Arabian Journal of Geosciences最新文献

This paper present field observations, petrology, and geochemical data to discuss the petrogenesis of the Bangoua basalts. The study area is located in the southern end of the Cameroon Volcanic Line within the Central PanAfrican Fold Belt. The rocks display fine to coarse-grained sizes, indicative of several crystallization phases. The geochemical data show non-dispersion, indicating a unique magmatic series. The samples are classified as transitional basalts with a tholeiitic affinity, and a sodic basaltic trachyandesite composition, belonging to the medium-K calc-alkaline series. These rocks evolved from the alkaline to transitional mafic magmas through crystal fractionation. The significant Sr anomaly observed in the primitive normalized Rare Earth Elements (REE), despite of none clear Eu anomaly, indicates plagioclase fractional crystallization. Geochemical analysis revealed that they were subject to medium - to - high crustal contamination. The Bangoua transitional basalts were formed through the partial melting of a mantle source at various depths, indicating a melting degree of around 4–5%. This process occurred at an approximative depth of around 100 km between 2 and 4 GPa, suggesting a partial melting of a garnet peridotite source at around 14–16%. Their magma was generated in an enriched primordial deep mantle source in the crustally contaminated lithospheric mantle, and Oceanic Island Basalts (OIB) fields within the Proterozoic oceanic plateau basalts, which were metasomatized by subduction processes. Mantle plume-derived basalts occur in both oceanic and continental settings; the worldwide continental volcanic series are linked to the mantle plumes. The samples plot in Enriched Mantled (EM) source, mainly EM1 - OIB like indicating that the emplacement of the Bangoua basalts were probably formed by the partial melting of a metasomatized subcontinental lithospheric mantle, followed by lithospheric thinning and rapid emplacement.

Ethiopian orogenic mesothermal gold and associated metallic mineral deposits occur within the greenstone ophiolitic fold and thrust belt of brittle-ductile shear zones. However, details of the gold and base metal mineral potential have not been well investigated in the Ropi Megada valley, west Guji, Ethiopia. This study, therefore, characterizes the gold and base metal mineral potential in the study area. Among the collected samples, 12 gold fire assays, 11 gold mineralogical physical studies, and 12 ore mineral analyses were determined using Inductively Coupled Plasma-Mass Spectrometry, Stereo Microscope, and Ore Microscope, respectively. The study of geology includes quartz-feldspathic gneiss, biotite gneiss, garnet-biotite schist, amphibole-biotite schist, granodiorite, and K-feldspar-rich granite rocks. Ore mineralogy assemblages in the mafic schists occurred within the narrow, N-S trending, and brittle-ductile shear zones. Pyrite deformation contained inclusions of chalcopyrite and sphalerite that were genetically younger than pyrite. The gold and base metal concentrations are situated in the central and southeastern parts near the brittle-ductile shear zone. The base metals and trace elements associated with Au include Cu, Zn, Pb, Co, Ni, Sc, Mo, Li, Tl, Cd, Ag, and As. The Au concentration anomaly was categorized as low (0.001 to 0.039 ppm), moderate (0.03901 to 0.176 ppm), and high (0.17601 to 0.489 ppm). Among these, the Au range of 0.001 to 0.489 ppm is deposited in the amphibole-biotite schist. The gold grain sizes ranged from fine to coarse and mostly showed angular and sub-angular morphology, indicating that the primary gold is located near the study area. The gold crystals were associated with quartz, ilmenite, rutile, tourmaline, magnetite, and calcite. The gold fire assay chemistry compositions were dominated by Au (0.13), Cu (43.43), Zn (74.99), Ni (324.43), Co (48.48), Sc (24.43), Li (15.54), Tl (4.17), Pb (3.6), As (1.25), and Ag (0.13) ppm. This study in the Ropi Megada valley demonstrated that the potential area for gold, base metals, and trace element mineralization is evidently associated with the hydrothermal type along the brittle-ductile deformation in the amphibole-biotite schist rock suites as a result of orogenic metamorphism and subordinate mafic magmatic fluid that originated from the nearby source rocks.

Flood evacuation channel system is intended for flood evacuation. However, it has become a source of waste disposal for the residents, leading to the blocking of flood channels and consequently flooding in some places. This study aimed to assess the impacts of anthropogenic activities that influence the flood evacuation channels system in Anambra State, Nigeria. Primary and secondary data sources were used. The primary data consist of field visits and observations, interviews-cum-questionnaires, and photographs. The secondary data include satellite images from Diva-GIS and other relevant literature. The generated data were analyzed using structural equation model (SEM) in Jamovi. The results revealed that flood channel system inefficiency is attributed to abuse by residents using the system as a waste disposal system. Drainage designs and construction defects in varying the size of the flood channels impede the free flow of runoffs. Drainage channels’ connection and under sizing down slope of the channel system negatively impact the flood evacuation channel system efficiency in some places in the study area.

This study assesses landslide susceptibility in the Rudraprayag to Badrinath region of the North Western Himalayas, Uttarakhand, India, using spatial statistics and machine learning techniques. A dataset of 268 landslide and 268 non-landslide points was analyzed to explore the spatial distribution of landslides. To achieve this, advanced spatial analysis methods including Average Nearest Neighbor (ANN), Moran’s I, K Function Analysis, and Getis-Ord Gi* Hotspot Analysis were integrated with Random Forest modeling. This integration aims to improve landslide susceptibility mapping. As a result of these analyses, the study found notable clustering of landslides impacted by environmental and geomorphological elements such as slope, elevation, seismic activity, and river proximity. Furthermore, cold spots were identified in more stable locations, while hotspot analysis highlighted high-risk areas, mostly in regions with steep slopes, weak lithology, and proximity to river systems. The Random Forest model further revealed elevation, slope, seismic activity, urbanization, and rainfall as key contributing factors in landslide susceptibility. Based on these findings, the study highlights the necessity of focused mitigation methods in high landslide prone locations and clearly identifies zones of varied susceptibility. In summary, the findings provide valuable insights into landslide dynamics and contribute to more effective landslide risk management in the region.

The petrogenesis of Middle Eocene Himalayan adakitic rocks is debated. This study investigates middle Eocene (42.4 ± 1.4 Ma) granite porphyries from Lianxiang, southern Tibet, using zircon U–Pb geochronology, whole-rock major-trace elements, and Sr–Nd isotopes, together with zircon Hf isotope to constrain their petrogenesis and geodynamic implications. The rock displays adakitic signatures (high SiO₂, Al₂O₃, Sr/Y, and La/Yb ratios) but enriched isotopes (high ⁸⁷Sr/⁸⁶Sr(i), ε_Nd(t) = –8.2 to –7.7; ε_Hf(t) = –24.4 to –14.9 and ancient crustal model ages (Nd T_DM2 ~ 1.47 Ga, Hf T_DM^C ~ 1.49 Ga). The samples exhibit ultralow MgO (0.28–0.46 wt.%), Cr (4.54–8.59 ppm), and Ni (2.47–3.76 ppm), precluding mantle-derived or subducted slab origins. Modeling shows predominant (> 85%) Paleoproterozoic crustal recycling with minimal mantle input (< 15%). Geochemical systematics (e.g., CaO/Na₂O = 0.04–0.06, Rb/Sr–Rb/Ba trends) indicate derivation from partial melting of thickened (> 50 km) ancient lower crust dominated by pelitic metasediments. We attribute magma generation to Neo-Tethyan slab break-off at ~ 45 Ma, which triggered asthenospheric upwelling and thermally facilitated anatexis of the Indian continental margin. This process records crustal thickening during India-Asia collision and highlights slab break-off as a key mechanism for syn-collisional adakitic magmatism in the Himalayas.

This study analyzes groundwater drought in the Konya Closed Basin over the period 1967–2019, with an emphasis on the anthropogenic pressures in affecting hydrological drought conditions. Standardized Groundwater Level Index method was employed for examining drought conditions for short-term datasets covering seasonal, 6, and 9-month periods, alongside long-term datasets spanning 12, 24, and 36-month periods. Our findings highlight the severity of drought occurrences during winter, spring, and across the 12, 24, and 36-month periods. Sub-basins such as Beyşehir, Altınekin, and Çumra stand out for experiencing the highest rates of severe and extreme drought. The Konya Closed Basin, characterized by limited surface water and excessive groundwater utilization, has witnessed a rapid proliferation of wells since the 1990s. The average decrease in water levels from 1954 to 2018 stands at 15.9 m, with an annual reduction rate of 56.8 cm. If the impacts of hydrological drought resulting from unplanned and improper irrigation practices in the Konya Closed Basin are not mitigated, the ensuing consequences could result in serious threats to food and water security, as well as desertification.

Radiation exposure from naturally occurring radioactive materials (NORMs) is a significant contributor to human health risks. The aim of this study was to access the levels of radionuclides in selected surface and groundwater sources in Abakaliki, southeastern Nigeria. A total of 24 water samples were collected and analyzed for their radioactive concentrations of NORMs like ⁴⁰K, ²²⁶Ra, and ²³²Th, using sodium iodide NaI(TI) detector. The parameters used for the calculations were radium equivalent activity (Ra_eq), gamma absorbed dose rate, annual gonadal equivalent dose rate (AGEDr), external radiation hazard (H_ex), internal radiation hazard, representative level indices (I_γr), and alpha indices (I_α). From the results, the activity concentrations of ⁴⁰K, ²²⁶Ra, and ²³²Th ranged from 120.83 ± 2.57–395.50 ± 10.27 Bqkg^− 1, 6.40 ± 1.01–10.56 ± 0.83 Bqkg^− 1, and 0.97 ± 0.05–3.48 ± 0.81 Bqkg^− 1, respectively. The mean values of specific activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th were 21.59 ± 8.13 Bqkg^− 1, 6.93 ± 3.31 Bqkg^− 1 , and 1.99 ± 37.51 Bqkg^− 1, for ⁴⁰K, ²²⁶Ra and ²³²Th, respectively. The mean values for Ra_eqwas 09.56 Bqkg^− 1, which was lower than the acceptable limit of 370 Bqkg^− 1. The AGEDr mean value was 59.04 mSv.y^–1, which was more than the United Nation Scientific Committee on the Effect of Atomic Radiation’s recommended reference value of 0.1 mSv.y^–1, resulting from 1 year’s intake of studied water samples. The mean values for Iγr and Iα were 2.58 g and 0.45 Bqkg^− 1, respectively. The results of all the derived parameters were below the permissible limits of 1.0 Bqkg^− 1, except AGEDr and I_yr, which were more than the worldwide reference value of 0.1 mSv.y^–1 and 1.0 Bqkg^− 1, respectively. Prolonged consumption of water from the study area may pose health risks due to elevated radionuclide levels. Thus, the natural water sources in the area must be treated adequately using appropriate water treatment methods, like reverse osmosis, before use, especially for drinking purpose to forestall health risks associated with radiological hazards. Such hazards include damage to the genetics system, eye defects, smear of skin, destruction of the circulatory system, lung cancer, and bone cancer and cavity.

Reliable streamflow assessment is essential for sustainable water resource management, particularly in large tropical basins affected by data scarcity, climatic variability, and land-use change. This study evaluates long-term streamflow dynamics in the Lower Godavari River Basin using the Soil and Water Assessment Tool (SWAT) within the ArcSWAT framework. Spatially distributed meteorological, land-use, topographic, and soil datasets were integrated to simulate hydrological processes over a 36-year period. Model calibration (1984–2014) and validation (2015–2020) were performed using the SUFI-2 algorithm in SWAT-CUP, with performance assessed through NSE, R², and RSR statistics. Sensitivity analysis identified the runoff curve number (CN2) and groundwater delay (GW_DELAY) as the most influential parameters controlling streamflow response. The model achieved satisfactory performance, yielding NSE values of 0.86 and 0.84 and R² values of 0.89 and 0.85 for calibration and validation, respectively. Results indicate that SWAT effectively captures the temporal variability and hydrological behaviour of this monsoon-driven, data-scarce basin. The study provides a robust multi-decadal assessment of catchment response and hydrological variability, offering valuable insights for basin-scale water management, climate-resilient planning, and flood risk mitigation in similar tropical and semi-humid river systems.

Dust events have been identified as one of the most significant environmental challenges in the Middle East region during the past decades and creating many difficulties for the inhabitants of the Khuzestan province in southwestern Iran. This study investigates a severe sand and dust storm (SDS) that occurred on July 1–2, 2008, in Khuzestan and its neighboring countries. Satellite images, synoptic analysis, numerical simulation with the WRF-Chem model, and air parcel trajectory using the HYSPLIT model were used for detailed analysis of mentioned dust events. Numerical simulation results demonstrated that about 4.11 Tg dust particles were emitted from the simulation area. Comparing the amount of emitted dust to the deposited dust in Khuzestan province indicates that the massive contribution of dust in Khuzestan originates from the Middle East dust sources. Although Khuzestan province has a share of about 0.11% in dust emission in the study period, it hosts 3.5% of the total deposited dust. According to the results of the synoptic analysis of the event and the backward trajectory of the air parcel using the HYSPLIT model and WRF-Chem results analysis, Upper Mesopotamia and southwestern Iraq were the main dust sources that affected Khuzestan province.

The Casamance-Bissau compartment is a sub-basin of the larger Senegal-Mauritania basin, of economic interest in the field of hydrocarbon exploration. It has been the subject of prospecting and exploration studies since the 1960s, requiring the use of advanced technologies and analytical methods. This study identified the petrophysical properties of the Maastrichtian reservoir, penetrated by 9 wells drilled in the AGC Shallow water zone. Gamma-ray analysis, sonic density, and resistivity measurements allowed us to determine the porosity and fluid saturation of the said reservoir. The Maastrichtian reservoir has thicknesses ranging from 6.8 m to 134.7 m. It consists of sandstones with excellent properties, including an average porosity of 28% and high permeabilities. A clay volume below 50% and minor traces of carbonate cement have been reported in certain wells in the reservoir section. The Upper Maastrichtian Reservoir is not present throughout the area, and no hydrocarbons were encountered. However, light oil with an API gravity of 33° was discovered in the deep Maastrichtian sandstones. The Upper Maastrichtian sandstones are widely spread in the region, as evidenced by wells previously drilled in Senegal and Guinea-Bissau. By exploiting detailed geophysical and geochemical data, we have developed a refined geological description of this region, highlighting the complex interactions between sedimentary structures and their petrophysical properties. This description not only allows for more precise predictions of the location and quality of hydrocarbon reservoirs but also offers prospects for more targeted and less invasive exploration.