Pub Date : 2021-01-01DOI: 10.1080/20909977.2020.1868659
Adedibu Sunny Akingboye, I. Osazuwa
ABSTRACT Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to resolve complexity in subsurface geology caused by inhomogeneity of the overburden strata and bedrock architectures. The subsurface geological, hydrogeophysical and engineering conditions of Etioro-Akoko, southwestern Nigeria, were investigated using electrical resistivity tomography (ERT). This was aimed at unravelling the hydrogeodynamic and litho-structural complexity that are responsible for low groundwater yield in wells/boreholes and foundation failures. Field 2D resistivity data sets of the study area were inverted and used to produce geotomographic models for detailed insights into the complex subsurface geological setting. Results of the 2D resistivity inverted models showed three to four distinct layers; the topsoil, weathered layer, partially weathered/fractured bedrock and fresh bedrock. Bedrock structures occasioned by fracturing and deep weathering of the bedrock were delineated with resistivities and thicknesses ranging from 40 to 950 Ωm and 10–25 m, respectively. The fracture systems; F1, F2, F3, F4 and F5 in NW-SE, NNW-SSE, NE-SW and ENE-WSW orientations act as the major groundwater collecting centres in the area. The orientations and geometries of these geologic features are the manifestations of structural deformation of the underlying geology. Fourteen hand-dug well and four borehole points were proposed based on the ERT results. Conversely, the localised bedrock structures and oscillating bedrock topography were suggestive of potential threats to the foundations of engineering structures in the studied area. Reinforcement of concrete foundations at certain sites where ERT suggested that the underlying strata were not capable of bearing loads was recommended as well. This study has offered a detailed understanding of the subsurface geological disposition for sustainable groundwater development and siting of durable civil engineering structures in the studied area and other areas with typical complex geological settings.
{"title":"Subsurface geological, hydrogeophysical and engineering characterisation of Etioro-Akoko, southwestern Nigeria, using electrical resistivity tomography","authors":"Adedibu Sunny Akingboye, I. Osazuwa","doi":"10.1080/20909977.2020.1868659","DOIUrl":"https://doi.org/10.1080/20909977.2020.1868659","url":null,"abstract":"ABSTRACT Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to resolve complexity in subsurface geology caused by inhomogeneity of the overburden strata and bedrock architectures. The subsurface geological, hydrogeophysical and engineering conditions of Etioro-Akoko, southwestern Nigeria, were investigated using electrical resistivity tomography (ERT). This was aimed at unravelling the hydrogeodynamic and litho-structural complexity that are responsible for low groundwater yield in wells/boreholes and foundation failures. Field 2D resistivity data sets of the study area were inverted and used to produce geotomographic models for detailed insights into the complex subsurface geological setting. Results of the 2D resistivity inverted models showed three to four distinct layers; the topsoil, weathered layer, partially weathered/fractured bedrock and fresh bedrock. Bedrock structures occasioned by fracturing and deep weathering of the bedrock were delineated with resistivities and thicknesses ranging from 40 to 950 Ωm and 10–25 m, respectively. The fracture systems; F1, F2, F3, F4 and F5 in NW-SE, NNW-SSE, NE-SW and ENE-WSW orientations act as the major groundwater collecting centres in the area. The orientations and geometries of these geologic features are the manifestations of structural deformation of the underlying geology. Fourteen hand-dug well and four borehole points were proposed based on the ERT results. Conversely, the localised bedrock structures and oscillating bedrock topography were suggestive of potential threats to the foundations of engineering structures in the studied area. Reinforcement of concrete foundations at certain sites where ERT suggested that the underlying strata were not capable of bearing loads was recommended as well. This study has offered a detailed understanding of the subsurface geological disposition for sustainable groundwater development and siting of durable civil engineering structures in the studied area and other areas with typical complex geological settings.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"9 1","pages":"43 - 57"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91296528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1913394
M. Gomaa, Hamed Sedeek
ABSTRACT Some electrical, geochemical, and mineralogical investigations and analyses were made on some cubic oxidized Pyrite crystals (Gabal El-Sibai). Samples (chemically) are constituted from Fe2O3, SiO2, and Al2O3. Electrical features measured at frequency range (100 Hz– 5 MHz). Oxidized Pyrite crystals (cubes) are homogeneous, with no distortion or high variation in their composition. Also, samples have roughly the same structure. Samples were measured in 3-directions. It is supposed that any difference in a lattice structure, in any direction, will be reflected directly in the measurements, i.e. electrical features will attempt to detect variations of homogeneity and anisotropy of samples. The alterations in electrical functions are from mineral composition changes. Changes in texture, at specimens, do not exist (grain size and shape, mineral constituents, and pore throats between grains), and it is supposed that electrical features will be similar in three directions. There were some slight changes in electrical characteristics, due to some imperfections in natural crystals, with some impurities on crystal surfaces that we could not remove. Conductivity rises with frequency increase and accordingly, dielectric constant decreases. The paper aims to prove that the electrical properties, due to homogeneity, are the same at the three perpendicular directions.
{"title":"Prediction of heterogeneity and anisotropy of oxidised pyrite crystals using electrical measurements","authors":"M. Gomaa, Hamed Sedeek","doi":"10.1080/20909977.2021.1913394","DOIUrl":"https://doi.org/10.1080/20909977.2021.1913394","url":null,"abstract":"ABSTRACT Some electrical, geochemical, and mineralogical investigations and analyses were made on some cubic oxidized Pyrite crystals (Gabal El-Sibai). Samples (chemically) are constituted from Fe2O3, SiO2, and Al2O3. Electrical features measured at frequency range (100 Hz– 5 MHz). Oxidized Pyrite crystals (cubes) are homogeneous, with no distortion or high variation in their composition. Also, samples have roughly the same structure. Samples were measured in 3-directions. It is supposed that any difference in a lattice structure, in any direction, will be reflected directly in the measurements, i.e. electrical features will attempt to detect variations of homogeneity and anisotropy of samples. The alterations in electrical functions are from mineral composition changes. Changes in texture, at specimens, do not exist (grain size and shape, mineral constituents, and pore throats between grains), and it is supposed that electrical features will be similar in three directions. There were some slight changes in electrical characteristics, due to some imperfections in natural crystals, with some impurities on crystal surfaces that we could not remove. Conductivity rises with frequency increase and accordingly, dielectric constant decreases. The paper aims to prove that the electrical properties, due to homogeneity, are the same at the three perpendicular directions.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"1 1","pages":"244 - 257"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86441301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1913393
H. Mahmoud, Adel D. M. Kotb, M. Tawfik
ABSTRACT New agriculture projects in the desert fringes along the western side of the Nile Valley of Egypt need exploring new groundwater resources. Time Domain Electromagnetic (TDEM) technique was used to acquire the field data. This technique is focusing on two main objectives. The first objective is to test the availability of applying TDEM in areas where other DC resistivity methods can’t be applied due to the presence of a high resistive layer on the ground surface such as in the investigated area. The second objective is detecting the geoelectrical succession, emphasising on the water-bearing layer, which is represented by the fractured Eocene limestone layers. Results obtained from TDEM soundings were represented in the forms of cross sections and maps to illustrate the aerial distribution of the different geoelectrical layers and pay attention on the water-bearing layer. These results show up a good agreement with the data obtained from the drilled wells in the study areas. Accordingly, TDEM method is a suitable choice when other DC resistivity tools were failed to acquire field data. Moreover, this technique helped to determine the parameters of the water-bearing layer such as resistivity, thickness, and extension. Also, it gives an idea about the hydrogeological setting of the study area where the water-bearing the fractured limestone layer overlays the low resistivity shale beds. New sites were recommended to drill productive wells in the western and southern parts of the study area based on the resistivity values and the thicknesses of the water-bearing layer.
{"title":"Application of Time Domain Electromagnetic survey to detect fractured limestone aquifer in desert fringes, West Assiut, Egypt","authors":"H. Mahmoud, Adel D. M. Kotb, M. Tawfik","doi":"10.1080/20909977.2021.1913393","DOIUrl":"https://doi.org/10.1080/20909977.2021.1913393","url":null,"abstract":"ABSTRACT New agriculture projects in the desert fringes along the western side of the Nile Valley of Egypt need exploring new groundwater resources. Time Domain Electromagnetic (TDEM) technique was used to acquire the field data. This technique is focusing on two main objectives. The first objective is to test the availability of applying TDEM in areas where other DC resistivity methods can’t be applied due to the presence of a high resistive layer on the ground surface such as in the investigated area. The second objective is detecting the geoelectrical succession, emphasising on the water-bearing layer, which is represented by the fractured Eocene limestone layers. Results obtained from TDEM soundings were represented in the forms of cross sections and maps to illustrate the aerial distribution of the different geoelectrical layers and pay attention on the water-bearing layer. These results show up a good agreement with the data obtained from the drilled wells in the study areas. Accordingly, TDEM method is a suitable choice when other DC resistivity tools were failed to acquire field data. Moreover, this technique helped to determine the parameters of the water-bearing layer such as resistivity, thickness, and extension. Also, it gives an idea about the hydrogeological setting of the study area where the water-bearing the fractured limestone layer overlays the low resistivity shale beds. New sites were recommended to drill productive wells in the western and southern parts of the study area based on the resistivity values and the thicknesses of the water-bearing layer.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"22 1","pages":"235 - 243"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78615647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1900527
O. Ademila
ABSTRACT Very low frequency electromagnetic (VLF-EM) and electrical resistivity methods involving 54 Schlumberger Vertical Electrical Sounding (VES) and 2-D geoelectrical resistivity imaging using dipole-dipole array were utilised along unstable (US) and stable sections (SS) of Owo-Ikare highway to establish causes of its persistent failure. Engineering evaluation of eighteen soil samples from test pits excavated on selected US and SS were investigated. VLF-EM models, geoelectric sections and 2-D resistivity structures revealed existence of conductive subsurface structures, suspected weak zones beneath the US. The road pavement is constructed on poor clayey subgrade with low resistivity values (<100 Ohm-m) which precipitate instability of the highway. Subgrade soils below US have poor geotechnical properties characterized by high moisture content, liquid limit (43.6–63.8% and 20.1–25.2%), plasticity index (13.4–34.4% and 6.5–8.3%), percentage fines (40–67% and 28–30%), A-7-5 to A-7-6 clayey soils, high linear shrinkage (>10%), low compacted density, low CBR, volume changes (Mv) and impervious soils against those of SS. . Thus, deep-weathering, fractured bedrock, uneven bedrock topography with subsurface structures, water-saturated clayey subgrade and unsuitability of the soils for subgrade and subbase road construction are responsible for instability of the road. Replacement of soil beneath the unstable sections and effective drainage enhances its stability.
{"title":"Combined geophysical and geotechnical investigation of pavement failure for sustainable construction of Owo-Ikare highway, Southwestern Nigeria","authors":"O. Ademila","doi":"10.1080/20909977.2021.1900527","DOIUrl":"https://doi.org/10.1080/20909977.2021.1900527","url":null,"abstract":"ABSTRACT Very low frequency electromagnetic (VLF-EM) and electrical resistivity methods involving 54 Schlumberger Vertical Electrical Sounding (VES) and 2-D geoelectrical resistivity imaging using dipole-dipole array were utilised along unstable (US) and stable sections (SS) of Owo-Ikare highway to establish causes of its persistent failure. Engineering evaluation of eighteen soil samples from test pits excavated on selected US and SS were investigated. VLF-EM models, geoelectric sections and 2-D resistivity structures revealed existence of conductive subsurface structures, suspected weak zones beneath the US. The road pavement is constructed on poor clayey subgrade with low resistivity values (<100 Ohm-m) which precipitate instability of the highway. Subgrade soils below US have poor geotechnical properties characterized by high moisture content, liquid limit (43.6–63.8% and 20.1–25.2%), plasticity index (13.4–34.4% and 6.5–8.3%), percentage fines (40–67% and 28–30%), A-7-5 to A-7-6 clayey soils, high linear shrinkage (>10%), low compacted density, low CBR, volume changes (Mv) and impervious soils against those of SS. . Thus, deep-weathering, fractured bedrock, uneven bedrock topography with subsurface structures, water-saturated clayey subgrade and unsuitability of the soils for subgrade and subbase road construction are responsible for instability of the road. Replacement of soil beneath the unstable sections and effective drainage enhances its stability.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"33 1","pages":"183 - 201"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78540247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1915080
M. M. Osman, G. El-Qady, Th. Abdel Fattah, M. Rashed, M. Mohamdeen
ABSTRACT Variations in conductivity in the near-surface, such as the presence of small and localized three-dimensional (3D) bodies, cause a galvanic distortion in direct current (DC), so the measured apparent resistivity is affected by a constant shift on a log scale called Static Shift. In this study, We used electromagnetic sounding techniques to correct for the static shift affecting the electric resistivity data only. The term “static shift” is used because apparent resistivity is distorted by a constant, shifting value (S) on a log scale, which lead to misleading interpretation. It was noticed that the two data sets' sounding curves at the same location have a concordant pattern. The problem was noticed in the 1D inversion models for VES and TEM were not matched together before removal of VES data shift. The TEM and VES measurements are represented on the same graph, then the shifting factor (S) is calculated for the VES curves to directly overlap the TEM curve. The 1D inversion model for VES curves after removing the shifting factor shows matched data with the TEM 1D model.
{"title":"Enhancement the VES models based on the TEM measurements and the application of static shift corrections.: case study from Egypt","authors":"M. M. Osman, G. El-Qady, Th. Abdel Fattah, M. Rashed, M. Mohamdeen","doi":"10.1080/20909977.2021.1915080","DOIUrl":"https://doi.org/10.1080/20909977.2021.1915080","url":null,"abstract":"ABSTRACT Variations in conductivity in the near-surface, such as the presence of small and localized three-dimensional (3D) bodies, cause a galvanic distortion in direct current (DC), so the measured apparent resistivity is affected by a constant shift on a log scale called Static Shift. In this study, We used electromagnetic sounding techniques to correct for the static shift affecting the electric resistivity data only. The term “static shift” is used because apparent resistivity is distorted by a constant, shifting value (S) on a log scale, which lead to misleading interpretation. It was noticed that the two data sets' sounding curves at the same location have a concordant pattern. The problem was noticed in the 1D inversion models for VES and TEM were not matched together before removal of VES data shift. The TEM and VES measurements are represented on the same graph, then the shifting factor (S) is calculated for the VES curves to directly overlap the TEM curve. The 1D inversion model for VES curves after removing the shifting factor shows matched data with the TEM 1D model.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"28 1","pages":"279 - 289"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73929817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1987118
A. A. Oludayo, Ozebo V Chidi, Oyedele F Kayode
ABSTRACT Water quality in Lagos's coastal area is prone to constant seawater intrusion due to its proximity to the Atlantic Ocean. Seawater intrusion in the coastal aquifer is a major challenge to human survival and therefore needs urgent attention due to deficiency in groundwater quality. This study applies integrated techniques to map groundwater suitability zone (GSZ) around the Lagos coastal area for sustainable development. The objectives were achieved by preparing eight different thematic layers that influence groundwater suitability viz; drainage density, geology, geomorphology, lineament density, rainfall, longitudinal conductance, slope, and transverse resistance. Weighting assignment, normalization and, pair-wise comparison of the thematic maps were done using Saaty’s Analytical Hierarchical Process (AHP) model before being integrated through the geographical information system (GIS) spatial analyst model with weight overlay to generate the overall groundwater suitability map. The integrated result reveals that 7% of the research location has very low suitability, 32.2% low, 47.8% moderate, and 13% high groundwater suitability. Thus, the groundwater suitability zone (GSZ) was validated via Electrical conductivity (EC) and total dissolved solids (TDS) and the result reveals a good correlation. The research has proven the efficacy of integrating different surface and subsurface data for effectively mapping the groundwater suitability zone (GSZ).
{"title":"Triangulation Approach for Mapping Groundwater Suitability Zones in Coastal Areas Around Lagos, Nigeria. Using Multi-Criteria Decision-Making Technique","authors":"A. A. Oludayo, Ozebo V Chidi, Oyedele F Kayode","doi":"10.1080/20909977.2021.1987118","DOIUrl":"https://doi.org/10.1080/20909977.2021.1987118","url":null,"abstract":"ABSTRACT Water quality in Lagos's coastal area is prone to constant seawater intrusion due to its proximity to the Atlantic Ocean. Seawater intrusion in the coastal aquifer is a major challenge to human survival and therefore needs urgent attention due to deficiency in groundwater quality. This study applies integrated techniques to map groundwater suitability zone (GSZ) around the Lagos coastal area for sustainable development. The objectives were achieved by preparing eight different thematic layers that influence groundwater suitability viz; drainage density, geology, geomorphology, lineament density, rainfall, longitudinal conductance, slope, and transverse resistance. Weighting assignment, normalization and, pair-wise comparison of the thematic maps were done using Saaty’s Analytical Hierarchical Process (AHP) model before being integrated through the geographical information system (GIS) spatial analyst model with weight overlay to generate the overall groundwater suitability map. The integrated result reveals that 7% of the research location has very low suitability, 32.2% low, 47.8% moderate, and 13% high groundwater suitability. Thus, the groundwater suitability zone (GSZ) was validated via Electrical conductivity (EC) and total dissolved solids (TDS) and the result reveals a good correlation. The research has proven the efficacy of integrating different surface and subsurface data for effectively mapping the groundwater suitability zone (GSZ).","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"28 1","pages":"423 - 442"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86968502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1918924
U. Ali Rahoma, S. Khalil, A. H. Hassan, A. A. Elminawy
ABSTRACT The main objective of this study is to obtain vartiation of solar spectrum during the recent solar eclipse in the range 350-1100nm. The net results are studying the spectral composition of global solar radiation which are collective of the direct and diffuse solar radiation values do not similar to the computation result (45% covering of the solar disk). The maximum absorption energy in the atmosphere is at range 820–900nm. The depression in the solar enenrgy is 0.11 (W.m-2.nm-1). The ultraviolet band is suffering low depression with respect to another bands but not given any risks on the human life as common. That the change in meteorological parameter related to variability in the solar spectrum that shift the short wave before 600 nmto long wave around 1000 nm. The most extreme drop in the solar spectrum lies in the interval which consists of the normal peak of the solar spectrum from 500 - 600nm. The percentage of radiant energy reaching the earth through 350-1100nm at the maximum of the solar eclipse was 54%. Consequently, the rate of depresion in energy is equal to 46%, which is very strange compared to the normal flow rate of 44%. During the eclipse, the maximum solar energy at the maximum eclipse are at 480nm (13.07 W.m-2.nm-1) and 630nm (13.17 W.m-2.nm-1). At the wavelength 580nm rpresents the absorbition of O2 , andthe absorbtion of H2O at 680, 730, 780 and the maximum absorbtion energy by the H2O is at 830nm (low enegy transimmted at 0.31 W.m-2.nm-1).
{"title":"Assessment of spectra of solar radiation during the partial solar eclipse of 21 June 2020 at, Tanta, Egypt","authors":"U. Ali Rahoma, S. Khalil, A. H. Hassan, A. A. Elminawy","doi":"10.1080/20909977.2021.1918924","DOIUrl":"https://doi.org/10.1080/20909977.2021.1918924","url":null,"abstract":"ABSTRACT The main objective of this study is to obtain vartiation of solar spectrum during the recent solar eclipse in the range 350-1100nm. The net results are studying the spectral composition of global solar radiation which are collective of the direct and diffuse solar radiation values do not similar to the computation result (45% covering of the solar disk). The maximum absorption energy in the atmosphere is at range 820–900nm. The depression in the solar enenrgy is 0.11 (W.m-2.nm-1). The ultraviolet band is suffering low depression with respect to another bands but not given any risks on the human life as common. That the change in meteorological parameter related to variability in the solar spectrum that shift the short wave before 600 nmto long wave around 1000 nm. The most extreme drop in the solar spectrum lies in the interval which consists of the normal peak of the solar spectrum from 500 - 600nm. The percentage of radiant energy reaching the earth through 350-1100nm at the maximum of the solar eclipse was 54%. Consequently, the rate of depresion in energy is equal to 46%, which is very strange compared to the normal flow rate of 44%. During the eclipse, the maximum solar energy at the maximum eclipse are at 480nm (13.07 W.m-2.nm-1) and 630nm (13.17 W.m-2.nm-1). At the wavelength 580nm rpresents the absorbition of O2 , andthe absorbtion of H2O at 680, 730, 780 and the maximum absorbtion energy by the H2O is at 830nm (low enegy transimmted at 0.31 W.m-2.nm-1).","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"18 1","pages":"290 - 299"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89392513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1938883
Michael Oluwaseyi Falufosi, O. Osinowo
ABSTRACT Attempts at regional gravity studies of the southwest Nigerian geologic terrain have been limited due to sparse distribution of gravity stations and prohibitive costs of gravity measurements. The use of satellite-based global gravity data provides a reliable and cost-effective means of regional-scale studies, and the WGM2012 gravity data was employed to evaluate the basement topography and structures. The aim of the work is to map regions in the Nigerian sector of the Dahomey Basin with suitable sediments thickness and fracture systems, capable of hydrocarbon generation and preservation. The Bouguer anomaly data was subjected to series of processing and anomaly enhancement, using the Oasis Montaj software. Observations of anomaly distributions reveal division of the study area into three geologic zones, namely, basement terrain, Dahomey Basin and Niger Delta Basin. The basement structures trend in a general north–south directions, but approximate orientations vary significantly, with abundance of sub-parallel and discordant alignments. The depths to basement range from <2000 to >5000 m, with the southwest being the deepest part of the study area. The results establish the Dahomey Basin as containing the minimum required sedimentary thickness of 3000 m and suitable structures necessary for hydrocarbon generation and accumulation.
{"title":"Evaluation of basement topography and structures in the Dahomey Basin and surrounding environs of Southwestern Nigeria, using satellite gravity data","authors":"Michael Oluwaseyi Falufosi, O. Osinowo","doi":"10.1080/20909977.2021.1938883","DOIUrl":"https://doi.org/10.1080/20909977.2021.1938883","url":null,"abstract":"ABSTRACT Attempts at regional gravity studies of the southwest Nigerian geologic terrain have been limited due to sparse distribution of gravity stations and prohibitive costs of gravity measurements. The use of satellite-based global gravity data provides a reliable and cost-effective means of regional-scale studies, and the WGM2012 gravity data was employed to evaluate the basement topography and structures. The aim of the work is to map regions in the Nigerian sector of the Dahomey Basin with suitable sediments thickness and fracture systems, capable of hydrocarbon generation and preservation. The Bouguer anomaly data was subjected to series of processing and anomaly enhancement, using the Oasis Montaj software. Observations of anomaly distributions reveal division of the study area into three geologic zones, namely, basement terrain, Dahomey Basin and Niger Delta Basin. The basement structures trend in a general north–south directions, but approximate orientations vary significantly, with abundance of sub-parallel and discordant alignments. The depths to basement range from <2000 to >5000 m, with the southwest being the deepest part of the study area. The results establish the Dahomey Basin as containing the minimum required sedimentary thickness of 3000 m and suitable structures necessary for hydrocarbon generation and accumulation.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"99 1","pages":"333 - 346"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83503997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.2005333
Joseph Aisabokhae
ABSTRACT The Precambrian basement complex in southern Kebbi hosts various sulphuric and iron-oxide deposits which contain ore minerals associated with hydrothermal processes that occur within geologic structures. This study applied integrated geophysical approach to map and classify the structures and lithotypes of the basement complex so as to delineate geologic features that may support mineral prospecting. Airborne magnetic and radiometric datasets were enhanced through data reduction to display characteristics of surface and subsurface geology of the area. The derivative and analytic signal maps processed from the magnetic data highlighted major geologic structures such as the Zuru-Bini Yauri lineament and Anka lineament. The ternary map of the area displayed several metasedimentary and metavolcanic lithotypes bearing characteristics of potassium, thorium and uranium dominance. The Anka shear zone showed an elongated stretch of lineament trending NE-SW among other NNE-SSW, N-S, E-W trending shallow and deep-seated faults. Several shallow structures connected to the regional hydrothermal conduits within the alteration zone were delineated as potential auriferous-rich veins. The results of this study showed that the delineated Anka shear zone borders a plutonic region of brittle-ductile deformation inferring tectonic fracturing for fluid movement and related hydrothermal alteration deposits towards mineralisation in the area.
{"title":"Geophysical mapping and mineralisation characterisation of the mesothermal auriferous basement complex in southern Kebbi, NW Nigeria","authors":"Joseph Aisabokhae","doi":"10.1080/20909977.2021.2005333","DOIUrl":"https://doi.org/10.1080/20909977.2021.2005333","url":null,"abstract":"ABSTRACT The Precambrian basement complex in southern Kebbi hosts various sulphuric and iron-oxide deposits which contain ore minerals associated with hydrothermal processes that occur within geologic structures. This study applied integrated geophysical approach to map and classify the structures and lithotypes of the basement complex so as to delineate geologic features that may support mineral prospecting. Airborne magnetic and radiometric datasets were enhanced through data reduction to display characteristics of surface and subsurface geology of the area. The derivative and analytic signal maps processed from the magnetic data highlighted major geologic structures such as the Zuru-Bini Yauri lineament and Anka lineament. The ternary map of the area displayed several metasedimentary and metavolcanic lithotypes bearing characteristics of potassium, thorium and uranium dominance. The Anka shear zone showed an elongated stretch of lineament trending NE-SW among other NNE-SSW, N-S, E-W trending shallow and deep-seated faults. Several shallow structures connected to the regional hydrothermal conduits within the alteration zone were delineated as potential auriferous-rich veins. The results of this study showed that the delineated Anka shear zone borders a plutonic region of brittle-ductile deformation inferring tectonic fracturing for fluid movement and related hydrothermal alteration deposits towards mineralisation in the area.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"14 1","pages":"443 - 465"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86351967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1080/20909977.2021.1913363
S. A. A. S. Araffa, M. Abdelazeem, Hassan S. S. Sabet, Ahmed M. M. Al Dabour
ABSTRACT Thirty-three groundwater samples were collected from recent drillings conducted as a part of the 1.5 million feddan (Acres) national reclamation project at El Moghra area. These samples were analysed for the concentrations of the major ions (Na, K, Ca, Mg, Cl, SO4, HCO3 and CO3) along with different physicochemical parameters (pH, TDS and EC). The assessment of these groundwater samples was obtained to evaluate groundwater suitability for different purposes (drinking, irrigation, and domestic purposes). The investigated aquifer has slightly acidic to alkaline water with pH value ranged from 6.71 to 8.7. The salinity (as TDS) value varies from 2236 mg/l (Brackish water) to 7830 mg/l (saline water). In the study area, the concentrations of major ions are generally higher than the maximum standard limits for drinking and domestic purposes. The main chemical water type according to the hydrochemistry composition is NaCl. The groundwater of the study area is unsuitable for drinking and domestic purposes; however, it can be used for irrigation as the cultivation of salt-tolerant crops (Jojoba and Olives) especially in the western part of the study area. Five VES stations were measured to identify by the subsurface section which consists of different alternated layers of sand intercalated with clay.
{"title":"Hydrogeochemistry of groundwater at El Moghra area, north Western Desert, Egypt","authors":"S. A. A. S. Araffa, M. Abdelazeem, Hassan S. S. Sabet, Ahmed M. M. Al Dabour","doi":"10.1080/20909977.2021.1913363","DOIUrl":"https://doi.org/10.1080/20909977.2021.1913363","url":null,"abstract":"ABSTRACT Thirty-three groundwater samples were collected from recent drillings conducted as a part of the 1.5 million feddan (Acres) national reclamation project at El Moghra area. These samples were analysed for the concentrations of the major ions (Na, K, Ca, Mg, Cl, SO4, HCO3 and CO3) along with different physicochemical parameters (pH, TDS and EC). The assessment of these groundwater samples was obtained to evaluate groundwater suitability for different purposes (drinking, irrigation, and domestic purposes). The investigated aquifer has slightly acidic to alkaline water with pH value ranged from 6.71 to 8.7. The salinity (as TDS) value varies from 2236 mg/l (Brackish water) to 7830 mg/l (saline water). In the study area, the concentrations of major ions are generally higher than the maximum standard limits for drinking and domestic purposes. The main chemical water type according to the hydrochemistry composition is NaCl. The groundwater of the study area is unsuitable for drinking and domestic purposes; however, it can be used for irrigation as the cultivation of salt-tolerant crops (Jojoba and Olives) especially in the western part of the study area. Five VES stations were measured to identify by the subsurface section which consists of different alternated layers of sand intercalated with clay.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"76 1","pages":"258 - 269"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80906291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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