Metallogenic Fingerprints of the Congo Shield with Predictions for Mineral Endowment Beneath the Congo Basin - Geology and Resource Potential of the Congo Basin - page 388

Fig. 19.7 Relative area
distribution (Y axis) of the
Central Africa, Central Africa
Shield, Congo Shield and the
Congo Basin expressed in terms
of their simplified Precambrian
geology. The insert at the top
illustrates
CA CAS CS CB

Conclusions
We assign an expert weight to the CS and CB by using the
data from known mineral deposits from their surrounding
regions, as well as knowledge of the distribution of Pre-
cambrian rocks in CA and CAS. Our expert weight is
data-driven and it is based on a

'
approach. The value of the weights are judged on an
ordinal scale (values between 0 and 0.5 are weak; 0.5-1
moderate; and

'

weight of evidence

1 strong). In general, the Archean areas
in the CB (and CS) have a strong affinity for Gold, and
CrNiPge; and a moderate affinity for SnSb. This seems
reasonable given the general mineral fields shown in
Fig. 19.1 . The Neoproterozoic areas in the CB (and CS)
has a weak affinity for CrNiPgeTi; a moderate affinity for
UThREE and a strong affinity for Cu(Co)ZnPbBa. The
MPP area beneath the CB contains a moderate affinity for
SnSb; however MPP only covers a very small area (less
than 1 %). Finally it must be noted that the extrapolation
of the basement geology beneath the CB is itself
extrapolated from the surrounding regions and has a
large uncertainty as is evident from the first two chapters
of this Topic.

>

Fig. 19.8 Area distribution of Congo Basin. The values represent the
areas in km 2

The final fingerprints that we assign to the CS and CB are
given in the last column of Table 19.3 . These fingerprints
(obtained from the CA and CAS) are based on weights
derived from a data-driven ' weight of evidence ' (WofE)
approach. The results from a data-driven technique can be
further enhanced by ' expert knowledge ' .