Integrated Geochemical and Geophysical Approach to Mineral Prospecting – A Case Study on the Basement Complex of Ilesa Area, Nigeria - Advances in Data, Methods, Models and Their Applications in Geoscience - page 77

Element Pb Fe Ni Cd Cr Cu Zn Mn

Pb 1. 00

Fe 0. 35 1. 00

Ni 0. 01 0. 48 1. 00

Cd 0. 12 0. 22 0. 37 1. 00

Cr -0. 05 0. 03 0. 22 0. 17 1. 00

Cu 0. 15 0. 01 0. 01 -0. 03 0. 08 1. 00

Zn 0. 33 0. 04 0. 14 0. 37 0. 11 0. 40 1. 00

Mn 0. 29 0. 94 0. 44 0. 27 0. 09 0. 09 0. 03 1. 00

Table 3. Correlation coefficients of the elements

U 1
(41. 11)

U 2
(27. . 65)

U 3
(16. 58)

U 4
(8. 31)

U 5
(3. 79)

U 6
(2. 51)

U 7
(0. 04%)

U 8
(0%) %

Pb X 1 - 0. 0022 0. 5905 -0. 1851 -0. 4640 0. 3429 - 0. 1434 -0. 2725 0. 4351

Fe X 2 - 0. 5046 0. 2445 0. 0376 0. 0729 -0. 1184 0 . 3095 0. 6589 0. 3674

Ni X 3 - 0. 3897 -0. 3036 -0. 1220 0. 5128 0. 5782 - 0. 0440 -0. 2619 0. 2707

Cd X 4 - 0. 1052 -0. 3599 -0. 6629 -0. 1409 -0. 4200 - 0. 3702 0. 0425 0. 2912

Cr X 5 0 . 0880 -0. 5187 0. 4400 -0. 3967 -0. 0550 0 . 2898 -0. 1527 0. 5118

Cu X 6 0 . 4073 0. 2412 0. 2444 0. 5520 -0. 3130 - 0. 2636 -0. 0585 0. 4905

Zn X 7 0. 4034 0. 0405 -0. 5018 0. 1695 0. 0080 0. 7336 -0. 0911 0. 0929

Mn X 8 -0. 5001 0. 2024 0. 0696 0. 0757 -0. 565 0. 2304 -0. 6214 -0. 0809

Eig. of Cov.
Matrix

3. 2890 2. 2120 1. 3262 0. 6653 0. 3033 0. 2008 0. 0034 0. 0000

T 2 6. 1250 6. 1250 6. 1250 6. 1250 6. 1250 6. 1250 6. 1250 6. 1250
Table 4. Coefficients of the Principal component transformation (Numbers in Bracket are the
proportion of total variance in %) of the elements

The principal components U 4 , U 5 , U 6 , U 7 and U 8 have smaller variability and have respective
eigenvalues of 0. 6653, 0. 3033, 0. 2008, 0. 0034 and 0. 0000. These when compared to the first
three components are very small which is an indication of their relative decrease in
significance in the data. So any association suggested by them cannot be realistic.
Results of a previous regional geochemical survey carried out by Ajayi and Suh (1993) using
the factor analysis statistical techniquerevealed the existence of : Zn - Co - Cd, Ni - Cr, Fe -
Mn and Cu - Pb as relevant associations mainly in the Amphibolites rocks. The results from
the present study compare favourably well to these earlier results obtained from factor
analysis but the association region extends to the quartz-schist rocks as can be seen in
Figures 3, 4 and 5. Figure 3 shows the association ratio of Fe - Mn. The range of values is
shown by the coloured circles. Values are classified as low (in purple circles) with
concentration less than 20ppm, moderate (in yellow circles) with concentration range of 21 -
40ppmand high (in blue circles) with concentration greater than 41ppm. It can be seen that
higher values are clustered at the central part of the figure which is on the Amphibolite,
Schist and Epidiorite Complex and also on the Quartzite/Quartz Schist. At other parts, the
values are distributed between moderate and lower values, though, with some isolated
higher values probably due to rock intrusions. For examples, the higher values near
Iperindo are surrounded by lower and moderate values.