Pub Date : 2022-11-10DOI: 10.1080/20909977.2022.2133766
Mohamed Abdel Aziz, Hassan Hassan Al Kady, S. Araffa, Mahmoud Zayed, Ahmed M Al Dabour
ABSTRACT The aeromagnetic data is utilised to determine the depth of the crystalline (basement) rocksand subsurface structures where the basement depth ranges from 1777 - 3778 m .and thearea is dissected by several faults with various trends, especially in the NNW-SSE direction. The well-logging data is used to investigate the subsurface stratigraphy where theinterpretation of well-logging data indicates that the area is composed of seven geologicunits, with the third, fifth, and seventh units representing the main aquifer. The first zone ofthe Nubian sandstone aquifer is represented by the sandstone that makes up the thirdgeologic unit with a low gamma ray, which is sandwiched by clay layers. The Nubiansandstone aquifer's second zone is represented by the fifth geologic unit, which is composedof sandstone with minor clay layers. It exhibits low to modest gamma-ray values andmoderate to high resistivity values. The seventh geologic unit is composed of sandstone andrepresents the third zone of the Nubian sandstone aquifer, which is sandwiched by claylayers. It has high resistivity values and a low gamma-ray. The aquifer in the study area hastransmissivity and belongs to a high-potential aquifer.The aquifer in the study area has transmissivity and belongs to a high potential aquiferV.
{"title":"Integrated geophysical interpretation and hydrogeochemistry investigation for groundwater aquifer assessment at El – Farafra depression, Western Desert, Egypt","authors":"Mohamed Abdel Aziz, Hassan Hassan Al Kady, S. Araffa, Mahmoud Zayed, Ahmed M Al Dabour","doi":"10.1080/20909977.2022.2133766","DOIUrl":"https://doi.org/10.1080/20909977.2022.2133766","url":null,"abstract":"ABSTRACT The aeromagnetic data is utilised to determine the depth of the crystalline (basement) rocksand subsurface structures where the basement depth ranges from 1777 - 3778 m .and thearea is dissected by several faults with various trends, especially in the NNW-SSE direction. The well-logging data is used to investigate the subsurface stratigraphy where theinterpretation of well-logging data indicates that the area is composed of seven geologicunits, with the third, fifth, and seventh units representing the main aquifer. The first zone ofthe Nubian sandstone aquifer is represented by the sandstone that makes up the thirdgeologic unit with a low gamma ray, which is sandwiched by clay layers. The Nubiansandstone aquifer's second zone is represented by the fifth geologic unit, which is composedof sandstone with minor clay layers. It exhibits low to modest gamma-ray values andmoderate to high resistivity values. The seventh geologic unit is composed of sandstone andrepresents the third zone of the Nubian sandstone aquifer, which is sandwiched by claylayers. It has high resistivity values and a low gamma-ray. The aquifer in the study area hastransmissivity and belongs to a high-potential aquifer.The aquifer in the study area has transmissivity and belongs to a high potential aquiferV.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"124 1","pages":"355 - 372"},"PeriodicalIF":0.0,"publicationDate":"2022-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88007607","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 : 2022-11-05DOI: 10.1080/20909977.2022.2141022
S. Oladele, E. Ayolabi, S. Olobaniyi, Caroline O. Dublin-Green
ABSTRACT Geothermal resource has attracted industrial and environmental interest in the last decades. However, the thermal condition of the Dahomey basin, which is instrumental to harnessing such geothermal resource, has remained largely unknown. The geothermal characterisation of Dahomey Basin was therefore undertaken to determine its thermal potential. The methodology involved analysis of the power spectra density of aeromagnetic data and interpretation of geo-resistivity data. The aeromagnetic dataset was divided into twenty one blocks with each block overlapping the adjacent blocks by 50%. Spectra peak, Curie depth, geothermal gradient, heat flow and temperature at depth were computed. Two-dimensional geo-resistivity profiling method was implemented to locate the top of the thermal aquifer. The results showed varied Curie depth (11–27 km) and heat flow (53–130 mW/m2) while the geothermal gradient ranges from 21 to 52 °C/km. Results of resistivity profiling showed the thermal aquifer to be sand (1–20 Ωm) whose top is located at 155 − 210 m depth. From the estimated geothermal parameters, two new geothermal prospect areas were identified. This study established that Dahomey basin is a thermally unstable basin with a very high potential for geothermal resource that is attributable to crustal thinning and possibly mantle dynamics.
{"title":"Investigation of geothermal potential of the Dahomey basin, Nigeria, through analysis of geomagnetic and geo-resistivity dataset","authors":"S. Oladele, E. Ayolabi, S. Olobaniyi, Caroline O. Dublin-Green","doi":"10.1080/20909977.2022.2141022","DOIUrl":"https://doi.org/10.1080/20909977.2022.2141022","url":null,"abstract":"ABSTRACT Geothermal resource has attracted industrial and environmental interest in the last decades. However, the thermal condition of the Dahomey basin, which is instrumental to harnessing such geothermal resource, has remained largely unknown. The geothermal characterisation of Dahomey Basin was therefore undertaken to determine its thermal potential. The methodology involved analysis of the power spectra density of aeromagnetic data and interpretation of geo-resistivity data. The aeromagnetic dataset was divided into twenty one blocks with each block overlapping the adjacent blocks by 50%. Spectra peak, Curie depth, geothermal gradient, heat flow and temperature at depth were computed. Two-dimensional geo-resistivity profiling method was implemented to locate the top of the thermal aquifer. The results showed varied Curie depth (11–27 km) and heat flow (53–130 mW/m2) while the geothermal gradient ranges from 21 to 52 °C/km. Results of resistivity profiling showed the thermal aquifer to be sand (1–20 Ωm) whose top is located at 155 − 210 m depth. From the estimated geothermal parameters, two new geothermal prospect areas were identified. This study established that Dahomey basin is a thermally unstable basin with a very high potential for geothermal resource that is attributable to crustal thinning and possibly mantle dynamics.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"10 1","pages":"373 - 386"},"PeriodicalIF":0.0,"publicationDate":"2022-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79534387","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 : 2022-10-02DOI: 10.1080/20909977.2022.2118982
Ahmed Al-Heety, H. A. Thabit
ABSTRACT Noises are common events in seismic reflection data that have very striking features in seismograms, affecting seismic data processing and interpretation. Noise attenuation is an essential phase in seismic processing data, usually resulting in enhancing the signal-to-noise ratio (SNR) and improving the subsurface seismic image. Groundroll presence is a major fashion of significant noise in land seismic surveys. It is a type of coherent noise present in seismograms that appears as linear events, in most cases overlapping the reflections and probably making it challenging to recognise. There are several domains used in noise attenuation techniques. The domain transformations are a complex algorithm used commonly during the processing of seismic data; Therefore, a large number of methods have been developed to attenuate these types of noise to preserve the frequency bandwidth and enhance the SNR of the seismic data. In the time-offset domain, the noise wave such as groundroll and random noises overlap over time; a different domain makes it easier to successfully isolate coherent, random noise and reflection events. We have used effective algorithms in different domains such as (shot, receiver, t-x, f-x, f-k, R-T, and offset class) to attenuate coherent and random noises present in the data. The results indicate that the different domains can reveal features and geological structures that have been masked by the noises present in current data. Because these filtering techniques encourage significant improvements in the final image quality in the 2D seismic section, possibly giving the interpreter an advantage, particularly in structural and stratigraphic interpretation.
{"title":"Random and coherent noise attenuation for 2D land seismic reflection line acquired in Iraq","authors":"Ahmed Al-Heety, H. A. Thabit","doi":"10.1080/20909977.2022.2118982","DOIUrl":"https://doi.org/10.1080/20909977.2022.2118982","url":null,"abstract":"ABSTRACT Noises are common events in seismic reflection data that have very striking features in seismograms, affecting seismic data processing and interpretation. Noise attenuation is an essential phase in seismic processing data, usually resulting in enhancing the signal-to-noise ratio (SNR) and improving the subsurface seismic image. Groundroll presence is a major fashion of significant noise in land seismic surveys. It is a type of coherent noise present in seismograms that appears as linear events, in most cases overlapping the reflections and probably making it challenging to recognise. There are several domains used in noise attenuation techniques. The domain transformations are a complex algorithm used commonly during the processing of seismic data; Therefore, a large number of methods have been developed to attenuate these types of noise to preserve the frequency bandwidth and enhance the SNR of the seismic data. In the time-offset domain, the noise wave such as groundroll and random noises overlap over time; a different domain makes it easier to successfully isolate coherent, random noise and reflection events. We have used effective algorithms in different domains such as (shot, receiver, t-x, f-x, f-k, R-T, and offset class) to attenuate coherent and random noises present in the data. The results indicate that the different domains can reveal features and geological structures that have been masked by the noises present in current data. Because these filtering techniques encourage significant improvements in the final image quality in the 2D seismic section, possibly giving the interpreter an advantage, particularly in structural and stratigraphic interpretation.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"20 1","pages":"337 - 354"},"PeriodicalIF":0.0,"publicationDate":"2022-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89215207","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 : 2022-09-28DOI: 10.1080/20909977.2022.2106667
A. Mohamed, G. Hassib, N. AbouAly, A. El-Kutb
ABSTRACT The High Dam is a strategic and vital installation because it is considered as the water strategic tool for Egypt. The dam plays vital role in mitigating risks of water shortages and floods. The body of the High Dam established on the basement Granite. The area around High Dam is suffering from seismic activities starting from the famous earthquake of 14 November 1981 (5.6 ML) southwest of the High Dam. On 7 November 2010, earthquake of magnitude 4.6 ML occurred at Spillway fault. Spillway fault is NNW-SSE trend. The fault was plotted by the High and Aswan Dams Authority and Soviet geologists as a normal fault. The fault is exposed as vertical on the cross section, but perhaps dips steeply to the west. This work is trying to study the stability of the area and its relation to the dams as well as estimating the horizontal displacements. For monitoring the horizontal movements, a local geodetic network consisting of 11 geodetic stations was established. A geodetic results showed a post-seismic deformation zone between the High Dam and Aswan Dam that resulted from 7 November 2010 earthquake occurring at Spillway fault and a distance of 4.5 km northwest the High Dam.
{"title":"Evaluation of recent crustal deformation and seismicity in spillway fault area, Aswan, Egypt","authors":"A. Mohamed, G. Hassib, N. AbouAly, A. El-Kutb","doi":"10.1080/20909977.2022.2106667","DOIUrl":"https://doi.org/10.1080/20909977.2022.2106667","url":null,"abstract":"ABSTRACT The High Dam is a strategic and vital installation because it is considered as the water strategic tool for Egypt. The dam plays vital role in mitigating risks of water shortages and floods. The body of the High Dam established on the basement Granite. The area around High Dam is suffering from seismic activities starting from the famous earthquake of 14 November 1981 (5.6 ML) southwest of the High Dam. On 7 November 2010, earthquake of magnitude 4.6 ML occurred at Spillway fault. Spillway fault is NNW-SSE trend. The fault was plotted by the High and Aswan Dams Authority and Soviet geologists as a normal fault. The fault is exposed as vertical on the cross section, but perhaps dips steeply to the west. This work is trying to study the stability of the area and its relation to the dams as well as estimating the horizontal displacements. For monitoring the horizontal movements, a local geodetic network consisting of 11 geodetic stations was established. A geodetic results showed a post-seismic deformation zone between the High Dam and Aswan Dam that resulted from 7 November 2010 earthquake occurring at Spillway fault and a distance of 4.5 km northwest the High Dam.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"88 1","pages":"325 - 336"},"PeriodicalIF":0.0,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73941240","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 : 2022-09-12DOI: 10.1080/20909977.2022.2079902
Afaf M. Abd El-Hameed
ABSTRACT The interactions of the composite materials with the space radiation environment are a considerably complex process. These interactions can lead to the occurrence of collective and extensive effects on the composite materials. These effects have resulted in damage and degradation of the electronics and components of satellites and spacecraft, and anomalies in the operational parts of space devices and other aerospace systems. The prediction of the material performances in this complicated environment is essential and considered the fundamental item for the success of any space mission. The presented research work focuses on studying the impact of space radiation sources on the composite materials used for satellite and spacecraft systems. The effects of some of the irradiation sources on a variety of composite materials are discussed. The protection and mitigation techniques from radiation damages are addressed.
{"title":"Radiation effects on composite materials used in space systems: a review","authors":"Afaf M. Abd El-Hameed","doi":"10.1080/20909977.2022.2079902","DOIUrl":"https://doi.org/10.1080/20909977.2022.2079902","url":null,"abstract":"ABSTRACT The interactions of the composite materials with the space radiation environment are a considerably complex process. These interactions can lead to the occurrence of collective and extensive effects on the composite materials. These effects have resulted in damage and degradation of the electronics and components of satellites and spacecraft, and anomalies in the operational parts of space devices and other aerospace systems. The prediction of the material performances in this complicated environment is essential and considered the fundamental item for the success of any space mission. The presented research work focuses on studying the impact of space radiation sources on the composite materials used for satellite and spacecraft systems. The effects of some of the irradiation sources on a variety of composite materials are discussed. The protection and mitigation techniques from radiation damages are addressed.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"51 1","pages":"313 - 324"},"PeriodicalIF":0.0,"publicationDate":"2022-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73334867","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 : 2022-08-18DOI: 10.1080/20909977.2022.2106666
W. Raji, R. B. Bale
ABSTRACT The utility of the electrical resistivity (ER) method of geophysics for delineating tantalite-rich zones is demonstrated. To avoid negative environmental consequences, the local authority refused the use of trial-and-error method by the artisanal and small-scale miners. 2D ER method was applied to delineate the locations and dimensions of the tantalite-rich zones. Data were acquired along nine profiles in the study area at predetermined locations, after reconnaissance field mapping, using SuperSting R8/IP Earth Resistivity Metre, 84 electrodes, and the full accessories. Each profile was 249 m long with 84 electrodes coupled to the ground at 3 m intervals on a straight line following the dipole–dipole electrode array. Data acquired were processed to obtain tomographic images of the subsurface. The results revealed low resistivity anomalies (1–60 Ωm) corresponding to tantalite-rich quartz veins that intruded into the high-resistive migmatite-gneisses-schist complex. The tantalite-rich zones were located at depths ranging from near-surface to about 45 m, their lengths and thicknesses range from 40 to 220 m and 3 to 32 m, respectively. A pit dug along profile six confirmed the low resistivity structures to be tantalite-rich quartz veins. Findings from the study are useful for economic evaluation of similar deposits, determining the extent of excavation required for mining, and planning land reclamation.
{"title":"2D electrical resistivity imaging of tantalite-bearing veins in Kaiama, Nigeria","authors":"W. Raji, R. B. Bale","doi":"10.1080/20909977.2022.2106666","DOIUrl":"https://doi.org/10.1080/20909977.2022.2106666","url":null,"abstract":"ABSTRACT The utility of the electrical resistivity (ER) method of geophysics for delineating tantalite-rich zones is demonstrated. To avoid negative environmental consequences, the local authority refused the use of trial-and-error method by the artisanal and small-scale miners. 2D ER method was applied to delineate the locations and dimensions of the tantalite-rich zones. Data were acquired along nine profiles in the study area at predetermined locations, after reconnaissance field mapping, using SuperSting R8/IP Earth Resistivity Metre, 84 electrodes, and the full accessories. Each profile was 249 m long with 84 electrodes coupled to the ground at 3 m intervals on a straight line following the dipole–dipole electrode array. Data acquired were processed to obtain tomographic images of the subsurface. The results revealed low resistivity anomalies (1–60 Ωm) corresponding to tantalite-rich quartz veins that intruded into the high-resistive migmatite-gneisses-schist complex. The tantalite-rich zones were located at depths ranging from near-surface to about 45 m, their lengths and thicknesses range from 40 to 220 m and 3 to 32 m, respectively. A pit dug along profile six confirmed the low resistivity structures to be tantalite-rich quartz veins. Findings from the study are useful for economic evaluation of similar deposits, determining the extent of excavation required for mining, and planning land reclamation.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"62 1","pages":"306 - 312"},"PeriodicalIF":0.0,"publicationDate":"2022-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81608477","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 : 2022-07-26DOI: 10.1080/20909977.2022.2094530
Obasaju Daniel Opemipo, O. Moroof, O. Sunday, Ojekunle Victor, Baiyegunhi Christopher
ABSTRACT Integrated seismic refraction tomography (SRT) and geotechnical tests were conducted on failed and stable sections of the Ajaokuta – Anyigba Highway, North-central Nigeria. This study was aimed at characterising the soil profile, determining the competence of the subgrade soils, and establishing relationships between geophysical and geotechnical parameters. Primary wave velocities (Vp) were calculated by using SeisImager/2D (V.2.9.1). The subgrade soils of the unstable segment were characterised by low Vp (358–607 m/s) while higher Vp (762–1417 m/s) characterised the stable segment. The geotechnical results confirmed the seismic refraction results. Geotechnical results revealed that the subgrades of the unstable section are generally classified as A-6 and A-7-6 clayey soils, with low to high plasticity, and a fair to poor subgrade rating. While the subgrades of the stable section are grouped as A-2-4 silty sands with low compressibility and good to excellent subgrade ratings. Simple linear regression analysis showed fairly strong positive correlations between Vp and sand with CBR (r = 0.81 and 0.78, respectively). On the other hand, fairly strong negative correlations were obtained between Vp and the plasticity index with fines (r = −0.63 and −0.82 respectively).
{"title":"Subgrade soil evaluation using integrated seismic refraction tomography and geotechnical studies: A case of Ajaokuta-Anyigba Federal highway, North-Central Nigeria","authors":"Obasaju Daniel Opemipo, O. Moroof, O. Sunday, Ojekunle Victor, Baiyegunhi Christopher","doi":"10.1080/20909977.2022.2094530","DOIUrl":"https://doi.org/10.1080/20909977.2022.2094530","url":null,"abstract":"ABSTRACT Integrated seismic refraction tomography (SRT) and geotechnical tests were conducted on failed and stable sections of the Ajaokuta – Anyigba Highway, North-central Nigeria. This study was aimed at characterising the soil profile, determining the competence of the subgrade soils, and establishing relationships between geophysical and geotechnical parameters. Primary wave velocities (Vp) were calculated by using SeisImager/2D (V.2.9.1). The subgrade soils of the unstable segment were characterised by low Vp (358–607 m/s) while higher Vp (762–1417 m/s) characterised the stable segment. The geotechnical results confirmed the seismic refraction results. Geotechnical results revealed that the subgrades of the unstable section are generally classified as A-6 and A-7-6 clayey soils, with low to high plasticity, and a fair to poor subgrade rating. While the subgrades of the stable section are grouped as A-2-4 silty sands with low compressibility and good to excellent subgrade ratings. Simple linear regression analysis showed fairly strong positive correlations between Vp and sand with CBR (r = 0.81 and 0.78, respectively). On the other hand, fairly strong negative correlations were obtained between Vp and the plasticity index with fines (r = −0.63 and −0.82 respectively).","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"1 1","pages":"293 - 305"},"PeriodicalIF":0.0,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83038388","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 : 2022-07-26DOI: 10.1080/20909977.2022.2072083
M. Abdelfattah
ABSTRACT The present research represents a new, fast and easy-to-apply semi-inversion technique for the direct separation of the Bouguer gravity anomaly to its corresponding depths or thicknesses of the prior known rock formations from a borehole (as a control point). As well as the possibility of tracing these formations on the profile points to the Bouguer gravity map according to their density contrasts with basement rock. The proposed method is based on the fact that the sum of the gravitational effect at a point on the Earth’s surface is equal to the sum of the subsurface gravity effects arising from the points of masses of the causal bodies along the vertical line between the Earth’s surface and the basement rocks. In this method, two sedimentary basin models were built based on the distribution of densities from a prior known borehole. Assuming that the depths of the pointed tops of these rock formations can be replaced by the centres of sphere bodies (or point masses) as causative sources of gravitational effect and by the use of a simple algorithm, it was possible to calculate the depths of the rock formations and trace them on the profile, using a new concept called the zero-offset gravity measurement. In this concept, the measuring gravity is vertically above the centre of the sphere-shaped body as it represents the causative source, and its depths are equal to the radius of the sphere body. The present method was assessed on hypothetical models and synthetic data and applied to two real data in field cases which vary in geological and lithological aspects. The first assessed location is Abu Roash Dome Area, southwest Cairo, Egypt, and the second location is the Mors Salt Dome, North Jutland, Denmark.
本研究代表了一种新的、快速和易于应用的半反演技术，用于直接将布格重力异常与钻孔(作为控制点)的已知岩层的相应深度或厚度分离。此外，根据这些地层与基底岩石的密度对比，在布格重力图的剖面上可以追踪到这些地层。所提出的方法是基于这样一个事实，即地球表面上某一点的引力效应之和等于沿地球表面与基底岩石之间的垂直线上因果体的质点所产生的地下引力效应之和。在该方法中，基于先前已知井眼的密度分布建立了两个沉积盆地模型。假设这些岩层尖顶的深度可以用球体(或点质量)的中心代替，作为引力效应的原因源，并通过使用简单的算法，就可以计算岩层的深度，并在剖面上追踪它们，使用一种称为零偏移重力测量的新概念。在这个概念中，测量重力垂直于球形物体的中心上方，因为它代表了诱发源，它的深度等于球体的半径。该方法在假设模型和综合数据上进行了评估，并应用于地质和岩性方面不同的两个实际现场案例。第一个评估地点是埃及开罗西南部的Abu Roash Dome地区，第二个地点是丹麦北日德兰半岛的Mors Salt Dome。
{"title":"A new approach automatic separation of the Bouguer gravity anomaly, using a new concept for 2D-semi-inversion of the sphere-shaped model","authors":"M. Abdelfattah","doi":"10.1080/20909977.2022.2072083","DOIUrl":"https://doi.org/10.1080/20909977.2022.2072083","url":null,"abstract":"ABSTRACT The present research represents a new, fast and easy-to-apply semi-inversion technique for the direct separation of the Bouguer gravity anomaly to its corresponding depths or thicknesses of the prior known rock formations from a borehole (as a control point). As well as the possibility of tracing these formations on the profile points to the Bouguer gravity map according to their density contrasts with basement rock. The proposed method is based on the fact that the sum of the gravitational effect at a point on the Earth’s surface is equal to the sum of the subsurface gravity effects arising from the points of masses of the causal bodies along the vertical line between the Earth’s surface and the basement rocks. In this method, two sedimentary basin models were built based on the distribution of densities from a prior known borehole. Assuming that the depths of the pointed tops of these rock formations can be replaced by the centres of sphere bodies (or point masses) as causative sources of gravitational effect and by the use of a simple algorithm, it was possible to calculate the depths of the rock formations and trace them on the profile, using a new concept called the zero-offset gravity measurement. In this concept, the measuring gravity is vertically above the centre of the sphere-shaped body as it represents the causative source, and its depths are equal to the radius of the sphere body. The present method was assessed on hypothetical models and synthetic data and applied to two real data in field cases which vary in geological and lithological aspects. The first assessed location is Abu Roash Dome Area, southwest Cairo, Egypt, and the second location is the Mors Salt Dome, North Jutland, Denmark.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"42 1","pages":"257 - 281"},"PeriodicalIF":0.0,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73849704","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 : 2022-07-25DOI: 10.1080/20909977.2022.2085992
Mahmoud S. Awad, Hassan H. El Kadi, A. M. Abbas, Sultan Awad Sultan Araffa
ABSTRACT Nabaa El Hammra lies in the northeastern part of Wadi El-Natrun, characterised by low lands and most parts of this area are cultivated with different crops. In the current study, gravity data are used to investigate the subsurface structural features that can directly affect the configuration and distribution of groundwater aquifers and oil reservoirs accumulations. The present study aims to delineate the subsurface structural elements and to define the basins and basement uplifts, which can directly affect the flow of groundwater or oil accumulations. Gravity data are processed and filtered in diverse approaches to outlining the prevailed structure. The results of gravity data interpretation reveal that the studied area is affected by many structural features as NE-SW, NW-SE, N-S and E-W trends. These structural features caused barriers to the groundwater movement from or to the study area. The study revealed that the depth of the crystalline (Pre-Cambrian) rocks ranges from 3800 metres in the south part to 5300 metres in the northeastern region. Meanwhile, the basement rocks represent a bridge of shallow depth of northwest-southeast trend at the centre of the investigated area.
纳巴哈姆拉(Nabaa El Hammra)位于瓦迪纳特伦(Wadi El- natrun)的东北部，地势低洼，大部分地区种植着不同的作物。在本研究中，重力数据被用于研究直接影响地下水含水层形态和分布以及油藏聚集的地下构造特征。本研究旨在圈定地下构造要素，明确直接影响地下水流动或油气聚集的盆地和基底隆升。重力数据以不同的方法进行处理和过滤，以概述普遍的结构。重力资料解释结果表明，研究区受NE-SW、NW-SE、N-S和E-W等多种构造特征的影响。这些构造特征对地下水进出研究区造成了障碍。研究结果表明，结晶(前寒武纪)岩石的深度从南部的3800米到东北部的5300米不等。同时，基岩在研究区中心呈西北—东南走向的浅深度桥状。
{"title":"Delineation of subsurface structures using gravity interpretation around Nabaa Al Hammara area, Wadi El Natrun, Egypt","authors":"Mahmoud S. Awad, Hassan H. El Kadi, A. M. Abbas, Sultan Awad Sultan Araffa","doi":"10.1080/20909977.2022.2085992","DOIUrl":"https://doi.org/10.1080/20909977.2022.2085992","url":null,"abstract":"ABSTRACT Nabaa El Hammra lies in the northeastern part of Wadi El-Natrun, characterised by low lands and most parts of this area are cultivated with different crops. In the current study, gravity data are used to investigate the subsurface structural features that can directly affect the configuration and distribution of groundwater aquifers and oil reservoirs accumulations. The present study aims to delineate the subsurface structural elements and to define the basins and basement uplifts, which can directly affect the flow of groundwater or oil accumulations. Gravity data are processed and filtered in diverse approaches to outlining the prevailed structure. The results of gravity data interpretation reveal that the studied area is affected by many structural features as NE-SW, NW-SE, N-S and E-W trends. These structural features caused barriers to the groundwater movement from or to the study area. The study revealed that the depth of the crystalline (Pre-Cambrian) rocks ranges from 3800 metres in the south part to 5300 metres in the northeastern region. Meanwhile, the basement rocks represent a bridge of shallow depth of northwest-southeast trend at the centre of the investigated area.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"20 1","pages":"282 - 292"},"PeriodicalIF":0.0,"publicationDate":"2022-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81319165","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 : 2022-07-10DOI: 10.1080/20909977.2022.2075160
K. Ishola, B. D. Amu, L. Adeoti
ABSTRACT The geological condition of the site in Lagos was investigated using integrated methods. This was necessary following evidence of structural defects prevalent in the area. Against this backdrop, measurements were carried out using in-situ geotechnical and geophysical techniques. The techniques were the Standard Penetration Test, Cone Penetration Test, Electrical Resistivity and seismic refraction surface waves. The various data were collected along eight (8) traverses established strategically in the study area in order to obtain the most desirable results. The results obtained generally show that a low resistive and highly compressive soft soils of organic peats/clays are prevalent in the study area. These geomaterials are characterised with low SPT-N values, low penetrative resistance, low bearing capacities and low electrical resistivity values. The shear (weak) zones have also been identified particularly in the inverted resistivity models. These geomaterials are unfriendly, inimical and severe enough to cause instability in ground conditions. The peat/clay and the weak zones could possibly be responsible for the various degrees of structural defects observed in the study area and should be avoided as foundation placements.
{"title":"Evaluation of near-surface conditions for engineering site characterization using geophysical and geotechnical methods in Lagos, Southwestern Nigeria","authors":"K. Ishola, B. D. Amu, L. Adeoti","doi":"10.1080/20909977.2022.2075160","DOIUrl":"https://doi.org/10.1080/20909977.2022.2075160","url":null,"abstract":"ABSTRACT The geological condition of the site in Lagos was investigated using integrated methods. This was necessary following evidence of structural defects prevalent in the area. Against this backdrop, measurements were carried out using in-situ geotechnical and geophysical techniques. The techniques were the Standard Penetration Test, Cone Penetration Test, Electrical Resistivity and seismic refraction surface waves. The various data were collected along eight (8) traverses established strategically in the study area in order to obtain the most desirable results. The results obtained generally show that a low resistive and highly compressive soft soils of organic peats/clays are prevalent in the study area. These geomaterials are characterised with low SPT-N values, low penetrative resistance, low bearing capacities and low electrical resistivity values. The shear (weak) zones have also been identified particularly in the inverted resistivity models. These geomaterials are unfriendly, inimical and severe enough to cause instability in ground conditions. The peat/clay and the weak zones could possibly be responsible for the various degrees of structural defects observed in the study area and should be avoided as foundation placements.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"27 1","pages":"237 - 256"},"PeriodicalIF":0.0,"publicationDate":"2022-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83446952","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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