Browsing by Author "Olatunji, Saminu"

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    Characterizing groundwater potentials in parts of the basement complex of Nigeria using GIS and remote sensing
    (Springer Nature Switzerland, 2023) Abubakar, Hussain Olanrewaju; Ige, Omoniyi Olusegun; Olatunji, Saminu; Iheme, Kenneth Obinna
    Groundwater prospect in parts of southwestern Nigeria was delineated by inferring the subsurface models from the responses of remote sensing and GIS data. In characterizing the area, both primary and secondary data were used. The primary data include landsat8 OLI and ASTER Digital Elevation Model, while the secondary data includes geology, soil, and topography maps of the area. Hence, thematic maps of potentials and lineament density, and land cover/use maps for the area were derived from the landsat8 OLI/TRS image. Thus, the area was characterized as follows: very low, low, moderate, high, and very high potentiality that covered 1.4 km2 (0.59%), 72.18 km2 (9.59%), 372.3 km2 (49.44%), 272.12 km2 (36.14%), and 35 km2 (4.64%), respectively. The western part of the area is dominated by very low to low potential, while the southern part of the area is dominated by high to very high potential. Hence, low and moderate potentials occupy the highest landmass (59.03%) in the area. In conclusion, the basement complex terrain in question has a moderately low aquifer capability.
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    Course Material for Geophysics I
    (National Open University of Nigeria (NOUN), 2010) Olatunji, Saminu
    This material targets students offering B.Sc. Physics in the National Open University of Nigeria (NOUN). It introduces students to Geophysics as a specialized field of study in which interested undergraduate students may pick interest as a specialization in their future careers. It discusses applications of physics principles to the study of the solid interior part of the earth. Editor: B. S. Badmus, Department of Physics, College of Natural Sciences, University of Agriculture, Abeokuta, Ogun State, Nigeria GENERAL TABLE OF CONTENTS FOR THE MODULES Module 1 EARTH: INTERNAL STRUCTURE AND CONSTITUTION, DENSITIES: ROCKS AND ORES. Unit 1 Origin of the Earth Unit 2 Motions of the Earth Unit 3 The Internal and External Structures of the Earth. Unit 4 Variation of Some Physical Properties within the Solid Earth. Unit 5 Rocks and Minerals Unit 6 Density Module 2 GEOMAGNETISM: ORIGIN, PROPERTIES OF ROCK Unit 1 Basic Facts in Magnetism Unit 2 Nature of Geomagnetic Field Unit 3 Characteristics of Magnetism in Rocks’ Components Unit 4 Magnetisation in Earth’s Rocks Unit 5 Magnetic Measurement Module 3 GRAVITY METHODS Unit 1 Newton’s Gravitation and Application Unit 2 Gravity Instrument Unit 1 Gravity Fieldwork Unit 4 Gravity Data Processing Unit 5 Gravity Data Interpretations. Module 4 MAGNETIC METHODS Unit1 Theory, Concept, and Instruments Unit 2 Magnetic Survey Unit 3 Magnetic Data Processing Unit 4 Qualitative Interpretation of Magnetic Data Unit 5 Quantitative Interpretation of Magnetic Data
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    Determination and Distribution of Formations Thickness in Baga/Lake Sub-Basin using Seismic Imaging and Well data, Chad Basin Nigeria
    (Alhikmah University,, 2021) Olatunji, Saminu; Omolaiye, GE; Ajadi, J
    The Borno Basin is located in North-Eastern Nigeria, formed in the Early Cretaceous. Deposition of sediments in the basin occurred during rifting. The sediments are mainly lacustrine shales and sandstones. This work was undertaken by the integration of 3D seismic interpretations and the well data analysis of eight wells fairly distributed in the study area to determine the thickness of the formations within the sub-basin. Da-1 well used in this study was subdivided into stratigraphic units based on the regional stratigraphic subdivision of the Chad basin and was later correlated with other wells using the similarity of observed log responses. Density and sonic logs were used to generate synthetic seismograms for seismic to well ties. Five horizons were interpreted, representing the tops of the formations on the 3D seismic data covering the block, average velocity function with a maximum residual of 0.48% was used for the time to depth conversion in all the generated maps. There is a general thickening of sediments from the west to the east and the estimated thicknesses of the various Formations in the Baga/Lake sub-basin are; Chad (400-750 m), Kerri-Kerri (300-1200 m), Fika (300-1000 m) and Gongila (100-1300 m). The thickness of the Bima Formation could not be established because the deepest well terminates within the Formation. This is a modification to the previous and widely referenced studies of over fifty decades that based the estimation of formation thickness within the study area on the observed outcrops and the use of a few water boreholes.
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    Electromagnetic Characterization of the Fracture System within Older Granite of North Central Nigeria
    (Faculty of Pure and Applied Sciences, Ladoke Akintola University of Technology, 2012) Olatunji, Saminu
    A VLF electromagnetics survey was carried out on the whole land area of the Federal College of Education, seated on the older part of the basement complex of north-central Nigeria. VLF machine, model EM/6, was used to collect data along 8 VLF profiles at a station spacing of 66 m across the strike of the geological formation. Fractures, sheared and faulted zones were reported all over the area, with the prominent ones concentrated at the north–western corner, which diminished progressively toward southwest direction of the site. The in-phase and quadrature component plots revealed conductivity high of +130% and 86% respectively around the northwest while the lowest conductivity occurred toward the eastern part of the campus. Consequently, northwestern side appears the most promising water-bearing zone.
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    Empirical Search for Suitable Experimental Periods for Gravitational Acceleration Determination
    (Faculty of Science University of Ilorin, Ilorin, 2012) Olatunji, Saminu
    Variations in the acceleration due to gravity, from place to place on the earth's surface are caused by parameters such as inequality of earth’s radius from pole to equator, temperature variation, density variation in the subsurface rocks, and many others. Hence, this work examined practically the temperature effect to determine the appropriate period when acceleration due to gravity could be determined with the least adverse effect of the diurnal temperature instability. Experiments were carried out in the laboratory. First diurnal temperature variation with time was monitored with a digital thermometer for two days from which three suitable experimental periods were determined as 2:30 am, 2:45 pm and 8:30 am, indicating the coldest, hottest, and moderate temperature periods. The free oscillation simple pendulum method was used to determine the acceleration due to gravity (g) at the periods identified above for 3 weeks. The values obtained were compared with 9.78031225 ms-2, the standard absolute gravity value obtained at the school of Aviation Technology, Zaria; the value which was tied to international standardization Net, (IGSN71) through Primary Gravity Network for Nigeria (PGNN85) An average of 9.74651200 ms-2 was obtained at 8:53 am (coldest period). 0.3% deviated from the standard, 9.72281780 ms-2 was obtained at 2:45 pm, a deviation of about 0.5%, and the largest deviation of 0.70% occurred at 2:30 am. It was concluded that a consistent and reliable acceleration due to gravity could be determined around 9:00 am to 2:40 pm. However, measurements around 2:30 am could surfer spurious variations.
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    Integration of Remote Sensing and Geophysical Methods for Structural and Lithological Mapping in a Part of Precambrian Basement Rocks, Northern Nigeria.
    (Faculty of sciences and technology of the University of El Oued Algeria, 2021) Olatunji, Saminu
    Landsat 8 OLI data, Aeromagnetic data, and Radial Vertical Electrical Sounding (RVES) survey data were integrated to map lithology, delineate structures and their trends, and delineate possible mineralized zones in the area. Landsat 8 OLI data yielded a color composite image, and surface lineaments map of the area. The aeromagnetic maps were utilized to map lithology, and subsurface structures. A radial survey confirmed the fractures derived from the structural maps. Results classified the area into three geological units viz: migmatite, banded gneiss, and quartzite. The banded gneiss is the most deformed and contains series of structures that are significant for mineral and groundwater explorations. Clay alteration is the most dominant in the area, followed by iron oxide alterations. Lineament alignments are N-S, NNW-SSE, NNE-SSW, NE-SW, and E-W directions.
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    Investigation of Magnifying Effects of some Semiconductor Diodes During A.C./D.C. Conversion
    (Faculty of Pure and Applied Sciences, Ladoke Akintola University of Technology, 2012) Olatunji, Saminu
    The work was prompted by the magnifying effect of Semi-conductor Diode Bridge on the output direct current (D.C) after rectification of a given quantity of alternating current (A.C). The work determined the causes of increase in voltage, the magnifying factor and remarkable trend of magnification. To this end a step-down transformer was constructed with a variable A.C output voltage viz: 2, 4, 6, 8, and 10 v. Five different bridges of 4 semi-conductor diodes, using five different sets of diodes with varying VRRM voltage specifications and a smoother/filter circuit each were constructed for use. The five full-wave rectifiers were connected in steps, to each A.C output simultaneously to obtain data to work with. The work confirmed a positive increase in the rectified output D.C with an increase in the input A.C source. There was 35.1% magnification using a diode with 345 VRRM voltage specification and as low as 26.88% magnification for 630 VRRM voltage specification. This signifies magnification increases with a decrease in diode VRRM voltage specification. It was observed that the magnification equally increased with an increase in the rectified A.C using the same type of Diode Bridge. A.C Rectification project out is a private endeavor. Thus, this work was designed to probe further on how, why and the causes of this magnifying effect of the rectifier.