate the nature of subsurface anomalous generated by different buried targets. It can serve as a guide for modelling new GTSs while bridging the gaps between hypothetical teaching and real-life problems through effective field-based exercises.

Rock material, such as sandstone, frequently shows a wide range of fracture characteristics and mechanical responses due to variations in weathering grades and the existence of natural fractures. These natural fractures in sandstone are regularly cemented by different minerals or cementation removed by weathering and/or stained with iron, which can affect the stress-induced fracture pattern and rock strength. These effects, along with fracture orientation and location on mechanical behavior and failure modes resulting from quasi-static loading, are poorly understood. The focus of this paper is to assess the effects of cemented and stained natural fractures on stress-induced sandstone failure mechanism and mechanical behavior, with a focus on natural fracture angle and location. To investigate sandstone mechanical behavior and failure mechanism, six unconfined compressive tests were conducted on specimens with pre-existing natural fractures at different angles (∅) to estimate unconfined compressive strength (UCS) and failure modes. ANSYS was also utilized for finite-element modeling and simulation to analyze comprehensive 3D fractured models. The results revealed that UCS of sandstone decreased with increasing fracture angles of 0°, 20°, 30°, 45°, 50°, to 60°, respectively. Sandstone with a 90° fracture angle exhibits higher UCS than samples with a 0° fracture angle. The findings indicated that sandstone with 0° and 20° fracture angles had multiple fracturing, while specimens with 90° fracture angles provided axial splitting. On the other hand, the shear failure in sandstone specimens occurred as the fracture angle superseded 50°. The simulation results demonstrate that fracture location affects only the UCS of sandstone.