Geology
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Item A GRAVITY PROFILE OF THE LOWER BENUE TROUGH OF NIGERIA(1976-06) ADIGHIJE, C. I.Gravity measurements were made along a roughly east-west profile across the lower Benue trough, with the main objectives of investigating the nature and configuration of the basement beneath the trough and determining the thickness of the sedimentary cover rocks. I87 gravity stations were established at 2-4km intervals and standard corrections were applied to the observed gravity values. A Bouguer gravity map of the whole Benue trough is compiled from the results of these measurements and data obtained from previous works. The map shows that the positive anomaly along the axis of the trough is a most prominent regional feature that extends over the whole length of the trough. The abrupt truncation of the positive anomalies along a NNE-SSE line may represent the Cretaceous continental margin. The axial positive is ascribed to the doming of the basement underlying relatively dense Albian Shales and their associated intermediate to basic intrusives along the trough axis as a result of tectonic processes. "Growth” of the positive anomaly towards the South is attributed to the basement being at a shallower depth in the lower Benue than in the upper Benue trough and to the probability that oceanic crust underlies the sediments at the southwestern end of the trough. The negative anomalies are due to thick sedimentary sequences which fill the flanks of the trough. The sediments are estimated to have a maximum thickness of 4.25km in the surveyed area of the lower Benue trough.Item Electromagnetic profiling and resistivity soundings in groundwater investigation near Egbeda- kabba, Kwara state(1990) Olayinka, A.I.As part of a borehole siting programme for rural water supply in a Precambrian crystalline basement terrain, 36 Offset - Wenner electrical soundings and about 4.5 line-kilometres of ground conductivity profiling with a Gconics EM34-3 equipment were made near Egbeda-Kabba. Kwara Slate, Nigeria. The EM34-3 measurements provided a rapid reconnaissance tool in identifying high conductivity anomalies thought to be due to deep weathering and/or bedrock fissuring. The apparent conductivities arc generally less than 50 mmho m'1. A quantitative interpretation of the vertical sounding data indicated that the resistivity of the weathered zone varies over a wide range, from about 10 to 200 ohm.m, and that the overburden is generally less than 40m thick. Three abstraction wells, each having a yield of about 11s"1, were drilled at deeply weathered sites (depth to bedrock > 20m) identified from the surface geophysical measurements.Item Electromagnetic profiling for groundwater in precambrian basement complex areas of Nigeria(1990) Olayinka, A.I.Ground electromagnetic profiling, using a Geonics EM34-3 instrument, has been employed to identify areas of high conductivity in a Precambrian basement complex terrain of Nigeria. Field examples, conducted as part of a rural water supply programme, are presented. They indicate that the apparent conductivities are generally lower than about 60 mmho m-1. Subsequent borehole drilling suggests a good correlation between high EM34 anomalies, deep weathering and high well yield (> 1 1 s-1). On the other hand, boreholes sited on conductivity lows penetrated a thinner regolith with relatively lower yields.Item Geophysical siting of boreholes in crystalline basement areas of Africa(Pergamon Press Ltd, 1992) Olayinka, A.I.This paper assesses the effectiveness of surface geophysical methods namely electrical resistivity, electromagnetic, seismic refraction, magnetic, gravity and induced polarization for groundwater exploration in crystalline basement complex areas. Most of these geophysical techniques can provide quantitative information on the characteristics of the weathered zone which relate to the occurrence of an economic aquifer. The critical factors in the choice of a particular method include the local geological setting, the initial and maintenance costs of the equipment, the speed of surveying, the manpower required as field crew, the degree of sophistication entailed in data processing to enable a geologically meaningful interpretation, and anomaly resolution. The particular advantages and limitations of each technique are highlighted. Several case histories from Nigeria and the rest of Africa indicate that electrical resistivity (both vertical sounding and horizontal profiling) is the most widely used, followed by electromagnetic traversing. These are often employed in combination to improve upon the percentage of successful boreholes. Due to the high cost of equipment, large scale of the field operations and difficulties in data interpretation, seismic refraction is not widely adopted in commercial- type surveys. Similarly, magnetic, gravity and induced polarization are used only sparinglyItem MINERALOGICAL AND GEOCHEMICAL STUDIES OF AGBAJA IRONSTONE FORMATION NUPE BASIN, CENTRAL NIGERIA(1994-07) ABIMBOLA, A. F.Agbaja Ironstone Formation of the Lokoja district, Central Nigeria occurs within the Upper Cretaceous sedimentary sequences of the NW-SE trending Nupe Basin. Three lithostratigraphic units were delineated; Lokoja Sandstone (the oldest), Patti Formation and Agbaja Ironstone Formation. Lokoja Sandstone rests unconformably on the basement complex and grades from conglomerate to arkosic sandstone. Patti Formation consists of intercalations of sandstone, siltstone and carbonaceous mudstone units. Agbaja Ironstone Formation is made up of colites, pisolites and bog ore. Textural studies show a very finely to very coarsely skewed mesokurtic sands for Lokoja Sandstone and leptokurtic for Patti Formation. ZTR index value ranges from 61 to 81% for Lokoja Sandstone and 83 to 95% for the Patti Formation. Higher ZTR index value for Patti Formation indicates a relative higher mineralogical maturity over the Lokoja Sandstone. These sedimentological studies indicate a basement source for the sedimentary materials deposited under low energy short fluvial regime, that evolved into two facies; alluvial fans and flood basin. Four petrographic varieties of the Agbaja Ironstone Formation were identified; ooidal pack-ironstone, pisoidal packironstone, detrital mud-ironstone and breccia mud-ironstone Kaolinite ooids are spherical, oblong and fragmented, usually with pseudomorphs of goethite after pyrite at the core. Goethite pisoids cemented in kaolinitic to goethitic matrix are elliptical, oval, subspherical in shape and composite in nature. Constituent minerals of the mud-ironstone are kaolinite, quartz and heavy minerals. Paragenetic studies show that pyrite, siderite, kaolinite, quartz, mica and heavy minerals are the initial minerals of the ironstone while secondary enrichment minerals are goethite, hematite, goyazite-crandallite, bolivarite and boehmite. Chemistry of these minerals further classified them into ferritic kaolinite, kaolinitic ferrite and ferrite. Si02 ranges between 23.71 and 56.41 % and AI203 between 22.01 and 36.54% in all the unferruginized portions of the Agbaja ironstone. But both components can jbe as low as 0.22% in the ferruginized equivalent. Si02 and AI203 contents are highest in the mud-ironstone varieties and lowest in the pack-ironstone varieties. Fe203 content increases from about 1.59% in the unferruginized to about 97.54% in the ferruginized equivalents, for all the petrographic varieties. The highest concentration of Fe203 is in the pisoidal pack-ironstone. P20S values range between 0% in the unferruginized to 5.10% in the ferruginized portions, and often increase with increasing Fe203 contents. MgO, CaO, MnO, Na20 and K20 are generally less than 1.0% in all the petrographic varieties. Element mobility during ferruginization indicates that iron enrichment is accompanied by a parallel depletion in Si02 and AI203, moderate to extreme reduction in CaO, MgO, MnO, Na20 and K20 and a significant gain in P205. This relationship confirms the supergene nature of the replacement process (desilicification, removal of alumina and iron enrichment process (ferruginization). Sedimentological, mineralogical and geochemical studies provided evidences for a kaolinitic precursor for the ironstone deposit, contrary to the earlier proposed chamositic precursor. Also the presence of pseudomorphs of pyrite in nuclei and as incorporation into the concentric laminae of ooids are reliable indicators for a possible accretionary model for the formation of ooids and pisoids prior to ferruginization. Two ferruginization periods unrelated to lateritization were established; first won enrichment is supply due to oxidation of the initial pyrite/siderite and reconcentration of absorbed FeOOH in the lattice structure of kaolinite; second period is linked to the presence of bacteria (framboids) which is oxidised to form iron phosphate complex in the bog ore. The Fe and P were remobilised into the underlying pack-ironstone by descending meteoric water.Item Error in depth determination from resistivity soundings due to non-identification of suppressed layers(Elsevier Science, 1997) Olayinka, A.I.The magnitude of errors in the determination of depth to bedrock from Wenner and Schlumberger resistivity sounding curves, caused by the nonidentification of a suppressed layer, has been investigated. The principal objective is to evaluate how the layer thicknesses and resistivities affect the accuracy of depth estimates. In the computations, the intermediate layer in a 3-layer model, in which the resistivity increases with depth, is removed and the 2-layer sounding curve that is electrically equivalent to the 3-layer curve is generated. The results indicate that there is a possibility for large depth underestimations when the resistivity contrast between layers 1 and 2 is very large. This is manifested in a steeply rising terminal branch on the sounding curve. There is a slight decrease in the depth underestimation as the resistivity contrast between layers 2 and 3 increases. Conversely, if the intermediate layer is fairly thick and the resistivity contrasts are not too large, the best-fit 2-layer curve shows large deviations from the 3-layer curve, in such cases, the intermediate layer can be identified, resulting in reliable depth estimates. A field example from Nigeria is presented in which the sounding data has been interpreted so as to account for a prebasement layer of intermediate resistivity, indicative of a fractured granite.Item MINERALOGICAL INVESTIGATION OF CORROSION PRODUCTS IN PROCESSING MACHINES(THE NIGERIAN SECURITY PRINTING AND MINTING COMPANY (NSPMC) LIMITED, LAGOS RESEARCH AND DEVELOPMENT DEPARTMENT, 1997) Nton, M. E.Item Sedimentology and depositional environment of Awi formation Calabar flank, southeastern Nigeria(Journal of mining and geology, 1999) Nton, M.E"A sequence of conglomerates, sandstones, siltstones, claystones carbonaceous shales and mudstones which rims the Oban Massif in the Calabar Flank, constitutes the Early Cretaceous (probably Aptian) Awi Formation In the southeastern Nigeria. Field studies and laboratory analyses were conducted on these sediments to determine their provenance and depositlonal environment. Field observations show that the sediments are grently dipping (.< 16°) in a southwesterly direction. They vary in thickness from thin to very thick beds and are laterally, discontinuous. The pattern of sedimentation is cyclic with fining upward sequences. The sediments are textually immature with angular to subangular grains dominating, thus indicating short distance transportation. The sandstones are medium to coarse-grained, poorly sorted, mostly leptokurtic, fine skewed and unimodal in distribution. They are subarkoslc with more than 70% quartz which are of Igneous and metamorphic origin while the associated claystones contain kaolinite. Heavy mineral assemblages show the presence of predominantly zircon, tourmaline, rutile, garnet and staurolite with a range of 66.7 to 96%. This indicates mature to superrnature sandstones and can be attributed to wet climatic conditions. The carbonaceous shales which grade into mudstone In some cases are non-fossillferous, poorly laminated, pyritized and rich in lignitised wood. All these indicate that sediments of Awi Formation were derived from the Oban Massif and deposited in environments ranging from channel lag and point bar to flood plain. "Item Aspects of equivalence in two-dimensional resistivity imaging and modelling(Nigerian Mining and Geosciences Society, 2000) Olayinka, A.I.The possibility for geoelectrical equivalence in two-dimensional (2-D) inversion of apparent resistivity data has been investigated. This involved the calculation of synthetic pscudosection data for simple geological structures using a finite difference approach. With the aid of statistical F-test, it is shown that identical or near-identical pseudosections can be generated from more than one 2-D model. In particular, the apparent resistivity pscudosection measured over2-D structures like basement fault, trough and horst resemble those arising from lateral variations In the overburden resistivity.Item Use of block inversion in the 2-D interpretation of apparent resistivity data and its comparison with smooth inversion(Elsevier, 2000) Olayinka, I. A.; Yaramanci, U.The ability of a block inversion scheme, in which polygons are employed to define layers and/or bodies of equal resistivity, in determining the geometry and true resistivity of subsurface structures has been investigated and a simple strategy for deriving the starting model is proposed. A comparison has also been made between block inversion and smooth inversion, the latter being a cell-based scheme. The study entailed the calculation (by forward modelling) of the synthetic data over 2-D geologic models and inversion of the data. The 2-D structures modelled include vertical fault, graben and horst. The Wenner array was used. The results show that the images obtained from smooth inversion are very useful in determining the geometry; however, they can only provide guides to the true resistivity because of the smearing effects. It is shown that the starting model for block inversion can be based on a plane layer earth model. In the presence of sharp, rather than gradational, resistivity discontinuities, the model from block inversion more adequately represents the true subsurface geology, in terms of both the geometry and the formation resistivity. Field examples from a crystalline basement area of Nigeria are presented to demonstrate the versatility of the two resistivity inversion schemes.Item Hydrochemical assessment of surface water in part of South-eastern Nigeria(Mineral wealth, 2001) Elueze, A. A.; Ephraim, B. E.; Nton, M. E."The area of study occurs mainly within the Calabar Flank and part of the adjacent basement terrain of the Oban Massif. The latter is composed of mainly migmatitic gneisses, phyllites, amphibolites, granites, schists and granodiorites, while the major lithologies of the Calabar Flank include carbonates, shales, claystones and sandstones. This study aims at determining the quality and usability of the water, in addition to ascertaining the possible pollutants and ways to ameliorate their effects. Results of some physical and hydrochemical parameters have average values of 5.53pH, 77.4mg/I TDS, 17.8mg/l Na+, 5.5mg/l Ca2+, 13.2mg/l Cl , 3.3mg/l S042', 0.7mg/I NO'3, and 49.6ms/cm conductivity. The water hardness and sodium absorption ratio (SAR) are respectively 20.5mg/l and fi.fi. The total hardness, Ca2+, S042' are higher for the water draining the carbonate rock environs, while the TDS, Na+, conductivity and Cl"" are greater in the basement rock areas. Hydrochemical parameters in the piper trilinear diagram, as well as the Gibbs plot, respectively suggest that the water is of sodium bicarbonate facies, and dissolved solids are mostly products of weathering. Application of R-mode factor analysis suggests that the main components of the water characteristics are related to hydrological, lithological and environmental controls. The factor containing CO32- and HCO3"", is derived from the carbonate rocks in the area, whereas Na+ and K+ which are possibly transported in solution as base exchange of clay minerals, notably characterize the basement rocks. The group showing enrichment in Cl , Mg2+ and NO3 is considered to be associated with environmental control, through precipitation of meteoric water, while the presence of S042"" is linkable to the aeration of sulfide minerals in the area. On the whole, the water is slightly acidic with low sodium hazard. It therefore satisfies the World Health Organisation (WHO) standards for domestic, agricultural and other industrial uses requiring usual treatment such as filtration and disinfection."Item Integrated use of geoelectrical imaging and hydrochemical methods in delineating limits of polluted surface and ground water at a landfill site in Ibadan area, Southwestern Nigeria(Nigerian Mining and Geosciences Society, 2001) Olayinka, A.I.; Olayiwola, M.A.The Impact of solid waste disposal at the Ring Road district of Ibadan metropolis, southwestern Nigeria, on the adjoining surface and ground-water sources, has been Investigated. The basement rocks include Precambrian quartzites and quartz-schists that have been extensively weathered. In this study, the geophysical survey Involved 5 electrical imaging lines, while the hydrochemical database comprised 4 samples of surface water and 6 samples of groundwater from dug wells. The samples were analysed for turbidity, pH, conductivity, total hardness, total dissolved solids (TDS), alkalinity, Cl, No3, SO42, PO43, Na, K+, Mg2 and Fe2. The results show that water bodies located in a down gradient direction and in close vicinity of the landfill, has received significant inputs of inorganic pollutants. Statistical analyses indicate positive correlation (p<0.05) between the following pairs of parameters: Ca2 and Mg2. (R=0.83; Na+ and K+ (R=0.95); (Na2+Mg2) and Cl (R = 0.92); (Na2 + K2) and Ca2 (R=0.96); pH and Cr (R = 0.87). Moreover. the electrical conductivity shows a positive correlation (p<0.05) with the concentrations of K+ (R = 0.97); Na+ (R = 0.96); Ca2+ (R = 0.93); Mg2+ (R = 0.82); Fe2+ (R = 0.85); Cl (R = 0.91) and TDS (R = 0.98). On the other hand, the conductivity shows a negative correlation with SO42 (R = 0.78). Corroborating evidence was provided from the geoelectrical imaging data which Indicate that the thickness of the waste dump ranges between about 2m to 17m, while its resistivity is low at between 4 and 8ohm-m. The low resistivity is due to the presence of leachate emanating from the site and this has also polluted the surface and ground-waters in the Immediate delineation of the limits of the probable polluted zone.Item Smooth and sharp-boundary inversion of two-dimensional pseudosection data in presence of a decrease in resistivity with depth(Geophysical Press, 2002) Olayinka, A.I.; Yaramanci, U.The smooth and sharp-boundary inversion of two-dimensional (2D) apparent resistivity pseudosection data in cases where the half-space has a lower resistivity than the overburden is investigated. The study entailed calculation (by forward modelling) of the synthetic data over simple 2D geologic models and inversion of the data. The 2D structures modelled include vertical fault, graben and horst. The Wenner array was used. The results show that there is generally an improvement in the model misfit with iteration number in smooth inversion; the algorithm can then be expected to iterate to the best solution at a high iteration number where the model resistivity of the substratum approaches the true bedrock resistivity. Inversion of the data using sharp boundaries indicates that the range of 2D equivalence, for which a reasonable interpretation could be attained, is relatively narrow. For the equivalent solutions, the data misfit between the observed and the calculated data is very small while model interpretations that are wrong can be readily identified on account of very large data misfits. A field example is given from Nauen, northern Germany, where partly-saturated sand of high resistivity is underlain in succession by less resistive saturated sand and glacial till; the smooth and sharp-boundary inversion results are in good agreement with the geo-radar and surface magnetic nuclear resonance (SNMR) and borehole informationItem Smooth and sharp-boundary inversion of two- dimensional pseudosection data in presence of a decrease in resistivity with depth(ELSEVIER, 2002) Olayinka, A.I.; Yaramanci, U.The smooth and sharp-boundary inversion of two-dimensional (2D) apparent resistivity pseudosection data in cases where the half-space has a lower resistivity than the overburden is investigated. The study entailed calculation (by forward modelling) of the synthetic data over simple 2D geologic models and inversion of the data. The 2D structures modelled include vertical fault, graben and horst. The Wenner array was used. The results show that there is generally an improvement in the model misfit with iteration number in smooth inversion; the algorithm can then be expected to iterate to the best solution at a high iteration number where the model resistivity of the substratum approaches the true bedrock resistivity. Inversion of the data using sharp boundaries indicates that the range of 2D equivalence, for which a reasonable interpretation could be attained, is relatively narrow. For the equivalent solutions, the data misfit between the observed and the calculated data is very small while model interpretations that are wrong can be readily identified on account of very large data misfits. A field example is given from Nauen, northern Germany, where partly-saturated sand of high resistivity is underlain in succession by less resistive saturated sand and glacial till; the smooth and sharp-boundary inversion results are in good agreement with the geo-radar and surface magnetic nuclear resonance (SNMR) and borehole informationItem 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 treatmentsItem Organic geochemical appraisal of limestones and shales in part of eastern Dahomey Basin, southwestern Nigeria(Journal of mining and geology, 2004) Elueze, A.A; Nton, M. E."The major lithostratigraphic units of the eastern Dahomey Basin are the Araromi, Ewekoro and Akinbo Formations. Field studies show that the Araromi and Akinbo Formations contain shaly facies, while the Ewekoro Formation contains essentially fossiliferous limestones. The Araromi shales are dark and bituminous, while those of the Akinbo are fissile and concretionary. Selected subsurface and outcrop samples of these lithotypes were analysed to ascertain their palaeodepositional environments and hydrocarbon prospects. Total organic carbon (TOC) of the limestones and shales range from 0.10 to 1.00 wt.% and 0.20 to 1.60wt% respectively. Bitumen yields are 896.20, 108.70 and 376.80ppm correspondingly for Araromi, Ewekoro and Akinbo Formations. Bitumen ratios are 68.70, 28.30 and 72.70mgext/g TOC respectively, for the three succeeding formations. CPI values and pristane/phytane ratios are 1.29, 1.19, 0.99 and 1.53, 1.33, 1.17, respectively for Araromi, Ewekoro and Akinbo Formations. Cross-plots of isoprenoids/n-alkanes show that the organic matter falls within the terrestrial and transitional environments. However, the fossil assemblages of the limestones made up of coralline algae, pelecypods, echinoids, gastropods and few other skeletal debris, indicate a nearshore marine environment. Organic petrography reveals preponderance of vitrinites (Type III O.M.) with subordinate inertinites (Type IV) in all the three formations. The dominance of terrestrial O.M. indicates gas rather than oil proneness of the kerogen. N-alkane profiles, plots of bitumen ratios with depth and the presence of unresolved complex mixture hydrocarbons in most gas chromatograms, indicate immature status for the kerogens. This suggests insufficient cooking of the sediments."Item Strengthening academic linkages and collaboration in universities(The Graduate School, University of Calabar, Calabar, Cross River State, 2004-07-28) Olayinka, I.