Geological setting,facies characteristics,and geochemistry,including TGA(thermo-gravimetric analysis)of Paleogene deposits in east Beni Suef region(Egypt),were studied in the present work.Lithostratigraphically,the ar...Geological setting,facies characteristics,and geochemistry,including TGA(thermo-gravimetric analysis)of Paleogene deposits in east Beni Suef region(Egypt),were studied in the present work.Lithostratigraphically,the area consists of three rock units,arranged from oldest to youngest:Tarbul Member of Beni Suef Formation(MiddleLate Eocene),Maadi Formation(Late Eocene),and Gebel Ahmar Formation(Oligocene),this last formation registered for the first time in the east of Beni Suef area(Egypt).Seven microfacies types(F1-F7)were determined by the microscopic examination of the studied samples in low-to high-energy and shallow-subtidal marine conditions.The lithostratigraphic,petrological,and geochemical results revealed that the Eocene succession in the present area is composed mainly of carbonates as well as siliciclastics.The Oligocene Gebel Ahmar Formation consists mainly of silica and iron oxides.The enrichment of the rock units with iron oxides in the studied area,as well as the high proportions of trace elements such as Zr,Ba,V,and Sr,in particular in the Gebel Ahmar Formation,reflects the influence of the hydrothermal solutions during the Oligocene.TGA,which monitors weight changes during heating at a constant rate,was used to determine the thermal stability and volatile component content of the materials.The ferruginous sandstone of Gebel Ahmar Formation exhibits various decomposition phases when exposed to thermal inf luences,with TGA indicating an initial mass decrease starting at 61.8℃.In contrast,the ferruginous limestone of the Maadi Formation shows a single-phase mass decrease between 650 and 875℃.展开更多
Hejiangkou W-Sn-polymetallic deposit is a newly found deposit in Xitian ore field,one of the important and large scale W-Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone.Re-Os isotope dati...Hejiangkou W-Sn-polymetallic deposit is a newly found deposit in Xitian ore field,one of the important and large scale W-Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone.Re-Os isotope dating was used on three molybdenite samples from Hejiangkou deposit to determine the ore forming period.The result is(224.9±2.6)Ma-(225±3.1)Ma and isochron age is(225.5±3.6)Ma.The field geological observations,geochronological data and optical petrography indicated that Hejiangkou deposit underwent multi-period of superimposed mineralization.It can be differentiated into three periods composed of six mineralization stages.The first period is the initial period for hydrothermal metasomatism and metal element enrichment during Indosinian Epoch.Further enrichment,strong brittle fracturing and hydrothermal metasomatism,remobilization and superimposition happened in the second period,during early Yanshanian.It is the major mineralization period of Hejiangkou deposit and can be subdivided into four mineralization stages,namely the skarn stage,oxide stage,high-temperature sulfide stage and low-temperature sulfide stage.And the third period is the mineralization period of a porphyry-skarn system related to the emplacement of the granite porphyry dyke.As minerogenic epoch of Hejiangkou deposit is similar with Hehuaping deposit,they show the possibility of Indosinian mineralization event in Nanling metallogenic zone.It can be an important perspective in any future mineral exploration in the same metallogenic zone.展开更多
The use of geomagnetic for geophysical and geological studies is a new method for receiving different information from new and old faults and lineaments. Accordingly, the present study is applied research and it use c...The use of geomagnetic for geophysical and geological studies is a new method for receiving different information from new and old faults and lineaments. Accordingly, the present study is applied research and it use combined the two methods, analytical signal and Euler’s combined method and invented a new combined method to estimate the depth, location and shape of the magnetic and gravity sources. As a case, this research selected Iran’s Zagros zone. This region due to the geological dynamics is considered by many geologists. In this regard, the 1:250,000 framework of Haji Abad was selected as a case study because of its convenient location for structural analysis. As a result, with airborne magnetic images survey, and applying filters in the vertical derivative and analytical signal, lineaments in depth of this region discovered and investigated.展开更多
The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical character- istics and the endogenous and exogenous proces...The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical character- istics and the endogenous and exogenous processes taking place in the catchment. This paper presents an analysis of the impact the changes in lithological conditions have on the morphological and morphometric parameters of the Udava River channel and their relation to the channel accumulation forms representative of the river＇s longitudinal profile as well as of its planform. Results document when accumulation forms occur and what is their spatial dis- tribution within the longitudinal and cross-sectional river profiles. More resistant structures created sections with a lower degree of sedimentation, while in depression segments the degree of sedimentation was higher. With the increase in longitudinal slope, the impact of channel width on the average channel bar size increased. Also a difference in the accumula- tion was observed between the left and right bank which could be possibly explained by the impact of Coriolis force.展开更多
There are many factors which affect the hydrological, geomorphologic and hydrogeological condition of the area. In order to better comprehend all processes, a Digital Elevation Model (DEM) was developed based on Geogr...There are many factors which affect the hydrological, geomorphologic and hydrogeological condition of the area. In order to better comprehend all processes, a Digital Elevation Model (DEM) was developed based on Geographical Information System. This latter appears as an essential tool to facilitate the decision support and can provide very important geological information. In fact, the use of the DEM is growing dramatically with the use of the GIS and the improvement of information extracted from elevation data such as mapping of floods, forest areas, erosion, and lineaments. The spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques. The main purpose of this study is to model the natural surface of the earth as the most accurate and the most precise. For this end we have tried in this work to develop various types of Digital Elevation Models DEM of the Foussana rift in Central Tunisia and to demonstrate the role of these models in geological, hydrogeological and hydrological study. The 3D model is also coupled in this study with piezometric and hydrochemistry study, so a new information’s plan was mapped by multiple GIS techniques like Spatial analysis and interpolation;in order 1) to comprehend the hydrodynamic of the aquifer, 2) to quantify surface and subsurface water resources and 3) to generate water management scenarios in the study area. To this end, several groundwater samples were collected and analyzed from wells and piezometers. Examining the corresponding physical and chemical parameters showed an increase in the concentrations of hydraulic conductivity in the center of the study area and it coincided with zones with high nutrient concentration. Recommendations are proposed in this zone.展开更多
The capital of Georgia</span><span style="font-family:Verdana;">—Tbilisi has a very convenient location and is a node of the transit corridor. Along with natural-geological conditions, its compl...The capital of Georgia</span><span style="font-family:Verdana;">—Tbilisi has a very convenient location and is a node of the transit corridor. Along with natural-geological conditions, its complexity is due to the rapid demographic growth of the city in a highly “sensitive” area of the geological environment and the pressure of high engineering and agricultural activities. In Tbilisi</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> it is observed almost all type</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of geological hazards, including landslide-gravitational, suffosion, debris/mudflows, river </span><span style="font-family:Verdana;">bank erosion and inundation </span></span><span style="font-family:Verdana;">were </span><span style="font-family:Verdana;">caused by groundwater. These hazard</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> cause</span><span style="font-family:""><span style="font-family:Verdana;"> high damages to the residential houses and other infrastructure facilities. Most importantly and most tragically is that these kind of negative geological events are often accompanied by human casualties. The study discusses the geological processes developed in March 2021 in the corridor of the Vashlij</span><span style="font-family:Verdana;">vari-Lisi road (Machavariani Street). The information obtained from the study,</span><span style="font-family:Verdana;"> reflects the triggering factors of the geological hazards, also damages caused by them, and provides recommendations for short-term and long-term protective measures that should ensure the sustainable operation of the road and other infrastructure facilities.展开更多
In the event of natural disasters, Sierra Leone like any other country loses lives as well as properties and natural resources. Despite notable occurrences of small disasters in the country, only on August 14th sugarl...In the event of natural disasters, Sierra Leone like any other country loses lives as well as properties and natural resources. Despite notable occurrences of small disasters in the country, only on August 14th sugarloaf landslide and the resulting flash flood (twin disasters) which affected Regent and other communities in 2017 have captured both national and international attention due to their alarming impacts. To obtain a better knowledge on the nature of the disasters, this research considered the geological context of the landslide and focused on statistical analysis of the impacts of the twin disasters using Statistical Package for Social Sciences (SPSS). Geological field-based approach and self-administered questionnaires of both closed and open-ended questions, personal interviews and observations were adopted as research techniques. Descriptive statistics and qualitative analysis were used to analyze the data of the research. Relevant literature from books, journals, and newspapers was also consulted, including Radio, Television discussions and the internet. Slope destabilization that caused the Landslide was linked to the geology of sub-surface formation (highly weathered olivine gabbro), lineaments and the rate of weathering. Study showed remarkable economic, social and political impacts as a consequence of the twin disasters. Study also revealed that families assisted the most in both financial and non-financial ways to the victims, and renowned misappropriation of donated disaster funds. All variables tested using student t-distribution and chi-square test of independence accepted the hypothesis. Information obtained from this work could be fundamental for policy makers and development practitioners (Osuteye & Leck, 2017).展开更多
The high Ziz’s basin, which is part of the Central High Atlas, contains Jurassic superficial and deep aquifers. The information sheets are still fragmentary and insufficient because of the basin’s large size and its...The high Ziz’s basin, which is part of the Central High Atlas, contains Jurassic superficial and deep aquifers. The information sheets are still fragmentary and insufficient because of the basin’s large size and its complex geological structure. In order to improve the knowledge of these aquifers and the determination of the structure of aquifers, a 3D geological model was developed in this study. It was constructed from information provided by 200 mechanical soundings and 81 electrical surveys and geological maps. Compiled holes were analyzed, coded and integrated in the software Groundwater Modeling System 6.0 (GMS 6.0). For doing this, five lithostratigraphic units were considered: the Domerian, the Toarcian, the Aalenian, the Bajo-Bathonian and the Quaternary. The operation of the 3D stratigraphic model allowed making it closer to the geometry of Jurassic aquifers.展开更多
This research deals with coarse grain sediments obtained from sieving of quaternary depression and valley fill sediments from desert and desert boarder’s regions southwest Najaf city-Iraq. Physical, chemical and mine...This research deals with coarse grain sediments obtained from sieving of quaternary depression and valley fill sediments from desert and desert boarder’s regions southwest Najaf city-Iraq. Physical, chemical and mineralogical analyses of these sediments were done to reveal the sedimentary origin of these sediments. The results indicated that parent rocks of these sediments were not from the Arabian shield where they were transported for short distances from sedimentary rocks cover that is located at the outskirts of the Arabian shield.展开更多
The continuous aquifers of the Congolese Cuvette basin constitute the seat of significant water tables reversibly supplying the Congo River basin as well as the water tables they drain. Consisting mainly of sandy-clay...The continuous aquifers of the Congolese Cuvette basin constitute the seat of significant water tables reversibly supplying the Congo River basin as well as the water tables they drain. Consisting mainly of sandy-clayey-sandstone formations, these aquifers contain groundwater which is the main source of drinking water supply for communities in this sector of the departments Cuvette and Cuvette-Ouest. The need for water being more and more acute, these aquifers have been subjected to drilling operations in order to supply drinking water to these populations. The information obtained from these operations is data which made it possible to obtain information relating to the lithology, the hydrogeological parameters of these aquifers and information on the depth and on the lateral variations of the water table. The purpose of this present work is to contribute to the hydrogeological characterization of the aquifer of the Cuvette basin in the departments of Cuvette and Cuvette-Ouest via data from the analysis of the technical sheets of drillings carried out by the ASPERBRAS Company, collected at the Ministry of Major Works and territory planning. This characterization was made using Visual MODFLOW Flex 2015.1 software coupled with Surfer 10 software and Rock Works 17 software. The hydrogeological interpretation of the data shows that this aquifer, whose constitution is essentially made up of sands, clayey sands and clay, is continuous, porous and free. This composition gives the aquifer of Cuvette basin a heterogeneous character. In addition, a piezometric map was produced in order to indicate the direction of the water flows which turned out to be from west to east towards the lowest areas occupied by the valleys of the rivers and rivers. The conceptual model shows that the depth of the aquifer deceases considerably from the Cuvette-Ouest towards the Cuvette.展开更多
The following paper presents an integrated geological (field observations, wells data) and geophysical data (Gravity measurements and seismic profiles) in Tellian foreland domain of the northeastern Tunisia (Mateur pl...The following paper presents an integrated geological (field observations, wells data) and geophysical data (Gravity measurements and seismic profiles) in Tellian foreland domain of the northeastern Tunisia (Mateur plain) served for a new proposed structural map with many faults already recognized or supposed by traditional structural studies and highlights major regional accidents.展开更多
The Mae Moh lignite-fired power plant is the only lignite-fired power plant and is the main point source of CO_(2)emissions in Thailand.This power plant uses lignite supplied from the Mae Moh lignite open-pit mine in ...The Mae Moh lignite-fired power plant is the only lignite-fired power plant and is the main point source of CO_(2)emissions in Thailand.This power plant uses lignite supplied from the Mae Moh lignite open-pit mine in the same vicinity.Carbon dioxide sequestration technologies can play a crucial role in reducing carbon emissions in the energy sector,particularly in coal-fired power plants.This case study provides the first assessment of the potential for geological CO_(2)storage in coal seams at the Mae Moh coal mine in northern Thailand based on literature reviews.The Mae Moh Basin is a rift basin with a complex normal fault and contains coal seams at different depths separated by claystones.The geological setting potentially offers favorable conditions for the geological storage of CO_(2)in the coal seams through a combination of physical and chemical trapping mechanisms.The findings suggest that the Mae Moh coal mine is suitable for geological CO_(2)storage,especially in K and Q coal seams.However,leakage risks,storage capacity,and CO_(2)-water-coal reactions could be problematic.Thus,more subsurface studies should be carried out,and more detailed criteria should be considered before CO_(2)sequestration is undertaken in the Mae Moh coal mine.展开更多
In the Fatira(Abu Zawal)mine area,located in the northern Eastern Desert of Egypt,fieldwork and mineralogical analysis,integrated with machine learning techniques applied to Landsat-8 OLI,ASTER,and Sentinel-2 multi-sp...In the Fatira(Abu Zawal)mine area,located in the northern Eastern Desert of Egypt,fieldwork and mineralogical analysis,integrated with machine learning techniques applied to Landsat-8 OLI,ASTER,and Sentinel-2 multi-spectral imagery(MSI)data delineate gold-sulfide mineralization in altered rocks.Gold(Au)anomalies in hydrothermal breccias and quartz veins are associated with NE-oriented felsite dykes and silicified granitic rocks.Two main alteration types are identified:a pyrite-sericite-quartz and a sulfide-chlorite-carbonate assemblage,locally with dispersed free-milling Au specks.Dimensionality reduction techniques,including principal component analysis(PCA)and independent component analysis(ICA),enabled mapping of alteration types.Sentinel-2 PC125 composite images offered efficient lithological differentiation,while supervised classifications,i.e.,the support vector machine(SVM)of Landsat-8 yielded an accuracy of 88.55%and a Kappa value of 0.86.ASTER mineral indices contributed to map hydrothermal alteration mineral phases,including sericite,muscovite,kaolinite,and iron oxides.Results indicate that post-magmatic epigenetic hydrothermal activity significantly contributed to the Au-sulfide mineralization in the Fatira area,distinguishing it from the more prevalent orogenic gold deposits in the region.展开更多
In the Maradi region,the alluvial aquifer of the Goulbi’N Maradi rests on the aquifers of the Continental Hamadien.It represents an essential reserve for irrigation and drinking water supply.However,due to its high d...In the Maradi region,the alluvial aquifer of the Goulbi’N Maradi rests on the aquifers of the Continental Hamadien.It represents an essential reserve for irrigation and drinking water supply.However,due to its high demand and the excessive use of chemical fertilizers and pesticides in irrigation,a ten-year analysis of the dynamics of this alluvial aquifer has proven necessary.Hence,this study,based on hydrodynamic and hydrochemical approaches,aims to improve knowledge of the dynamics of the alluvial aquifer from 2015 to 2023.The novelty of this study lies in its comprehensive coverage of the entire Goulbi N’Maradi valley in Niger,employing a multidimensional approach.The data used were composed of water samples taken from forty-five structures,piezometric monitoring sheets,and digital terrain models.The results reveal that the Goulbi’N Maradi aquifer exhibits continuous piezometry,characterized by a general flow pattern from south to northwest and a relatively strong hydraulic gradient in the southern part,indicating recharge from recent infiltration of rain and floodwaters.The water balances calculated at a monthly time step showed that only July and August had surpluses,with average infiltrations of 25.4 mm and 23.9 mm for 2018 and an RFU of 50 mm.For 2021,the average infiltrations were 30.8 mm and 6.6 mm,respectively,for August and September,and for the same RFU.The water conductivity values between 115 and 800μS·cm^(-1).The hydrogen potential varied between 5 and 7 pH units,giving the water an acidic character that makes it corrosive to equipment.展开更多
Fractal geometry quantitatively analyzes the irregular distribution of geological features,highlighting the dynamic aspects of tectonics,seismic heterogeneity,and geological maturity.This study analyzed the active fau...Fractal geometry quantitatively analyzes the irregular distribution of geological features,highlighting the dynamic aspects of tectonics,seismic heterogeneity,and geological maturity.This study analyzed the active fault data along the Kuhbanan fault zone in southeastern Iran by applying the boxcounting method and observing the changes in Coulomb stress and tried to find the potential triggering parts.The entire region was divided into 16subzones with the box-counting method,and then the fractal dimension(D)in each zone was calculated.The analysis of the fractal dimension for active faults and earthquake epicenters along with the seismicity parameter(b)and their ratio in the Kuhbanan region indicates an imbalance between seismic fractals and faults.This finding suggests that the area may have the potential for future earthquakes or hidden faults.In conjunction with b-value and changes in Coulomb stress change,D-value analysis reveals intense tectonic activity and stress accumulation,particularly within the Ravar,Zarand,and Kianshahr sections.It may be considered a potential location for future earthquakes.The changes in Coulomb stress resulting from the 2005Dahuieh earthquake have also placed this region within the stress accumulation zone,potentially triggering the mentioned areas.This integrative approach,backed by historical earthquake data,highlights the impact of fault geometry and stress dynamics,offering an enhanced framework for earthquake forecasting and seismic risk mitigation applicable to other tectonically active areas within the Iranian plateau.展开更多
Offshore Nile Delta in Egypt represents an enormous hydrocarbon province with recent projected gas and condensate discoveries of more than 50 trillion cubic feet“TCF”.Most of these occur in the post-salt hydrocarbon...Offshore Nile Delta in Egypt represents an enormous hydrocarbon province with recent projected gas and condensate discoveries of more than 50 trillion cubic feet“TCF”.Most of these occur in the post-salt hydrocarbon plays where biogenic gases are dominant.This study integrates organic geochemistry,seismic geomorphology and petrophysics in order to decipher the origin,and accumulation conditions of the wet gas/condensate blend in the Upper Miocene sub-salt Wakar Formation sandstones in Port Fouad Marine“PFM”Field,offshore Nile Delta.Hydrocarbon pay zones are scattered thin(<10 m)sandstones deposited in as turbiditic channel/levee complex facies.Spatial distribution of vertical gas chimneys(~2 km wide)rooting-down to the Messinian Rosetta salt is associated with the lateral pinching-out of the turbiditic sandstones.Organically-rich(total organic carbon“TOC”>1 w.t.%,hydrogen index“HI”>200 mgHC/gTOC)and mature(Tmax>430℃,vitrinite reflectance“VR”>0.6%R_(o)),source rocks are restricted to Upper Miocene Wakar and Oligo-Miocene Tineh formations.The latter contains more mature organofacies(up to 1.2%R_(o))and type Ⅱ/Ⅲ kerogen,thereby demonstrating a good capability to generate wet gases.The studied gas is wet and has thermogenic origin with signs of secondary microbial alteration,whereas the condensate contains a mixture of marine and terrestrial input.Molecular bio-markers of the condensate,isotopic and molecular composition of the gas reveals a generation of condensate prior to gas expulsion from the source.The Wakar sandstones have a heterogeneous pore system where three reservoir rock types(RRTⅠ,RRTⅡ and RRTⅢ).RRTI rocks present the bulk compo-sition of the Wakar pay zones.Spatial distribution of RRTⅠ facies likely control the accumulation of the sub-salt hydrocarbons.Our results provide a new evidence on an active petroleum system in the sub-salt Paleogene successions in the offshore Nile Delta where concomitant generation of gas/condensate blend has been outlined.展开更多
Leucogranite,pegmatite,and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their petrogenesis.These rocks represent a significant episod...Leucogranite,pegmatite,and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their petrogenesis.These rocks represent a significant episode of felsic magmatism during the late stage of the Pan-African orogeny in the evolution of the Arabian–Nubian Shield(ANS)during the Late Neoproterozoic.On a petrographic basis,the leucogranite is sometimes garnetiferous and can be distinguished into monzogranite,syenogranite,and alkali feldspar granite.The analyses of muscovite,biotite,garnet,and apatite reveal the magmatic nature of the studied leucogranite.The investigated leucogranite,pegmatite,and aplite are alkali-calcic,calc-alkaline,and peraluminous.The peraluminous nature of these rocks is evidenced by using the chemical analyses of biotite.These studied rocks show a slight enrichment in light rare-earth elements(LREEs)and large-ion lithophile elements(LILE,especially Rb and Th),with an insignificant depletion of heavy rareearth elements(HREEs).On a geochemical basis,the leucogranite,pegmatite,and aplite in the study area crystallized from multiple-sourced melts that include mafic,metagraywake,and pelitic.They were derived from melts generated at crystallization temperatures around 568-900℃ for leucogranite,553-781℃ for pegmatite,and 639-779℃ for aplite based on the Zr saturation geothermometers,and at a pressure around 0.39-0.48 GPa,i.e.shallow depth intrusions.The studied felsic rocks have strong negative Eu anomalies,which are very consistent with an upper crust composition,indicating fractionation of feldspar cumulates.Also,they show a moderate La/Sm ratio indicating combined magmatic processes represented by partial melting and fractional crystallization.Integration of whole-rock chemical composition and mineral microanalysis suggests that felsic magmatism in the west Wadi El Gemal area produced voluminous masses of syn-to post-collisional granite,pegmatite,and aplite.An evolutionary three-stage model is presented to understand late magmatism in the ANS in terms of a geodynamic model.Such a model discusses the propagation of felsic magmatism in the ANS during syn-collisional to post-collisional stages.展开更多
Coal is formed from ancient plants through biochemical and physicochemical stages.Lignite gives a low amount of energy compared to higher rank coal.The Eocene Khadsaliya Formation lignite(Surkha mine)and shale(Khadsal...Coal is formed from ancient plants through biochemical and physicochemical stages.Lignite gives a low amount of energy compared to higher rank coal.The Eocene Khadsaliya Formation lignite(Surkha mine)and shale(Khadsaliya mine)sediments were collected to investigate their evolution,maturity,and source rock potential.The main objectives of this study were to update and verify previous claim of possible hydrocarbon showings and to gain new insights about the petroleum potential and paleodepositional conditions using diferent geochemical analysis approach.The primary methodology employed in this study is the pyrolysis technique and complemented by petrographic analysis.Petrographic indices indicate that Khadsaliya shale and Surkha lignite were deposited in limnic and limno-telmatic conditions,respectively,with slow subsidence rates under mesotrophic hydrological condition.Signifcant concentration of corpogelinite indicates highly varying water table and low oxygen levels during peat accumulation.At the same time,the presence of funginite,framboidal pyrite,and relatively high sulfur in some studied samples shows marine water infuence in the basin.The refectance values(0.37%-0.57%)reveal that organic matter(OM)in Surkha lignites is immature,while immature to marginally mature in Khadsaliya shale.Furthermore,the pyrolysis data like Tmax(385℃-430℃)and production index(PI 0.02-0.13)also indicate immature to marginally mature OM.Oxygen index(OI)versus hydrogen index(HI),Tmax versus HI,and Total organic carbon(TOC)versus S2 plots of lignite and shale of Khadsaliya Formation indicate that the OM is mainly type Ⅲ kerogen and can act as fair to good source rock.The distribution of n-alkene/n-alkane doublets,o-Xylene,and 2,3-dimethylthiophene in the Py-GC pyrogram exhibits that most studied shale and lignite samples have type Ⅲ kerogen and the capability to produce mainly gas.展开更多
The Barud gneissic dome complex is situated along the ENE-trending dextral shear zone of the Qena-Safaga Line that serves as a significant tectonic boundary between the basement terrains of the Northern and Central Ea...The Barud gneissic dome complex is situated along the ENE-trending dextral shear zone of the Qena-Safaga Line that serves as a significant tectonic boundary between the basement terrains of the Northern and Central Eastern Desert.These terrains exhibit distinct differences in crustal composition and deformation style.The Northern Eastern Desert and its extension into Sinai are predominantly composed of gneissic granites that are intruded by large batholiths of calc-alkaline and alkaline granites.Conversely,the Central and Southern Eastern Desert are commonly blanketed by a carapace of ophiolite-bearing volcano-sedimentary rocks of the Pan-African cover nappes.These northern terrains,just north of the Barud dome complex,the crust underwent significant NW-SE regional crustal extension across the Qena-Safaga Line,which sharply delineates the northern limit of the transpressional deformations linked to the Najd fault system in the Central and Southern Eastern Desert.Through comprehensive geological mapping and the integration of various geophysical,geochemical and geochronological data,this paper offers explanations for the contrasting geological features of the basement terrains on both sides of the Qena-Safaga Line and its analogous Fatira Shear Zone that plays a significant role in tectonic modeling of the Barud dome complex region.The Barud gneissic protolith experienced crustal shortening approximately 697 million years ago in the NW-SE direction,initiating dextral motion along the Fatira Shear Zone.Large batholiths of granodiorite/tonalite complex intruded the Barud gneissic dome protolith around 630 million years ago along the Qena-Safaga Line,at relatively shallow crustal depths,following the same orientation as the earlier shortening direction.Ongoing magmatic activity along the Qena-Safaga Line indicates intense magmatic underplating,resulting in significant intrusions of granodioritic melts into the early rifted crust of the Northern Eastern Desert and Sinai terrains.The crust of these northern terrains likely underwent isostatic compensation through uplifting and subsequent erosion.The disappearance of ophiolite-bearing belts and the presence of Paleo-to Mesoproterozoic continental-derived cobbles and ignimbrites in Sinai metasedimentary belts and Northern Eastern Desert molasse basins suggest that the northern terrains,located north of the Qena-Safaga Line,originated as a cohesive,thin continental crust that rifted off the eastern passive margin of the Sahara Metacraton during the early Neoproterozoic rifting of the Rodinia supercontinent.展开更多
Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,loc...Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,located along the Minab-Zendan Fault,represents a convergence boundary between the Zagros continental domain and the Makran accretionary prism in southern Iran from the Cretaceous onwards.Several tectonic slices,including Neotethys ophiolitic remnants and the Ganj and Bajgan-Durkan complexes,have accreted along the southern margin of the Eurasian Plate during subduction in the western Makran wedge.To clarify the growth steps of the Makran Prism and the internal deformation associated with arc-continent collision,we used a provenance study of sandstones from the western Makran accretionary prism involving petrography of the main detrital components and U–Pb dating,Hf isotopic values,and trace elements of detrital zircon grains.Our findings reveal a progressive scenario in which oceanic arc-related rocks of the∼99 Ma Ganj Complex with Hf values ranging from+10 to+16 were uplifted during the Early to Late Eocene.The Eocene fore-arc sediments were sourced from the∼49–47 Ma Urumieh-Dokhtar Magmatic Arc with Hf values between−5 and+12,as well as from the Ganj Complex.The Jurassic–Cretaceous Bajgan-Durkan Complex was uplifted due to the Late Eocene to Oligocene collision of various terranes along the southern margin of the Eurasian Plate.This led to a major sediment influx into the Makran trench with a detrital signal in the range∼175–160 Ma with Hf isotopic values from−3 to+4 and alongside the Urumieh-Dokhtar Magmatic Arc with detrital ages ranging∼46–37 Ma and ca.80 Ma.Notably,metamorphic lithic grains began to appear in the sediments in the Late Eocene.The initial arrival of sediments from the Arabian margin to the arc-continent suture zone along the Minab-Zendan Fault indicates the onset of initial collision.During the Late Oligocene–Early Miocene,detrital zircon ages in the range of∼610–520 Ma,sourced from the Arabian basement,were deposited in the trench basin together with components from the Eocene Urumieh-Dokhtar Magmatic Arc and Cretaceous ophiolitic clasts of∼93 Ma with Hf isotopic values of+12 to+16.Following the development and uplift of the orogen from the Middle Miocene onward,detrital zircon grains from the Cretaceous–Miocene Urumieh-Dokhtar Magmatic Arc,Jurassic–Cretaceous Bajgan-Durkan Complex,and Cretaceous ophiolites are present in both the Makran and Zagros sedimentary domains.展开更多
文摘Geological setting,facies characteristics,and geochemistry,including TGA(thermo-gravimetric analysis)of Paleogene deposits in east Beni Suef region(Egypt),were studied in the present work.Lithostratigraphically,the area consists of three rock units,arranged from oldest to youngest:Tarbul Member of Beni Suef Formation(MiddleLate Eocene),Maadi Formation(Late Eocene),and Gebel Ahmar Formation(Oligocene),this last formation registered for the first time in the east of Beni Suef area(Egypt).Seven microfacies types(F1-F7)were determined by the microscopic examination of the studied samples in low-to high-energy and shallow-subtidal marine conditions.The lithostratigraphic,petrological,and geochemical results revealed that the Eocene succession in the present area is composed mainly of carbonates as well as siliciclastics.The Oligocene Gebel Ahmar Formation consists mainly of silica and iron oxides.The enrichment of the rock units with iron oxides in the studied area,as well as the high proportions of trace elements such as Zr,Ba,V,and Sr,in particular in the Gebel Ahmar Formation,reflects the influence of the hydrothermal solutions during the Oligocene.TGA,which monitors weight changes during heating at a constant rate,was used to determine the thermal stability and volatile component content of the materials.The ferruginous sandstone of Gebel Ahmar Formation exhibits various decomposition phases when exposed to thermal inf luences,with TGA indicating an initial mass decrease starting at 61.8℃.In contrast,the ferruginous limestone of the Maadi Formation shows a single-phase mass decrease between 650 and 875℃.
基金Project(41403035)supported by the National Natural Science Foundation of ChinaProject(13JJ4041)supported by Hunan Provincial National Natural Science Foundation,China
文摘Hejiangkou W-Sn-polymetallic deposit is a newly found deposit in Xitian ore field,one of the important and large scale W-Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone.Re-Os isotope dating was used on three molybdenite samples from Hejiangkou deposit to determine the ore forming period.The result is(224.9±2.6)Ma-(225±3.1)Ma and isochron age is(225.5±3.6)Ma.The field geological observations,geochronological data and optical petrography indicated that Hejiangkou deposit underwent multi-period of superimposed mineralization.It can be differentiated into three periods composed of six mineralization stages.The first period is the initial period for hydrothermal metasomatism and metal element enrichment during Indosinian Epoch.Further enrichment,strong brittle fracturing and hydrothermal metasomatism,remobilization and superimposition happened in the second period,during early Yanshanian.It is the major mineralization period of Hejiangkou deposit and can be subdivided into four mineralization stages,namely the skarn stage,oxide stage,high-temperature sulfide stage and low-temperature sulfide stage.And the third period is the mineralization period of a porphyry-skarn system related to the emplacement of the granite porphyry dyke.As minerogenic epoch of Hejiangkou deposit is similar with Hehuaping deposit,they show the possibility of Indosinian mineralization event in Nanling metallogenic zone.It can be an important perspective in any future mineral exploration in the same metallogenic zone.
文摘The use of geomagnetic for geophysical and geological studies is a new method for receiving different information from new and old faults and lineaments. Accordingly, the present study is applied research and it use combined the two methods, analytical signal and Euler’s combined method and invented a new combined method to estimate the depth, location and shape of the magnetic and gravity sources. As a case, this research selected Iran’s Zagros zone. This region due to the geological dynamics is considered by many geologists. In this regard, the 1:250,000 framework of Haji Abad was selected as a case study because of its convenient location for structural analysis. As a result, with airborne magnetic images survey, and applying filters in the vertical derivative and analytical signal, lineaments in depth of this region discovered and investigated.
文摘The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical character- istics and the endogenous and exogenous processes taking place in the catchment. This paper presents an analysis of the impact the changes in lithological conditions have on the morphological and morphometric parameters of the Udava River channel and their relation to the channel accumulation forms representative of the river＇s longitudinal profile as well as of its planform. Results document when accumulation forms occur and what is their spatial dis- tribution within the longitudinal and cross-sectional river profiles. More resistant structures created sections with a lower degree of sedimentation, while in depression segments the degree of sedimentation was higher. With the increase in longitudinal slope, the impact of channel width on the average channel bar size increased. Also a difference in the accumula- tion was observed between the left and right bank which could be possibly explained by the impact of Coriolis force.
文摘There are many factors which affect the hydrological, geomorphologic and hydrogeological condition of the area. In order to better comprehend all processes, a Digital Elevation Model (DEM) was developed based on Geographical Information System. This latter appears as an essential tool to facilitate the decision support and can provide very important geological information. In fact, the use of the DEM is growing dramatically with the use of the GIS and the improvement of information extracted from elevation data such as mapping of floods, forest areas, erosion, and lineaments. The spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques. The main purpose of this study is to model the natural surface of the earth as the most accurate and the most precise. For this end we have tried in this work to develop various types of Digital Elevation Models DEM of the Foussana rift in Central Tunisia and to demonstrate the role of these models in geological, hydrogeological and hydrological study. The 3D model is also coupled in this study with piezometric and hydrochemistry study, so a new information’s plan was mapped by multiple GIS techniques like Spatial analysis and interpolation;in order 1) to comprehend the hydrodynamic of the aquifer, 2) to quantify surface and subsurface water resources and 3) to generate water management scenarios in the study area. To this end, several groundwater samples were collected and analyzed from wells and piezometers. Examining the corresponding physical and chemical parameters showed an increase in the concentrations of hydraulic conductivity in the center of the study area and it coincided with zones with high nutrient concentration. Recommendations are proposed in this zone.
文摘The capital of Georgia</span><span style="font-family:Verdana;">—Tbilisi has a very convenient location and is a node of the transit corridor. Along with natural-geological conditions, its complexity is due to the rapid demographic growth of the city in a highly “sensitive” area of the geological environment and the pressure of high engineering and agricultural activities. In Tbilisi</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> it is observed almost all type</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of geological hazards, including landslide-gravitational, suffosion, debris/mudflows, river </span><span style="font-family:Verdana;">bank erosion and inundation </span></span><span style="font-family:Verdana;">were </span><span style="font-family:Verdana;">caused by groundwater. These hazard</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> cause</span><span style="font-family:""><span style="font-family:Verdana;"> high damages to the residential houses and other infrastructure facilities. Most importantly and most tragically is that these kind of negative geological events are often accompanied by human casualties. The study discusses the geological processes developed in March 2021 in the corridor of the Vashlij</span><span style="font-family:Verdana;">vari-Lisi road (Machavariani Street). The information obtained from the study,</span><span style="font-family:Verdana;"> reflects the triggering factors of the geological hazards, also damages caused by them, and provides recommendations for short-term and long-term protective measures that should ensure the sustainable operation of the road and other infrastructure facilities.
文摘In the event of natural disasters, Sierra Leone like any other country loses lives as well as properties and natural resources. Despite notable occurrences of small disasters in the country, only on August 14th sugarloaf landslide and the resulting flash flood (twin disasters) which affected Regent and other communities in 2017 have captured both national and international attention due to their alarming impacts. To obtain a better knowledge on the nature of the disasters, this research considered the geological context of the landslide and focused on statistical analysis of the impacts of the twin disasters using Statistical Package for Social Sciences (SPSS). Geological field-based approach and self-administered questionnaires of both closed and open-ended questions, personal interviews and observations were adopted as research techniques. Descriptive statistics and qualitative analysis were used to analyze the data of the research. Relevant literature from books, journals, and newspapers was also consulted, including Radio, Television discussions and the internet. Slope destabilization that caused the Landslide was linked to the geology of sub-surface formation (highly weathered olivine gabbro), lineaments and the rate of weathering. Study showed remarkable economic, social and political impacts as a consequence of the twin disasters. Study also revealed that families assisted the most in both financial and non-financial ways to the victims, and renowned misappropriation of donated disaster funds. All variables tested using student t-distribution and chi-square test of independence accepted the hypothesis. Information obtained from this work could be fundamental for policy makers and development practitioners (Osuteye & Leck, 2017).
文摘The high Ziz’s basin, which is part of the Central High Atlas, contains Jurassic superficial and deep aquifers. The information sheets are still fragmentary and insufficient because of the basin’s large size and its complex geological structure. In order to improve the knowledge of these aquifers and the determination of the structure of aquifers, a 3D geological model was developed in this study. It was constructed from information provided by 200 mechanical soundings and 81 electrical surveys and geological maps. Compiled holes were analyzed, coded and integrated in the software Groundwater Modeling System 6.0 (GMS 6.0). For doing this, five lithostratigraphic units were considered: the Domerian, the Toarcian, the Aalenian, the Bajo-Bathonian and the Quaternary. The operation of the 3D stratigraphic model allowed making it closer to the geometry of Jurassic aquifers.
文摘This research deals with coarse grain sediments obtained from sieving of quaternary depression and valley fill sediments from desert and desert boarder’s regions southwest Najaf city-Iraq. Physical, chemical and mineralogical analyses of these sediments were done to reveal the sedimentary origin of these sediments. The results indicated that parent rocks of these sediments were not from the Arabian shield where they were transported for short distances from sedimentary rocks cover that is located at the outskirts of the Arabian shield.
文摘The continuous aquifers of the Congolese Cuvette basin constitute the seat of significant water tables reversibly supplying the Congo River basin as well as the water tables they drain. Consisting mainly of sandy-clayey-sandstone formations, these aquifers contain groundwater which is the main source of drinking water supply for communities in this sector of the departments Cuvette and Cuvette-Ouest. The need for water being more and more acute, these aquifers have been subjected to drilling operations in order to supply drinking water to these populations. The information obtained from these operations is data which made it possible to obtain information relating to the lithology, the hydrogeological parameters of these aquifers and information on the depth and on the lateral variations of the water table. The purpose of this present work is to contribute to the hydrogeological characterization of the aquifer of the Cuvette basin in the departments of Cuvette and Cuvette-Ouest via data from the analysis of the technical sheets of drillings carried out by the ASPERBRAS Company, collected at the Ministry of Major Works and territory planning. This characterization was made using Visual MODFLOW Flex 2015.1 software coupled with Surfer 10 software and Rock Works 17 software. The hydrogeological interpretation of the data shows that this aquifer, whose constitution is essentially made up of sands, clayey sands and clay, is continuous, porous and free. This composition gives the aquifer of Cuvette basin a heterogeneous character. In addition, a piezometric map was produced in order to indicate the direction of the water flows which turned out to be from west to east towards the lowest areas occupied by the valleys of the rivers and rivers. The conceptual model shows that the depth of the aquifer deceases considerably from the Cuvette-Ouest towards the Cuvette.
文摘The following paper presents an integrated geological (field observations, wells data) and geophysical data (Gravity measurements and seismic profiles) in Tellian foreland domain of the northeastern Tunisia (Mateur plain) served for a new proposed structural map with many faults already recognized or supposed by traditional structural studies and highlights major regional accidents.
基金financial support from the creation of a teaching-led research platform,the Ratchadaphisek Somphot Endowment Fund,Chulalongkorn University。
文摘The Mae Moh lignite-fired power plant is the only lignite-fired power plant and is the main point source of CO_(2)emissions in Thailand.This power plant uses lignite supplied from the Mae Moh lignite open-pit mine in the same vicinity.Carbon dioxide sequestration technologies can play a crucial role in reducing carbon emissions in the energy sector,particularly in coal-fired power plants.This case study provides the first assessment of the potential for geological CO_(2)storage in coal seams at the Mae Moh coal mine in northern Thailand based on literature reviews.The Mae Moh Basin is a rift basin with a complex normal fault and contains coal seams at different depths separated by claystones.The geological setting potentially offers favorable conditions for the geological storage of CO_(2)in the coal seams through a combination of physical and chemical trapping mechanisms.The findings suggest that the Mae Moh coal mine is suitable for geological CO_(2)storage,especially in K and Q coal seams.However,leakage risks,storage capacity,and CO_(2)-water-coal reactions could be problematic.Thus,more subsurface studies should be carried out,and more detailed criteria should be considered before CO_(2)sequestration is undertaken in the Mae Moh coal mine.
基金the National Science Foundation of China (Grant No. NSFC: 92162213)the Geology Department Faculty of Science of Al-Azhar University (Assiut Branch)+2 种基金the China Scholarship CouncilChang'an UniversityIstanbul Technical University's Scientific Research Project (BAP Project ID: 45396, code: FHD-2024-45396)
文摘In the Fatira(Abu Zawal)mine area,located in the northern Eastern Desert of Egypt,fieldwork and mineralogical analysis,integrated with machine learning techniques applied to Landsat-8 OLI,ASTER,and Sentinel-2 multi-spectral imagery(MSI)data delineate gold-sulfide mineralization in altered rocks.Gold(Au)anomalies in hydrothermal breccias and quartz veins are associated with NE-oriented felsite dykes and silicified granitic rocks.Two main alteration types are identified:a pyrite-sericite-quartz and a sulfide-chlorite-carbonate assemblage,locally with dispersed free-milling Au specks.Dimensionality reduction techniques,including principal component analysis(PCA)and independent component analysis(ICA),enabled mapping of alteration types.Sentinel-2 PC125 composite images offered efficient lithological differentiation,while supervised classifications,i.e.,the support vector machine(SVM)of Landsat-8 yielded an accuracy of 88.55%and a Kappa value of 0.86.ASTER mineral indices contributed to map hydrothermal alteration mineral phases,including sericite,muscovite,kaolinite,and iron oxides.Results indicate that post-magmatic epigenetic hydrothermal activity significantly contributed to the Au-sulfide mineralization in the Fatira area,distinguishing it from the more prevalent orogenic gold deposits in the region.
文摘In the Maradi region,the alluvial aquifer of the Goulbi’N Maradi rests on the aquifers of the Continental Hamadien.It represents an essential reserve for irrigation and drinking water supply.However,due to its high demand and the excessive use of chemical fertilizers and pesticides in irrigation,a ten-year analysis of the dynamics of this alluvial aquifer has proven necessary.Hence,this study,based on hydrodynamic and hydrochemical approaches,aims to improve knowledge of the dynamics of the alluvial aquifer from 2015 to 2023.The novelty of this study lies in its comprehensive coverage of the entire Goulbi N’Maradi valley in Niger,employing a multidimensional approach.The data used were composed of water samples taken from forty-five structures,piezometric monitoring sheets,and digital terrain models.The results reveal that the Goulbi’N Maradi aquifer exhibits continuous piezometry,characterized by a general flow pattern from south to northwest and a relatively strong hydraulic gradient in the southern part,indicating recharge from recent infiltration of rain and floodwaters.The water balances calculated at a monthly time step showed that only July and August had surpluses,with average infiltrations of 25.4 mm and 23.9 mm for 2018 and an RFU of 50 mm.For 2021,the average infiltrations were 30.8 mm and 6.6 mm,respectively,for August and September,and for the same RFU.The water conductivity values between 115 and 800μS·cm^(-1).The hydrogen potential varied between 5 and 7 pH units,giving the water an acidic character that makes it corrosive to equipment.
基金financial support received through a grant from the Vice-President's Research Office at Bu-Ali Sina University,Iran(Grant Number 09.99)。
文摘Fractal geometry quantitatively analyzes the irregular distribution of geological features,highlighting the dynamic aspects of tectonics,seismic heterogeneity,and geological maturity.This study analyzed the active fault data along the Kuhbanan fault zone in southeastern Iran by applying the boxcounting method and observing the changes in Coulomb stress and tried to find the potential triggering parts.The entire region was divided into 16subzones with the box-counting method,and then the fractal dimension(D)in each zone was calculated.The analysis of the fractal dimension for active faults and earthquake epicenters along with the seismicity parameter(b)and their ratio in the Kuhbanan region indicates an imbalance between seismic fractals and faults.This finding suggests that the area may have the potential for future earthquakes or hidden faults.In conjunction with b-value and changes in Coulomb stress change,D-value analysis reveals intense tectonic activity and stress accumulation,particularly within the Ravar,Zarand,and Kianshahr sections.It may be considered a potential location for future earthquakes.The changes in Coulomb stress resulting from the 2005Dahuieh earthquake have also placed this region within the stress accumulation zone,potentially triggering the mentioned areas.This integrative approach,backed by historical earthquake data,highlights the impact of fault geometry and stress dynamics,offering an enhanced framework for earthquake forecasting and seismic risk mitigation applicable to other tectonically active areas within the Iranian plateau.
文摘Offshore Nile Delta in Egypt represents an enormous hydrocarbon province with recent projected gas and condensate discoveries of more than 50 trillion cubic feet“TCF”.Most of these occur in the post-salt hydrocarbon plays where biogenic gases are dominant.This study integrates organic geochemistry,seismic geomorphology and petrophysics in order to decipher the origin,and accumulation conditions of the wet gas/condensate blend in the Upper Miocene sub-salt Wakar Formation sandstones in Port Fouad Marine“PFM”Field,offshore Nile Delta.Hydrocarbon pay zones are scattered thin(<10 m)sandstones deposited in as turbiditic channel/levee complex facies.Spatial distribution of vertical gas chimneys(~2 km wide)rooting-down to the Messinian Rosetta salt is associated with the lateral pinching-out of the turbiditic sandstones.Organically-rich(total organic carbon“TOC”>1 w.t.%,hydrogen index“HI”>200 mgHC/gTOC)and mature(Tmax>430℃,vitrinite reflectance“VR”>0.6%R_(o)),source rocks are restricted to Upper Miocene Wakar and Oligo-Miocene Tineh formations.The latter contains more mature organofacies(up to 1.2%R_(o))and type Ⅱ/Ⅲ kerogen,thereby demonstrating a good capability to generate wet gases.The studied gas is wet and has thermogenic origin with signs of secondary microbial alteration,whereas the condensate contains a mixture of marine and terrestrial input.Molecular bio-markers of the condensate,isotopic and molecular composition of the gas reveals a generation of condensate prior to gas expulsion from the source.The Wakar sandstones have a heterogeneous pore system where three reservoir rock types(RRTⅠ,RRTⅡ and RRTⅢ).RRTI rocks present the bulk compo-sition of the Wakar pay zones.Spatial distribution of RRTⅠ facies likely control the accumulation of the sub-salt hydrocarbons.Our results provide a new evidence on an active petroleum system in the sub-salt Paleogene successions in the offshore Nile Delta where concomitant generation of gas/condensate blend has been outlined.
基金finational supported by the Foundation of Science,Technology and Innovation Funding Authority(STDF)(Award Number:47106Recipient:Mokhles K K.Azer)。
文摘Leucogranite,pegmatite,and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their petrogenesis.These rocks represent a significant episode of felsic magmatism during the late stage of the Pan-African orogeny in the evolution of the Arabian–Nubian Shield(ANS)during the Late Neoproterozoic.On a petrographic basis,the leucogranite is sometimes garnetiferous and can be distinguished into monzogranite,syenogranite,and alkali feldspar granite.The analyses of muscovite,biotite,garnet,and apatite reveal the magmatic nature of the studied leucogranite.The investigated leucogranite,pegmatite,and aplite are alkali-calcic,calc-alkaline,and peraluminous.The peraluminous nature of these rocks is evidenced by using the chemical analyses of biotite.These studied rocks show a slight enrichment in light rare-earth elements(LREEs)and large-ion lithophile elements(LILE,especially Rb and Th),with an insignificant depletion of heavy rareearth elements(HREEs).On a geochemical basis,the leucogranite,pegmatite,and aplite in the study area crystallized from multiple-sourced melts that include mafic,metagraywake,and pelitic.They were derived from melts generated at crystallization temperatures around 568-900℃ for leucogranite,553-781℃ for pegmatite,and 639-779℃ for aplite based on the Zr saturation geothermometers,and at a pressure around 0.39-0.48 GPa,i.e.shallow depth intrusions.The studied felsic rocks have strong negative Eu anomalies,which are very consistent with an upper crust composition,indicating fractionation of feldspar cumulates.Also,they show a moderate La/Sm ratio indicating combined magmatic processes represented by partial melting and fractional crystallization.Integration of whole-rock chemical composition and mineral microanalysis suggests that felsic magmatism in the west Wadi El Gemal area produced voluminous masses of syn-to post-collisional granite,pegmatite,and aplite.An evolutionary three-stage model is presented to understand late magmatism in the ANS in terms of a geodynamic model.Such a model discusses the propagation of felsic magmatism in the ANS during syn-collisional to post-collisional stages.
基金the authors A.K.and K.A.M and is associated with grant number IF064-2019.
文摘Coal is formed from ancient plants through biochemical and physicochemical stages.Lignite gives a low amount of energy compared to higher rank coal.The Eocene Khadsaliya Formation lignite(Surkha mine)and shale(Khadsaliya mine)sediments were collected to investigate their evolution,maturity,and source rock potential.The main objectives of this study were to update and verify previous claim of possible hydrocarbon showings and to gain new insights about the petroleum potential and paleodepositional conditions using diferent geochemical analysis approach.The primary methodology employed in this study is the pyrolysis technique and complemented by petrographic analysis.Petrographic indices indicate that Khadsaliya shale and Surkha lignite were deposited in limnic and limno-telmatic conditions,respectively,with slow subsidence rates under mesotrophic hydrological condition.Signifcant concentration of corpogelinite indicates highly varying water table and low oxygen levels during peat accumulation.At the same time,the presence of funginite,framboidal pyrite,and relatively high sulfur in some studied samples shows marine water infuence in the basin.The refectance values(0.37%-0.57%)reveal that organic matter(OM)in Surkha lignites is immature,while immature to marginally mature in Khadsaliya shale.Furthermore,the pyrolysis data like Tmax(385℃-430℃)and production index(PI 0.02-0.13)also indicate immature to marginally mature OM.Oxygen index(OI)versus hydrogen index(HI),Tmax versus HI,and Total organic carbon(TOC)versus S2 plots of lignite and shale of Khadsaliya Formation indicate that the OM is mainly type Ⅲ kerogen and can act as fair to good source rock.The distribution of n-alkene/n-alkane doublets,o-Xylene,and 2,3-dimethylthiophene in the Py-GC pyrogram exhibits that most studied shale and lignite samples have type Ⅲ kerogen and the capability to produce mainly gas.
基金The Egyptian ministry for higher education and the Stipendium Hungaricum scholarship are thanked for funding Mohamed Badawi under the joint executive program between Hungary and Egypt.
文摘The Barud gneissic dome complex is situated along the ENE-trending dextral shear zone of the Qena-Safaga Line that serves as a significant tectonic boundary between the basement terrains of the Northern and Central Eastern Desert.These terrains exhibit distinct differences in crustal composition and deformation style.The Northern Eastern Desert and its extension into Sinai are predominantly composed of gneissic granites that are intruded by large batholiths of calc-alkaline and alkaline granites.Conversely,the Central and Southern Eastern Desert are commonly blanketed by a carapace of ophiolite-bearing volcano-sedimentary rocks of the Pan-African cover nappes.These northern terrains,just north of the Barud dome complex,the crust underwent significant NW-SE regional crustal extension across the Qena-Safaga Line,which sharply delineates the northern limit of the transpressional deformations linked to the Najd fault system in the Central and Southern Eastern Desert.Through comprehensive geological mapping and the integration of various geophysical,geochemical and geochronological data,this paper offers explanations for the contrasting geological features of the basement terrains on both sides of the Qena-Safaga Line and its analogous Fatira Shear Zone that plays a significant role in tectonic modeling of the Barud dome complex region.The Barud gneissic protolith experienced crustal shortening approximately 697 million years ago in the NW-SE direction,initiating dextral motion along the Fatira Shear Zone.Large batholiths of granodiorite/tonalite complex intruded the Barud gneissic dome protolith around 630 million years ago along the Qena-Safaga Line,at relatively shallow crustal depths,following the same orientation as the earlier shortening direction.Ongoing magmatic activity along the Qena-Safaga Line indicates intense magmatic underplating,resulting in significant intrusions of granodioritic melts into the early rifted crust of the Northern Eastern Desert and Sinai terrains.The crust of these northern terrains likely underwent isostatic compensation through uplifting and subsequent erosion.The disappearance of ophiolite-bearing belts and the presence of Paleo-to Mesoproterozoic continental-derived cobbles and ignimbrites in Sinai metasedimentary belts and Northern Eastern Desert molasse basins suggest that the northern terrains,located north of the Qena-Safaga Line,originated as a cohesive,thin continental crust that rifted off the eastern passive margin of the Sahara Metacraton during the early Neoproterozoic rifting of the Rodinia supercontinent.
基金This research was supported by the NSFC grant(No.92255303)The first author is grateful for support from the IGGCAS postdoctoral program(2016IFPR01)under the guidance of Prof.Bo Wan.
文摘Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,located along the Minab-Zendan Fault,represents a convergence boundary between the Zagros continental domain and the Makran accretionary prism in southern Iran from the Cretaceous onwards.Several tectonic slices,including Neotethys ophiolitic remnants and the Ganj and Bajgan-Durkan complexes,have accreted along the southern margin of the Eurasian Plate during subduction in the western Makran wedge.To clarify the growth steps of the Makran Prism and the internal deformation associated with arc-continent collision,we used a provenance study of sandstones from the western Makran accretionary prism involving petrography of the main detrital components and U–Pb dating,Hf isotopic values,and trace elements of detrital zircon grains.Our findings reveal a progressive scenario in which oceanic arc-related rocks of the∼99 Ma Ganj Complex with Hf values ranging from+10 to+16 were uplifted during the Early to Late Eocene.The Eocene fore-arc sediments were sourced from the∼49–47 Ma Urumieh-Dokhtar Magmatic Arc with Hf values between−5 and+12,as well as from the Ganj Complex.The Jurassic–Cretaceous Bajgan-Durkan Complex was uplifted due to the Late Eocene to Oligocene collision of various terranes along the southern margin of the Eurasian Plate.This led to a major sediment influx into the Makran trench with a detrital signal in the range∼175–160 Ma with Hf isotopic values from−3 to+4 and alongside the Urumieh-Dokhtar Magmatic Arc with detrital ages ranging∼46–37 Ma and ca.80 Ma.Notably,metamorphic lithic grains began to appear in the sediments in the Late Eocene.The initial arrival of sediments from the Arabian margin to the arc-continent suture zone along the Minab-Zendan Fault indicates the onset of initial collision.During the Late Oligocene–Early Miocene,detrital zircon ages in the range of∼610–520 Ma,sourced from the Arabian basement,were deposited in the trench basin together with components from the Eocene Urumieh-Dokhtar Magmatic Arc and Cretaceous ophiolitic clasts of∼93 Ma with Hf isotopic values of+12 to+16.Following the development and uplift of the orogen from the Middle Miocene onward,detrital zircon grains from the Cretaceous–Miocene Urumieh-Dokhtar Magmatic Arc,Jurassic–Cretaceous Bajgan-Durkan Complex,and Cretaceous ophiolites are present in both the Makran and Zagros sedimentary domains.
