Pub Date : 2020-01-01DOI: 10.35248/2381-8719.19.9.474
B. Moges, M. Meten, H. Solomon
Gullele Botanic Garden is one of the largest botanical gardens in Ethiopia, which is found northwest of Addis Ababa. For this garden, a dam was proposed to be constructed for irrigation and recreational purposes. The intended dam will have a height of 30 m and a dam axis length of around 180 m. The main objective of this work is to investigate and evaluate the engineering geological aspects of the proposed dam site based on detailed geological, geotechnical and geophysical investigations. The investigation conducted in the area includes, electrical resistivity imaging, VES, borehole drilling and single packer permeability test. Geologically the area is covered by the different volcanic rock such as ignimbrite, rhyolite, tuff, basalt, and residual soil; and geological structures such as joint, fracture, flow banding, and cooling joint. The dominant orientations of geological structures are N-S and E-W directions. Results from different investigations revealed that three geotechnical layers were identified. These are overburden (completely weathered ignimbrite and soil), highly to moderately weathered ignimbrite and moderately to slightly weathered ignimbrite rock mass. The rock mass permeability test from six boreholes has Lugeon values ranging from 0 to 9. The maximum Lugeon (permeability of the rock mass) values investigated at the left abutment and riverbed of the proposed dam site showed wash out and dilation behavior respectively. The permeability result indicates that possible seepage problem at left abutment, riverbed and reserviour of the proposed dam. Therefore, during the construction of the dam, those specific locations, which are identified as problematic areas, need effective ground improvement works and special monitoring.
{"title":"Integrated Geophysical and Packer Test for the Water Tightness Evaluation of Gullele Botanic Garden Dam Site, Northwest of Addis Ababa, Ethiopia","authors":"B. Moges, M. Meten, H. Solomon","doi":"10.35248/2381-8719.19.9.474","DOIUrl":"https://doi.org/10.35248/2381-8719.19.9.474","url":null,"abstract":"Gullele Botanic Garden is one of the largest botanical gardens in Ethiopia, which is found northwest of Addis Ababa. For this garden, a dam was proposed to be constructed for irrigation and recreational purposes. The intended dam will have a height of 30 m and a dam axis length of around 180 m. The main objective of this work is to investigate and evaluate the engineering geological aspects of the proposed dam site based on detailed geological, geotechnical and geophysical investigations. The investigation conducted in the area includes, electrical resistivity imaging, VES, borehole drilling and single packer permeability test. Geologically the area is covered by the different volcanic rock such as ignimbrite, rhyolite, tuff, basalt, and residual soil; and geological structures such as joint, fracture, flow banding, and cooling joint. The dominant orientations of geological structures are N-S and E-W directions. Results from different investigations revealed that three geotechnical layers were identified. These are overburden (completely weathered ignimbrite and soil), highly to moderately weathered ignimbrite and moderately to slightly weathered ignimbrite rock mass. The rock mass permeability test from six boreholes has Lugeon values ranging from 0 to 9. The maximum Lugeon (permeability of the rock mass) values investigated at the left abutment and riverbed of the proposed dam site showed wash out and dilation behavior respectively. The permeability result indicates that possible seepage problem at left abutment, riverbed and reserviour of the proposed dam. Therefore, during the construction of the dam, those specific locations, which are identified as problematic areas, need effective ground improvement works and special monitoring.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"40 1","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86129366","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 : 2020-01-01DOI: 10.35248/2381-8719.19.9.472
N. Thapa, P. Kiran, ey, S. Ghimire, K. K. Acharya
The Mw 7.8 Gorkha Earthquake (25th April 2015) is powerful earthquake ripped through Central Nepal occurs about 77 Km northwest of Kathmandu Valley. Several studies reveal the fact that comparatively larger earthquake damage in the Kathmandu valley are associated with the valley ground structure. Study focus on reason behind clustering of damages due to mainshock (7.8 Mw) inside Kathmandu valley in certain pattern and its dependency with frequency content of the shattered waves. Data used to meet objective of present research are ground motion data and damage data, for ground motion data seismic stations inside the valley are use. The damage data are collected by both primary and secondary sources. Frequency domain spectral analysis is incorporated in research and found that the maximum power and amplitude, associated, and attributed for particular narrow frequency band. Spatial component of frequency is wavelength which may indicate periodic repetition of maximum power with crest and trough. To estimate spatial distribution of maximum amplitude simplified wave relation is used. Study reveals that the lateral extension of the peak destruction zone as fourth of wavelength and the successive distance between peak destruction zones is half of wavelength. Peak destruction zone, the zone where the damage is maximum and lies either on crest or trough of the propagated wave. Study reveals that propagation of waves is S45oE form the epicenter of Gorkha Earthquake. Heterogeneity in damage on peak destruction zone can be contributed by the variation in geology of Kathmandu Valley.
{"title":"Frequency Dependent Damage Pattern in Kathmandu Valley Due to Mw 7.8 Gorkha Earthquake","authors":"N. Thapa, P. Kiran, ey, S. Ghimire, K. K. Acharya","doi":"10.35248/2381-8719.19.9.472","DOIUrl":"https://doi.org/10.35248/2381-8719.19.9.472","url":null,"abstract":"The Mw 7.8 Gorkha Earthquake (25th April 2015) is powerful earthquake ripped through Central Nepal occurs about 77 Km northwest of Kathmandu Valley. Several studies reveal the fact that comparatively larger earthquake damage in the Kathmandu valley are associated with the valley ground structure. Study focus on reason behind clustering of damages due to mainshock (7.8 Mw) inside Kathmandu valley in certain pattern and its dependency with frequency content of the shattered waves. Data used to meet objective of present research are ground motion data and damage data, for ground motion data seismic stations inside the valley are use. The damage data are collected by both primary and secondary sources. Frequency domain spectral analysis is incorporated in research and found that the maximum power and amplitude, associated, and attributed for particular narrow frequency band. Spatial component of frequency is wavelength which may indicate periodic repetition of maximum power with crest and trough. To estimate spatial distribution of maximum amplitude simplified wave relation is used. Study reveals that the lateral extension of the peak destruction zone as fourth of wavelength and the successive distance between peak destruction zones is half of wavelength. Peak destruction zone, the zone where the damage is maximum and lies either on crest or trough of the propagated wave. Study reveals that propagation of waves is S45oE form the epicenter of Gorkha Earthquake. Heterogeneity in damage on peak destruction zone can be contributed by the variation in geology of Kathmandu Valley.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"78 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73882562","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 : 2020-01-01DOI: 10.35248/2381-8719.19.9.470
A. Ca, Akint Frinwa Oj, Ademilua Lo
Gravimetric and mechanical parameters of Basement rocks in Ado-Ekiti, South-western Nigeria were correlated for engineering foundation studies with the aim of establishing an empirical relationship between the two parameters. Field operations revealed Charnockite, Migmatite, Granite Gneiss and Quartzite as principal basement rocks in the study area. Fresh rock samples were taken from thirty (30) locations cutting across the geology of the study area. Simple pendulum principle and Archimede’s principles were employed to determine the gravity and the specific gravity of the rock specimens repectively. The mechanical analyses (uniaxial compressive strength, shear strength, Young’s modulus, Bulk modulus and Poisson’s ratio) for the thirty rock samples were determined employing standard method. This is applicable to all engineering foundation studies to determine the compence of such areas for engineering developments. The engineering studies revealed the reliability, stiffness, soundness and resistance of the subsurface rocks to the prevailing overhead loads. The results indicated that the gravity and specific gravity values ranged from 935055.46 mgal to 1038167.647 mgal and 2.61 to 2.83 respectively. The values of Uniaxial Compressive Strength (UCS), Young’s modulus (E), Shear modulus (μ), Bulk modulus (K) and Poisson’s ratio (N´) ranged from 49–107 mpa, 1003–3321 mpa, 416–1310 mpa,707–2728 mpa and 0.232-0.316 respectively. The cross plots of the mechanical parameters with gravity and specific gravity showed good correlation with coefficient of correlation (R) ranging from 0.52 to 0.84 and 0.52 to 0.81 respectively. Results validation exercise also indicated that some of the Uniaxial Compressive Strength and Poisson’s ratio have good representation in the derived empirical equation with the two geophysical parameters in this study. The established relationship between the gravimetric and the mechanical parameters revealed that; the mechanical strength of rock is a function of the gravitational pull effect on the rocks and that migmatitic and granitic rocks possessed more mechanical strength than the gneissic and quarzitic rocks that characterised the study area. Some of the equations generated has been found reliable and useful in the determination of the mechanical properties. The physical methods adopted being faster, cheaper, proven and more comprehensive would solve some engineering problems in examining the engineering properties of these basement rocks related terrains.
{"title":"Empirical Relationship between Gravimetric and Mechanical Properties of Basement Rocks in Ado-Ekiti, Southwestern Nigeria","authors":"A. Ca, Akint Frinwa Oj, Ademilua Lo","doi":"10.35248/2381-8719.19.9.470","DOIUrl":"https://doi.org/10.35248/2381-8719.19.9.470","url":null,"abstract":"Gravimetric and mechanical parameters of Basement rocks in Ado-Ekiti, South-western Nigeria were correlated for engineering foundation studies with the aim of establishing an empirical relationship between the two parameters. Field operations revealed Charnockite, Migmatite, Granite Gneiss and Quartzite as principal basement rocks in the study area. Fresh rock samples were taken from thirty (30) locations cutting across the geology of the study area. Simple pendulum principle and Archimede’s principles were employed to determine the gravity and the specific gravity of the rock specimens repectively. The mechanical analyses (uniaxial compressive strength, shear strength, Young’s modulus, Bulk modulus and Poisson’s ratio) for the thirty rock samples were determined employing standard method. This is applicable to all engineering foundation studies to determine the compence of such areas for engineering developments. The engineering studies revealed the reliability, stiffness, soundness and resistance of the subsurface rocks to the prevailing overhead loads. The results indicated that the gravity and specific gravity values ranged from 935055.46 mgal to 1038167.647 mgal and 2.61 to 2.83 respectively. The values of Uniaxial Compressive Strength (UCS), Young’s modulus (E), Shear modulus (μ), Bulk modulus (K) and Poisson’s ratio (N´) ranged from 49–107 mpa, 1003–3321 mpa, 416–1310 mpa,707–2728 mpa and 0.232-0.316 respectively. The cross plots of the mechanical parameters with gravity and specific gravity showed good correlation with coefficient of correlation (R) ranging from 0.52 to 0.84 and 0.52 to 0.81 respectively. Results validation exercise also indicated that some of the Uniaxial Compressive Strength and Poisson’s ratio have good representation in the derived empirical equation with the two geophysical parameters in this study. The established relationship between the gravimetric and the mechanical parameters revealed that; the mechanical strength of rock is a function of the gravitational pull effect on the rocks and that migmatitic and granitic rocks possessed more mechanical strength than the gneissic and quarzitic rocks that characterised the study area. Some of the equations generated has been found reliable and useful in the determination of the mechanical properties. The physical methods adopted being faster, cheaper, proven and more comprehensive would solve some engineering problems in examining the engineering properties of these basement rocks related terrains.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"143 1","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74757938","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 : 2019-01-01DOI: 10.4172/2381-8719.1000453
O IbrahimAdewuyi, O FalaePhilips
An integrated geophysical and geotechnical investigation for a proposed building foundation of an industrial plant layout was carried out to determine the competency of the subsoil as foundation materials. Electrical Resistivity Imaging (ERI) and soil analyses techniques were adopted. Two traverses of four Vertical Electrical Sounding (VES) points were carried out and 8 Boreholes for Standard Penetration Test (SPT) were drilled. In addition soil samples were taken at 1.5 m and 10 m depths and subjected to various laboratory analyses. Three geoelectric layers were delineated from VES including topsoil, saturated sandy clay soil and limestone. The SPT N value indicates that the relative density of the soils is medium dense to very dense while the result of the geotechnical analyses shows that maximum dry density of the soils range from 1680-1900 kg/m3 and 1600-1850 kg/m3 respectively at 1.5 m and 10 m while the optimum moisture content range from 14-19% and 13-19% respectively at 1.5 m and 10 m. The soils are silty sand with low plasticity depiting low to medium swelling potential. Conclusively, the subsurface on which the foundation of the industrial structures will be located within the study area is safe and fairly competent for any engineering work. Owning to the water lodge nature of the area it is advice that the building should rest on pill between 5 m and 10 m depth.
{"title":"Integrated Geophysical and Geotechnical Methods for Pre-Foundation Investigations","authors":"O IbrahimAdewuyi, O FalaePhilips","doi":"10.4172/2381-8719.1000453","DOIUrl":"https://doi.org/10.4172/2381-8719.1000453","url":null,"abstract":"An integrated geophysical and geotechnical investigation for a proposed building foundation of an industrial plant layout was carried out to determine the competency of the subsoil as foundation materials. Electrical Resistivity Imaging (ERI) and soil analyses techniques were adopted. Two traverses of four Vertical Electrical Sounding (VES) points were carried out and 8 Boreholes for Standard Penetration Test (SPT) were drilled. In addition soil samples were taken at 1.5 m and 10 m depths and subjected to various laboratory analyses. Three geoelectric layers were delineated from VES including topsoil, saturated sandy clay soil and limestone. The SPT N value indicates that the relative density of the soils is medium dense to very dense while the result of the geotechnical analyses shows that maximum dry density of the soils range from 1680-1900 kg/m3 and 1600-1850 kg/m3 respectively at 1.5 m and 10 m while the optimum moisture content range from 14-19% and 13-19% respectively at 1.5 m and 10 m. The soils are silty sand with low plasticity depiting low to medium swelling potential. Conclusively, the subsurface on which the foundation of the industrial structures will be located within the study area is safe and fairly competent for any engineering work. Owning to the water lodge nature of the area it is advice that the building should rest on pill between 5 m and 10 m depth.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73055291","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 : 2019-01-01DOI: 10.4172/2381-8719.1000457
O JosephOsumeje, Oniku As, M. Oc, M MatthewOgwuche, A. Usman
High resolution aeromagnetic data and satellite data covering part the Maru Schist Belt, northwestern Nigeria was interpreted in order to understand the distribution of the surface and the sub-surface magnetic materials within the study area, delineate geologic lineaments and estimate the depth to magnetic sources. Results of the satellite map, the analytic signal and horizontal derivative filters applied on the residual magnetic intensity data reveal that the Maru Schist Belt contains highly magnetic materials suspected to be iron. There is a positive correlation between the lithological map, the satellite map, the aeromagnetic map and the lineament maps. Further analysis of the results shows that iron mineralization (Ferric and Ferrous types) is present in various degrees in the study area. The Euler depth solution has estimated the geological source bodies to be within a depth range of 300–600 m. This is evidence that the Maru Schist Belt was accompanied by series of intense deformation during the orogenic process.
{"title":"Interpretation of Aeromagnetic and Satellite Data over Part of Maru Schist Belt, Northwestern Nigeria","authors":"O JosephOsumeje, Oniku As, M. Oc, M MatthewOgwuche, A. Usman","doi":"10.4172/2381-8719.1000457","DOIUrl":"https://doi.org/10.4172/2381-8719.1000457","url":null,"abstract":"High resolution aeromagnetic data and satellite data covering part the Maru Schist Belt, northwestern Nigeria was interpreted in order to understand the distribution of the surface and the sub-surface magnetic materials within the study area, delineate geologic lineaments and estimate the depth to magnetic sources. Results of the satellite map, the analytic signal and horizontal derivative filters applied on the residual magnetic intensity data reveal that the Maru Schist Belt contains highly magnetic materials suspected to be iron. There is a positive correlation between the lithological map, the satellite map, the aeromagnetic map and the lineament maps. Further analysis of the results shows that iron mineralization (Ferric and Ferrous types) is present in various degrees in the study area. The Euler depth solution has estimated the geological source bodies to be within a depth range of 300–600 m. This is evidence that the Maru Schist Belt was accompanied by series of intense deformation during the orogenic process.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89395689","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 : 2019-01-01DOI: 10.24105/2327-5146.8.462
A. Usman, Sani Ma, Lawal Km, M. Ss
The study area falls within the basement complex of northwestern Nigeria and covers four adjacent quarter degree sheets of Funtua, Malumfashi, Masks and Zaria. Gold occurrence in the area was not reported until the recent discovery by artisanal miners. Previous works have shown that primary gold mineralization within the Nigerian basement complex is controlled by geologic structures where they act as conduits for fluids flow and as loci for mineralization. This paper is aimed at characterizing the major structural controls of gold mineralization in the study area. This was achieved by determining depth to basement, producing a magnetization map showing magnetic susceptibility range across the entire study area, and a model of the shape, location and depth of structures in the study area. The anomalies on the aeromagnetic map were defined by fitting a first order polynomial to the total fields, by the method of least squares to obtain the residual field data. First vertical derivative and analytic signal computed, defined distinct pattern of the magnetic signatures. Depths to the surface of the geologic structures (which appears as lineaments on aeromagnetic maps) were obtained from Euler deconvolution solutions which gives an average depths range of 200.2 m to 2229.1 m, with very few solutions having depths less than 300 m. The most prominent lineament and all major subtle lineaments have a depth range of 200 m to 600 m which shows that the structures are deep seated. The magnetic susceptibility values obtained from the magnetization map ranges from 0.000666 to 0.000996 SI. The lineament expected to be the major conduit for possible fluid flow that emplaced the Gold mineralization in the area is suspected to be the continuation of Kalangai fault which trends NE-SW along Malumfashi in the study area.
{"title":"Aeromagnetic Investigation of Geologic Structures Associated with Gold Mineralization along Danja, Northwestern Nigeria","authors":"A. Usman, Sani Ma, Lawal Km, M. Ss","doi":"10.24105/2327-5146.8.462","DOIUrl":"https://doi.org/10.24105/2327-5146.8.462","url":null,"abstract":"The study area falls within the basement complex of northwestern Nigeria and covers four adjacent quarter degree sheets of Funtua, Malumfashi, Masks and Zaria. Gold occurrence in the area was not reported until the recent discovery by artisanal miners. Previous works have shown that primary gold mineralization within the Nigerian basement complex is controlled by geologic structures where they act as conduits for fluids flow and as loci for mineralization. This paper is aimed at characterizing the major structural controls of gold mineralization in the study area. This was achieved by determining depth to basement, producing a magnetization map showing magnetic susceptibility range across the entire study area, and a model of the shape, location and depth of structures in the study area. The anomalies on the aeromagnetic map were defined by fitting a first order polynomial to the total fields, by the method of least squares to obtain the residual field data. First vertical derivative and analytic signal computed, defined distinct pattern of the magnetic signatures. Depths to the surface of the geologic structures (which appears as lineaments on aeromagnetic maps) were obtained from Euler deconvolution solutions which gives an average depths range of 200.2 m to 2229.1 m, with very few solutions having depths less than 300 m. The most prominent lineament and all major subtle lineaments have a depth range of 200 m to 600 m which shows that the structures are deep seated. The magnetic susceptibility values obtained from the magnetization map ranges from 0.000666 to 0.000996 SI. The lineament expected to be the major conduit for possible fluid flow that emplaced the Gold mineralization in the area is suspected to be the continuation of Kalangai fault which trends NE-SW along Malumfashi in the study area.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"21 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89542426","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 : 2019-01-01DOI: 10.4172/2381-8719.1000454
M. Hicheri, B. Ramdhane, S. Yahyaoui, T. Gonenc
In Northern Tunisia, geological structuring is very diverse. This diversification is due to its localization, which is situated within the convergence zone between Africa and Eurasia plates. This situation allows to a complicated geodynamic evolution from Permian Tethy’s opening to the quaternary. Our study area is a key zone because we find several structures (Triassic extrusions, reefs, folds, grabens). The Surface studies (structural, sedimentology, etc.) leave controversies and many directions are only indicated as supposed faults. Thus, to understand geodynamic evolution is very important for petroleum and mining exploration. For this purpose geophysical method, which corresponds to a gravity data interpretation, is used to explore the subsurface structures. In this study, different techniques (regionalresidual separation, Horizontal gradient magnitude, upward continuation, Euler DE convolution) were applied to the gravity anomaly map. The results obtained allowed to draw up a structural map showing faults system responsible for structuring the study area. The obtained structural map is consistent with several faults already identified in previous studies and shows new directions. This map leads to better understanding the geological structures and the geodynamic evolution of the region and is a very useful document to guide future mining and hydrocarbons operations research.
{"title":"New Insights from Gravity Data on the Geodynamic Evolution of Northern African Passive Margin, Case Study of the Tajerouine Area (Northern Tunisian Atlas)","authors":"M. Hicheri, B. Ramdhane, S. Yahyaoui, T. Gonenc","doi":"10.4172/2381-8719.1000454","DOIUrl":"https://doi.org/10.4172/2381-8719.1000454","url":null,"abstract":"In Northern Tunisia, geological structuring is very diverse. This diversification is due to its localization, which is situated within the convergence zone between Africa and Eurasia plates. This situation allows to a complicated geodynamic evolution from Permian Tethy’s opening to the quaternary. Our study area is a key zone because we find several structures (Triassic extrusions, reefs, folds, grabens). The Surface studies (structural, sedimentology, etc.) leave controversies and many directions are only indicated as supposed faults. Thus, to understand geodynamic evolution is very important for petroleum and mining exploration. For this purpose geophysical method, which corresponds to a gravity data interpretation, is used to explore the subsurface structures. In this study, different techniques (regionalresidual separation, Horizontal gradient magnitude, upward continuation, Euler DE convolution) were applied to the gravity anomaly map. The results obtained allowed to draw up a structural map showing faults system responsible for structuring the study area. The obtained structural map is consistent with several faults already identified in previous studies and shows new directions. This map leads to better understanding the geological structures and the geodynamic evolution of the region and is a very useful document to guide future mining and hydrocarbons operations research.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87261826","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}
2D electrical resistivity imaging, vertical electrical sounding and magnetic methods have been conducted for site characterization for large building foundations at Samara University, one of the emerging institutions of learning in Ethiopia. The main objective of the study was to examine the suitability of the subsurface geological formations and structures for foundation on the on-going construction and future expansion of the university. From the results of the survey, it has been possible to map the stratification of the subsurface layers, areas of weakness in the subsurface and the vertical as well as lateral extents of the different lithologies. Moreover, the depth to the substratum suitable for foundation is determined. From interpretation of the geophysical survey results, the near surface geology of the study area includes three layers: a first layer, which is the top soil having considerably varying thickness over the area; a second layer which is interpreted as a layer of vesicular basalt which is the best lithology for the foundation purpose. This layer extends to depth of about 6 m on the north and eastern parts of the area whereas it goes up to 11 m depth on the south and south-western part of the survey area. The third layer which is characterized by very low apparent resistivity response is interpreted as weathered basalt and clay. From a combined interpretation of the geophysical data, three weak zones have been identified over the survey area. Out of these one is oriented N-S while the other two are oriented in a near NW-SE direction. From all the above interpretations, it was possible to suggest that the university must expand towards the northern part of the campus compound. Moreover, special considerations should be taken during designing and implementation of buildings in the eastern and southern part of the area, where the weak zones detrimental to foundation of large buildings are mapped.
{"title":"Joint Application of Geophysical Techniques for Engineering Site Characterization of Samara University Area, Ethiopia","authors":"Solomun Atsbahaa, Hindeya Gebrub, Tigistu Haileb, Anteneh Legessec","doi":"10.35248/2381-8719.19.8.467","DOIUrl":"https://doi.org/10.35248/2381-8719.19.8.467","url":null,"abstract":"2D electrical resistivity imaging, vertical electrical sounding and magnetic methods have been conducted for site characterization for large building foundations at Samara University, one of the emerging institutions of learning in Ethiopia. The main objective of the study was to examine the suitability of the subsurface geological formations and structures for foundation on the on-going construction and future expansion of the university. From the results of the survey, it has been possible to map the stratification of the subsurface layers, areas of weakness in the subsurface and the vertical as well as lateral extents of the different lithologies. Moreover, the depth to the substratum suitable for foundation is determined. From interpretation of the geophysical survey results, the near surface geology of the study area includes three layers: a first layer, which is the top soil having considerably varying thickness over the area; a second layer which is interpreted as a layer of vesicular basalt which is the best lithology for the foundation purpose. This layer extends to depth of about 6 m on the north and eastern parts of the area whereas it goes up to 11 m depth on the south and south-western part of the survey area. The third layer which is characterized by very low apparent resistivity response is interpreted as weathered basalt and clay. From a combined interpretation of the geophysical data, three weak zones have been identified over the survey area. Out of these one is oriented N-S while the other two are oriented in a near NW-SE direction. From all the above interpretations, it was possible to suggest that the university must expand towards the northern part of the campus compound. Moreover, special considerations should be taken during designing and implementation of buildings in the eastern and southern part of the area, where the weak zones detrimental to foundation of large buildings are mapped.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"19 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84157811","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 : 2019-01-01DOI: 10.4172/2381-8719.1000455
A. Abbas, Hongtao Zhu, A. Anees, U. Ashraf, N. Akhtar
Missakeswal is an important hydrocarbon field, lying on active foreland fold and thrust belt of Himalayan orogeny in Potwar plateau. Integrated study of 2D seismic data (SEG-Y, Navigation and seismic velocities) and well logs helps us to delineate the potential reservoir rock of the area. Seismic interpretation based on stratigraphic studies and well tops, aids to mark four reflectors; Chorgali, Sakesar, Lockhart and Basement. Time sections are converted to depth section using velocity analysis system to delineate subsurface structure. Besides this, fault-bounded anticlines and crustal shortening analysis of the depth sections, revealed that folding in the sedimentary successions pre-date reverse faulting and regime of the Potwar basin, is suitable for hydrocarbon accumulation. 2D modeling of the interpreted seismic sections confirms reverse faulting in the sedimentary successions and normal faulting in the basement. Moreover, Seismic Attributes Analysis has carried out which helps in understanding the lateral continuity, bedding sequences and thickness of desired beds highlighted the petroleum system and affirmed the interpretation. The identified structural variations would help in the understanding of the regional tectonic settings, besides this, reservoir character in terms of lateral thickness variation, fault offsets and lithological dissimilarities are achieved. It also reveals that carbonate successions of the Sakesar and Chorgali formations acted as potential reservoirs in Missakeswal area.
{"title":"Integrated Seismic Interpretation, 2D Modeling along with Petrophysical and Seismic Attribute Analysis to Decipher the Hydrocarbon Potential of Missakeswal Area, Pakistan","authors":"A. Abbas, Hongtao Zhu, A. Anees, U. Ashraf, N. Akhtar","doi":"10.4172/2381-8719.1000455","DOIUrl":"https://doi.org/10.4172/2381-8719.1000455","url":null,"abstract":"Missakeswal is an important hydrocarbon field, lying on active foreland fold and thrust belt of Himalayan orogeny in Potwar plateau. Integrated study of 2D seismic data (SEG-Y, Navigation and seismic velocities) and well logs helps us to delineate the potential reservoir rock of the area. Seismic interpretation based on stratigraphic studies and well tops, aids to mark four reflectors; Chorgali, Sakesar, Lockhart and Basement. Time sections are converted to depth section using velocity analysis system to delineate subsurface structure. Besides this, fault-bounded anticlines and crustal shortening analysis of the depth sections, revealed that folding in the sedimentary successions pre-date reverse faulting and regime of the Potwar basin, is suitable for hydrocarbon accumulation. 2D modeling of the interpreted seismic sections confirms reverse faulting in the sedimentary successions and normal faulting in the basement. Moreover, Seismic Attributes Analysis has carried out which helps in understanding the lateral continuity, bedding sequences and thickness of desired beds highlighted the petroleum system and affirmed the interpretation. The identified structural variations would help in the understanding of the regional tectonic settings, besides this, reservoir character in terms of lateral thickness variation, fault offsets and lithological dissimilarities are achieved. It also reveals that carbonate successions of the Sakesar and Chorgali formations acted as potential reservoirs in Missakeswal area.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75647572","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 : 2019-01-01DOI: 10.35248/2381-8719.19.8.465
R. M. E. Gammal, O. Orabi
Investigated sediments of the Duwi and Quseir formations in Gebel Duwi and Zug El Bahar area of the Quseir Region confirmed the presence of Cenomanian-Turonian (C/T) succession for the first time. The recorded planktonic foraminifera characterized by either juvenile or dwarfed, and complete absence of benthic foraminifera due to either its extremely short duration or its restriction to nearshore, rather than open ocean environments. The C/T boundary lies within the Whiteinella archeocretacea Zone, where there is a flooding of free and isolated calcispheres of spherical and ovoidal shapes characterize this boundary in Gebel Duwi section. In the Quseir Region, the C/T sediments have been extremely low thickness and condensed, creating no hiatus in sedimentation during the overall global high stands of shallow water environments. Four detected planktonic foraminiferal zones in the Quseir Region; Rotalipora cushmani, Whiteinella archeocretacea, Helvetoglobotruncana helvetica and Marginotruncana schneeganzi.
{"title":"New Findings of the Cenomanian-Turonian Successions in the Quseir Region, Red Sea, Egypt","authors":"R. M. E. Gammal, O. Orabi","doi":"10.35248/2381-8719.19.8.465","DOIUrl":"https://doi.org/10.35248/2381-8719.19.8.465","url":null,"abstract":"Investigated sediments of the Duwi and Quseir formations in Gebel Duwi and Zug El Bahar area of the Quseir Region confirmed the presence of Cenomanian-Turonian (C/T) succession for the first time. The recorded planktonic foraminifera characterized by either juvenile or dwarfed, and complete absence of benthic foraminifera due to either its extremely short duration or its restriction to nearshore, rather than open ocean environments. The C/T boundary lies within the Whiteinella archeocretacea Zone, where there is a flooding of free and isolated calcispheres of spherical and ovoidal shapes characterize this boundary in Gebel Duwi section. In the Quseir Region, the C/T sediments have been extremely low thickness and condensed, creating no hiatus in sedimentation during the overall global high stands of shallow water environments. Four detected planktonic foraminiferal zones in the Quseir Region; Rotalipora cushmani, Whiteinella archeocretacea, Helvetoglobotruncana helvetica and Marginotruncana schneeganzi.","PeriodicalId":80381,"journal":{"name":"AGSO journal of Australian geology & geophysics","volume":"10 1","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79710581","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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