Hindawi Publishing Corporation, Journal of Geochemistry Volume 2014 (2014), Article ID 960139, 13 pages, Dec 28, 2014
ABSTRACT
Provenance analysis serves to reconstruct the pre-depositional history of a sediment/se... 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.
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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 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
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.
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 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
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.