Arabian Journal of Geosciences最新文献

The late Paleozoic to early Mesozoic sandstones of the Fincha’a Valley in the Blue Nile Basin, Northwestern Ethiopia, were investigated to assess their Paleocurrents and tectonic provenance. The study used systematic measurement of sedimentary structures for paleocurrent analysis and petrographic examination of twenty-three sandstone samples to constrain paleotectonic provenance. The paleocurrent analysis results show a systematic change in sediment transport direction from predominantly west-derived paleoflow during the late Paleozoic (pre-Adigrat sandstone) to northeast- and southeast-derived paleoflow during the early Mesozoic (Adigrat sandstone), indicating a major reorganization of the Blue Nile Basin. The quantitative investigation of detrital framework grains from Adigrat sandstone shows that the sandstones primarily consist of quartz (33–100%), feldspar (0–50%), and lithic fragments (0–54%). Common cements include quartz, iron oxides (hematite), clay, and calcite. The modal composition data indicate that the pre-Adigrat sandstone is classified as quartz arenite, whereas the Adigrat sandstones are lithic arenite and sublithic arenite. The integrated petrographic and modal evidence suggests that the pre-Adigrat sandstones were derived mainly from compositionally mature, deeply weathered granitic and medium to high-grade metamorphic source rocks subjected to prolonged transport. In contrast, the Adigrat sandstone reflects a more heterogeneous provenance, including contributions from metamorphic, plutonic, and subordinate mafic igneous sources, but mainly derived from felsic source rocks. Combined paleocurrent trends and provenance triangular plots indicate that the Fincha’a Valley sandstones were sourced from the western Ethiopian basement complex, recycled sedimentary rocks, the metacraton, and nearby plutonic intrusions.

The southeastern coast of India, between Pondicherry and Point Calimere, features a highly dynamic shoreline shaped by complex interactions between natural processes and human activities. This study provides a comprehensive assessment of shoreline changes over 48 years (1972–2020) across four tectonically distinct zones: Zone I (Pondicherry–Cuddalore), Zone II (Parangipettai), Zone III (Poompuhar), and Zone IV (Vedaranyam), using multi-temporal Landsat images and the Digital Shoreline Analysis System (DSAS). Shorelines were extracted using the High-Water Line (HWL) proxy, following rigorous preprocessing steps including geometric and radiometric corrections, tidal stage consideration, and positional uncertainty evaluation. Two statistical methods, End Point Rate (EPR) and Net Shoreline Movement (NSM), were used to measure long- and short-term changes, respectively. Results show significant spatial variation: Zone I remains mostly stable with localized erosion and accretion; Zone II is prone to erosion (47% by EPR, 49% by NSM); Zone III is strongly erosion-dominated (60% by EPR, 85% by NSM) with limited sediment supply; and Zone IV displays a near balance between accretion and erosion, influenced by shoreline orientation and current patterns. The combined analysis highlights the dominance of erosion in Zones II and III, the role of hydrodynamic forces in shaping spatial variability, and the need for zone-specific management approaches. This research underscores the importance of combining remote sensing, GIS, and DSAS based analysis for informed coastal management. It offers a decision-support framework for addressing shoreline instability along the Tamil Nadu coast.

The left-lateral Dead Sea Fault (DSF) system is the main structural feature along which Africa and Arabia slide past one another in the eastern Mediterranean. Extending for about 170 km north of the Dead Sea, the Lebanese Restraining Bend (LRB) encompasses the NNE-runing Mount Lebanon and the NE Anti-Lebanon ranges which are detached by the Valley of the Bekaa. Pre-instrumental earthquakes with fatalities are recorded along these active segments of the DSF system. In this study, we use a seismic tomography technique to invert a large number of P- and S-wave arrival times collected from the ISC seismological bulletins to demonstrate the crustal heterogeneity and map 3-D seismic velocity distributions along the central segment of the DSF system. Using the obtained P- and S-wave velocity (Vp, and Vs) models, we further compute Vp/Vs models for a better understanding of the crustal structures. The 3-D seismic velocity and Vp/Vs models exhibit strong lateral heterogeneities. Slower crustal and upper mantle velocities are revealed along the fault segments of the LRB and to the west along the easterly-dipping Mount-Lebanon thrust (MLT) fault system. Average to high Vp/Vs anomalies are revealed at crustal depths, especially close to the hypocentral zones of large crustal earthquakes which are generally located at the edge portions of the low-velocity anomalies. The ray path coverage of the present data set and the results of the resolution test imply that the imaged seismic anomalies are reliable features down to the uppermost mantle layers. Moreover, the present results are, in general, compatible with several geological and geophysical studies beneath the eastern Mediterranean such as passive Sn propagation, strong attenuation, slower than average velocities, emplacement of ophiolite suites, as well as Cenozoic volcanics.

This study of reservoir fluid properties and phase behavior of Titas gas field investigates the intricate dynamics of hydrocarbon fluids within the reservoir, methodically examining variations in composition and properties across temporal and spatial dimensions. Through a holistic analysis, the research shows the potential for hydrocarbon accumulation and provides actionable insights for optimizing production strategies. This study analyzes reservoir fluid samples collected at different times at the wellheads of different wells for the studied gas field. After analyzing the data, no significant variations are observed over time or between wells in terms of reservoir fluid composition, properties, or the phase envelope. All variations remain within a few percent. For instance, variation in C1 mole percentage is within 0.86% over time, and 0.43% between different wells under consideration. Moreover, average higher and lower heating values are 1036.443 BTU/SCF and 934.459 BTU/SCF, respectively. A slight difference is observed in the BC sand phase envelope compared to the A sand. It can be concluded that the reservoir is of a dry gas type, and there is no possibility of liquid hydrocarbon accumulation in the reservoir with its pressure depletion. Moreover, this field has long been recognized as a volumetric type. Therefore, applying compressors to deplete the reservoir to very low pressures is possible, resulting in a high recovery factor.

Soil and Street dust (SD) of Guwahati city were studied for 16 Polycyclic Aromatic Hydrocarbons (PAHs). The PAHs concentrations, spatial distribution, seasonal variation, and PAHs profiles of soil and SD have been examined. The highest concentrations of ΣPAHs in soil and SD sample were observed at the industrial site, with means of 24,137 ± 5000 ng g^− 1 and 24944.9 ± 21,036 ng g^− 1, respectively. Seasonal variation was observed in PAHs concentrations and the post-monsoon period exhibited the maximum concentration, ranging from 1271.4 ng g^− 1 to 51299.7 ng g^− 1, which was followed by the pre-monsoon and monsoon periods. The Benzo[a]pyrene (BaP) concentration ranged from below detection limit (BDL) to 322.41 ng g^− 1 in soil and from BDL to 273.78 ng g^− 1 in SD. The maximum BaP concentration was found at the industrial site during pre-monsoon. The 2-ring PAHs dominated the profiles of soil and SD accounting for 60% and 58% of the total contribution, respectively. The Analysis of Variance (ANOVA) supported that PAHs in soil and in SD had similar means, which could infer that the sources of PAHs were similar in terms of strength and types of sources. The calculated Incremental Lifetime Cancer Risk (ILCR) showed seasonal variation of PAHs in both SD and soil. Carcinogenic risks of PAHs were higher during monsoon and pre-monsoon periods and ingestion and dermal contact were the significant pathways for intake in children and adult, respectively. The Monte Carlo simulation results indicated that the exposure risk of PAHs in SD at the 75th percentile was 2.5 times higher than the permissible limit for both adult and children, but relatively lower risk was observed in the soil-bound PAHs.

This study investigates the occurrence and distribution of Radon-222 (²²²Rn) in groundwater, Tigris River water, and tap water in the Al-Baitha area, southeast of Baghdad, where local communities rely heavily on groundwater for drinking and irrigation purposes. A total of 21water samples (15 groundwater, 3 river, 3 tap water samples) were analyzed using a RAD7 detector, along with measurements of δ¹⁸O isotopes, pH, well depth, and total dissolved solids (TDS).The results indicate that ²²²Rn concentrations in groundwater ranged between 6.79 and 14.41 Bq/L, exceeding the U.S. EPA guideline value 11.1 Bq/L at several locations, particularly in wells located farther from the Tigris River. Radon concentrations were positively correlated with TDS and distance from the nearest river, whereas pH and well depth showed no statistically significant influence. Oxygen-18 isotope signatures indicate that groundwater recharge is primarily derived from the Tigris River, with isotopic enrichment reflected as less negative δ¹⁸O values in distant wells, consistent with longer groundwater flow paths and enhanced radon accumulation .The estimated annual effective doses ranged from 17 to 37 µSvy^-1 for ingestion and from 17 to 36 µSvy^-1 for inhalation, while river and tap water doses 4 to 5 µSvy^-1 remained well below the WHO recommended limit 100 µSvy^-1. These results highlight the importance of systematic groundwater monitoring and underscore the role of hydrogeological factors in controlling radon accumulation in groundwater systems.

To determine the scientific understanding of both mineralogy and geochemistry, in addition to establishing the pH values of healing clays, twenty (20) clay-like materials, which are believed to be used as therapeutic agents for treating various ailments, were procured. The samples were sourced from in situ field materials, stockpile materials brought up from 4 m below ground level for processing, and finished clay products that originated from the study area and are sold in markets. All 20 samples of weight 100 g each were sent to ALS geochemical laboratory for multi-elemental analysis using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). X-ray Diffraction (XRD) technique was used on four in situ clay materials to analyze the mineralogical composition. To establish the pH and EC values of the healing clays, 8 clay materials from different locations, each weighing 10 g, were analyzed using JENWAY 350 pH meter and Hanna Instrument, respectively. The findings from the XRD Qualitative Analytical technique identified Quartz, Muscovite and Kaolinite as the predominant minerals in the analyzed clay samples. Rutile and Anatase were also revealed in some of the samples, although in trace amounts. The pH values of all samples ranged from 7.43 to 8.60, indicating an alkaline environment. The EC values of the clay samples fell below 2.0 dS/m, indicating non-saline conditions according to FAO guidelines, and are far lower than the threshold for saline materials (≥ 4 dS/m). From the geochemical analysis, most of the elements found in the clay sampled media showed depletion of macro, micro and toxic elements, which can be attributed to their low EC values. The implication is that the clay consumed by the practitioners would be harmless, as it lacks deleterious constituents and possesses alkaline properties that neutralize the acidic conditions within the stomach. It is evident that ingesting clay to alleviate stomach discomfort caused by excessive acid secretion that causes heartburn or ulcers seems to be justifiable because of the alkaline nature of the sampled clays. However, caution should be exercised when considering its use as a wholesale product due to potential variations in mineralogy and associated narratives. To add to this, the abundance of quartz in the clay samples poses a potential threat to human dental enamel upon ingestion. Thus, it is imperative that mineralogical and geochemical analyses be conducted prior to the consumption of clay as a medicinal product.

Urban flooding has emerged as a critical challenge for rapidly expanding cities, necessitating proactive flood risk assessment and mitigation strategies. Gurugram, located in the National Capital Region (NCR) of India, was selected as the study area due to its rapid, unplanned urbanization and increasing incidence of waterlogging. This study applied the Integrated Valuation of Ecosystem Services and Tradeoffs–Urban Flood Risk Mitigation (InVEST-UFRM) model to simulate urban flood behavior across a 48.42 km² urban catchment, analyzing the impact of 1-hour rainfall events with varying depths corresponding to 2-, 5-, and 10-year return periods. The results indicate that approximately 44.6% of the area is covered by impervious surfaces, with high runoff generation observed in central and northern sectors. Under the highest rainfall scenario (43.6 mm rainfall in 1 h), more than 80% of stormwater became runoff, and the runoff retention index falls below 0.2 in densely built-up zones. A sharp 47% increase in flood volume was recorded with a 46% rise in rainfall depth, indicating the nonlinear nature of urban flood risks. Green and open spaces demonstrated the highest stormwater retention, storing up to 4.36 m³ per pixel, while impervious surfaces retained less than 2.0 m³. These findings highlight the increasing flood risk in Gurugram and the diminishing capacity of the landscape to manage extreme rainfall. Mitigation recommendations focus on managing precipitation intensity, reducing surface runoff through green infrastructure, and enhancing runoff retention using nature-based solutions. The InVEST-UFRM model, due to its spatial clarity and ease of application, proves effective for evaluating flood risk and guiding urban flood resilience planning in semi-arid environments like Gurugram.

Obtaining the values of the uniaxial compressive strength (UCS) of coal is crucial to the design and analysis at a coal mine. The laboratory measurement of the UCS of coal is difficult and may be impossible because of the nature of coal and the sample preparation requirements of uniaxial compression tests, resulting in limited or no UCS test values at most coal sites. To overcome the challenge, a probabilistic characterization of the UCS of coal is developed using results from point load and P-wave velocity tests at a coal mine. The probabilistic characterization is based on Bayesian updating (BU) framework. The framework systematically incorporates prior knowledge and observational data, enabling dynamic updating as new data becomes available, which is an improvement over static empirical model. In addition, the framework provides a transparent method to update and quantify uncertainty in UCS predictions and improves interpretability of results. Using the parameters of point load strength (Is₍₅₀₎) and P-wave velocity (Vp) from a coal mine together with the ranges of UCS available in literature, the distribution and statistics of the UCS of coal is updated. The BU approach satisfactorily provides probabilistic characterization of the UCS of coal. The approach is further validated using simulated Is₍₅₀₎ and Vp data to investigate how number of input data, and different prior knowledge affect the approach. Such characterization allows mining engineers and practitioners to directly use the values of the UCS of coal from the approach to perform probability-based designs and reliability analyses at coal sites.

In geothermal areas, the presence of hot underground fluids and cracks in the rocks helps radon gas move from the deep underground to the surface. Consequently, such regions often exhibit higher radon levels in soil and water. We carried out a detailed field survey to assess radon levels in the Unai geothermal area of Gujarat, India. The team collected 60 water samples and measured soil radon at 45 different locations using the RAD7 radon detector. The amount of radon gas in the soil ranged from 2.5 to 348.8 Bq/m³, with an average of 33.7 Bq/m³. In comparison, thoron gas in the soil varied from 27 to 2677 Bq/m³, with an average of 373 Bq/m³. However, the difference in radon and thoron levels across the area was small, possibly because a thick layer of basalt rock in the region blocks the gas from rising easily to the surface. In the water samples, radon levels ranged from 0.07 to 14.53 Bq/L, with an average value of 3.79 Bq/L. The groundwater sources consistently showed higher radon levels compared to the surface water. Importantly, all measured concentrations remained below the U.S. Environmental Protection Agency (USEPA) recommended limit of 11.1 Bq/L, with the exception of one site (P29) located near a hot spring, where a peak concentration of 14.53 Bq/L was recorded. Spatial analysis revealed elevated water radon levels near the Unai hot spring and higher soil radon and thoron concentrations in the northeastern region, indicating localized geological controls on radon release. The radiological risk assessment showed that annual effective doses from soil and water radon exposure remained well below the WHO safety limits (100 µSv/year). The combined inhalation and ingestion doses from water radon varied from 0.27 to 78.81 µSv/year (mean: 20.56 µSv/year), whereas the inhalation doses from soil radon ranged from 0.00002 to 0.0033 mSv/year (mean: 0.0002 mSv/year). These results indicate no immediate health risk but highlight the importance of continued monitoring in geothermal areas such as Unai.