SAMUEL ONI
University of Ibadan Nigeria, GEOLOGY, Graduate Student
The mineral content of coal affects the type of ash that will be produced on combustion. Despite the same volatile matter content, the Okobo 1 FSI is 3.7 with ash content of 16.7 while Okobo 2 FSI is 6.8 with an ash content of 8.2. Ash... more
The mineral content of coal affects the type of ash that will be produced on combustion. Despite the same volatile matter content, the Okobo 1 FSI is 3.7 with ash content of 16.7 while Okobo 2 FSI is 6.8 with an ash content of 8.2. Ash fusion is 1,400ºC, various ash slagging index indices such as silica ratio (Sr), basic to acidic oxide (B/A), and sulphur index (Rs) for Okobo coal are: 85, 0.13, 0.23 respectively implying low slagging characteristics. The Gross Calorific Value GCV of Okobo 1 and Okobo 2 are 20.88 MJ/Kg (8796 Btu/lb) and 19.86MJ/Kg (8536 Btu/lb) respectively congruous with lowest grade of sub-bituminous coal termed the " sub-bituminous C grade " according to ASTM classification.
Research Interests:
Attempts have been made to classify the sediment on their degree of maturity. Compositional maturity is a reflection of intensity of weathering and a function of labile grains, unstable/stable rock fragments and stable quartz arenites.... more
Attempts have been made to classify the sediment on their degree of maturity. Compositional maturity is a reflection of intensity of weathering and a function of labile grains, unstable/stable rock fragments and stable quartz arenites. The main aim of this study is to investigate maturity and area of deposition and attempt to shed light on source area paleo-weathering conditions. Twenty one samples of shales and sandstones units were collected from a depth precisely between 1160 to 11,480m at a well in western Niger Delta, grinded, pulverized and sieved with less than 75μm. About 10g was packed and sent to From the results, various plots and indexes inferring maturity and area of deposition were utilized. Using the A-K-F ternary plots of Englund and Jørgensen (1973), the depositional environment is transition zone. The silicate weathering indexes CIA, CIW and PIA values ranges from 45-65, on average indicates low to moderate weathering in the source area with extreme weathering of some sand fraction. Various calculated values of the weathering indices: Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA), Chemical Index of Weathering (CIW) and scatter plots of formulated ratios of Al/Na, K/Na, and Rb/K vs chemical index of alteration (CIA) were plotted. The moderate values below average suggest low to moderate weathering conditions in the source area or during transportation. This also inferred their recycling processes are insignificant. The clay content is low and feldspars are averagely high implying immaturity. The calculated ZTR index for the sand ranges from 36.4-75.0 from with an average mode of 55.5% implying almost all contain mineralogically immature sediments. The calculated Zircon-Tourmaline-Rutile (ZTR) index shows that majority of the sample depths have >43% ZTR index but below 75% which corresponds to generally immature sediments.
Research Interests:
Free-swelling index (FSI) and dilation are useful indicators to predict the strength of coke that may be derived from a particular coal. FSI is a measure of a coal ability to swell and cake during heating. Both coal from Ovbiowun and... more
Free-swelling index (FSI) and dilation are useful indicators to predict the strength of coke that may be derived from a particular coal. FSI is a measure of a coal ability to swell and cake during heating. Both coal from Ovbiowun and Oloku are considered to have poor coking and swelling tendencies as inferred from the derived FSI values (2.04 and 1.48 respectively) as well as > 36% in volatiles. GCV/HHV is determined from both proximate and ultimate analyses values as input parameters using a generally proven formula. GCV of Ovbiowun coal is 28.7MJ/Kg which is within range of 26.7 – 30.2 MJ/Kg for " high volatile C bituminous ". Oloku coal has GCV of 25.3 MJ/Kg which is within the range of 24.4 – 26.7 MJ/Kg for " Sub bituminous A grade ". For Ovbiowun coals, the Ibs of CO2/ MMBtu (gross) = 167.44 Ibs/Btu, 4596 Ib/tonne and for Oloku coals, Ibs of CO2/ MMBtu (gross) = 164.21 Ibs/Btu, 4376 Ib/tonne. This strongly agrees with Oloku coals as sub-bituminous and Ovbiowun coals as bituminous, having higher carbon content and thus more CO2 production. The fuel ratio for both Ovbiowun and Oloku is 0.98 and 0.91 respectively which is a referral to bituminous grade. The vitrinite reflectance as determined for the studied samples was 0.48 for Ovbiowun coals and 0.43 for Oloku coals implying bituminous and sub-bituminous coals respectively. No coal bedded methane is produced from both coals. The Roga index as well as their dilation is inferred to be around 0-20. Ovbiowun coals have 65 HGI and Oloku coal is 87 HGI due to higher moisture content. The moisture content of Oloku coal (15.0) is higher than Ovbiowun (10.8) while the volatile matter (as received) for Oloku (40.7) is lower than Ovbiowun (41.7). From the > 10% moisture and ash content, coal in both study area is unsuitable for coke production. Also the derived Hydrogen % for Ovbiowun (63.3%) is greater than Oloku (57.43) implying more maturity in Ovbiowun coals.
Research Interests:
Abstract The combination of geophysical and geotechnical methods in foundation investigation has shown to be invaluable in deciphering the depth to bedrock, characterizing the earth materials and extent of variation of allowable bearing... more
Abstract
The combination of geophysical and geotechnical methods in foundation investigation has shown to be invaluable in deciphering the depth to bedrock, characterizing the earth materials and extent of variation of allowable bearing pressure of foundation soils. Geophysical and geotechnical methods involving electrical resistivity and cone penetration test have been carried out to investigate the foundation conditions of a bridge site in Ajibode and the newly constructed Abadina-Ajibode Road, located in University of Ibadan, Ibadan, southwestern Nigeria.
Eleven vertical electrical sounding (VES) were carried out, seven at the investigated portion of the road and four at the bridge site. While four cone penetration tests were also carried out at the Bridge site. The vertical electrical sounding for investigated portion of the road revealed 2-4 different lithological layers. The first layers is topsoil which has resistivity ranges from 17-321Ωm with a mean of 220Ωm. The wide range in resistivity values of the topsoil can be due to different degree of compaction. The thickness of the topsoil ranges from 0.5-1.7m with a mean of 1.1m. The second layer resistivity from VES 1-VES 6 ranges from 19-46Ωm with a mean of 32Ωm. The resistivity of this layer is less than 100Ωm which is characteristics of clayey formation. The thickness of this layer ranges from 5.9-12.6m with a mean of 8.0m. For VES 7, the second layer is made up of lateritic pan with resistivity of 336Ωm and depth of 6.1m. The fractured/fresh basement layer resistivity ranges from 171-2364Ωm with a mean of 998Ωm and depth value ranges between 7.4-22.3m with mean depth of 10.9m. While for the investigated bridge site, the vertical electrical sounding revealed 2-3 geoelectric layers. The geoelectric layers include: the first layer is topsoil which has resistivity ranges from 31-320Ωm with a mean of 132Ωm. The wide range in resistivity of the topsoil can be due to different degree of compaction. The thickness of this layer ranges from 0.7m-2.5m with a mean of 1.5m. The second layer resistivity for VES 1-VES 2 ranges from 85-138Ωm with a mean of 116Ωm. The thickness of this layer ranges from 1.0-1.1m with a mean of 1.0m: this layer is characterized by weathered basement. The fresh basement layer resistivity ranges from 920-2853Ωm with a mean resistivity of 2067Ωm, is characterize with fresh bedrock. The cone penetrometer tests also revealed that the investigated bridge site has 2-3 different lithologies with cone resistance of 5-40Kg/cm2 with a mean of 18Kg/cm2 at depth range from 0.25-1.0m and at depth range of 1.25-1.7m, the penetrative resistance at CPT 1 and CPT 2 range from 25-250Kg/cm2 with a mean of 148Kg/cm2, this is a characteristics of competent materials which are weathered basement. CPT 3 and CPT 4 penetrative resistance range from 5-10Kg/cm2 with a mean of 9Kg/cm2 at depth range from 1.0-3.75m but from depth range between 4.0m and 5.0m, the penetrative resistance ranges from 200-250Kg/cm2 with a mean of 225Kg/cm2.
The results obtained from this study have emphasized the usefulness of geophysical methods in complementing geotechnical studies in variation in lithology accompanied by variation in the allowable bearing pressure of foundation soils.
Keywords: Ajibode, VES, Cone penetration test, Schlumberger configuration, Geotechnical survey, cone penetration test, pile foundation
The combination of geophysical and geotechnical methods in foundation investigation has shown to be invaluable in deciphering the depth to bedrock, characterizing the earth materials and extent of variation of allowable bearing pressure of foundation soils. Geophysical and geotechnical methods involving electrical resistivity and cone penetration test have been carried out to investigate the foundation conditions of a bridge site in Ajibode and the newly constructed Abadina-Ajibode Road, located in University of Ibadan, Ibadan, southwestern Nigeria.
Eleven vertical electrical sounding (VES) were carried out, seven at the investigated portion of the road and four at the bridge site. While four cone penetration tests were also carried out at the Bridge site. The vertical electrical sounding for investigated portion of the road revealed 2-4 different lithological layers. The first layers is topsoil which has resistivity ranges from 17-321Ωm with a mean of 220Ωm. The wide range in resistivity values of the topsoil can be due to different degree of compaction. The thickness of the topsoil ranges from 0.5-1.7m with a mean of 1.1m. The second layer resistivity from VES 1-VES 6 ranges from 19-46Ωm with a mean of 32Ωm. The resistivity of this layer is less than 100Ωm which is characteristics of clayey formation. The thickness of this layer ranges from 5.9-12.6m with a mean of 8.0m. For VES 7, the second layer is made up of lateritic pan with resistivity of 336Ωm and depth of 6.1m. The fractured/fresh basement layer resistivity ranges from 171-2364Ωm with a mean of 998Ωm and depth value ranges between 7.4-22.3m with mean depth of 10.9m. While for the investigated bridge site, the vertical electrical sounding revealed 2-3 geoelectric layers. The geoelectric layers include: the first layer is topsoil which has resistivity ranges from 31-320Ωm with a mean of 132Ωm. The wide range in resistivity of the topsoil can be due to different degree of compaction. The thickness of this layer ranges from 0.7m-2.5m with a mean of 1.5m. The second layer resistivity for VES 1-VES 2 ranges from 85-138Ωm with a mean of 116Ωm. The thickness of this layer ranges from 1.0-1.1m with a mean of 1.0m: this layer is characterized by weathered basement. The fresh basement layer resistivity ranges from 920-2853Ωm with a mean resistivity of 2067Ωm, is characterize with fresh bedrock. The cone penetrometer tests also revealed that the investigated bridge site has 2-3 different lithologies with cone resistance of 5-40Kg/cm2 with a mean of 18Kg/cm2 at depth range from 0.25-1.0m and at depth range of 1.25-1.7m, the penetrative resistance at CPT 1 and CPT 2 range from 25-250Kg/cm2 with a mean of 148Kg/cm2, this is a characteristics of competent materials which are weathered basement. CPT 3 and CPT 4 penetrative resistance range from 5-10Kg/cm2 with a mean of 9Kg/cm2 at depth range from 1.0-3.75m but from depth range between 4.0m and 5.0m, the penetrative resistance ranges from 200-250Kg/cm2 with a mean of 225Kg/cm2.
The results obtained from this study have emphasized the usefulness of geophysical methods in complementing geotechnical studies in variation in lithology accompanied by variation in the allowable bearing pressure of foundation soils.
Keywords: Ajibode, VES, Cone penetration test, Schlumberger configuration, Geotechnical survey, cone penetration test, pile foundation
Research Interests:
Abstract The objective of this geophysical survey is to evaluate the hydrological characteristics of the study area. This includes the availability of groundwater, depth of aquifer, determining whether the underlying geology is competent... more
Abstract
The objective of this geophysical survey is to evaluate the hydrological characteristics of the study area. This includes the availability of groundwater, depth of aquifer, determining whether the underlying geology is competent basement/weathered basement or fractured bedrock and the delineation of the subsurface into various geo-electric layers. The availability of groundwater in an area is controlled by varying geological factors such as hydrogeological units, stratigraphical faults/folds, and geological sequences
The methodology used is the direct current method using the schlumberger configuration. In this electrical resistivity method, artificially-generated electric currents are introduced into the ground and the resulting potential differences are measured at the surface. Deviations from the expected pattern of potential differences from homogeneous ground provide information on the lithological formations and electrical properties of subsurface anomalies. A total of 10 vertical electric sounding was carried out on the study area, which covers the entire community and the data plotted and computer software designed by Vander Velpen BPA was used to iterate the result. This removes the noise and field errors incorporated in the data. The result of the VES curve reveals that there are three major geoelectric layers
The fist layer has an intermediate resistivity implying a sandy soil. Very low resistivity corresponds to clayey/clayey sand (VES 4, VES 5, and VES 6) while exceedingly high resistivity (VES 10) implies a lateritic cover. The second layer is the weathered layer sub-divided into minor geoelectric layers such as clays, gravels and weathered rocks. The weathered layers have low resistivity values, possibly due to the presence of conduction fluids such as water. The third layer is the basement or bedrock which may be fractured basement or fresh bedrock. Ajaokuta has more of fresh unfractured bedrocks except in some cases (VES 2 and VES 4)
The resistivity of topsoil varies from 12.6Ω to 3247.9Ω with a mean of 657.1Ω ± 947.7. The thickness of topsoil is within the range of 0.4m to 14.9m with a mean of 2.2m ± 4.2. The resistivity of weathered layer ranges from 27.9Ω to 175.5Ω with a mean of 59.2Ω ± 43.5. The thickness of the weathered layer is from minimum of 5.8m to maximum of 37.0 m having a mean of 12.4m ± 9.5. The depth to basement varies from 6.2m to 37.5m with a mean of 13.38 ± 9.07. The resistivity of the basement in the area varies from 183.3Ωm to 4294.2Ωm with a mean 0f 905Ωm ± 1170.The thickness of the topsoil is very low except for (VES 4) The average depth to basement is 13.38m±9.07.
Keywords: Boreholes, Ajaokuta, schlumberger configuration, resistivity, VES
The objective of this geophysical survey is to evaluate the hydrological characteristics of the study area. This includes the availability of groundwater, depth of aquifer, determining whether the underlying geology is competent basement/weathered basement or fractured bedrock and the delineation of the subsurface into various geo-electric layers. The availability of groundwater in an area is controlled by varying geological factors such as hydrogeological units, stratigraphical faults/folds, and geological sequences
The methodology used is the direct current method using the schlumberger configuration. In this electrical resistivity method, artificially-generated electric currents are introduced into the ground and the resulting potential differences are measured at the surface. Deviations from the expected pattern of potential differences from homogeneous ground provide information on the lithological formations and electrical properties of subsurface anomalies. A total of 10 vertical electric sounding was carried out on the study area, which covers the entire community and the data plotted and computer software designed by Vander Velpen BPA was used to iterate the result. This removes the noise and field errors incorporated in the data. The result of the VES curve reveals that there are three major geoelectric layers
The fist layer has an intermediate resistivity implying a sandy soil. Very low resistivity corresponds to clayey/clayey sand (VES 4, VES 5, and VES 6) while exceedingly high resistivity (VES 10) implies a lateritic cover. The second layer is the weathered layer sub-divided into minor geoelectric layers such as clays, gravels and weathered rocks. The weathered layers have low resistivity values, possibly due to the presence of conduction fluids such as water. The third layer is the basement or bedrock which may be fractured basement or fresh bedrock. Ajaokuta has more of fresh unfractured bedrocks except in some cases (VES 2 and VES 4)
The resistivity of topsoil varies from 12.6Ω to 3247.9Ω with a mean of 657.1Ω ± 947.7. The thickness of topsoil is within the range of 0.4m to 14.9m with a mean of 2.2m ± 4.2. The resistivity of weathered layer ranges from 27.9Ω to 175.5Ω with a mean of 59.2Ω ± 43.5. The thickness of the weathered layer is from minimum of 5.8m to maximum of 37.0 m having a mean of 12.4m ± 9.5. The depth to basement varies from 6.2m to 37.5m with a mean of 13.38 ± 9.07. The resistivity of the basement in the area varies from 183.3Ωm to 4294.2Ωm with a mean 0f 905Ωm ± 1170.The thickness of the topsoil is very low except for (VES 4) The average depth to basement is 13.38m±9.07.
Keywords: Boreholes, Ajaokuta, schlumberger configuration, resistivity, VES
Research Interests:
ABSTRACT Provenance analysis serves to reconstruct the pre-depositional history of a sediment/sedimentary rock. The provenance analysis which is combination of petrography and geochemistry can reveal the nature of source regions and... more
ABSTRACT
Provenance analysis serves to reconstruct the pre-depositional history of a sediment/sedimentary
rock. The provenance analysis which is combination of petrography and geochemistry can reveal
the nature of source regions and the tectonic setting of sedimentary basins. This paper focuses on
the reconstruction of the provenance and tectonic settings of the Niger delta clastic facies using
geochemical approach. The main types of geochemical tests include major, trace, and rare earth
element (REE) tests. Major element geochemistry data is used to construct variation diagrams
and to correlate with rock compositions that its conditions of formation has been established..
Twenty one samples of shales and sandstones units were purposely collected from a depth
between 1160 to 11,480 m, grinded, pulverized and sieved with a < 75μm. About 5g was packed
and sent to sent to Acme analytical Laboratory LTD., Vancouver, Canada. The analyses were
carried out by both Induced Coupled Plasma-Mass Spectrometry (ICP-MS) and Induced Coupled
Plasma-Emission Spectrometry (ICP-ES). Bulk-rock geochemistry of major oxides, trace
elements and rare earth elements were determined with the data and discrimination as well as
bivariate plots was utilized for the provenance and tectonic setting determination.
Based on the discrimination diagram for major oxides, the probable provenance of the south
eastern Delta clastic sediments was mainly of the active continental margins. The bivariate plots
of La vs Th, La/Y vs Sc/Cr, Ti/Zr vs La/Sc and the trivariate plots of La-Th-Sc, Th-Sc-Zr/10,
and Th-Co-Zr/10 all plotted on the fields of active continental margin sediments which is
consistent with the known actively opening of a failed arm of triple junction. The trace elements
and REE analysis indicates that they are virtually Fe-rich, lithic /quartz arkosic sandstones. The
normalizing factors used for the REE are Wakita chondrite. Their Rare Earth Elements (REE)
pattern displays high Light REE/Heavy REE (LREE/ HREE) ratio, flat HREE and a significant
negative Eu anomaly which correlate well with the UCC and PAAS average composition. The
source area may have contained felsic igneous rocks.
Keywords: Geochemistry, Provenance, Niger delta, Felsic, active margins, REE, clastic
sediments.
Provenance analysis serves to reconstruct the pre-depositional history of a sediment/sedimentary
rock. The provenance analysis which is combination of petrography and geochemistry can reveal
the nature of source regions and the tectonic setting of sedimentary basins. This paper focuses on
the reconstruction of the provenance and tectonic settings of the Niger delta clastic facies using
geochemical approach. The main types of geochemical tests include major, trace, and rare earth
element (REE) tests. Major element geochemistry data is used to construct variation diagrams
and to correlate with rock compositions that its conditions of formation has been established..
Twenty one samples of shales and sandstones units were purposely collected from a depth
between 1160 to 11,480 m, grinded, pulverized and sieved with a < 75μm. About 5g was packed
and sent to sent to Acme analytical Laboratory LTD., Vancouver, Canada. The analyses were
carried out by both Induced Coupled Plasma-Mass Spectrometry (ICP-MS) and Induced Coupled
Plasma-Emission Spectrometry (ICP-ES). Bulk-rock geochemistry of major oxides, trace
elements and rare earth elements were determined with the data and discrimination as well as
bivariate plots was utilized for the provenance and tectonic setting determination.
Based on the discrimination diagram for major oxides, the probable provenance of the south
eastern Delta clastic sediments was mainly of the active continental margins. The bivariate plots
of La vs Th, La/Y vs Sc/Cr, Ti/Zr vs La/Sc and the trivariate plots of La-Th-Sc, Th-Sc-Zr/10,
and Th-Co-Zr/10 all plotted on the fields of active continental margin sediments which is
consistent with the known actively opening of a failed arm of triple junction. The trace elements
and REE analysis indicates that they are virtually Fe-rich, lithic /quartz arkosic sandstones. The
normalizing factors used for the REE are Wakita chondrite. Their Rare Earth Elements (REE)
pattern displays high Light REE/Heavy REE (LREE/ HREE) ratio, flat HREE and a significant
negative Eu anomaly which correlate well with the UCC and PAAS average composition. The
source area may have contained felsic igneous rocks.
Keywords: Geochemistry, Provenance, Niger delta, Felsic, active margins, REE, clastic
sediments.