The extra-peninsular Gondwana Group rocks are exposed in narrow patches within the Lesser Himalayan sequence of the NE-Arunachal Himalayas,India.The bulk of sediments for the sandstones of the Gondwana Group were deri...The extra-peninsular Gondwana Group rocks are exposed in narrow patches within the Lesser Himalayan sequence of the NE-Arunachal Himalayas,India.The bulk of sediments for the sandstones of the Gondwana Group were derived from felsic/acidic to intermediate igneous rocks,with minor mafic input from the upper continental crust(UCC),as supported by various discrimination diagrams based on quantification of detrital minerals coupled with sandstone geochemistry.The inputs from metamorphic sources in subordinate amounts cannot be ruled out,as indicated by quantification of the quartz varieties.These sediments were found to be sourced from the interior part of a craton or shield and recycled platformal sediments which were derived from both passive and active margin settings.The sediments experienced a wide variance in climatic conditions,from arid to humid,suffering low-moderate-inten-sity weathering(CIA:63.43;CIW:86.18;WIP:44.84;PIA:75.37;ICV:2.39;C-value:0.42;PF:0.49;Sr/Cu:9.23 and Rb/Sr:1.68)within the vicinity of the low plains to moderate hills.Additionally,redox-sensitive elements indicate the deposition of sediments under oxygenated or oxygen-rich conditions(U_(au):−2.91;Th/U:7.37;U/Th:0.18;V/Cr:1.71;δU:0.67 and Ce/Ce^(*):0.93).展开更多
The tectonic setting of the Himalaya during the Early Paleozoic has been a subject of enduring debate within the scientific community.Newly discovered bimodal intrusive rocks from comprehensive field geological invest...The tectonic setting of the Himalaya during the Early Paleozoic has been a subject of enduring debate within the scientific community.Newly discovered bimodal intrusive rocks from comprehensive field geological investigation in the central mountain range were subjected to petrology,zircon U-Pb geochronology,zircon Hf isotopes and whole-rock geochemistry analyses.The Palie bimodal intrusive rocks,comprising amphibolite and granitic gneiss,were formed at~489 Ma.The amphibolite exhibits geochemical characteristics consistent with N-MORB,while the granitic gneiss is classified as high potassium calc-alkaline peraluminous S-type granite.Both igneous rocks exhibit negative zirconε_(Hf)(t)values and display ancient T_(DM)^(C)ages.In conjunction with regional geological survey findings,it can be inferred that the formation of the Palie bimodal intrusive rocks occurred within a post-collision extensional tectonic setting.The amphibolite genesis involved partial melting of an enriched lithospheric mantle with some crustal assimilation,whereas the origin of the granitic gneiss can be attributed to partial melting of pre-existing felsic crust.Our data indicate that during the Early Paleozoic,the Himalaya underwent a transition from a pan-African collisional setting to post-collisional extensional tectonics.展开更多
The 2019 Typhoon Lekima triggered extensive landslides in Zhejiang Province.To explore the impact of typhoon paths on the distribution of landslide susceptibility,this study proposes a spatiotemporal zoning assessment...The 2019 Typhoon Lekima triggered extensive landslides in Zhejiang Province.To explore the impact of typhoon paths on the distribution of landslide susceptibility,this study proposes a spatiotemporal zoning assessment framework based on typhoon paths and inner rainbands.According to the typhoon landing path and its rainfall impact range,the study area is divided into the typhoon event period(TEP)and the annual non-typhoon period(ANP).The model uses 14 environmental factors,with the only difference between TEP and ANP being the rainfall index:TEP uses 48-hour rainfall during the typhoon,while ANP uses multi-year average annual rainfall.Modeling and comparative analysis were conducted using six machine learning models including random forest(RF)and support vector machine(SVM).The results show that the distribution pattern of high-risk landslide areas during TEP is significantly correlated with typhoon intensity:when the intensity is level 12,high-risk areas are radially distributed;at levels 10-11,they tend to concentrate asymmetrically along the coast;and when the intensity drops to below level 9,the overall susceptibility decreases significantly.During ANP,the distribution of landslides is relatively uniform with no obvious spatial concentration.Analysis on the factor contribution rate indicates that the rainfall weight in TEP is as high as 32.1%,making it the dominant factor;in ANP,the rainfall weight drops to 13.6%while the influence of factors such as slope and topographic wetness index increases,revealing differences in landslide formation mechanisms between the two periods.This study demonstrates that the spatiotemporal zoning method based on typhoon paths can effectively characterize the spatial susceptibility patterns of landslides and improve disaster identification capabilities under extreme weather conditions.The finally generated annual susceptibility zoning map divides the study area into four types of risk regions,providing a reference for dynamic monitoring and differentiated risk management of landslides in typhoon-prone areas.展开更多
Geological strength index(GSI)has been widely used as an input parameter in predicting the strength and deformation properties of rock masses.This study derived a series of equations to satisfy the original GSI lines ...Geological strength index(GSI)has been widely used as an input parameter in predicting the strength and deformation properties of rock masses.This study derived a series of equations to satisfy the original GSI lines on the basic GSI chart.Two axes ranging from 0 to 100 were employed for surface conditions of the discontinuities and the structure of rock mass,which are independent of the input parameters.The derived equations can analyze GSI values ranging from 0 to 100 within±5%error.The engineering dimensions(EDs)such as the slope height,tunnel width,and foundation width were used together with representative elementary volume(REV)in jointed rock mass to define scale factor(sf)from 0.2 to 1 in evaluating the rock mass structure including joint pattern.The transformation of GSI into a scaledependent parameter based on engineering scale addresses a crucial requirement in various engineering applications.The improvements proposed in this study were applied to a real slope which was close to the time of failure.The results of stability assessments show that the new proposals have sufficient capability to define rock mass quality considering EDs.展开更多
The subsurface urban heat island(UHI)effect can provide latent clean geothermal potentials for cities.Understanding the city-wide subsurface temperature evolution under different land surfaces is significant in making...The subsurface urban heat island(UHI)effect can provide latent clean geothermal potentials for cities.Understanding the city-wide subsurface temperature evolution under different land surfaces is significant in making better use of geothermal energy.This research presents a study of Nanjing to identify the city-wide temperature distribution and evolution characteristics and further estimates the geothermal potential in Nanjing.Low-cost satellite-measured temperatures were used to derive the subsurface temperatures through a liner regression correction method,with higher accuracy verified by measured borehole data.The simulation results indicate that the concrete surface exhibits higher average temperatures than the grassland surface,resulting in relatively higher subsurface temperatures.The deviations of simulated subsurface temperatures are attributed to many factors,including the influence of complex atmospheric conditions on satellite-measured temperature accuracy,land surface heat absorption,and infiltration in the shallower layer.Furthermore,it reveals that the urban areas have 14.7%greater geothermal potential compared to rural areas,due to the subsurface UHI effect.This study provides a potentially efficient and convenient method for the estimation of potential urban geothermal energy.展开更多
Subduction polarity reversal typically occurs in intra-oceanic arc settings;the existence of an ancient intraoceanic arc and its associated back-arc system within the Neotethyan plate has been deliberated.In this stud...Subduction polarity reversal typically occurs in intra-oceanic arc settings;the existence of an ancient intraoceanic arc and its associated back-arc system within the Neotethyan plate has been deliberated.In this study,we investigate the possible role of subduction initiation of polarity reversal in the formation of Nagaland-Manipur ophiolite(NMO),evaluate the petrological and geochronological data and compare it with the neighboring natural examples of subduction polarity reversal of the Andaman-Nicobar ophiolite(ANO).The ancient intra-oceanic arc,namely the Incertus-Woyla Arc,and its associated back-arc remnant have been correlated with the back-arc mafic of the ANO.We found that the geochemical signatures of mafic rocks of NMO and ANO are comparable,and the available geochronology data of~145 Ma from the NMO basalt and chert fit well with the evolution and formation of the intra-oceanic arc,i.e.,Incertus-Woyla Arc.The evolution and age of the Incertus-Woyla Arc are between 135 and 150 Ma.Although the oldest age of the ANO has been reported from metamor-phic sole at about 106.4 and 105.3 Ma,the back-arc affinity of the amphibole has been credited to the back-arc spreading that occurred behind the Woyla Arc.Previous paleomagnetic and geochronological studies have suggested that the development of the back-arc basin behind the Incertus-Woyla Arc was a result of divergent double subduction.Therefore,we have inferred a similar scenario for the development of the back-arc affinity rocks of the NMO behind the Incertus-Woyla Arc and the reinterpretation for the evolution of the supra-subduction zone affinity rocks of NMO and ANO during subduction initiation after subduction polarity reversal.展开更多
Geodetic observations over the past several decades identify the Tien Shan as a prominent and active intracontinental mountain belt,characterized by a meridional shortening rate of up to 20 mm/a.The region has experie...Geodetic observations over the past several decades identify the Tien Shan as a prominent and active intracontinental mountain belt,characterized by a meridional shortening rate of up to 20 mm/a.The region has experienced significant seismic events,particularly along its northern boundary,highlighting the recurrent seismic activity in the Kyrgyz Republic.The Issyk-Ata fault,stretching 120 km from west to east in the northern Tien Shan,bounds from the north a young,growing anticline demarcating the foothills of the Kyrgyz Range and the Chui depression.This region is susceptible to strong earthquakes,posing a significant threat to the Chui region and Bishkek,the capital city with over a million residents.The youngest fault in the area is the Issyk-Ata fault,traversing the southern part of Bishkek,where modern construction has obscured its features.This study integrates remote sensing,detailed fieldwork,and paleoseismological investigations to map and analyze surface ruptures,quantify vertical displacements,and assess seismic hazards along the Issyk-Ata fault.Using optically stimulated luminescence and radiocarbon dating,we determined ages for documented paleoseismic events,placing two ancient earthquakes in the Holocene.Magnitude estimates suggest seismic events with magnitudes ranging from 6.6 to 7.1.In the Dzhal area,geological and geomorphological analysis yielded a longterm fault-slip rate of 1.15 mm/a.The Issyk-Ata fault shows variable rupture behavior,with distinct segments demonstrating different seismic characteristics and histories of activity.This variability necessitates comprehensive seismic hazard modeling to better understand and mitigate potential risks in the region.展开更多
The Knowledge Economic City (KEC) of Al Madinah Al Munawwarah is one of the major projects and represents the cornerstone for the new development activities for Al Madinah. The study area contains different geological...The Knowledge Economic City (KEC) of Al Madinah Al Munawwarah is one of the major projects and represents the cornerstone for the new development activities for Al Madinah. The study area contains different geological units dominated by basalt and overlain by surface deposits. The surface soils vary in thickness and can be classified into well-graded SAND with silt and gravel (SW-SM), silty SAND with gravel (SM), silty GRAVEL with sand (GM), and sandy SILTY clay (CL-ML). The subsurface soil obtained from the drilled boreholes can be classified into poorly graded GRAVEL (GP), well-graded GRAVEL with sand (GW), poorly graded GRAVEL with silt (GP-GM), silty CLAYEY gravel with sand (GC-GM), silty SAND with gravel (SM), silt with SAND (ML), and silty CLAY with sand (CL-ML), sandy lean CLAY (CL), and lean CLAY (CL). The relative density of the deposit and the different gravel sizes intercalated with the soil influenced the Standard Penetration Test (SPT) values. The SPT N values are high and approach refusal even at shallow depths. The shallow refusal depth (0.10 to 0.90 m) of the Dynamic Cone Penetration Test (DCPT) was observed. Generally, the soil can be described as inactive with low plasticity and dense to very dense consistency. The basalt of the KEC site is characterized by slightly (W2) to highly (W4) weathering, their strength ranges from moderate (S4) to very strong (S2), and the Rock Quality Designation (RQD) ranges from very poor (R5) to excellent (R1). The engineering geological map of the KEC characterized the geoengineering properties of the soil and rock materials and classified them into many zones. The high sulphate (SO42−) and chloride (Cl−) contents in groundwater call for protective measures for foundation concrete. The current study revealed that geohazard(s) mitigation measures concerning floods, volcanic eruptions, and earthquakes should be considered.展开更多
The title of the online version of the original article was revised.The title of the original article has been revised to:Hydrochemical characterization of surface waters in Northern Tehran:Integrating cluster-based t...The title of the online version of the original article was revised.The title of the original article has been revised to:Hydrochemical characterization of surface waters in Northern Tehran:Integrating cluster-based techniques with Self-Organizing Maps.展开更多
Water quality is a critical global issue,especially in urban and semi-urban regions where natural and anthropogenic factors significantly influence surface water systems.This study evaluates the hydrochemical characte...Water quality is a critical global issue,especially in urban and semi-urban regions where natural and anthropogenic factors significantly influence surface water systems.This study evaluates the hydrochemical characteristics of surface water in the North of Tehran Rivers(NTRs),an essential water resource in a rapidly urbanizing region,using advanced clustering techniques,including Hierarchical Clustering Analysis(HCA),Fuzzy CMeans(FCM),Genetic Algorithm Fuzzy C-Means(GAFCM),and Self-Organizing Map(SOM).The research aims to address the scientific challenge of understanding spatial and temporal variability in water quality,focusing on physicochemical parameters,hydrochemical facies,and contamination sources.Water samples from six rivers collected over four seasons in 2020 were analyzed and classified into distinct clusters based on their chemical composition,revealing significant seasonal and spatial differences.Results showed that FCM and GAFCM consistently categorized the NTRs into two clusters during winter and spring and three in summer and autumn.These findings were supported by HCA and SOM,which identified clusters corresponding to specific river segments and contamination levels.The primary hydrochemical processes identified were mineral dissolution and weathering,with calcite,dolomite,and aragonite significantly influencing water chemistry.Additionally,human activities,such as wastewater discharge,were shown to contribute to elevated sulfate,nitrate,and phosphate concentrations,further corroborated by microbial analyses.By integrating HCA,FCM,and GAFCM with an artificial neural network(ANN)-based clustering method(SOM),this study provides a robust framework for evaluating surface water quality.The findings,supported by Gibbs diagrams,Hounslow ion ratio,and saturation indices,highlight the dominance of rock weathering and human impacts in shaping the hydrochemical dynamics of the NTRs.These insights contribute to the scientific understanding of water quality dynamics and offer practical guidance for sustainable water resource management and environmental protection in developing urban areas.展开更多
Elemental concentrations of the siliciclastic sediments from a sedimentary basin provide clues on paleo-weathering,paleoclimate,provenance,and tectonic setting of the basin.Records for Permo-Triassic mass extinction a...Elemental concentrations of the siliciclastic sediments from a sedimentary basin provide clues on paleo-weathering,paleoclimate,provenance,and tectonic setting of the basin.Records for Permo-Triassic mass extinction and climatic fluctuations are commonly traced from the sediments in the Gondwana basins.Nevertheless,our understanding on sedimentation,provenance,and regional tectonics of the Raniganj Basin,a Gondwana basin in the eastern India is poor.Minerals including clay particles and major and trace element concentrations of the siliciclastic sediments from different formations of the Raniganj Basin have been studied to establish the paleo-weathering,paleoclimate,provenance,and tectonic settings of the basin.This study suggests that the Talchir Formation experienced cold and dry climatic conditions at the sediment source area,while the Barakar,Raniganj,and Panchet formations had prevailing semiarid climates.The sources of the siliciclastic sediments are from the felsic rocks of the Chotanagpur Granite Gneissic Complex(CGGC).Further,the geochemical results suggest a rift-like(passive)tectonic setting for the Raniganj Basin,while few samples represent the collision tectonic setting of the basement CGGC,formed due to collision of major Indian blocks during the Paleo-Neoproterozoic time.展开更多
The cartography of floods by two different approaches enabled us to determine the limits and the advantages of each one of them. This cartography has been applied to the El Maleh basin situated in the South-East of Mo...The cartography of floods by two different approaches enabled us to determine the limits and the advantages of each one of them. This cartography has been applied to the El Maleh basin situated in the South-East of Morocco. The HEC-RAS approach consists of a combination of the surface hydrologic model and the digital terrain model data. This combination allows thereafter the mapping of the flood zones by the use of the WMS software. Thus it can predict the probability occurrence of floods at various frequency times and determine the intensity of the flood (depth and velocity of flood water) inside the El Maleh river by using the existing hydrological data. Otherwise FHI method approach introduces a multi-criteria index to assess flood risk areas in a regional scale. Six parameters (flow accumulation, distance from drainage network, drainage network density, slope, land use, and geology) were used in this last method. The relative importance of each parameter for the occurrence and severity of flood has been connected to weight values. These values are calculated following an Analytical Hierarchy Process: AHP, a method originally developed for the solution of Operational Research problems. According to their weight values, information of the different parameters is superimposed, resulting to flood risk mapping. The use of the WMS model allowed us to accurately map the flood risk areas with precisely flood heights in different levels. However, this method is only applicable for a small portion of the basin located downstream of the hydrological station. Otherwise, the FHI method allows it to map the entire basin but without giving an indication of the water levels reached by floods. One method does not exclude the other since both approaches provide important information for flood risk assessment.展开更多
Dikko area, Niger State, North Central Nigeria falls within the Pan-African thermo-tectonic event which occurred in Nigeria as in other parts of West Africa with widespread effect on the mineralization of rejuvenated ...Dikko area, Niger State, North Central Nigeria falls within the Pan-African thermo-tectonic event which occurred in Nigeria as in other parts of West Africa with widespread effect on the mineralization of rejuvenated basement and geosynclinal trough deposits. The Pan-African Belt in Nigeria forms part of the Benin-Nigeria (Dahomeyan) shield which is regarded as the southern prolongation of the circumcratonic Pan-African belt of the West African Craton. Structurally controlled, gold-bearing quartz veins were measured and studied in the area from an extensive geological ground investigation. Field and petrographical studies indicate that the Neoproterozoic rocks constitute gneisses, amphibolite schist, amphibolites and migmatites. The amphibolites are intruded by pegmatites. The associated quartz veins are generally concordant with the main N</span></span><span><span><span>-</span></span></span><span><span><span>S regional structural trend. The lithological and structural studies carried out in these areas have demonstrated the relationship between structures and mineralization and/or lithology. The main characteristics of the gold mineralization in the area appear to indicate hydrothermal mineralization in connection with shear zones. This study allows us to predict that quartz veins in the amphibolite can be mined at a profit and a detailed geochemical and resource valuation needs to be carried out for the Au and associated Galena and Ag mineralization to fully exploit their economic potential.展开更多
The sandstones of the Late miocene–Pliocene Dibdibba Formation in the Najaf–Karbala Plateau and Basra were examined to determine their source rocks and origin. The rare earth elements(REE) and trace elements(Sc, Co,...The sandstones of the Late miocene–Pliocene Dibdibba Formation in the Najaf–Karbala Plateau and Basra were examined to determine their source rocks and origin. The rare earth elements(REE) and trace elements(Sc, Co, V, and Th) concentrations in these sandstones revealed that they likely derived from a single source. The steep light rare earth elements(LREE) and flat, heavy rare earth element(HREE) patterns, negative Eu anomaly, and high ΣREE contents in sandstones suggest its derivation from a suggests that a passive continental margin environment and originated from felsic source rocks. The average concentration of ΣREE is 93.5 ppm, which is lower than that of the average crustal compositions like Upper Continental Crust and Post Archean Australian Shale. The higher proportion of LREE compared to HREE implies that these sandstones were recycled and derived from a distal source. The Th/Co, Th/Sc, La/Sc, La/Co, Eu/Eu*and(La/Lu)cn elemental ratios indicated that these Late Miocene–Pliocene sandstones were derived from felsic rocks located in the marginal region of the Arabian Shield.展开更多
The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed...The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed by orogenic domain,namely the North-east Arunachal Himalayas.The river system that gave rise to the Brahmaputra River(Yarlung-Tsangpo),which flowed through several tectonic domains of the Himalayan ranges,primarily from BomiChayu,Gangadese Granitoid,Higher Himalayan Leucogranites,and Namche Barwa into the proto Bengal Basin now a part of Assam Arakan Basin and Naga Schuppen Belt,was the main source of the sandstone formation of the Barail Group.The purpose of sandstone petrography,which combines modal analysis with XRF(Major Oxides)and HR-ICPMS(Trace&Rare Earth Elements)research,is to identify the type of source rock(s),their weathering pattern,and its paleo-environmental circumstances.These sandstones were formed from recycled orogen and include lithic and sublithic arenite variants with advanced texture and chemical maturity.The sediments were felsic(Th/Co:1.38,Cr/Th:9.78,La/Lu:11.58,Th/Sc:0.99,Eu/Eu*:0.66,La/Sc:3.05,La/Co:4.18),with contributions from intermediate source rocks and low-rank metamorphics deposited in an active continental margin to a continental island arc setting.Climatic conditions impacted the sediments of Barails,characterised by being warm and semi-humid to humid which resulted in moderate to a high degree of chemical weathering,as shown by weathering indices like CIA(79.14),PIA(85.47),CIW(86.9),WIP(32.50),ICV(0.71),and Th/U(6.03),which were further additionally supported by C-Value(1.01),PF(1.20),Sr/Cu(2.04),and Rb/Sr(0.97).展开更多
The present study is devoted to understanding the evolution of the Upper Jurassic Sab'atayn Formation in the Marib-Shabwa Basin,Yemen,through a sequence stratigraphic analysis based on integrating datasets of sedi...The present study is devoted to understanding the evolution of the Upper Jurassic Sab'atayn Formation in the Marib-Shabwa Basin,Yemen,through a sequence stratigraphic analysis based on integrating datasets of sedimentology,seismic sections,and well logs.The Sab'atayn Formation(Tithonian age)is represented by a series of clastic and evaporites that were deposited under fluvio-deltaic to prodeltaic settings.It is divided into four members including Yah(at the base),upwards to Seen,Alif,and Safir at the top.Two third-order depositional sequences were determined for the Tithonian succession which were separated by three sequence boundaries.These sequences were classified into their systems tracts signifying several sedimentation patterns of progradational,aggradational,and retrogradational parasequence sets.The first depositional sequence corresponds to the early-middle Tithonian Yah and Seen units that can be classified into lowstand,transgressive,and highstand systems tracts.The second sequence comprises the late Tithonian Alif unit that can be subdivided into transgressive and highstand systems tracts.The sandy deposits of the Alif Member(highstand deposits)represent the most productive hydrocarbon reservoir in the basin.The Upper Jurassic sediments in the study area were resulted from a combination of eustatic and tectonic effects.展开更多
Petrographic and geochemical studies of syenite-looking Ayetoro and Sasaro plutons within Igarra Schist Belt were carried out in order to classify them and determine their tectonic setting and mineralization potential...Petrographic and geochemical studies of syenite-looking Ayetoro and Sasaro plutons within Igarra Schist Belt were carried out in order to classify them and determine their tectonic setting and mineralization potential. Petrographic study and geochemical classification revealed that while Ayetoro boss is microgranite constituting an aggregate of medium grained muscovite, quartz and biotite minerals, Sasaro stock is micromonzonite made up of medium grained albite, orthoclase, biotite, hornblende and pyroxene. Geotectonic setting showed the boss and stock are orogenic, probably derived from the same upper mantle magma as Igarra batholith that got contaminated by crustal materials responsible for their difference in lithology. Their mineralization potential showed that the massive Ayetoro microgranite with no appreciable trace-element contents cannot serve as host of any metallic deposit, and should be suitable for industrial applications. Whereas, the silicified, highly sheared Sasaro monzonite, with elevated level of some trace elements contents as Ag, Au and Cu, could harbor Ag-Au-Cu deposit.展开更多
This study aims to delineate the spatial distribution of nitrate and fluoride in groundwater and to estimate the non-carcinogenic risks using the human health risk assessment model recommended by the United States Env...This study aims to delineate the spatial distribution of nitrate and fluoride in groundwater and to estimate the non-carcinogenic risks using the human health risk assessment model recommended by the United States Environmental Protection Agency (USEPA). Forty-two samples were collected from wells and boreholes and analyzed for nitrate, fluoride and other water quality parameters. Results of the study indicate that fluoride and nitrate concentrations vary respectively from 0.13 to 9.41 mg·L−1 and from 0.13 to 432.24 mg·L−1 with respective median values of 2.65 and 13.85. About 69% of groundwater samples exceed the allowable limit (1.5 mg·L−1) of fluoride for drinking water. Spatial distribution of fluoride shows high concentrations in certain localities with values ranging from 6.74 mg·L−1 to 9.41 mg·L−1. The spatial distribution of nitrate indicates that the majority of water samples (87.18%) have nitrate concentrations lower than the World Health Organization (WHO) standard guideline value of 50 mg·L−1. Assessment of non-carcinogenic risks associated with intake of polluted groundwater in local populations indicates that 82.05% and 87.18% of groundwater samples have a THI > 1 in adults and children, respectively. However, the highest THI value (15.87) was recorded for children suggesting that children face greater non-carcinogenic risks than adults. The results of this study can be used as a support by the policymakers and practitioners to develop appropriate policies for effective and sustainable groundwater management and to monitor human health implications.展开更多
Extracting gas from unconventional shale reservoirs with low permeability is challenging.To overcome this,hydraulic fracturing(HF)is employed.Despite enhancing shale gas production,HF has drawbacks like groundwater po...Extracting gas from unconventional shale reservoirs with low permeability is challenging.To overcome this,hydraulic fracturing(HF)is employed.Despite enhancing shale gas production,HF has drawbacks like groundwater pollution and induced earthquakes.Such issues highlight the need for ongoing exploration of novel shale gas extraction methods such as in situ heating through combustion or pyrolysis to mitigate operational and environmental concerns.In this study,thermally immature shales of contrasting organic richness from Rajmahal Basin of India were heated to different temperatures(pyrolysis at 350,500 and 650℃)to assess the temperature protocols necessary for hydrocarbon liberation and investigate the evolution of pore structural facets with implications for CO_(2) sequestration in underground thermally treated shale horizons.Our results from low-pressure N_(2) adsorption reveal reduced adsorption capacity in the shale splits treated at 350 and 500 C,which can be attributed to structural reworking of the organic matter within the samples leading to formation of complex pore structures that limits the access of nitrogen at low experimental temperatures.Consequently,for both the studied samples BET SSA decreased by~58%and 72%at 350℃,and~67%and 68%at 500℃,whereas average pore diameter increased by~45%and 91%at 350℃,and~100%and 94%at 500℃ compared to their untreated counterparts.CO_(2) adsorption results,unlike N_(2),revealed a pronounced rise in micropore properties(surface area and volume)at 500 and 650℃(~30%-35%and~41%63%,respectively for both samples),contradicting the N_(2) adsorption outcomes.Scanning electron microscope(SEM)images complemented the findings,showing pore structures evolving from microcracks to collapsed pores with increasing thermal treatment.Analysis of the SEM images of both samples revealed a notable increase in average pore width(short axis):by~4 and 10 times at 350℃,~5 and 12 times at 500℃,and~10 and 28 times at 650℃ compared to the untreated samples.Rock-Eval analysis demonstrated the liberation of almost all pyrolyzable kerogen components in the shales heated to 650℃.Additionally,the maximum micropore capacity,identified from CO_(2) gas adsorption analysis,indicated 650℃ as the ideal temperature for in situ conversion and CO_(2) sequestration.Nevertheless,project viability hinges on assessing other relevant aspects of shale gas development such as geomechanical stability and supercritical CO_(2) interactions in addition to thermal treatment.展开更多
Urban air pollution is a major challenge facing rapidly growing cities in the Middle East and North Africa (MENA) region, with vehicle emissions being a significant contributor. This study aims to analyze the spatial ...Urban air pollution is a major challenge facing rapidly growing cities in the Middle East and North Africa (MENA) region, with vehicle emissions being a significant contributor. This study aims to analyze the spatial and temporal patterns of air pollutants, particularly nitrogen dioxide (NO2), in Casablanca, Morocco, and investigate the relationship with urban development and transportation characteristics. By integrating satellite remote sensing data and Google Earth Engine (GEE) techniques, we provide a comprehensive assessment of air quality in Casablanca and demonstrate the value of using geospatial approaches for informing policymakers and urban planners. The results highlight seasonal variations in NO2 levels, the identification of pollution hotspots, and the quantification of the influence of urban features and traffic on air quality. We discuss the implications of these findings for targeted interventions to improve air quality and the potential for expanding the methodology to other pollutants and cities in the region.展开更多
文摘The extra-peninsular Gondwana Group rocks are exposed in narrow patches within the Lesser Himalayan sequence of the NE-Arunachal Himalayas,India.The bulk of sediments for the sandstones of the Gondwana Group were derived from felsic/acidic to intermediate igneous rocks,with minor mafic input from the upper continental crust(UCC),as supported by various discrimination diagrams based on quantification of detrital minerals coupled with sandstone geochemistry.The inputs from metamorphic sources in subordinate amounts cannot be ruled out,as indicated by quantification of the quartz varieties.These sediments were found to be sourced from the interior part of a craton or shield and recycled platformal sediments which were derived from both passive and active margin settings.The sediments experienced a wide variance in climatic conditions,from arid to humid,suffering low-moderate-inten-sity weathering(CIA:63.43;CIW:86.18;WIP:44.84;PIA:75.37;ICV:2.39;C-value:0.42;PF:0.49;Sr/Cu:9.23 and Rb/Sr:1.68)within the vicinity of the low plains to moderate hills.Additionally,redox-sensitive elements indicate the deposition of sediments under oxygenated or oxygen-rich conditions(U_(au):−2.91;Th/U:7.37;U/Th:0.18;V/Cr:1.71;δU:0.67 and Ce/Ce^(*):0.93).
基金supported by the China Geological Survey Program(Grant No.DD20220989)the National Natural Science Foundation of China(Grant No.41972118)。
文摘The tectonic setting of the Himalaya during the Early Paleozoic has been a subject of enduring debate within the scientific community.Newly discovered bimodal intrusive rocks from comprehensive field geological investigation in the central mountain range were subjected to petrology,zircon U-Pb geochronology,zircon Hf isotopes and whole-rock geochemistry analyses.The Palie bimodal intrusive rocks,comprising amphibolite and granitic gneiss,were formed at~489 Ma.The amphibolite exhibits geochemical characteristics consistent with N-MORB,while the granitic gneiss is classified as high potassium calc-alkaline peraluminous S-type granite.Both igneous rocks exhibit negative zirconε_(Hf)(t)values and display ancient T_(DM)^(C)ages.In conjunction with regional geological survey findings,it can be inferred that the formation of the Palie bimodal intrusive rocks occurred within a post-collision extensional tectonic setting.The amphibolite genesis involved partial melting of an enriched lithospheric mantle with some crustal assimilation,whereas the origin of the granitic gneiss can be attributed to partial melting of pre-existing felsic crust.Our data indicate that during the Early Paleozoic,the Himalaya underwent a transition from a pan-African collisional setting to post-collisional extensional tectonics.
基金supported by the project of National Natural Science Foundation of China(Grant No.42371203 and U21A2032)the project Financial Fund of Sichuan Institute of Geological Survey(SCIGSCZDXM-2024008)+1 种基金Sichuan Provincial Science and Technology Department Program Funding(No.2025YFHZ0010)Science and Technology Program of Aba City(NO.R24YYJSYJ0001)。
文摘The 2019 Typhoon Lekima triggered extensive landslides in Zhejiang Province.To explore the impact of typhoon paths on the distribution of landslide susceptibility,this study proposes a spatiotemporal zoning assessment framework based on typhoon paths and inner rainbands.According to the typhoon landing path and its rainfall impact range,the study area is divided into the typhoon event period(TEP)and the annual non-typhoon period(ANP).The model uses 14 environmental factors,with the only difference between TEP and ANP being the rainfall index:TEP uses 48-hour rainfall during the typhoon,while ANP uses multi-year average annual rainfall.Modeling and comparative analysis were conducted using six machine learning models including random forest(RF)and support vector machine(SVM).The results show that the distribution pattern of high-risk landslide areas during TEP is significantly correlated with typhoon intensity:when the intensity is level 12,high-risk areas are radially distributed;at levels 10-11,they tend to concentrate asymmetrically along the coast;and when the intensity drops to below level 9,the overall susceptibility decreases significantly.During ANP,the distribution of landslides is relatively uniform with no obvious spatial concentration.Analysis on the factor contribution rate indicates that the rainfall weight in TEP is as high as 32.1%,making it the dominant factor;in ANP,the rainfall weight drops to 13.6%while the influence of factors such as slope and topographic wetness index increases,revealing differences in landslide formation mechanisms between the two periods.This study demonstrates that the spatiotemporal zoning method based on typhoon paths can effectively characterize the spatial susceptibility patterns of landslides and improve disaster identification capabilities under extreme weather conditions.The finally generated annual susceptibility zoning map divides the study area into four types of risk regions,providing a reference for dynamic monitoring and differentiated risk management of landslides in typhoon-prone areas.
文摘Geological strength index(GSI)has been widely used as an input parameter in predicting the strength and deformation properties of rock masses.This study derived a series of equations to satisfy the original GSI lines on the basic GSI chart.Two axes ranging from 0 to 100 were employed for surface conditions of the discontinuities and the structure of rock mass,which are independent of the input parameters.The derived equations can analyze GSI values ranging from 0 to 100 within±5%error.The engineering dimensions(EDs)such as the slope height,tunnel width,and foundation width were used together with representative elementary volume(REV)in jointed rock mass to define scale factor(sf)from 0.2 to 1 in evaluating the rock mass structure including joint pattern.The transformation of GSI into a scaledependent parameter based on engineering scale addresses a crucial requirement in various engineering applications.The improvements proposed in this study were applied to a real slope which was close to the time of failure.The results of stability assessments show that the new proposals have sufficient capability to define rock mass quality considering EDs.
基金supports from the National Natural Science Foundation of China(Grant Nos.42222707,41761134089)are gratefully acknowledged.
文摘The subsurface urban heat island(UHI)effect can provide latent clean geothermal potentials for cities.Understanding the city-wide subsurface temperature evolution under different land surfaces is significant in making better use of geothermal energy.This research presents a study of Nanjing to identify the city-wide temperature distribution and evolution characteristics and further estimates the geothermal potential in Nanjing.Low-cost satellite-measured temperatures were used to derive the subsurface temperatures through a liner regression correction method,with higher accuracy verified by measured borehole data.The simulation results indicate that the concrete surface exhibits higher average temperatures than the grassland surface,resulting in relatively higher subsurface temperatures.The deviations of simulated subsurface temperatures are attributed to many factors,including the influence of complex atmospheric conditions on satellite-measured temperature accuracy,land surface heat absorption,and infiltration in the shallower layer.Furthermore,it reveals that the urban areas have 14.7%greater geothermal potential compared to rural areas,due to the subsurface UHI effect.This study provides a potentially efficient and convenient method for the estimation of potential urban geothermal energy.
基金supported by the Ministry of Earth Sciences(MoES),Government of India,New Delhi,through a research grant(No.MoES/P.O.(Geo)/80/2015)to A.K.Singh.
文摘Subduction polarity reversal typically occurs in intra-oceanic arc settings;the existence of an ancient intraoceanic arc and its associated back-arc system within the Neotethyan plate has been deliberated.In this study,we investigate the possible role of subduction initiation of polarity reversal in the formation of Nagaland-Manipur ophiolite(NMO),evaluate the petrological and geochronological data and compare it with the neighboring natural examples of subduction polarity reversal of the Andaman-Nicobar ophiolite(ANO).The ancient intra-oceanic arc,namely the Incertus-Woyla Arc,and its associated back-arc remnant have been correlated with the back-arc mafic of the ANO.We found that the geochemical signatures of mafic rocks of NMO and ANO are comparable,and the available geochronology data of~145 Ma from the NMO basalt and chert fit well with the evolution and formation of the intra-oceanic arc,i.e.,Incertus-Woyla Arc.The evolution and age of the Incertus-Woyla Arc are between 135 and 150 Ma.Although the oldest age of the ANO has been reported from metamor-phic sole at about 106.4 and 105.3 Ma,the back-arc affinity of the amphibole has been credited to the back-arc spreading that occurred behind the Woyla Arc.Previous paleomagnetic and geochronological studies have suggested that the development of the back-arc basin behind the Incertus-Woyla Arc was a result of divergent double subduction.Therefore,we have inferred a similar scenario for the development of the back-arc affinity rocks of the NMO behind the Incertus-Woyla Arc and the reinterpretation for the evolution of the supra-subduction zone affinity rocks of NMO and ANO during subduction initiation after subduction polarity reversal.
基金financial support of the Faculty Research Grant project of the American University of Central Asia(AUCA)supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea(NRF-2023S1A5B5A16080131)。
文摘Geodetic observations over the past several decades identify the Tien Shan as a prominent and active intracontinental mountain belt,characterized by a meridional shortening rate of up to 20 mm/a.The region has experienced significant seismic events,particularly along its northern boundary,highlighting the recurrent seismic activity in the Kyrgyz Republic.The Issyk-Ata fault,stretching 120 km from west to east in the northern Tien Shan,bounds from the north a young,growing anticline demarcating the foothills of the Kyrgyz Range and the Chui depression.This region is susceptible to strong earthquakes,posing a significant threat to the Chui region and Bishkek,the capital city with over a million residents.The youngest fault in the area is the Issyk-Ata fault,traversing the southern part of Bishkek,where modern construction has obscured its features.This study integrates remote sensing,detailed fieldwork,and paleoseismological investigations to map and analyze surface ruptures,quantify vertical displacements,and assess seismic hazards along the Issyk-Ata fault.Using optically stimulated luminescence and radiocarbon dating,we determined ages for documented paleoseismic events,placing two ancient earthquakes in the Holocene.Magnitude estimates suggest seismic events with magnitudes ranging from 6.6 to 7.1.In the Dzhal area,geological and geomorphological analysis yielded a longterm fault-slip rate of 1.15 mm/a.The Issyk-Ata fault shows variable rupture behavior,with distinct segments demonstrating different seismic characteristics and histories of activity.This variability necessitates comprehensive seismic hazard modeling to better understand and mitigate potential risks in the region.
文摘The Knowledge Economic City (KEC) of Al Madinah Al Munawwarah is one of the major projects and represents the cornerstone for the new development activities for Al Madinah. The study area contains different geological units dominated by basalt and overlain by surface deposits. The surface soils vary in thickness and can be classified into well-graded SAND with silt and gravel (SW-SM), silty SAND with gravel (SM), silty GRAVEL with sand (GM), and sandy SILTY clay (CL-ML). The subsurface soil obtained from the drilled boreholes can be classified into poorly graded GRAVEL (GP), well-graded GRAVEL with sand (GW), poorly graded GRAVEL with silt (GP-GM), silty CLAYEY gravel with sand (GC-GM), silty SAND with gravel (SM), silt with SAND (ML), and silty CLAY with sand (CL-ML), sandy lean CLAY (CL), and lean CLAY (CL). The relative density of the deposit and the different gravel sizes intercalated with the soil influenced the Standard Penetration Test (SPT) values. The SPT N values are high and approach refusal even at shallow depths. The shallow refusal depth (0.10 to 0.90 m) of the Dynamic Cone Penetration Test (DCPT) was observed. Generally, the soil can be described as inactive with low plasticity and dense to very dense consistency. The basalt of the KEC site is characterized by slightly (W2) to highly (W4) weathering, their strength ranges from moderate (S4) to very strong (S2), and the Rock Quality Designation (RQD) ranges from very poor (R5) to excellent (R1). The engineering geological map of the KEC characterized the geoengineering properties of the soil and rock materials and classified them into many zones. The high sulphate (SO42−) and chloride (Cl−) contents in groundwater call for protective measures for foundation concrete. The current study revealed that geohazard(s) mitigation measures concerning floods, volcanic eruptions, and earthquakes should be considered.
文摘The title of the online version of the original article was revised.The title of the original article has been revised to:Hydrochemical characterization of surface waters in Northern Tehran:Integrating cluster-based techniques with Self-Organizing Maps.
文摘Water quality is a critical global issue,especially in urban and semi-urban regions where natural and anthropogenic factors significantly influence surface water systems.This study evaluates the hydrochemical characteristics of surface water in the North of Tehran Rivers(NTRs),an essential water resource in a rapidly urbanizing region,using advanced clustering techniques,including Hierarchical Clustering Analysis(HCA),Fuzzy CMeans(FCM),Genetic Algorithm Fuzzy C-Means(GAFCM),and Self-Organizing Map(SOM).The research aims to address the scientific challenge of understanding spatial and temporal variability in water quality,focusing on physicochemical parameters,hydrochemical facies,and contamination sources.Water samples from six rivers collected over four seasons in 2020 were analyzed and classified into distinct clusters based on their chemical composition,revealing significant seasonal and spatial differences.Results showed that FCM and GAFCM consistently categorized the NTRs into two clusters during winter and spring and three in summer and autumn.These findings were supported by HCA and SOM,which identified clusters corresponding to specific river segments and contamination levels.The primary hydrochemical processes identified were mineral dissolution and weathering,with calcite,dolomite,and aragonite significantly influencing water chemistry.Additionally,human activities,such as wastewater discharge,were shown to contribute to elevated sulfate,nitrate,and phosphate concentrations,further corroborated by microbial analyses.By integrating HCA,FCM,and GAFCM with an artificial neural network(ANN)-based clustering method(SOM),this study provides a robust framework for evaluating surface water quality.The findings,supported by Gibbs diagrams,Hounslow ion ratio,and saturation indices,highlight the dominance of rock weathering and human impacts in shaping the hydrochemical dynamics of the NTRs.These insights contribute to the scientific understanding of water quality dynamics and offer practical guidance for sustainable water resource management and environmental protection in developing urban areas.
基金funded by SERB-DST,New Delhi,India for Early Career Research(ECR/2016/001100)during 2017 to 2021.
文摘Elemental concentrations of the siliciclastic sediments from a sedimentary basin provide clues on paleo-weathering,paleoclimate,provenance,and tectonic setting of the basin.Records for Permo-Triassic mass extinction and climatic fluctuations are commonly traced from the sediments in the Gondwana basins.Nevertheless,our understanding on sedimentation,provenance,and regional tectonics of the Raniganj Basin,a Gondwana basin in the eastern India is poor.Minerals including clay particles and major and trace element concentrations of the siliciclastic sediments from different formations of the Raniganj Basin have been studied to establish the paleo-weathering,paleoclimate,provenance,and tectonic settings of the basin.This study suggests that the Talchir Formation experienced cold and dry climatic conditions at the sediment source area,while the Barakar,Raniganj,and Panchet formations had prevailing semiarid climates.The sources of the siliciclastic sediments are from the felsic rocks of the Chotanagpur Granite Gneissic Complex(CGGC).Further,the geochemical results suggest a rift-like(passive)tectonic setting for the Raniganj Basin,while few samples represent the collision tectonic setting of the basement CGGC,formed due to collision of major Indian blocks during the Paleo-Neoproterozoic time.
文摘The cartography of floods by two different approaches enabled us to determine the limits and the advantages of each one of them. This cartography has been applied to the El Maleh basin situated in the South-East of Morocco. The HEC-RAS approach consists of a combination of the surface hydrologic model and the digital terrain model data. This combination allows thereafter the mapping of the flood zones by the use of the WMS software. Thus it can predict the probability occurrence of floods at various frequency times and determine the intensity of the flood (depth and velocity of flood water) inside the El Maleh river by using the existing hydrological data. Otherwise FHI method approach introduces a multi-criteria index to assess flood risk areas in a regional scale. Six parameters (flow accumulation, distance from drainage network, drainage network density, slope, land use, and geology) were used in this last method. The relative importance of each parameter for the occurrence and severity of flood has been connected to weight values. These values are calculated following an Analytical Hierarchy Process: AHP, a method originally developed for the solution of Operational Research problems. According to their weight values, information of the different parameters is superimposed, resulting to flood risk mapping. The use of the WMS model allowed us to accurately map the flood risk areas with precisely flood heights in different levels. However, this method is only applicable for a small portion of the basin located downstream of the hydrological station. Otherwise, the FHI method allows it to map the entire basin but without giving an indication of the water levels reached by floods. One method does not exclude the other since both approaches provide important information for flood risk assessment.
文摘Dikko area, Niger State, North Central Nigeria falls within the Pan-African thermo-tectonic event which occurred in Nigeria as in other parts of West Africa with widespread effect on the mineralization of rejuvenated basement and geosynclinal trough deposits. The Pan-African Belt in Nigeria forms part of the Benin-Nigeria (Dahomeyan) shield which is regarded as the southern prolongation of the circumcratonic Pan-African belt of the West African Craton. Structurally controlled, gold-bearing quartz veins were measured and studied in the area from an extensive geological ground investigation. Field and petrographical studies indicate that the Neoproterozoic rocks constitute gneisses, amphibolite schist, amphibolites and migmatites. The amphibolites are intruded by pegmatites. The associated quartz veins are generally concordant with the main N</span></span><span><span><span>-</span></span></span><span><span><span>S regional structural trend. The lithological and structural studies carried out in these areas have demonstrated the relationship between structures and mineralization and/or lithology. The main characteristics of the gold mineralization in the area appear to indicate hydrothermal mineralization in connection with shear zones. This study allows us to predict that quartz veins in the amphibolite can be mined at a profit and a detailed geochemical and resource valuation needs to be carried out for the Au and associated Galena and Ag mineralization to fully exploit their economic potential.
文摘The sandstones of the Late miocene–Pliocene Dibdibba Formation in the Najaf–Karbala Plateau and Basra were examined to determine their source rocks and origin. The rare earth elements(REE) and trace elements(Sc, Co, V, and Th) concentrations in these sandstones revealed that they likely derived from a single source. The steep light rare earth elements(LREE) and flat, heavy rare earth element(HREE) patterns, negative Eu anomaly, and high ΣREE contents in sandstones suggest its derivation from a suggests that a passive continental margin environment and originated from felsic source rocks. The average concentration of ΣREE is 93.5 ppm, which is lower than that of the average crustal compositions like Upper Continental Crust and Post Archean Australian Shale. The higher proportion of LREE compared to HREE implies that these sandstones were recycled and derived from a distal source. The Th/Co, Th/Sc, La/Sc, La/Co, Eu/Eu*and(La/Lu)cn elemental ratios indicated that these Late Miocene–Pliocene sandstones were derived from felsic rocks located in the marginal region of the Arabian Shield.
基金Financial Support to conduct the Geochemical Analysis in NGRIHyderabad under the Project Contract No.6111264。
文摘The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed by orogenic domain,namely the North-east Arunachal Himalayas.The river system that gave rise to the Brahmaputra River(Yarlung-Tsangpo),which flowed through several tectonic domains of the Himalayan ranges,primarily from BomiChayu,Gangadese Granitoid,Higher Himalayan Leucogranites,and Namche Barwa into the proto Bengal Basin now a part of Assam Arakan Basin and Naga Schuppen Belt,was the main source of the sandstone formation of the Barail Group.The purpose of sandstone petrography,which combines modal analysis with XRF(Major Oxides)and HR-ICPMS(Trace&Rare Earth Elements)research,is to identify the type of source rock(s),their weathering pattern,and its paleo-environmental circumstances.These sandstones were formed from recycled orogen and include lithic and sublithic arenite variants with advanced texture and chemical maturity.The sediments were felsic(Th/Co:1.38,Cr/Th:9.78,La/Lu:11.58,Th/Sc:0.99,Eu/Eu*:0.66,La/Sc:3.05,La/Co:4.18),with contributions from intermediate source rocks and low-rank metamorphics deposited in an active continental margin to a continental island arc setting.Climatic conditions impacted the sediments of Barails,characterised by being warm and semi-humid to humid which resulted in moderate to a high degree of chemical weathering,as shown by weathering indices like CIA(79.14),PIA(85.47),CIW(86.9),WIP(32.50),ICV(0.71),and Th/U(6.03),which were further additionally supported by C-Value(1.01),PF(1.20),Sr/Cu(2.04),and Rb/Sr(0.97).
文摘The present study is devoted to understanding the evolution of the Upper Jurassic Sab'atayn Formation in the Marib-Shabwa Basin,Yemen,through a sequence stratigraphic analysis based on integrating datasets of sedimentology,seismic sections,and well logs.The Sab'atayn Formation(Tithonian age)is represented by a series of clastic and evaporites that were deposited under fluvio-deltaic to prodeltaic settings.It is divided into four members including Yah(at the base),upwards to Seen,Alif,and Safir at the top.Two third-order depositional sequences were determined for the Tithonian succession which were separated by three sequence boundaries.These sequences were classified into their systems tracts signifying several sedimentation patterns of progradational,aggradational,and retrogradational parasequence sets.The first depositional sequence corresponds to the early-middle Tithonian Yah and Seen units that can be classified into lowstand,transgressive,and highstand systems tracts.The second sequence comprises the late Tithonian Alif unit that can be subdivided into transgressive and highstand systems tracts.The sandy deposits of the Alif Member(highstand deposits)represent the most productive hydrocarbon reservoir in the basin.The Upper Jurassic sediments in the study area were resulted from a combination of eustatic and tectonic effects.
文摘Petrographic and geochemical studies of syenite-looking Ayetoro and Sasaro plutons within Igarra Schist Belt were carried out in order to classify them and determine their tectonic setting and mineralization potential. Petrographic study and geochemical classification revealed that while Ayetoro boss is microgranite constituting an aggregate of medium grained muscovite, quartz and biotite minerals, Sasaro stock is micromonzonite made up of medium grained albite, orthoclase, biotite, hornblende and pyroxene. Geotectonic setting showed the boss and stock are orogenic, probably derived from the same upper mantle magma as Igarra batholith that got contaminated by crustal materials responsible for their difference in lithology. Their mineralization potential showed that the massive Ayetoro microgranite with no appreciable trace-element contents cannot serve as host of any metallic deposit, and should be suitable for industrial applications. Whereas, the silicified, highly sheared Sasaro monzonite, with elevated level of some trace elements contents as Ag, Au and Cu, could harbor Ag-Au-Cu deposit.
文摘This study aims to delineate the spatial distribution of nitrate and fluoride in groundwater and to estimate the non-carcinogenic risks using the human health risk assessment model recommended by the United States Environmental Protection Agency (USEPA). Forty-two samples were collected from wells and boreholes and analyzed for nitrate, fluoride and other water quality parameters. Results of the study indicate that fluoride and nitrate concentrations vary respectively from 0.13 to 9.41 mg·L−1 and from 0.13 to 432.24 mg·L−1 with respective median values of 2.65 and 13.85. About 69% of groundwater samples exceed the allowable limit (1.5 mg·L−1) of fluoride for drinking water. Spatial distribution of fluoride shows high concentrations in certain localities with values ranging from 6.74 mg·L−1 to 9.41 mg·L−1. The spatial distribution of nitrate indicates that the majority of water samples (87.18%) have nitrate concentrations lower than the World Health Organization (WHO) standard guideline value of 50 mg·L−1. Assessment of non-carcinogenic risks associated with intake of polluted groundwater in local populations indicates that 82.05% and 87.18% of groundwater samples have a THI > 1 in adults and children, respectively. However, the highest THI value (15.87) was recorded for children suggesting that children face greater non-carcinogenic risks than adults. The results of this study can be used as a support by the policymakers and practitioners to develop appropriate policies for effective and sustainable groundwater management and to monitor human health implications.
文摘Extracting gas from unconventional shale reservoirs with low permeability is challenging.To overcome this,hydraulic fracturing(HF)is employed.Despite enhancing shale gas production,HF has drawbacks like groundwater pollution and induced earthquakes.Such issues highlight the need for ongoing exploration of novel shale gas extraction methods such as in situ heating through combustion or pyrolysis to mitigate operational and environmental concerns.In this study,thermally immature shales of contrasting organic richness from Rajmahal Basin of India were heated to different temperatures(pyrolysis at 350,500 and 650℃)to assess the temperature protocols necessary for hydrocarbon liberation and investigate the evolution of pore structural facets with implications for CO_(2) sequestration in underground thermally treated shale horizons.Our results from low-pressure N_(2) adsorption reveal reduced adsorption capacity in the shale splits treated at 350 and 500 C,which can be attributed to structural reworking of the organic matter within the samples leading to formation of complex pore structures that limits the access of nitrogen at low experimental temperatures.Consequently,for both the studied samples BET SSA decreased by~58%and 72%at 350℃,and~67%and 68%at 500℃,whereas average pore diameter increased by~45%and 91%at 350℃,and~100%and 94%at 500℃ compared to their untreated counterparts.CO_(2) adsorption results,unlike N_(2),revealed a pronounced rise in micropore properties(surface area and volume)at 500 and 650℃(~30%-35%and~41%63%,respectively for both samples),contradicting the N_(2) adsorption outcomes.Scanning electron microscope(SEM)images complemented the findings,showing pore structures evolving from microcracks to collapsed pores with increasing thermal treatment.Analysis of the SEM images of both samples revealed a notable increase in average pore width(short axis):by~4 and 10 times at 350℃,~5 and 12 times at 500℃,and~10 and 28 times at 650℃ compared to the untreated samples.Rock-Eval analysis demonstrated the liberation of almost all pyrolyzable kerogen components in the shales heated to 650℃.Additionally,the maximum micropore capacity,identified from CO_(2) gas adsorption analysis,indicated 650℃ as the ideal temperature for in situ conversion and CO_(2) sequestration.Nevertheless,project viability hinges on assessing other relevant aspects of shale gas development such as geomechanical stability and supercritical CO_(2) interactions in addition to thermal treatment.
文摘Urban air pollution is a major challenge facing rapidly growing cities in the Middle East and North Africa (MENA) region, with vehicle emissions being a significant contributor. This study aims to analyze the spatial and temporal patterns of air pollutants, particularly nitrogen dioxide (NO2), in Casablanca, Morocco, and investigate the relationship with urban development and transportation characteristics. By integrating satellite remote sensing data and Google Earth Engine (GEE) techniques, we provide a comprehensive assessment of air quality in Casablanca and demonstrate the value of using geospatial approaches for informing policymakers and urban planners. The results highlight seasonal variations in NO2 levels, the identification of pollution hotspots, and the quantification of the influence of urban features and traffic on air quality. We discuss the implications of these findings for targeted interventions to improve air quality and the potential for expanding the methodology to other pollutants and cities in the region.
