Characterisation of a laterite-type bauxite orebody geometry using a plurigaussian simulation approach

A typical laterite-type bauxite deposit is formed from tropically weathered mafic-ultramafic complexes. The components of the weathering profile such as bauxite and underlying ferricrete units can be discontinuous with a relatively significant lateral variability. Understanding the major process of the lateritic weathering system and local lateral variability of the orebody contacts are of utmost importance in terms of an accurate orebody volume calculation and ore recovery at the alumina refinery. The plurigaussian simulation provides a tool that is used to simulate the lithotypes present in the regolith profile, which in turn reproduces the natural contacts between the geological units. The plurigaussian simulation approach was demonstrated in a case study where the geometry of the lateritic bauxite deposit was delineated. Four lithotypes including overburden, redsoil, bauxite and ferricrete were used in the simulation. The resulting realisation indicated a good reproduction of the conditioning data both laterally and vertically. Contrary to the deterministic models, the simulated realisation represented a possible geological model without the smoothing effect