A

FIELD RFEPORT

ON

THE INDEPENDENT FIELD MAPPING EXERCISE

TO ILUDUN-EKITI, ILEJEMEJE LOCAL GOVERNMENT AREA,

EKITI STATE

BY

MAGBAGBEOLA FIYINFOLUWA ADEOLU

AGY/07/0830

SUBMITTED TO

THE DEPARTMENT OF APPLIED GEOLOGY,

THE FEDERAL UNIVERSITY OF TECHNOLOGY AKURE,

ONDO STATE.

IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE

AWARD OF BACHELOR OF TECHNOLOGY (B.TECH) IN APPLIED GEOLOGY.

MAY 2010

CERTIFICATION

I hereby certify that Magbagbeola Fiyinfoluwa Adeolu with the matriculation number

AGY/07/0830 carried out the independent geological field mapping at Iludun in Ekiti State and

submitted to the department of Applied Geology, School of Earths and Mineral Sciences (SEMS) Federal

University of Technology, Akure Ondo State.

...................................... ……………………………………..

DR.C.T OKONKWO MR ADETUNJI

(H.O.D APPLIED GEOLOGY (FIELD CO-ORDINATOR)

DATE DATE

DEDICATION

This report is dedicated to the Lord Almighty, the provider of wisdom and knowledge. The

report is also dedicated to my parents for their immense support and encouragement financially and

spiritually.

ACKNOWLEDGEMENT I give the Almighty God all my gratitude. I appreciate my loving parents, Mr. and Mrs.

Magbagbeola for their endless support towards the success of my chosen field. A big thank you goes to

my siblings for their thoughtful gestures towards the success of my career. To the Dean of the School of

Earth and Mineral Sciences, Prof. J.A. Adekoya,the Head of Department of Applied Geology, DR C.T

Okonkwo, Dr Asiwaju Bello, Dr Anifowose, Dr Ashidi, Dr Opeloye, Mr Adetunji, Mrs Bamisaye, Mr

Owoseni ,Mr Adepoju and all technologists,may God reward you bountifully.

Many thanks goes to my efficient group members, Olofinyo Olabode, Ayeni Ademola and

Ayodele Adeyemi . To all other groups in the surrounding villages, thank you for the love shown.

TABLE OF CONTENT

TITLE PAGE

CERTIFICATION

DEDICATION

ACKNOWLEDGEMENT

TABLE OF CONTENT

LIST OF FIGURES

LIST OF TABLES

LIST OF PLATES

ABSTRACT

CHAPTER ONE

1.0 Introduction

1.1 Aims and Objectives

1.2 Location

1.3 Topography

1.4 Drainage System

1.5 Vegetation

1.6 Soil and Weathering Condition

1.7 Method of Study

1.8 Previous Work

CHAPTER TWO

2.0 DETAILED PETROLOGY

2.1 Gneisses

2.2 Migmatite - Gneiss

2.3 Charnockite

2.4 Modal analysis

CHAPTER THREE

3.0 STRUCTURAL GEOLOGY

3.1 Foliations

3.2 Faults

3.3 Folds

3.4 Joints

3.5 Veins

3.6 Dykes

CHAPTER FOUR

4.0 ECONOMIC GEOLOGY

4.1 Migmatite-Gneiss

4.2 Gneisses

4.3 Charnockites

CHAPTER FIVE

5.0 Geologic History of Study Area

CHAPTER SIX

6.0 Conclusion and Recommendation

References

LIST OF FIGURES

Fig: 1 Map of Nigeria

Fig: 2 Geological Map of Nigeria

Fig: 3 Map of Ekiti State

Fig: 4 Topographic map of Iludun Ekiti

Fig: 5 Drainage pattern of Iludun- Ekiti

Fig: 6 Photomicrograph of Rocks

Fig: 7 Foliation

Fig: 8 Folds

Fig: 9 Faults

Fig:10 Joints

Fig:11 Veins

Fig:12 Dyke

Fig:13 Rose diagram

Fig:14 Beta Diagram of Rock attitude

Fig:15 Geologic map of Iludun

Fig: 16 Geologic Section of Mapped area.

LIST OF TABLES

Table 1 Modal analysis of charnockite at location 25

Table 2 Modal analysis of migmatite gneiss at location 10

Table 3 Modal analysis of migmatite gneiss at location 13

Table 4 Modal analysis of gneiss at location 36

Table 5 Modal analysis of gneiss at location 18

Table 6 Orientation of joints

Table 7 Orientation of veins

LIST OF PLATES

PHOTOMICROGRAPH OF MIGMATITE GNEISS (L10) UNDER CROSS NICOL: PLATE A

PHOTOMICROGRAPH OF MIGMATITE GNEISS (L10) UNDER PLANE POLARIZED LIGHT: PLATE A1

PHOTOMICROGRAPH OF MIGMATITE GNEISS (L13) UNDER CROSS NICOL: PLATE B

PHOTOMICROGRAPH OF MIGMATITE GNEISS (L13) UNDER PLANE POLARIZED LIGHT: PLATE B1

PHOTOMICROGRAPH OF GNEISS (L18) UNDER CROSS NICOL: PLATE C

PHOTOMICROGRAPH OF GNEISS (L18) UNDER PLANE POLARIZED LIGHT: PLATE C1

PHOTOMICROGRAPH OF CHARNOCKITE (L25 UNDER CROSS NICOL: PLATE D

PHOTOMICROGRAPH OF CHARNOCKITE (L25) UNDER PLANE POLARIZED LIGHT: PLATE D1

PHOTOMICROGRAPH OF GNEISS (L36) UNDER CROSS NICOL: PLATE E

PHOTOMICROGRAPH OF GNEISS (L36) UNDER PLANE POLARIZED LIGHT: PLATE E1

ABSTRACT

The mapping exercise was carried out in Iludun-Ekiti and its surrounding villages; Iye-Ekiti,

Eda-Oniyo, all within Ilejemeje Local Government Area, Ekiti State, South Western Nigeria. The

area mapped is part of the Nigerian basement complex.

The main purpose of the mapping exercise is to prepare a geologic map out of the

topographic map provided which served as a guide to the outcrops in the mapped area.

Properties observed on the outcrops encountered in the field include its extent, lithology,

structural features, attitude and mineral composition. In the laboratory, the rocks were

analyzed as thin sections using the polarizing microscope.

CHAPTER ONE

1.0 INTRODUCTION

Nigeria can be divide into two based on its lithology;

1. Sedimentary Basins

2. The Basement Complex

The area mapped is in the South Western part of the Nigerian basement Complex. The Basement

Complex is made up of crystalline rocks, both igneous and metamorphic. The rocks in this part of the

crystalline complex are charnockite, migmatite gneiss and gneiss. The mapped are covers an area of

33Km2.

Charnockites are the most dominant rocks in the mapped area covering about half of the map.

The charnockites occur as massive, rounded and distinct bodies with a few found to be extensive. The

migmatites and gneisses are highly deformed with joints and faults on their surfaces orienting in all

directions. Their mineral lineation are folded and are covered with quartzitic and in some places,

quartzofeldspathic veins. Exfoliation surfaces as well as biological weathering are the most dominant

forms of weathering encountered. The soil in this area is loamy and is used for agricultural purposes.

Figure 1: Map of Nigeria

1.1 Aims and Objectives

The main purpose for this mapping exercise is to create a geological map and its

cross section out of the topographic map provided and this was achieved by locating the

outcrops in the area. This helps in delineating the contact between the various rock types in the

area and correlating the rock units. Mapping techniques taught in the school premises and in

Igarra, Edo State during AGY 318 were applied.

Figure 2: Geologic Map of Nigeria

1.2 LOCATION

The area mapped; Iludun Ekiti is located in Ilejemeje Local Government area of Ekiti

State, south western Nigeria. The mapped area covers an area of 33Km2 and is located between

latitude 7049IN and 7050IN and longitude 5013IE and 5014IE.

Figure 3: Map of Ekiti Showing Ilejemeje Local Government Area

1.3 TOPOGRAPHY

The mapped area is generally highland rising about 1600m above sea level on the

average. Few shrubs and light forests are scattered around the area.The topography of the

mapped area is shown in figure 4.

Figure 4: Topographic map of Iludun

SCALE: 5cm represents 2 Km

1.4 Drainage Pattern

The mapped area is well drained having a dendritic pattern and flowing towards

the western part of the map. The direction of flow is mainly controlled by the underlying

crystalline rocks. The rivers are not down cutting because of the hardness of the

underlying rocks which are highly resistant to fluvial weathering. The drainage is shown

in figure 5

Figure 5: Drainage parrern of Iludun area

1.5 Vegetation

The mapped area is located within the rain forest belt with slightly thick forests with

scrubs and scattered cultivation. Most of the land is used is used for agricultural purposes with

food crops being cultivated.

1.6 SOIL AND WEATHERING

The soil encountered in the mapped area is dark, loamy soil which is very good for

agricultural purposes because it is rich in organic matter. The weathering type present in

the area are biotic and exfoliation.

1.7 Method of Study

Traversing was applied during this mapping exercise. This involves moving from

one outcrop to the other in a systematic pattern following major roads as well as

through bush paths. The traversing was carried out on foot. The lithology, mineral

composition and visible structures on the encountered outcrops were noted on the

field.

Locating outcrops were carried out using the compass clinometers and distances

were measured using our pace lengths. Hand specimens were chipped off using a sledge

hammer before further chipping was carried out in the laboratory using the cutting

machine. The process of converting to thin sections involved cutting, lapping (using

Carborundum of 200,400 and 600 grit), grinding and then mounting. The slides are then

analyzed under the polarizing microscope for mineral identification.

1.8 Previous Works

Detailed studies has been carried out on the south western part of the basement

complex in which Iludun, Ekiti is part of. These studies were used as reference materials

for the completion of this report. Notable among these studies were those of Rahaman,

M.A (1976), Odeyemi, I.B (1993) and Hockey et al (1964).

CHAPTER TWO

2.0 DETAILED PETROLOGY OF THE MAPPED AREA

This is the systematic study of rocks as hand specimens collected directly from the field

and as thin sections studied under the polarizing microscope. The rocks encountered during

mapping exercise in Iludun Ekiti are

2.1 GNEISS

This is a rock consisting of light and dark mineral layers alternating each other. High

temperature and pressure have altered the texture of the initial rock (granite) so that the

minerals have separated into layers. The platy minerals which make up the dark layers are

composed of amphiboles, chlorite, biotite and some muscovite while the light layers are made

up of coarse grained quartz and feldspars (plagioclase, orthoclase). Some garnets are also

present .The rocks is similar in composition to granite but is distinguishable by its foliation.

The rock is generally light coloured with a characteristic gneissic texture. The outcrops

are extensive with orientation of its trend in the NW-SE direction.

2.2 MIGMATITE GNEISS

Migmatite gneiss is the second most dominant rock type in mapped area. Migmatite is

a rock at the boundary between igneous and metamorphic rocks. They probably formed under

extreme conditions of regional metamorphism (Pan-African Orogeny, 600±250 m.y.) where

partial melting occurs in the previously existing rocks. They resulted from tectonic activities

arising from the injection of igneous material into the pre existing rock.

Migmatite gneiss contains feldspars (microcline, plagioclase), amphibole, garnet,

biotite, and some muscovite. The rock is highly deformed and fairly extensive and low lying

with a large number of folds and veins cutting across its surface in different directions.

2.3 CHARNOCKITE

These are hypersthene bearing rocks. They are orthopyroxene bearing granites

composed of hypersthenes (pyroxene) and are of magmatic origin emplaced during the

Eburnean Orogeny (1950±250 m.y.) and the Pan African Orogeny (600±150 m.y.). In the

outcrops encountered, there is the presence of strongly pleochroic reddish or green

hypersthenes when observed under the polarizing microscope.

The charnockites are dark green to black in colour with some appearing whitish to

reddish impacted by the orthopyroxene present which is the most abundant mineral. The

outcrops are rounded and weathered, having exfoliated surfaces with a coarse grained in

texture. Joints and veins as well as faults are present on its surface. A dolerite dyke is observed

on one of the charnockite outcrops.

Plate A: Migmatite Gneiss at location 10 under cross nicol

Plate A1: Migmatite Gneiss at location 10 under plane polarized light

Figure 6

Plate B: Migmatite Gneiss at location 13 under cross nicol

Plate B1: Migmatite Gneiss at location 13 under plane polarized light

Figure 6

PlateC: Gneiss at location 18 under cross nicol

Plate C1: Gneiss at location 18 under plane polarized light

Figure 6

Plate D: Charrnockite at location 25 under cross nicol

Plate D1: Charrnockite at location 25 under plane polarized light

Figure 6

Plate E: Gneiss at location 36 under cross nicol

Plate E1: Gneiss at location 36 under plane polarized light

Figure 6

2.4 Modal analysis

Location 25- Charnockite

Mineral 1st count 2nd count 3rd count 4th count Total Percentage

Composition

Feldspar 2 1 2 ------- 5 5.3

Quartz 3 2 3 2 10 10.5

Biotite 5 6 6 5 22 23

Amphibole 3 2 4 3 12 12.6

Opaque

mineral

14 12 9 11 46 48.4

Grand

Total

95

Table 1

Location 10-Migmatite Gneiss

Mineral 1st count 2nd count 3rd count 4th count Total Percentage

composition

Quartz 8 9 8 9 34 30

Feldspar 6 6 5 6 23 20

Biotite 10 12 10 10 42 39

Opaque 4 3 4 4 15 13

Grand

Total

114

Table 2

Location 13-Migmatite Gneiss

Mineral 1st count 2nd count 3rd count 4th count Total Percentage

Composition

Quartz 5 4 5 3 17 20.9

Feldspar 9 10 10 13 42 51.8

Biotite 4 4 4 3 15 18.5

Opaque 3 2 0 2 7 8.6

Grand

Total

Table 3

Location 36- Gneiss

Mineral 1st count 2nd count 3rd count 4th count Total Percentage

Composition

Quartz 10 9 11 10 40 32

Biotite 14 12 8 13 47 37.6

Feldspar 7 7 5 7 26 20.8

Opaque 4 2 4 2 12 9.6

Grand

Total

125

Table 4

Location 18-Gneiss

Mineral 1st count 2nd count 3rd count 4th count Total Percentage

Composition

Quartz 12 13 14 12 51 36

Feldspar 9 8 10 9 36 25.5

Biotite 9 9 7 8 33 23.4

Opaque

Minerals

4 4 1 3 12 8.5

Total 141

Table 5

CHAPTER THREE

3.0 STRUCTURAL GEOLOGY

This refers to structures developed as a result of deformation forces acting on rocks

due to orogenic activities. The first set structures developed as a result of the first orogenic

event are the bands and mineral lineation. This was followed by deformation of the bands

which of the bands which resulted in the formation of folds and are associated with joints,

fractures and faults.

3.1 FOLIATION

The foliations are most common in the gneisses made distinct by the parallel layers

consisting of alternating dark and light minerals. The foliations are of tectonic origin as

indicated by the presence of small, tight, minor folds on the straight limbs of the folded bands.

The foliations are defined as repetitive or penetrative planar features in a rock which

may be defined by compositional layering. They define the trend of the rock in the mapped

area with most of them in the NW-SE direction with very few in the NE-SW direction.These are

observed in figure 7.

3.2 FOLDS

A fold is a curved or angular shape of an originally planar surface. They are wave like

undulations formed during deformation of rock layers or planar structures on rocks. Most folds

found in the area occurred on the surface of the migmatite gneisses as a result of folding of

their mineral lineation . Some of the locations have more than one fold generation as observed

in figure 8b. Their fold axis generally tend towards the NE-SW direction. Some folds are

fractured while some occur as parasitic folds on the limbs of larger folds. They are seen in

figure 8a

3.3 FAULTS

A fault is a surface of discontinuity along which there has been displacement of rock

on either sides of the outcrop. It is characterized by a plane along which the rock bodies could

have moved on either of its sides. The faults observed were identified in the discontinuity if

lineation, veins and the dolerite dyke. A reverse fault was encountered as seen in fig 9a

occurring across a quartzofeldspathic vein and in fig 9b across a dolerite dyke within a

charnockite outcrop.

3.4 JOINTS

A joint is a plane of fracture along which there has been no relative displacement of

rocks along either side of the plane. Joints are developed as a result of the brittle nature of the

rocks that are close to the earth surface when they react to tectonic disturbances. A fracture

along which microscopic displacement has occurred but is invisible with the unaided eye might

also be referred. The joints found in the mapped area were oriented in different directions

pointing to the fact that most were formed during tectonic activities. Some joints found in the

outcrops are shown in figure 10. The rose diagram for the joints are shown in figyre 13A

3.5 VEINS

A vein is a tabular discordant body cutting across a rock. It is made up of minerals

that were crystallized out of magmatic fluids during the latter part of crystallization. The

minerals fill the fracture partially or wholly depending on the amount of mineralizing fluids

available after the rock forming minerals have crystallized. The veins encountered were mostly

quartzofeldspathic with a few quartzitic veins. They were mostly encountered on the migmatite

gneisses with a few found on the charnockitic rocks.

The orientations of the veins encountered are shown in the rose diagram in

Figure 13B. Some of the veins are shown in figure II

3.6 DYKES

A dyke is a sheet-like, near vertical minpor igneous intrusion that cuts across

horizontal to gently dipping planar structures in the country rock.

A dolerite dyke was observed on a charnockite outcrop in location 3 and it cuts across

the outcrop. Some part of the charnockitic host rock was found within the dolerite indicating

that the dyke was formed after the charnockite had crystallized. The dolerite is fine grained and

melanocratic. The contact vbetween the dyke and the host rock is distinct as shown in fig 12b

Some part of the dyke is faulted(fig 12c)

a b

Figure 7 a & b: Foliation in Gneissic Rocks

a b

Figure 8 a & b; Folds in Migmatite Gneiss

Figure 9a; Fault in a quartzofeldspathic vein Figure 9b : Fault along a dolerite dyke.

Figure 10: Joint in Charnockite Figure 11: Quartz vein in Charnockite

(a) (b)

(c)

Figure 12 : A dolerite dyke cutting across a charnockite. Note the relics of charnockite within

the dolerite In (b)

INTERVAL 0-20 21-40 41-60 61-80 81-100 101-120 121-140 141-160 161-180

FREQUENCY 2 4 3 4 2 3 1 4 8

Table 6A: Orientation of Joints

Scale: 2cm represents 1 unit

Figure !3A; Rose Diagram for Joint Orientation.

INTERVAL 0-20 21-40 41-60 61-80 81-100 101-120 121-140 141-160 161-180

FREQUENCY 1 4 2 8 2 4 1 3 6

Table 6B : Orientation of Veins

1cm represents 1 unit

Figure 13B: Rose Diagram for Vein Orientation.

Trend 1560

Plunge 100

Figure 14: Beta Diagram for Rock Attitude.

CHAPTER FOUR

4.0 ECONOMIC GEOLOGY

Economic geology is the geological study for the exploration and exploitation of

materials which can be profitably extracted by man. It deals with the usefulness of geological

materials for mankind. The delineation of mineralized deposits are carried out during field

mapping exercises. Rocks and their minerals as well as the accessory minerals they are

associated with are found useful in various industries.

4.1 MIGMATITE GNEISS

They are used as large cabochons for such things as belt buckles, bolo ties and

brooches; diverse decorative and functional pieces such as paperweights and bookends.

Polished migmatite can be used as gemstones and as ornaments in the home. Its polished form

can also be used for flooring it bis also used as foundation materials .

4.2 GNEISS

Polished gneiss has a shiny appearance and can be used as ornaments and for

construction purposes. They are used as building materials such as for flooring, as gravestones

and for work surfaces on furniture and in the kitchen. They are also used as facing stones on

buildings.

4.3 CHARNOCKITE

Charnockite can be crushed into dimension stones for construction purposes.They are

also used as geobarometers due to the presence of plagioclase, pyroxenes and quartz.

4.4 STRUCTURAL FEATURES

Fractures and joints occurring on the surface of rocks serve as conduits for water

movement and also for water accumulation. Partially filled veins also promote water

accumulations.

Open spaces in rocks such as fault planes, joints, cracks or fractures serve as zones

for deposition of economic minerals such as pegmatite which produce gemstones and quartz

which is used in manufacturing time pieces and silicon chips.

4.5 DRAINAGE

The rivers in the area are generally used for agricultural and domestic purposes. Most of

the rivers are perennial in nature realized from the fact that the field exercise was carried out in

the heart of the dry season.

CHAPTER FIVE

5.0 GEOLOGICAL HISTORY OF MAPPED AREA

The mapped area is part of the Nigerian Basement Complex which is divided into five

major groups in the south western part (Rahaman 1976);

1. The Migmatite-Gneiss Group.

2. The Charnockite Group.

3. The slightly migmatized to unmigmatized paraschists and metaigneous group.

4. Older Granite Group.

5. Unmetamorphosed dolerite dykes which are believed to be the youngest occurrences.

Not less than two orogenic episodes have modified the rocks in this area. No actual

age determination technique has been applied on rocks in this area to determine the

absolute ages . From the field studies and geologic section, the oldest rock in the area is

charnockite followed vby migmatite gneiss and then the gneiss as observed in the

geologic section in figure 16

The charnockite is coarse grained and occur as massive bodies. There is a dyke which

intrude one of the charnockite outcrops indicating that it was formed after the host had

crystallized. The charnockite are of magmatic origin, crystallizing at depth and exposed

due to the weathering of the overburden. The intrusion of the charnockite during the

Pan African Orogeny (600±150 m.y.) possibly modified the pre existing rocks to gneissic

rocks. Further intrusion of charnockites gave rise to migmatite gneiss and then gneiss at

the edge of the mapped area with deformation reducing in the western direction. This

further intrusion gave rise to the high deformation found in the migmatite gneisses.

Figure 15: Geologic map of Iludun Ekiti.

LEGEND

Gneiss

Migmatite Gneiss

Charnockite

Figure 16; Geologic cross section between points A & B

CHAPTER SIX

6.0 Conclusion and Recommendation

6.1 CONCLUSION

The mapped area, Iludun Ekiti is part of the Nigerian Basement Complex. Rocks present

in this area are grouped into two;

The Charnockite Group

The Migmatite- Gneiss Group.

The dolerite dyke group is found in only one outcrop and is not extensive. The

charnockitic rocks are the most widespread in the mapped area as indicated by the

geologic section. The intrusion of the charnockites altered the pre existing in to

migmatite gneiss snd gneiss with deformation reducing in the north eastern direction.

The migmatite gneiss dips at680E while the gneiss dips at 640E. The migmatites and

gneiss were probably homogenous before the igneous intrusion. The dolerite dyke

which was found as intrusions is younger than the charnockites and is oriented in the

north western direction.

6.2 RECOMMENDATION

The university should provide G. P. S for all students to make locationing much

easier and the work, less tedious. The university should also provide better welfarepackages

and make adequate accommodation available before sending students out for individual field

work.

The indigenes of the town must always be informed about the mapping exercise

before the arrival of the students to avoid attracting hostile behavior from them.

REFERENCES

RAHAMAN, M.A(1976), Review the Basement Geology of South Western Nigeria in

Geology of Nigeria Edited by C.A Kogbe P 39-53

PLUMBER, C.C,CARDSON D.H,(2008):Physical Geology, twelve Edition.

ROBERT,J.T.(1992): STRUCTURAL Geology.

GHOSH,S.K. (1993): Structural geology,fundermentals and modern development.