Towards compositional geochemical potential mapping

Mineral potential mapping aims at defining target zones of future local mineral exploration efforts on the basis of regional geochemical and geological surveys. Geochemical potential mapping typically involves using a small set of elements to predict an anomalous presence of a mineral commodity related with them. In this context it is common to work with logarithmically transformed concentrations of elements. This contribution explores a compositionally compliant approach to potential mapping using geochemical evidences, in which the whole set of components is applied a log-ratio transformation before any potential mapping technique is used. In this way, candidate zones can be identified by its high value in a certain ratio of elements, implying that the important information is a contrast betweeen two or more elements, and not an absolute concentration of one of them. Two different potential mapping techniques are used (a method equivalent to the Fisher rule, and a hierarchical binary logistic regression, both accounting for spatial dependence), with equivalent results.