Kenex has undertaken prospectivity modelling in Zambia which evaluates the potential for iron-oxide copper gold (IOCG) deposits throughout the country and also south into Namibia and Botswana. We used the GIS based fuzzy logic spatial modelling technique with publically available geological, geophysical and geochemical databases to generate new targets for IOCG exploration. These targets are being used to target tenement acquisition in Zambia and plan exploration programmes.
IOCG deposits include many diverse ore systems and are found on all continents generally in post-Archean rocks from the Early Proterozoic to the Pliocene and are located in zones of extensional tectonics along pre-existing rift zones. IOCG mineralisation environments are usually known to contain significant amounts of igneous activity, high heat flow, and source rocks that are relatively oxidised. The IOCG deposits of western Zambia, north western Botswana, and northern Namibia are found in rocks of the Lufilian Arc, a Mesoproterozoic to Neoproterozoic rift basin which closed during the Pan-African orogeny.
Our modelling was based on information from the weights of evidence modelling of the Eastern Fold Belt of the Mt Isa Inlier in Queensland, Australia where the relationships between IOCG deposits and their source, transport pathways and traps are well known. This enabled us to reduce the subjective element of the fuzzy logic modelling technique and understanding of the mineral system model in Zambia where there are few known IOCG deposits. From the modelling in Mt Isa and literature on IOCG systems in the Lufilian Arc we created predictive maps for the model which represented all stages of the mineral system model. These maps were combined using the fuzzy logic modelling technique and the result has mapped areas in Zambia, Namibia and Botswana with the same geological features as IOCG deposits in the Mt Isa region. These target regions therefore have increased potential to host IOCG mineralisation in Zambia.
The fuzzy logic modelling reduced the exploration search area down by 90% and has generated several targets for follow-up data collection and new modelling with detailed geological databases. Kenex clients are currently following up on these targets and renewed modelling for IOCG and other mineral systems are currently planned for Zambia, Namibia and Botswana.
You can read more about IOCG modelling in Africa in the paper presented by Katie at the SGA / SEG conference in Townsville in 2009