A regional geochemical soil sampling was conducted around Ilesha, Osun State to assess the area's economic potential for gold mineralization. Soil and sediment samples were collected on a grid system and analyzed to identify anomalous gold zones. Artisanal mining sites were observed. It is recommended to conduct more detailed sampling based on initial results, additional stream sediment sampling to delineate drainage catchments, and geophysical surveying to investigate subsurface geology and structures related to gold mineralization.

1. REPORT OF THE
REGIONAL GEOCHEMICAL
SAMPLING AROUND
ILESA, OSUN STATE.
GISL
OLUWABUNMI ADENIYI
bunmiadeniyi26@yahoo.com
December, 2016

2. Introduction
A regional geochemical soil sampling around Ilesha exploration license area 36EL belonging to
ENL Limited was carried in order to appraise the economic potential of the area with respect to
Gold Mineralization. The geochemical soil sampling in combination with few stream sediment
sampling was carried out with the view to analyze the chemical composition of residual soils
within the prospect area, which are composite product of erosion and weathering, and thus reflect
the source/catchment area of Gold mineralization within the area.
Location and Accessibility
The sampling area located in Iregun and some other villages near Ilesha, Ilesha West Local
Government Area, Osun State, lies between longitude 684,100E and 689,600E, and latitude
845,200N and 852,200N.
Accessibility into the site area is made possible along the Ilesha – Osogbo road which runs NE –
SW through the western side of the sampling area, and a network of other minor roads and
footpaths through Iregun, Aba Aremu, Aba Odogbo and other settlements within the area.
Aims & Objectives:
The aim of the regional geochemical soil sampling is to determine the economic potential of the
area with respect to Gold mineralization. This is accompanied with the following objectives
 To identify zones of anomalous gold within the 36EL;
 To delineate the trend(s) and extent of gold mineralization within the area and;
 To determine the source of the alluvial and lode deposit of gold mineralization within the
area.

3. Figure 1: Grided Map of the 36EL Licensed Area

4. The Geology of the Area:
The area forms a part of the Nigerian Basement Complex comprising of the Ilesha Schist Belt with
Amphibolite and Amphibole-Schist being the major rock units. Some rubbles, cobbles and pebbles
of weathered quartzite/quartz form another notable unit within the area.
Scopes and Procedure
The regional geochemical soil sampling of the 36EL prospect, was carried out using a Grid
Systematic sampling method with 200m sample spacing along a profile and an inter-profile
spacing of 200m within the prospect area.
The following materials/tools were used for the soil sampling
1. Well Gridded Maps showing sampling points – to aid navigation to sampling point
locations
2. Global Positioning System (GPS) Meters – used for navigating to locations where samples
were to be collected, as well as to store coordinates of sampled points.
3. Iron Bar-Diggers – used for digging within the soil to an Iron-rich layer where samples for
analysis are collected
4. Measuring Tape – for measuring the depth at which samples were collected
5. Plastic Bags – used for storing wet samples from the field
6. Sieve (2mm fraction) and a Sieve Base: used for sieving samples collected from the iron-
rich layer of the soil
7. Scooping spoons and Small Ziplock Bags – to collect and store sieved and dried samples
for analysis

5. 8. Soil Sample Register, Pen, Marker and Masking Tape – used for recording observation of
sampled soil, and labelling with the appropriate sample ID
9. Camera – used for taking good pictures on the field
Operating Procedures
1.5 – 2kg of soil samples were collected at each sampling point with the aid of the bar digger, and
were stored in the plastic bags for air drying at the base. After drying, the samples were removed
from their original bags and disaggregated by hand, before sieving them with the 2mm fraction
sieve, where 100 – 200g fraction of the sieved soil sample were later packed in a small ziplock
bag, well labelled with the appropriate sample ID.
Figure 2: Air Drying of the Samples

6. Table 1: Summary Table of the Geochemical Sampling.
Samples Total no. of
profile line
Total no. of
projected samples to
be taken
Total no. of
samples taken
Total no. of sample not
taken
Gridded 30 336 281 55
(samples were not taken
as a result of settlement,
river and some swampy
area that couldn’t be
accessed)
Stream Sediment 8
Grand Total 289
Field Observation:
There are few exposures of amphibolite and amphibole schist within the area. Most rock units in
the area have been lateralized. Evidence of artisanal mining activities at various locations within
the licensed area were observed while carrying out the geochemical sampling, some of which have
been abandoned while some are very active with numerous pits around them. Most of the artisanal
mining are located close to a flowing stream concentrating on the alluvial while very few excavate
in situ weathered material from a dip pit for washing using a carpet.

7. Figure 3: Abandoned Site of Artisanal Mining within the licensed area (688380N 847913E; RL = 358m)
Figure 4: Abandoned Site of Artisanal Mining within the licensed area (688397N 847925E; RL = 359m)
Figure 5: Abandoned Site of Artisanal Mining within the licensed area (687679N 847811E; RL = 351)

8. Figure 6: Active Site of Artisanal Mining within the licensed Area (687999N 847781E; RL = 355m)

9. Recommendation:
 A more detailed geochemical sampling should be planned and carried out based on the
results of the analysis of this regional sampling in order to delineate specific area with
high Au percentage within a zone
 The licensed area has a major river with tributaries that flow through, therefore proper
stream sediment sampling which are composite product of erosion and weathering in the
area, should be carried out in order to delineate the source catchment area of the stream
drainage network.
 Also, direct methods such as test pitting and trenching should be carried out to delineate
possible veins hosting the gold mineralization.
 Geophysical survey can also be carried out in the environment to investigate the
subsurface geology in order to delineate subsurface structures that can aid gold
mineralization