In 2008 Greg completed a prospectivity model for iron oxide-copper-gold (IOCG) mineralisation for the Volta basin in Ghana using the geographic information systems (GIS) based fuzzy logic modelling technique.
The model was completed using the minerals systems approach. The essential geological components that define a mineral system are:
- A source of energy that drives the system.
- Sources of fluids, metals and ligands (felsic and mafic intrusives).
- Pathways along which fluids can migrate to trap zones.
- Trap zones (i.e. narrow, effective pathways or host rock reactivity and competency).
Ore deposit formation is precluded where a particular mineral system lacks one or more of these essential components.
Available data were matched with the themes derived from detailed analysis and modelling previously conducted in the Mt Isa region of Australia. These variables were then developed into the predictive maps used in the modelling process using various spatial and statistical techniques.
Historically the Volta Basin has not been a high priority target for copper or gold metal mineralisation. This is due partly to the thick basin sequence and the abundance of accessible deposits in the nearby Birrimian Supergroup. However, the existence of large magnetic and gravity anomalies have recently been interpreted as intrusive rocks underlying the younger deposits and this has opened the way to alternative mineralisation possibilities.
The Ghanaian spatial data modelling aims to reduce the search area for potentially undiscovered IOCG deposits by constraining spatial geological data based on a predefined IOCG deposit model. The results of this model when combined with current cultural and tenement information and viewed in relation to specific strategic and exploration priorities can enhance acquisition planning and exploration risk management in Ghana.