ABSTRACT
The study is located in Nsukka Local Area of Enugu State Nigeria. It lies between 6° 49′ N, and 6° 50′ N, and longitudes 7° 15′ E, and 7° 21′ E respectively.
The area is underlain by Nsukka , which is capped by the , and underlain by heterolithic Sandstone / Siltstone layers with some clays or shale at some deeper horizons.
Geophysical investigation using Electrical Resistivity and IP methods with ABEM Terameter, SAS 1000, reveal the presence of fault in one section of the area, (Profiles 1 and 2, see Fig. 13, 14a and 14b of pages,
47 and 48 respectively) which potentially serves as the conduit through which water percolates to aquifer which eventually feeds the pond throughout the seasons.
This is indicated by the interpretation of anomalous low resistivity values within this zone, which shows a downward continuity within the geo-electric section in these profiles. A shallow possible source of the water in a perched aquifer following precipitation during the wet season, serves as recharge to the deep seated aquifer.
The result of the Profile 3 shows no continuity of the fault across that point, hence no anomalous drop in the resistivity in this area. (See Fig. 15 0f page 49).
TABLE OF CONTENTS
Title Page – i
Approval Page – ii
Dedication – iii
Acknowledgement – – iv
Abstract – – v
Lists of Figures – vi
Lists of Tables – – vii
Table of Contents – viii
CHAPTER ONE: INTRODUCTION
1.1 Location of Study – 1
1.2 Statement of Problem – – – 3
1.3 Objective of Study/Expected Result – 3
1.4 Study Methodology – 4
1.4.1 Desktop Study – – 4
1.4.2 General Field Work Approach – 4
1.4.3 Field Method at Ohe Pond – – 5
1.4.4. Field Data Acquisition – – – 7
1.5 Geomorphology and Topography – – – 7
1.6 DRAINAGE – – 10
1.7 Climate, Soil Type and Vegetation – – 10
1.8 WEATHERING – 11
CHAPTER TWO:
2.1 Literature Review – – – 12
2.2 Regional Geologic Setting – – – 13
2.3 Structural / Regional Tectonic Setting – 17
2.4 Regional Stratigraphic Setting – 21
CHAPTER THREE
3.1 Local Geology of the Area – 26
3.1.1 Outcrop 1, along St. Cyprian Special Science School, at Ohe Pond 27
3.1.2 Outcrop 2, at Mechanic Village Nuka 29
3.1.3 Outcrop 3, along Obimo-Adani Nsukka road – 31
CHAPTER FOUR: Geophysical Method of Investigation
4.1 Electrical Resistivity Survey – 33
4.2 Basics of Electrical Resistivity Survey 34
4.3 Advantages of Electrical Resistivity Survey – 35
4.4 Limitations of Electrical Resistivity Survey – 35
4.5 Field Precaution – 36
4.6 Equipments Used / Electrode Installation Method – 36
4.6.1 Installation of the Electrodes Followed this Procedure – 37
4.7 Resistivity of Natural Materials – 37
4.8 Resistivity and Conduction through Rocks – 38
4.9 Electrode Configuration 38
CHAPTER FIVE: Induced Polarization Method
5.1 INTRODUCTION 43
5.2 Advantages of Induced Polarization – 44
5.3 Limitations of Induced Polarization – 44
5.4 Instrumentations of Induced Polarization – – 45
5.5 Survey Design, Procedure and Quality Assurance- 46
456 Profiling Mode – – 46
CHAPTER SIX: Results and Interpretations.
6.1 Presentation of Results – 47
6.2 Interpretation of Results – 53
6.3 Discussion of Results – – 54
CHAPTER SEVEN: CONCLUSIONS
7.1 CONCLUSIONS – – 55
REFERENCES. – – 56
Lists of Appendices – 59
INTRODUCTION
1.1 Location and Accessibility
The study area is located within Nsukka town of Enugu State in Southeastern Nigeria. It lies within Latitudes 6° 49′ N and 6° 50′ N and Longitudes 7° 15′ E and 7° 21′ E. The area is bounded by major communities which include Nsukka town, Obimo town, and Edem town.
The study area is accessible through a network of tarred and untarred roads. The major roads include Obimo road, Ogurugu–Adani road, and Barracks Junction-Obimo road via St. Cyparin Special Science School.
The minor roads include Umukashi road, Odoru-Nsukka road, and Edem road. Many foot paths connect the study area to the tarred and untarred roads.
1.2 Statement of Problem
The Ohe pond is situated within the lateritic Sandstone cap of the Nsukka Formation. The Nsukka Formation is essentially made up of layers of Sandstone, Shales and Clays with some heterolithic of Siltsone and Clay, and capped by the lateritic overburden.
The lateritic overburden is extensive and covers large area. Naturally a laterite serves as an unconfined aquifer for accumulation of water following precip
itation. The Clay lenses serve as stratigraphic trap by terminating the downward percolation of the accumulated water.
The Ohe pond has been observed to be perennial having water throughout the year both wet and dry seasons.
One striking feature about the area is that as much as an extensive area surrounding the pond is occupied by the same rock material which is the lateritic sandstone, yet the pond is only confined within a small radius of about 85m.
REFERENCES
Adegoke, O. S, (1969.) Eocene Stratigraphy of Southern Nigeria, B.R.G.M. Main. No. 69:23-48.
Aguga, O. K., (1978.) Geology and Petroleum Potential of Santonian to Maastrichtian Maastrichtian Sediments in Anambra Basin, Eastern Nigeria. Unpublished Ph.D. Thesis, University of Ibadan, Nigeria.
Agagu, K. O., Fayose, E.A and Peters, S.W., (1985.) Stratigraphy and Sedimentation in th Santonian Anambra Basin of Eastern Nigeria. Jour. Main. Geol, vol.22, pp. 25-26.
Arua, I., (1980.) Episodic Sedimentation: an example from the Nkporo Shale (Campano-Maastrichtian), Nigeria. Journal of African Earth Sciences, vol.7, pp.726-759.
De Swart, A.M.J., Casey,O.P., (1963). Coal Resources of Nigeria Geologic Survey Nigeria. Bull., No. 26.
Egboka, B.C.E.(1981), Analysis of the Ground Water Resources of Nigeria Area and its Environs, Anambra State, Nigeria Journal Min. Geology, vol.20 pp. 1-16.
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