Geology
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Item Aspects of source rock evaluation and diagenetic history of the akinbo' shale eastern dahomey basin, southwestern Nigeria(Department of Geology, 2006) Nton, M. E.; Ezeh, F. P.; Elueze, A.A."The Akinbo Formation comprises a sequence of mostly dark, pale-greenish grey, laminated shale, slightly glauconitic shale, sandy shale with subordinate claystone lenses. Selected subsurface samples of the shaly facies as penetrated by Akinside 1582 well in eastern Dahomey basin, were investigated by sedimentological, mineralogical and geochemical parameters to ascertain the hydrocarbon potential and deduce the influence of variations of clay mineral indicators on the prospect. Values of total organic carbon (TOC) range from 0.46 to 1.98wt. % while the soluble organic matter (SOM) ranges from 71 to 1940 ppm and portrays that the organic matter is fair to good and adequate. Bitumen ratios have values of 15.25 to 98.98mg ext/gTOC which suggest that the sediments are immature to marginally mature. Average major elemental composition indicates 68.08% SiO2 17.55% Alc23. 4.07%K2O, 1.82%CaO, 1.57%Na2O, 1.29%MgO,• 0.62%Fe,03 and 0.50%MnO. A moderate increase in K2O from 2.26 to 4.92wt. % with depth was observed and this corresponds with increase in illite content. Equally, an increase in AI203/ (Fe203 + MgO) ratio from 7.27 to 22.07 with depth points to increasing diagenetic conditions. Illite and illite/smectite (mixed layer clays) dominate the clay mineral assemblage (>50%) while kaolinite and smectite (ca.35%) are comparatively low. Kaolinite and smectite were observed to disappear with depth as well as an increase in illite crystallinity. Smectite disappearance occurs at approximately vitrinite reflectance of 0.5 %(VRo) and illite crystallinity values are from 0.16 to 1.6°20 , which are within values of normal burial diagenesis. It can be deduced that the shale is a potential source rock varying from immature to marginally mature with prospects to generate gas rather than oil at appropriate thermal maturity. The clay mineral diagenetic indicators show that the hydrocarbon potential might have been affected by geothermal and tectonic history. "Item " Compositional characteristics and industrial assessment of sedimentary clay bodies in part of eastern Dahomey Basin, southwestern Nigeria "(Nigerian mining and geosciences society, 2005) Nton, M.E; Elueze, A.A."Clay bodies occur as lenses and interbeds within the predominantly shaley Akinbo Formation in the eastern Dahomey Basin. They are greenish to grayish, plastic, and in some places contain concretions. In order to assess their sedimentological significance as well as evaluate their potential as industrial raw materials, representative outcrop arid borehole samples .were subjected to mineralogical, chemical and physical characterization. Mineralogical determination by X-ray diffraction (XRD) method, indicates kaolinite as the major clay mineral, with a range of 32.86-58.33%. Other constituents are illite (4.95%), smectite (2.87-14.29%) and palygorskite (2.87%). The non-clay minerals are quartz, K-feldspar, micas and graphite. In terms of chemical composition, the clay bodies. are characterised by the following; Si02 (52.96-55.84%), Al2O3 (16.22-17.74%) Fe203 (7.13-10.35%); CaO (4.65-7.95%)-; MgO (2.26-3.98%) while Na20, K2O, MnO, Ti02 and P2Os have individual values < 1%. The relatively high CaO reflect some contribution from the limestone bed underlying this formation. The clay specimens generally display colour ranging from grayish in fresh, to brownish-red on firing. Corresponding values of physical parameters include linear shrinkage (3.75-7.50%), plastic limit (23- 31%), liquid limit (48-56%), plasticity index (21-30%) and water absorption capacity (5.80-11.90%). The average silica sesquioxide and alumina-iron oxide ratios are respectively 2.17 and 2.08. These values are within the range suitable for clays or shales to be used in the manufacture of good quality cement. The clays have high silica content and are relatively rich in fluxing elements such as Ca and Mg, and could be utilized in the manufacture of domestic and sanitary earth wares. The high plasticity as reflected by the values of the relevant physical indices, and the general fineness qualify the clays to be useful as fillers or coating materials in paper and paint industries. They could also be useful in the production of construction bricks, ceramics, and with beneficiation, the quality might improve for other applications. "Item Preliminary investigation on industrial properties of the olode-falansa pegmatite, southwestern Nigeria(Bachudo science, 2004) Elueze, A.A.; Itiola, O. A.; Nton, M.E.In olode-falansa area, which is part of the southwestern basement complex of Nigeria near Ibadan, the major rock types are granite gneiss, quartzite, mediun-grained granite and pegmatite. In particular, the pegmatites which occur as low-lying bodies, with a mineralogy dominated by pinkish-white microcline perthite, quartz, muscovite and plagioclase plus accessory constituents of garnet, beryl and tourmaline have been investigated for their distribution, physical, chemical and mineralogical characteristics in order to evaluate their industrial qualities. Chemical analysis shows variations in the major elements contents of the main minerals. In particular, quarta samples have 64.02 to 97.30% SiO2; 0.86 to 2.60% Ai2O3, 0.05 to 1.02% K2O and 0.13 to 1.29% Fe2O3 while the feldspar samples are61.37 to 67.83% SiO2; 16.85 to 18.40% AI2O; 11.35 to 14.32% K2O and 0.04 to 0.11% Fe2O3 respectively. The total alkalis (Na2O+k2O) indicate k-feldspar composition. The specific gravity for quartz ranges from 2.60-2.63, while that of feldspar is from 2.55-2.58. Water absorption capacity is higher for quartz (25.10-27.10%) than feldspar (4.61-5.80%). Compressive strength of selected pegmatite minerals indidcates values from 133.24 to 223.84MN/m2. The investigation shows that the pegmatites have good potential for industrial uses. They can be used directly as raw materials or after beneficiation. In particular, the quartz and feldspar can find application in the refractory, glass, ceramic and abrasive industries. They can also be found useful in minor construction works especially in homes and offices. Muscovite can be used as thermal and electrical insulators while the beryl can be useful as ornaments. The associated rocks such as gneisses, quartzites and granites can be useful in interior and exterior decorations as well as tiles manufacturing.Item Hydrogeocheraical investigation of surface water and groundwater around Ibokun, Ilesha area, southwestern Nigeria(Journal of mining and geology, 2004) Elueze, A.A.; Omidiran, J.O.; Nton, M.E.In the Ibokun area of the Ilesha schist belt of southwestern Nigeria, the dominant rock types are granite gniess and amphibolite. The granite gneiss is medium to coarse grained, with lineation marked by alignment of biotite and microcline porphyroblasts. The amphibolite is commonly massive to weakly foliated, consisting to bluish-green to yellowish-green to sheaf-like aggregate of hornblende set in a fine grain matrix of tabular plagioclase. A total of 25 water samples, obtained from both groundwater and surface water sources in sites within the two dominant tock types, were analysed for their physico-chemical characteristics with ~ the aim of assessing their quality and usability. i Result of some physical and hydrochemical parameters show average values of 7.83pH, 177.40mg/l TDS; 30.86mg/l ca2*, ] 10.1 lmg/1 Na*; 14.79mg/l K \ 4.36mg/l Mg2*, 29.59mg/l, HCO,; 25.67mg/l CT, 0.17 mg/1 Fe2*, 4.74 mg/1 NO, and 318.22ms/cm conductivity. The water hardness and sodium absorption ratio (SAR) are respectively 11.71 mg/1 and 0.72. , The total hardness, HCO'; and Ca2* are higher in the groundwater than the surface water, while NO ,, Mg2* and conductivity are comparatively higher in the surface water than the ground water. ‘ ' Statistical analysis, using the product-moment coefficient of correlation, indicate positive correlation between the following pairs of parameters: Total Hardness and TDS (r = 0.70); Na* and K* (r = 0.69); TDS and Ec (r=0.60). Weaker correlations were obtained between Ca2* and HCOj' (r = 0.51); Ca2* and Mg2* (r = 0.36) while very weak correlations were observed between pH and TH (r = 0.22) and pH and C l- (r = 0.10). Four water groups were identified, based on characterization in the Piper trilinear diagram. These include Ca - (Mg) - Na - HCOj, Ca - Na - Cl - (S04) - HCO,, Ca - (Mg) - HCO, and Na - (K) - Cl - S04. They reflect diverse effects of bedrock lithologies, base exchange processes, precipitation and weathering. In general, both water sources are slightly alkaline. They have low sodium hazard, with SAR and other related parameters such as pH, NO', and Fe2* falling within the permissible limits for potable water. The sources are generally suitable for both domestic and agriculture uses requiring minor treatments