Browsing by Author "Alebiosu, M.T."
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Item Axis Rotation of a Major F1 Fold during a Retrograde F2 Deformation in Southwestern Nigeria(Centrepoint Journal (Science Edition), 2017) Adedoyin, A.D.; Ojo, O. j.; Alebiosu, M.T.; Adekeye, J.I.D.; Bamigboye, O.S.North east of Ilorin, South-western Nigeria, a NE-SW trending (F1) fold which was later refolded, was identified in part of the Basement Complex of the country. The area falls within the West African domain of the Pan African (600±150Ma) remobilized metamorphic terrain. Polyphase deformations, which involved at least three tectono-thermal episodes, were also identified. The area falls within the N-S trending Schist Belts where a large-scale sheeted S1 penetrative metamorphic imprint was successively deformed into an overturned antiformal (F1)fold and, later, to a broad synformal (F2) fold whose axial traces are generally NE-SW and E-W, respectively. The first deformation episode was essentially metamorphic while the subsequent ones were tectonic. Petrological associations indicate that the rocks are mainly gneisses, psamites and psamitic to semi-pelitic schists, cut by Pan African granitoids. These rocks were deformed under high-temperature, low-pressure amphibolite facies conditions, but downgraded from high to medium grade metamorphic interface during a later tectonic event, under a high geothermal gradient within the upper crust. An occurrence of an overturned fold in the northern end of the axial trace of F1 is attributed to irregular strain distribution that culminated in the open F2 antiform during the third deformation episode. Of interest, within the context of the structural geology of Nigeria, is the E-W trend of the axis of the F2 fold, which is apparently discordant to the observed general N-S structural trends in the Basement Complex of Nigeria. The origin of this latter structure is attributed to localized tangential deformation, culminating in fold axis rotation in the direction of the X axis, and subsequently overturning and tightening of the original F1 fold during the late- to post- tectonic phases of the Pan African tectonism.Item Geochemical characteristics of sediments in river Niger fadama, central Nigeria(European Water Resources Association, 2017) Omotoso, O.A; Ojo, O.J.; Alebiosu, M.T.Floodplain also known as Fadama in Nigeria is a large centre of agricultural activities but usually faced with challenges of contamination. This study focused on the floodplain of River Niger at Jebba, Central Nigeria and the objectives of the study were to assess the geochemical characteristics of the sediments as well as their weathering indications. Thirty sediment samples were randomly collected over the entire Fadama and subjected to pulverization and geochemical analysis using X-ray Fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICPMS) for major oxides, trace and rare earth elements determinations. The geochemical results show that the average concentrations of the major ions (SiO2, Al2O3, Fe2O3, CaO, MgO Na2O, K2O, MnO, TiO2, P2O5, and Cr2O3) are: 66.14 wt%, 13.16 wt%, 4.48 wt%, 0.57 wt%, 0.56 wt%, 0.59 wt%, 1.86 wt%, 0.07 wt%, 0.99 wt%, 0.06 wt% and 0.01 wt% respectively. According to Upper Continental Crust Average Concentration (UCC), the major ions are depleted in the sediment except TiO2 that is enriched having an average value of 1.98; the trace elements are also depleted in the sediments except Ba, Co, Cs, Ga, Hf, U, V and Zr that are enriched having average values greater than 1; and the rare earth elements are highly enriched in the sediments with average values greater than unity. The weathering indications show that CIA, PIA and CIW give average values of 80, 89 and 92, respectively. This shows that the sediments have undergone intensive weathering. The intensive weathering of the sediments would have contributed to the concentration of metals in the water phase. Contamination Factor and Enrichment Factor of the sediments show that the sediments are enriched in trace and rare earth elements from geogenic and anthropogenic sources.Item Geochemistry of Aliphatic Hydrocarbon Compounds in Core Sediments from Sadong River, Malaysia(FUW Trends in Science & Technology Journal; Federal University Wukari, 2023) Omorinoye, O.A.; Assim, Z.B.; Bamigboye, O.S.; Alebiosu, M.T.Item GEOLOGICAL AND GEOCHEMICAL ASSESSMENTS OF STREAM SEDIMENTS OF EJUKU AREA(NSUK Journal of Science & Technology, Nasarawa State University, 2016) Alebiosu, M.T.; Adekeye, J.I.D.; Adedoyin, A.D.Geological and Geochemical assessments of Ejuku area, North-Central, Nigeria, was carried out with the aim of identifying the mineralization potential as well as delineating mineralized zones in the area. The geological investigation revealed that the area is underlain by porphyritic granite, medium-coarse granite, granitic and banded gneisses, amphibolite, quartzite and mica schist. Twenty five representative stream sediment samples were digested in aqua regia solution and analyzed by ICP-MS method for trace and rare earth elemental concentrations. The analysis of the stream sediment samples, revealed the following range of concentration for each element: Fe (0.59-4.97%), Mn (60-1273 ppm), Ce (19.3-608 ppm), La (2.5-307.5 ppm), Ba (8.5-149.8 ppm), Cr (9.0-125.2 ppm), V (3-121 ppm), Cu (6.78-40.10 ppm), Pb (2.18-30.19 ppm), Zn (3.7-44.0), Ag (2-24ppb), Ni (2.9-13.6 ppm), Co (0.9-18.6 ppm), U(0.57-11.18 ppm), Th (3.0-76.5 ppm), Rb (5.7-46.9 ppm), Au (0.2-0.9 ppb), Y (0.81-27.79 ppm) and Li (1.2-17.2 ppm). The correlation coefficient for the selected elements show very strong correlation between Pb, Co, Fe, Ba and Mn as well as between Th, La, Rb, Ce, Zn and Y. The isograde plots show that most elements have their peaks in the western and northeastern part of the study area. The study therefore revealed that the area is rich in manganese, iron, K-feldspar and mica which are hosted, possibly, by schist and amphibolites.Item Multivariate Analysis of Stream Sediments Geochemical Data from part of Egbe-Isanlu Schist Belt(Adamawa State University Journal of Scientific Research; Adamawa State University, 2015) Alebiosu, M.T.; Adekeye, J.I.D.; Adedoyin, A.D.; Bamigboye, O.S.; Omorinoye, O.A.Item Petrography, Geochemistry and Petrogenesis of Grey Gneisses of Part of Oke-Ode Area, South-western Nigeria(COOU Journal of Physical Sciences; Faculty of Physical Sciences, Chukwuemeka Odumegwu Ojukwu University, 2022) Adedoyin, A.D.; Alebiosu, M.T.; Bamigboye, O.S.; Olobaniyi, S.B.; Omorinoye, O.A.; Iheme, K.O.Item PETROGRAPHY, GEOCHEMISTRY AND PETROGENESIS OF GREY GNEISSES OF PART OF OKE-ODE AREA, SOUTH-WESTERN NIGERIA(Published by Faculty of Physical Sciences, Chukwuemeka Odumegwu Ojukwu University, Anambra State, Nigeria., 2022) Adedoyin, A.D.; Alebiosu, M.T.; Bamigboye, O.S.; Olobaniyi, S.B.; Omorinoye, O.A.; Iheme, K.O.Oke-Ode area, northeast of Ilorin, is part of the Precambrian Basement Complex of southwestern Nigeria. There are no published data on the gneisses, which are well exposed, unlike the adjacent terrains. The area was mapped in order to determine the petrographic, geochemical and petrogenetic attributes of the grey gneisses. The acquired sets of field, mineralogical, and geochemical data indicated that the medium-to coarse-grained gneisses are of igneous origin, and have witnessed multiple tectono-thermal readjustments. Occurrence of xenoliths in the rocks points to magmatic origin. The range of anorthite molecular contents of the plagioclase (An26-34) suggests an andesine to oligoclase composition, indicating derivation from granodioritic to tonalitic progenitors. Petrographic studies showed that the rocks witnessed complex interplay between metamorphism, deformation, and migmatization, which culminated in grain-boundary migration under a relatively stable, low-strain, high temperature conditions involving mechanical rotation, during grain-scale dynamic recrystallization. Geochemically, plots of Ni vs Zr/TiO₂ and K₂O/Al₂O₃ vs Na₂O₃/Al₂O₃ also constrained the the gneisses to the igneous field while the TiO2 - K2O - P₂O₅ ternary plot further indicated a continental tectonic setting prior to the widespread Pan African magmatism. The rocks are essentially peraluminous calc-alkaline rocks, which are moderately saturated with respect to silica. They are products of fractional crystallization of a basaltic magma in a continental setting but later reworked during the Pan African time. The grey gneises have similar geo-chemical characteristics with some gneisses from other parts of the Basement Complex of Nigeria, but at distinct variance with others.