| 1 |
Author(s):
Ale, T.O., Ogunribido, T.H.T, Olatunji, Y.I..
Page No :
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Engineering Properties of Soil Samples From Stable and Failed Sections: An Example of Akure-Idanre Road, Southwestern Nigeria
Abstract
The engineering properties of the subsoil determine the longevity of the structure placed above it. This study is aimed
at determining the engineering properties of the subsoil taken from both the failed and stable sections of Idanre road,
south western Nigeria. Both Index and strength tests were conducted on the sampled soils. The grain size analysis
shows that the coarse contents of the sampled soils range between 73.3% and 93.9% while the fine content range
between 6.2% and 26.7% The natural moisture content, liquid limit, plastic limit, plasticity index, linear shrinkage
and specific gravity tests range from 4.1% to 13.0%, 22.2% to 40.8%, 0.0% to 25.2%, 2.9% to 38.5%, 6.4% to 10.7%
and 2.53 to 2.66 respectively. These tests results show that all the sampled soils are within the acceptable limit of a
Nigeria soil. The sampled soils are classified as either silty sand or sand. AASHTO classification shows that the
3 3 sampled soils have ratings of good to excellent. The MDD values range from 1492kg/m to 1607kg/m while the OMC
range from 10.0% to16.0%. The CBR values range from 22% to 54% which means that the soils are good as
subgrade/subbase materials and not as base materials.
| 2 |
Author(s):
Egwuonwu, G.N, Umeobika, M.N, Okpala, P.K, Orji, O.
Page No : 1-13
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Geoelectric Investigation of Shallow Subsurface Stability at Oko-Nanka Prominent Gully Erosion Site in Niger Delta Basin, South-Eastern Nigeria
Abstract
The shallow subsurface horizons at vicinity of Oko-Nanka prominent gully erosion site in Niger Delta Basin were
surveyed. Using two-dimensional electrical resistivity tomography (2DERT) geophysical technique, the survey was
aimed at inferring the stability gully's wall and its surrounding for engineering development. The 2DERT was carried
out along accessible survey lines laid parallel and perpendicular to the flanks of the gully. Apparent resistivity data
6
collected ranging from low to high resistivity (1.22 to 1.0 x 10 Ùm) were processed using modelling software namely
Res2DInv version 3.56 hence, 2DERT models obtained with the registered data. The tomographic models obtained
show that the gully erosion site is predominantly characterized by unconsolidated earth materials. Holistic
interpretation unveils the fact that weak formations such saturated sand, sandy clay and some consolidated soil
occurrences at various depths predominates the gully site. Based on resistivity model values, the Oko and Nanka
flanks were noticed to bear significant contrast comparatively Oko-flank bearing lower resistivity range. The landsliding tendency was found to be lower at Nanka side of the gully compared Oko flank of it. Predominantly,
differential saturation was observed to be more across the profiles surveyed at the Oko side compared with those at the
Nanka side of the gully site. The variations the 2DERT models resistivity values have provided useful information for
measures of various civil engineering constructions and superstructures at the Oko-Nanka gully vicinity
| 3 |
Author(s):
Enebeli, V.C, Okorafor, C.N., Usiabulu, G.I..
Page No : 17-24
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Geophysical Investigation for the Delineation of Lithology at Novena University, Ogume, Delta State Using the Vertical Electrical Sounding (VES) Method and Electrical Profiling
Abstract
Lithology is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of
mapping and correlation between areas. Geophysical investigation for the delineation of lithology has been carried
out at Novena University, Ogume, Delta State using the Vertical Electrical Sounding (VES) method and electrical
profiling. The major aim of this research work is to obtain the internal distribution of physical properties of a
subsurface geological structure or materials within the study area so as to guide against the challenge of dry water
wells, effective drainage channels and other geotechnical issues. The VES was acquired using Schlumberger array.
For Profiling, data acquisition was executed with 5m inter electrodes spacing in Wenner configuration. The
Petrozenith Earth Resistivity Meter was used for the field measurement in both cases. For the VES, the apparent
resistivity data were input into IP2WIN software running on personal computer. The data was inverted to obtain the
subsurface true resistivity. The VES reveals that at a probing point of about 10.11m, a resistivity less than 100? m was
encountered originating from the surface. This suggests that the near surface layer is made up of sandy clay / clay just
underlain by an unsaturated coarse sand. Beneath it is a high resistivity material of 6857? m. The high resistivity is
probably due to very low water content since the upper layer, sandy clay and clay has very low permeability for water
to reach the coarse sand layer. The line plot gotten from the profiling indicates that the near- surface geologic section
investigated is not homogeneous. The curve of profile 2 is more irregular than that of profile1. This is most likely due
to lateral changes in water content, sand grading, clay content and mineralogical compositions or texture of near
surface sand changes laterally.
| 4 |
Author(s):
Okunlola, O.A., Adeosun, B., Olisa, O.G.
Page No : 25-31
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Compositional Features and Industrial Appraisal of Talcose Rocks around Arigbabu South-Western Nigeria
Abstract
Talc bearing rocks around Arigbabu area, in the Ife-Ilesha schist belt, were studied to delineate their compositional
features, petrogenesis and their suitability as industrial raw material. Systematic geological mapping was carried out
to identify talcose bodies in the area; petrographic studies and X -ray Diffraction (XRD) were carried out to identify
the minerals in the talcose bodies, geochemical analysis to determine elemental concentration was carried out using
Inductively Coupled Plasma Mass Spectrometry (ICPMS). Samples were also subjected to firing and geotechnical
test to determine its geotechnical properties. Results revealed the talc deposit are closely association with mafic -
ultramafic rocks, quartzite, mica schist and granites. Petrographic and XRD studies revealed that the talcose body are
composed of talc, tremolite, chlorite and anthophyllite while geochemical analysis revealed mean values of 56.02%,
25.27%, 6.6%, 2.92% and 1.13 % for SiO MgO, Fe O , Al O and CaO respectively which are comparable to other 2, 2 3 2 3
talc occurrences of southwestern Nigeria. Firing of the talc samples revealed an average Loss On Ignition (LOI) of
6.74%, average linear shrinkage value of 1.52% and mean values of water absorption capacity and pH are 10.36% and
8.08 respectively. Economic appraisal of the talc deposits indicates they are suitable as raw materials for paint,
fertilizer, paper, rubber and ceramic manufacturing, subject to appropriate beneficiation.
| 5 |
Author(s):
Okunlola, O.A., Babatunde, D.A., Olisa, O.G..
Page No : 33-41
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Mineralisation Potential of Feldspar and Muscovite Extracts from Olode Pegmatite, Southwestern Nigeria
Abstract
Rare metal mineralisation potential of pegmatites in different pegmatite fields of Nigeria are being studied to
understand the type and level of rare metal mineralisation and provide guidelines for small and large scale mining in
the pegmatite fields of Nigeria. The Olode pegmatites in the Ibadan- Osogbo field intrudes biotite gneiss and granite
gneiss; they are characterized by large crystals of quartz, muscovite and k-feldspar with subordinate plagioclase,
while schorl and beryl are accessory minerals. Samples of pegmatites were obtained during systematic geological
mapping and minerals extracts were extracted from the samples and analyzed using Inductively Coupled Plasma
Mass Spectrometry (ICPMS). Geochemical analysis results revealed high SiO values in feldspar extract compared to 2
muscovite extracts and higher Al O value in muscovite extracts compared to feldspars extracts. The muscovite 2 3
extracts are enriched in rare metals compared to the feldspar extracts; Na/K ratio low (less than 1.0), this indicates
poor degree of albitization and this is responsible for poor mineralization of Sn. Average concentration (ppm) are 131,
24, 796 and 79 for Ba, Cs, Rb and Sr respectively in feldspar extracts and average values (ppm) are 120, 144, 42, 11
and 20 for Ga, Nb, Sn, Ta and W respectively in muscovite extracts. Plot of K/Rb against Rb showed that pegmatite
has characteristics of a unmineralised muscovite class pegmatite and Nb is mineralized in preference to Ta in the
muscovite extracts. Geochemical plots such as the Ta against Cs plot, Ta against Ga plot all show that Olode pegmatite
is a rare metal depleted pegmatite as the mineral extracts plots below the limes of mineralisation.
| 6 |
Author(s):
Aniwetalu, E., Ilechukwu, J, Ikegwuonu, O., Omoja, U.
Page No : 43-52
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Time-lapse Porosity and Velocity Analysis Using Rock Physics Models in Niger Delta, Nigeria
Abstract
In reservoir characterization, modeling the effects of production-related changes on elastic properties of the reservoir
is a very challenging task because of the non-uniqueness and uncertainty of reservoir system. However, the analysis
of 3-D and time-lapse seismic data has offered the possibility of dynamic characterization of the porosity and velocity
changes in the reservoir during hydrocarbon production using rock physics models and vertical information available
from the well logs. The changes in the fluid properties as production progresses was analysed using fluid substitution
and depth domain seismic velocity models. The result of the initial average porosity of the reservoirs was 29.50% with
a very low water saturation of 12%. The oil and gas drive maintained average saturation of 40% and 48% respectively.
The average compressional and shear wave velocities is 2905m/s and 1634m/s respectfully with velocity increasing
with decrease in porosity. However, in fluid substitution modeling, the results reflect a change in fluid properties
where average gas and oil saturation assume new status of 34% and 24% which indicates a decrease by 14% and 16%
respectively.The average water saturation increases by 30% with an average value of 42%. The decrease in
hydrocarbon saturation and increase in the water saturation influence the elastic moduli of the reservoir rocks,
pressure, temperature and porosity. Thus, porosity decreased by 4.16% which probably arose from the closure of the
aspect ratio crack due to pressure increase. The velocity depth model of the monitor shows significant increase in
velocity and water saturation that are gradually replacing hydrocarbon in the reservoir which is an indication of
reservoir depletion.
| 7 |
Author(s):
Ogbahon, O.A, Opeloye, S.A., Oluwajana, O.A.
Page No : 53-61
|
Paleoecology and Paleodepositional Environment of Ostracod from Igumale Formation, Southern Benue Trough, Nigeria
Abstract
Ostracod fauna from Igumale Formation of the Cenomanian-Turonian Eze Aku Group in the Southern Benue Trough
have been studied to document the assemblage, paleoecology and depositional environment of the sediment in the
stratigraphic interval. Seventeen core samples spanning a stratigraphic interval of 85.34 m were analyzed for
ostracod. The lithologic composition of lithostratigraphic unit consists of siliciclastic-carbonate sequences with the
carbonates more conspicuous at the upper portion of the stratigraphic section. A total number of eight species
belonging to five genera and five families were recovered from the samples. The recorded ostracod taxa are
Bythocypris sp., Bairdia malzi, Bairdia illaroensis, Bairdia sp., Cytherella aegyptopuntata, Cytherella farafraensis,
Xestoleberis sp.and Paracosta parakefensis listed in order of decreasing abundance. Of the total population
abundance of 138, Bythocypris sp is the dominant taxa, accounts for 69.6 % of the population. Its distribution is
however cyclical, suggesting fluctuation in sea level. Based on the low species diversity, environmental preferences
of the recorded taxa and distributional pattern, shallow marine depositional environment (inner to middle shelf) is
deduced for the fossiliferous portion of the section with dissolved oxygen levels fluctuating between well oxygenated
and disaerobia
| 8 |
Author(s):
Ogunsanwo, F.O., Olurin, O.T, Ozebo, V.C., Saheed, G.A..
Page No : 63-73
|
Application of Enhancement and Filtering Technique to Aeroradiometric data of Ogun State, South-Western, Nigeria
Abstract
Enhancement and filtering primarily design for potential field problem have gained more importance in the recent
time since it can now be successfully applied to non-potential field data. They are found mostly applicable for
smoothing, noise reduction and in source edge detection. In this study, these techniques were applied to airborne
radiometric data (non-potential field) of Ogun State, in order to identify some areas which are subtle for radioelement
deposition and possible geomorphic activities attached. Three enhancement techniques, namely; Analytical Signal
Amplitude (ASA), Horizontal Gradient Magnitude (HGM) and Tilt Derivatives (TDR) were used. Filtering
techniques such as Upward Continuation, Low Pass and High Pass Filter were as well employed. The result obtained
shows variation in the responses of radiometric flux for different enhancement techniques with respect to the
geological and bedrock composition. ASA and HGM revealed unique similar trend in the radioelement distribution
compared to TDR. Upward continuation distance at 100 and 1000m was demonstrated to investigate the magnitude of
enhancement or attenuation of the radioelements and their total count. Low pass (regional) filter results revealed the
amplitude of radioelement to approach the original value while that of high pass (residual) filter approaches zero.
High pass (residual) filter result therefore shows anomalous feature similar to HGM. In this study, ASA and HGM
were found most suitable and appropriate in enhancing the trend/ pattern of distribution of radioelements and their
total count. Hence, the enhancement and filtering techniques should not be limited to only potential field but to other
non-potential, in particular, radiometric field data.
| 9 |
Author(s):
Aigbadon, G.O., Okoro, A.U, Ocheli, A.
Page No : 75-83
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Geochemical analysis of Cenozoic Usani sandstone reservoirs, Niger Delta Basin, Nigeria: implications for reservoir quality and petroleum geology.
Abstract
Geochemical (XRD), gamma-ray log, thin section, porosity, and permeability data were integrated to interpreting the
depositional environments and evaluate the diagenetic changes, and then assess the reservoir quantity and quality of
the wells from the Usani field, Niger delta basin, Nigeria. Gamma-ray log suites and core samples descriptions show
that the reservoirs are made up of fine, medium to coarse sandstone lithofacies capped by mudstone and shale
lithofacies of different depositional settings ranging from storm dominated shelf, offshore bar to offshore regressive
bar depositional environments. The XRD and thin section data show that the dominating mineral is quartz with the
presence of feldspar, illite- smectite, siderite, and traces of hematite, pyrites minerals. The high cation exchange
capacity values of 8.10 - 8.40meq/100g for reservoirs A, A2, C2, A3, B4, B4 in the wells indicate high clay contents,
coupled with the presence of kaolinite, siderite, feldspar, illite-smectite, illite in reservoirs A, A2, C2, A3, B4, B4 at a
o
depth range of 9400 to 11800ft within a temperature range of 98-110 C in the wells in the field. These characteristics
make the sediments of the reservoirs respond faster to diagenetic changes such as compaction and cementation which
result in variation in reservoir quantity and quality by reducing the primary porosity of the Usani sandstone reservoirs
as the depth of burial increases which contribute to a decline in the quantity of hydrocarbon. The presence of sulphur
contents from the pyritic coatings affects the quality of hydrocarbon in terms of worldwide ranking.
| 10 |
Author(s):
Odunlami, B.E, Olatunji, A.S.
Page No : 85-97
|
Delineation of Hydrothermally Altered Zones in Tegina Area, North Central Nigeria
Abstract
Hydrothermally altered areas have been known to be good prospects for gold and copper mineralisation but are
difficult to map. Airborne Geophysical data (airborne radiometric and aeromagnetic) and Advanced Spaceborne
Thermal Emission and Reflection Radiometer (ASTER) data have been used to circumvent this challenge in many
places. This study was aimed at delineating possible hydrothermally altered areas around Tegina and its adjoining
areas using Geophysical and ASTER data. Surface structures were extracted from Aeromagnetic data, while Airborne
Radiometric and ASTER data using Band ratio and Spectral Angler Mapper (SAM) classification were used to
delineate zones of possible hydrothermal alterations. Geological mapping of two selected areas (A and B) were
undertaken for the validation of the results from the remotely delineated zones of presumed anomalies, while the soil
mineralogical composition was determined by X-ray diffractometer (XRD) technique. The interpreted ASTER data
revealed areas of with suspected hydrothermal alterations. These areas also coincided with areas with anomalous
K/Th ratios calculated from the radiometric data. Chlorite, montmorillonite, and kaolinite were the minerals
identified these areas confirming possible hydrothermal alterations. The structural orientation of these possible
hydrothermal trends in the NE-SW and E-W directions from the interpreted aeromagnetic data while the field
structural elements were in the NNE-SSW directions. The alteration anomalies were more pronounced in Area A than
B as observed from the mineral constituents of the soil samples from A. Argillic alteration is affirmed to be
preponderant in Area A and absent in the soil samples from Area B.
| 11 |
Author(s):
Agidi, B.M, Eze, C.I, Schoeneich, K, Irefin, M.O..
Page No : 99-108
|
Geology and Groundwater Potential of Doma 230 Topographical Sheet NE, Middle Benue Trough, Nigeria.
Abstract
Geology and Groundwater Potential of Doma 230 Topographical Sheet NE,
Middle Benue Trough, Nigeria.
| 12 |
Author(s):
Offor, C, Obasi, A.I., Ezeh, H.N, Igwe, E.O..
Page No : 109-116
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Integrating both Air and Ground Magnetic Data in Evaluating the Magnetic Properties of the Ironstone Deposits in Lokoja Area, North Central Nigeria
Abstract
Both air and ground magnetic data were integrated into determining the magnetic character of the ironstone deposits
in Lokoja area, northcentral Nigeria. The result of the analysis indicates that their susceptibilities in residual
aeromagnetic data range from 146.68 – 168.17 nT. The susceptibility of the ores varies between those in the basement
section and those in the sedimentary environment within the study area. Those in the basement section have a lower
residual magnetic susceptibility range (194.410 – 292.99 nT) as compared with their counterparts in the sedimentary
area (375.46 – 631.27 nT). This implies that the ores in the sedimentary basins are richer in metalliferous materials
than those hosted by the basement rocks. The influence of the host rocks on the residual susceptibility anomalies in the
study area is quite minimal. The popular trend of the iron ores in the basement section is east-west direction, while
those in the sedimentary basin trend majorly in the north-south direction. The significant difference in the residual
susceptibilities of the ores from the two geologic environments, coupled with differences in their orientations
suggests that they are of different geologic ages, and could have been formed under different geologic conditions. An
analysis of the depth of occurrence of the ores indicates that they are shallow sited ( 150 m)
| 13 |
Author(s):
Akpofure, E., Debekeme, E.S..
Page No : 117-121
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Estimated Iron (Fe) Percentage in Weathered and Ferruginized Ajali Sandstone in Western Anambra Basin, Nigeria
Abstract
A total of Ten (10) samples from Ajali Sandstone in Ayogwiri, in Etsako West Local Government Area of Edo State,
Nigeria, were collected: five representing fresh Sandstone and five representing ferruginized, weathered section of
the Sandstones. They were taken to the laboratory for quantitative determination of some chemical elements: Fe, Cu,
Mg, Na and Mn, in order to quantify the Fe percentage, using Atomic absorption spectroscopy (AAS). The result
shows that the percentage of iron ranges from 18.4% – 32.2% with an average of 26.34% in the ferruginized sandstone
- Ironstone, whereas, the percentage of iron ranges from 0.19% - 2-81% with an average of 1.61% in the fresh
sandstone samples. There is also, a slight increase in the concentration of Manganese (Mn) in the Ironstone but no
much noticeable difference in the concentration of Cu, Mg, and Na in both fresh sandstone samples and ironstone
samples. The increase of Fe percentage in the Ironstone results from weathering, leaching and accumulation of
released elements from the top layer of the Sandstone to a lower level and the hardening of the sesquioxide - rich
materials and secondary minerals. The result indicates the viability of the "Ajali Ironstone" with an average Fe
percentage of about 26.34% for the smelting of Fe at both small and large scale as the weathered zone is pervasive
