http://196.220.128.81:8080/xmlui/handle/123456789/178 Mon, 27 Apr 2026 05:35:29 GMT 2026-04-27T05:35:29Z http://196.220.128.81:8080/xmlui/handle/123456789/5633 LITHO-BIOFACIES CHARACTERISATION OF THE CENOMANIANTURONIAN SEDIMENTS IN THE SOUTHERN BENUE TROUGH, NIGERIA OGBAHON, OSAZUWA ABIFADE This research on the litho-biofacies characterisation of the Cenomanian-Turonian interval in the southern Benue Trough, is an encompassing approach towards facies relationships of the stages. The aim of this research is to establish the depositional environments and depositional system of the Cenomanian-Turonian successions through integrated lithofacies and micropaleontological analyses. Various attributes of rock units including texture, fossil content, sedimentary structures and architecture, complimented with petrographic analysis were used to identify lithofacies and biofacies. Sample preparation for foraminifera and ostracod as well as palynomorphs followed standard preparation procedures. The sandstones are classified as subarkose, sublitharenite, quartz arenite and lithic arkose. The carbonate microfacies include mixed siliciclastic-carbonate facies, bioclastic packstone, bioclastic oolitic packstone, planktic foraminifera wackestone and ostracod wackestone. The microfacies indicate deposition in low to moderate energy marine environments. A total of 30 foraminifera species identified comprised 10 species of agglutinated tests of Ammobaculites, Ammotium and Haplophragmoides, six (6) calcareous benthic species distributed among six (6) genera and five (5) families; and 14 planktic species, distributed among eight (8) genera and six (6) families. The calcareous benthic group include Cibicidoides, Valvulineria and Praebulimina. The planktic group, characterized by low diversities, are dominated by Heterohelicids and Hedbergella. The benthic assemblages are characterized by low diversity indices (Fisher α diversity range 1.0 -7.0; dominance, range 0.7-1.0), low to high planktic/benthic values ranging from 0.0 -100.0 %, as well as occurrence of only two agglutinated foraminiferal tests morphotypes. A total of nine (9) species of marine ostracods, distributed among six genera and five families were recorded namely, Bythocypris sp., Bairdia malzi, Bairdia illaroensis, Bairdia sp., Cytherella ix aegyptopuntata, Cytherella farafraensis, Xestoleberis sp., Paracosta parakefensis , and Basslerite sp, listed in other of decreasing abundance. Palynological analysis yielded low to moderate diversity of palynomorphs of terrestrial and marine origins. The recorded pollen and spores include: Longapertites marginatus, Longapertites sp., Cyathidites minor, Zlivisporites blanensis and Retidiporites sp. Based on assemblage distribution, environmental preferences of foraminifera and ostracod taxa, diversity indices, planktic diversity, P/B ratios and morphotypes, an inner neritic to upper bathyal depositional settings is deduced. Facies analysis on outcrops and subsurface drill cores allowed recognition of 17 sedimentary facies namely, matrix supported, massive conglomerate (Gmm), clast-supported massive conglomerate (Gcm), massive mudstone/shale or siltstone facies (Fm), laminated mudstone/shale or siltstone facies (Fl), massive sandstone facies (Sm), horizontally stratified sandstone facies (Sh), trough cross bedded sandstone facies (St) and normally graded sandstone facies (Sg). Others include herringbone cross stratified sandstone facies (S-hb), planar cross stratified sandstone facies (Sp), swaley cross stratified sandstone facies (Ssc), parallel to wavy laminated sandstone facies (Slw) and sandstone-shale heterolith facies (Hsf). Remaining ones are bioturbated sandstone facies (Sb), coal facies (C), massive limestone facies (Lm) and rippled cross bedded limestone facies (Lr(w).The facies were grouped into six facies associations (FAs). The FAs are tidally influenced channel deposit (FA1), tidally influenced foreshore to shoreface deposit (FA2), middle to lower shoreface deposit (FA3), offshore deposit (FA4), flood plain/marsh/lagoon deposit (FA5) and fluvial deposit (FA6) with implications of relative sea level changes and some stratal bounding surfaces. The study has led to the identification of two depositional sequences in the Cenomanian to Turonian strata of the southern Benue Trough. PhD. Sat, 01 Apr 2023 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5633 2023-04-01T00:00:00Z http://196.220.128.81:8080/xmlui/handle/123456789/5627 BIOSTRATIGRAPHY, CHEMOSTRATIGRAPHY AND PALEOECOLOGY OF PALEOCENE TO MIOCENE SEQUENCES OF THE BENIN BASIN, SOUTHWESTERN NIGERIA. ADELABU, IFEOLUWADUN OLUWADUNSIN The Paleocene – Miocene of the Benin Basin has paucity of information, when compared with the contiguous oil producing Niger Delta Basin. The available information is attended with ambiguities, particularly, the stratigraphy as well as the microfauna and microflora in the sequences. There is therefore the need for further study to improve on the knowledge of the basin, which will aid hydrocarbon exploration. Detailed palynological, foraminifera, nannofossil and geochemical studies were carried out on surface and subsurface sediments (BH, IL, EW, AJ and XY wells) of the Paleocene – Miocene sequences of the Benin Basin, in order to identify the biozones and reconstruct environment of deposition. 263 samples were subjected to standard palynological preparation, using HCl, HF, HNO3 and ZnBr and were studied under the transmitted light microscope for occurrences of the acid insoluble microfossils. 290 samples, were prepared and analyzed for the nannofossil content. These samples were observed under the transmitted light microscope at about 1000x magnification. 47 samples were also analyzed for foraminifera occurrences. Major, trace and rare earth elemental composition analysis were carried out using the multi-acid, ultra- trace ICP-ES/MS (MA250, 30 samples) and whole rock Lithium Fusion ICP finish (LF300, 30 samples) methods. The measurement of variations in the stable isotopes of carbon and oxygen of 15 samples, were carried out at the University of Wyoming Stable Isotope Facility, USA. XRD analysis was carried out on 13 limestone samples and 17 clay samples, so as to ascertain the mineralogical contents. The palynological samples yielded fairly abundant palynomorphs. Based on the marker palynomorphs recovered from studied samples, five palynological Zones were identified in the Paleocene to Miocene sequences of the basin and the zones were labelled, PfI – PfV Zones. About 128 species of calcareous nannofossils belonging to 59 genera of about 24 families were identified in BH, IL, AJ and wells. Five calcareous nannofossil zones (CI – CV) were delineated using marker species. The zones correspond to NP1 – NN6 Zones in the Paleocene – Late Miocene Epochs. The absence of typical Late Oligocene to earliest Miocene forms (Discoaster druggii, Helicosphaera recta and Sphenolithus ciperoensis) indicated stratigraphic gaps just below the middle Miocene. So also, an unconformity was identified above the Early Eocene, as typical Late Eocene assemblage was missing (Chiasmolithus oomaruensis, Rhabdolithus gladius,Nannoterina fulgens and Discoaster saipanensis). At least, four recognizable major and trace element chemostratigraphic boundaries were established in the study column. The estimated paleotemperature from the stable isotopes of carbon and oxygen in the limestone samples was between 190C and 390C. The Paleocene Eocene Thermal Maximum event was identified at around 11m in the EW core. The relative low occurrence of herbaceous species, savanna and montane species in the Early Paleocene indicates warm tropical climate, while the preponderance of rain forest elements and spores can be associated with humid and wet conditions, as well as increased fluvial activities. The presence of Braarudosphaera bigelowii, Broinsina, Nannoconus spp., and also the presence of some species of the Calyptrosphaeraceae family, Holodiscolithus solidus and Calculites ovalis, indicates shallow marine or near shore deposition. Overall, a warm, wet tropical climate was inferred for the Early Paleocene and cooling conditions in the Miocene. PhD. Sat, 01 Apr 2023 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5627 2023-04-01T00:00:00Z http://196.220.128.81:8080/xmlui/handle/123456789/5557 DIVERSE EXHUMATION IN THE CRETACEOUS BORNU BASIN DETERMINED BY APATITE FISSION TRACK THERMOCHRONOLOGY OLAWUMI, EMMANUEL OLAWALE This research work is designed to investigate the magnitude and the temporal, as well as spatial extent of exhumation events in the Bornu basin. This is to be able to identify major periods of heating and cooling, so as to quantify how the temperature has varied through time and; as pointer to how they affect the generation of liquid Hydrocarbon in the basin as a guide to further exploration. The Apatite Fission Track Analysis data were obtained from the ditch cutting samples of Six carefully selected wells in the Three major depressions identified in the Bornu basin : Kutchali – 1, Mbeji – 1 and Kasade-1 in the Chadian section (Depression A); Gaibu-1 and Kinasar-1 in the Maiduguri SE (Depression C) and Ngor-1 in the Maiduguri SW (Depression D). The data collection procedure began with mineral separation, mounting and etching using FrantzTM isomagnetic separator, Epoxy-ResinTM (epo-thin) and 5.5M Nitric acid (HNO3) at exactly 200C, respectively. Temperature-time histories are calculated by inverse modelling approach using the version 1.67 of HeFTy with a multi-compositional annealing model and the Dpar values as kinetic parameters. The Apatite Fission Track ages of data point of each well was plotted against both their Mean Track Length and their stratigraphic ages to produce the thermal history and consequently exhumation events in each well. Inferences and observations from the results show that it can be strongly argued that the paleotemperatures observed in the area of study are due primarily to greater depth of burial, with contribution from increased paleogeothermal gradient and other factors such as intrusions caused by magmatism. Hence, it is clear that two significant paleothermal events are captured by the AFTA data obtained from the Bornu basin i.e the Upper Cretaceous (89 – 67 Ma) cooling episode, which is widespread and; the Paleocene (62.5 – 62 Ma) episode which may be much restricted. The Temperature-time plots also shows that cooling from paleothermal maximum did not begin at the same period M.Tech. Sun, 01 Dec 2019 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5557 2019-12-01T00:00:00Z http://196.220.128.81:8080/xmlui/handle/123456789/5556 PAVEMENT FAILURE ALONG OTA-LAFENWA- ITELE HIGHWAY, SOUTHWESTERN NIGERIA AKINLOLU, OLADIMEJI OLUGBENGA Ota-Lafenwa-Itele highway has experienced severe failure of various forms over the years. Being an interstate road that link some Nigerian border communities in Ogun State to Lagos, the effect of the failure has significant negative impact on socio-economic growth. In order to assess the causes of the road failure and proffer preventive measures for future reconstruction of the road, geotechnical engineering properties of the subsoil and visual pavement condition were evaluated. Twenty five disturbed and nine undisturbed soil samples were collected from nine test pits at depths of 1.5 m to 2 m. The soil tests carried out on the disturbed samples were Atterberg limits, linear shrinkage, grain size, hydrometer, standard compaction, California Bearing Ratio (CBR), consolidation and triaxial tests. Those carried out on undisturbed samples were natural moisture content, bulk density, dry density and specific gravity tests. The study area is underlain by Coastal Plain Sand (CPS) formation, a Tertiary age sediment of the uppermost Dahomey Basin. Pavement failures observed are rutting, potholes, corrugation, side drain, edge collapse. The natural moisture content values obtained ranged from 9.98 to 16.89%, specific gravity ranged from 2.65 to 2.71, liquid limit values ranged from 26.7 to 58.18%, plastic limit values varied from 13 to 40.1%, while linear shrinkage ranged from 3.6 to 14.8, plastic index ranged from 11.35 to 28.43, swell index values ranged from 0.1765 to 0.67621, liquidity index varied from -1.0532 to -0.0004, activity index varied from 0.39 to 0.69. Dominant subgrade soil types are CH,CL,MH and ML groups based on USCS classification system and A-7 soil group based on the AASHTO classification system. Grain size analysis shows that gravel fraction ranged from 0.1 to 2.4%, sand fraction ranged from 20.6 to 52.8%, silt fraction ranged from 13.8 to 29%. The MDD ranged from 1350 to 1672kg/m3 and the OMC ranged from 13.4 to 25.5%. unsoaked CBR values ranged from 19 to 44% and soaked CBR ranged from 4 to 13%, coefficient of consolidation ranged from 0.0067 to 0.4236m3/yr, final void ratio ranged from 0.407 to 0.878, the rate of settlement ranged from 0.6024 to 1.1622mm/yr, angle of internal friction ranged from 35.40 to 39.30, cohesion ranged from 43.5 to 150.1kPa, shear strength ranged from 101.1 to 202.5kPa. The negative and weak correlation between CBR and clay content (r=-0.10), CBR and swell index (r=-0.08), CBR and plastic index (r = - 0.11) suggest that the clayey, plastic and swelling property of the soils has less effect on their bearing capacities. The correlation between CBR and coefficient of consolidation (r = + 0.52), CBR and MDD (r=+0.33) implied that increase in MDD values and consolidation characteristics increases the CBR values. The correlations between MDD and Settlement (r =-0.47), MDD and void ratio (r =-0.65) indicate that the soil’s improvement through compaction has strong effect on compressibility. The weak correlation between MDD and shear strength (r = +0.15) implied that the shear strength has less effect on the MDD. Dominance of low CBR, low MDD, high linear shrinkage, and A-7 soil group expectedly contributed to the road failure. Total overhaul of the road, treatment of the subgrade soil, replacement of the base course material and construction of drainage are recommended for the highway. M.Tech. Sun, 01 Aug 2021 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5556 2021-08-01T00:00:00Z