ABSTRACT
This work presents a detailed geology of Enugu-Ngwo and environments. The study area is bounded by latitudes 7o23’N and 7o30’N and longitude 7o23’E and 7o30’E.The area extent covers approximately 167.7km. Three distinct formations such as Enugu Shale, Mamu Formation and Ajali Formation are exposed in the area.
The Enugu Shale is carbonaceous, fissile, grey and jointed with beds of siltstone and clay. The Mamu Formation contains a distinctive assemblage of sandstone, Shale, mudstone and sandy shale with coal seams at several horizons. Field measurement shows that it has average dip amount of about 5.6o in the south western direction and average strike direction of about 126oAzimuth. Results from sieve analysis show that Mamu Formation is moderately well sorted to moderately sorted, coarse skewed to strongly fine skewed and very leptokurtic to extremely lepkurtics. The plastic and liquid limit test show that the shale has plasticity of 19% and liquid limit of 29%.
The Ajali Sandstone is white in colour and some places iron stained. It consists of friable, poorly sorted, fine to coarse grained sandstone and lies conformably on the Mamu Formation. It is a good aquifer to the study area. Field measurement shows that it has average dip amount of about 6.25o in the southwestern direction and average strike direction of about 5.6o Azimuth.
Results from sieve analysis show that Ajali Sandstone is poorly sorted, coarse skewed to nearly symmetrical, and very platykurtic to mesokurtic. The hydrochemical analysis of some of the surface water shows that the water is not fit for human consumption but could be used for other purposes. Among the sedimentary structures present in the area are cross bedding, laminae, joints, faults and biogenic structures. The area has a dendntic drainage pattern and has a high potential for groundwater as well as surface water supply. A significant geologic deposit found in the study area is coal. Others are sandstone, laterite, ironstone, shale and fire clay.
TABLE OF CONTENT
Title page --------i
Certification -------ii
Dedication -------iii
Acknowledgements ------iv
Abstract --------vi
Table of Content ------viii
List of figures -------xii
List of tables -------xv
List of plates -------xvii
CHAPTER ONE
1.0Location -------1
1.1Accessibility ------1
1.2Objective and Scope of study ---2
1.3method of Investigation ----3
1.3.1Desk study ------3
1.3.2Reconnaissance survey ----4
1.3.3Detailed Geologic Survey ----4
1.3.4Laboratory studies -----5
1.4Problems encountered ----5
1.5Precautions ------6
1.6Literature Review -----7
CHAPTER TWO
2.0Geomphology of the study Area ---11
2.1Topography ------11
2.2Climate and Vegetation ----12
2.3Drainage -------13
2.4Weathering ------14
2.5Erosion -------14
CHAPTER THREE
3.0General Geology -----16
3.0.1Geological History and Tectonics ---16
3.0.2Basin fill -------17
3.0.3Regional sedimentation pattern in the study area 18
3.1Geology of the study area ----18
3.1.1Description of Lithologic Units ---20
3.1.1.1 Enugu shale ------20
3.1.1.2Mamu Formation -----20
3.1.1.3 Ajali Sandstone -----28
3.1.1.4 Subsuface Lithostatgraphy ---35
3.2Structural Geology -----37
3.2.1Primary Sedimentary Structures---38
3.2.2Secondary Sedimentary Structures --40
3.3Grain Size Analysis -----42
3.3.1Statistical Size Subtraction Analysis --43
3.3.2Summary of the Sieve Analysis Data --59
3.4Plastic and Liquid Limit Test ---60
3.4.1Plastic Limit Test ------60
3.4.2Liquid Limit Test ------62
CHAPTER FOUR
4.0Hydrogeology and Environmental Geology -66
4.1Hydrogeology------66
4.1.1Surface Water Hydrology ----66
4.1.2Groundwater Hydrology ----67
4.2Hydrogeochemistry-----70
4.2.1PH--------71
4.2.2Hardness ------71
4.2.3Iron --------72
4.2.4Coliform count ------72
4.2.5Manganese ------73
4.3Environmental Geology ----77
4.3.1Weathering ------77
4.3.2Geotechnic ------78
4.3.3Erosion -------78
4.3.3.1 Erosion Control Measure ----79
4.3.4Quarry -------80
4.3.5Pollution and Contamination----81
CHAPTER FIVE
5.0Economic Geology -----83
5.1Coal --------83
5.1.2Important of Coal Mining ----85
5.1.3Coal as a Source Rock-----86
5.2Shale and Clay ------86
5.3Sandstone/sands ----88
5.4Laterites -------89
Summary and Conclusion ----90
Summary ------90
Conclusion ------92
References ------93
LIST OF FIGURES
Fig. 1 Geologic map of Enugu – Ngwo and Environs
Fig. 2Accessibility map of the study area
Fig. 3 Map of Enugu showing the study area
Fig. 4Diagram showing cross a section of Enugu Escarpment
Fig. 5 Map showing wet season winds and rainfall
Fig. 6Map showing dry season winds and rainfall
Fig. 7 Map of Nigeria showing natural vegetation
Fig. 8Map showing the drainage pattern of the area
Fig. 9Tectonic map of southeastern Nigeria during the Albian – Santonian
Fig. 10Tectonic map of southeastern Nigeria during the campanian to Eocere
Fig. 11Geological sketch map of Eastern Nigeria
Fig. 12Diagram showing a section of Mamu formation around Milliken Hill Enugu – Ngwo23
Fig. 13Outcrop section of Mamu at Ekulu River 25
Fig. 14Outcrop section of Mamu Formation along Enugu-Onitsha expressway 25
Fig. 15Outcrop section of Mamu along PRODA road 26
Fig. 16Outcrop section of A