GIS-Based ( W+ — W−) Weight of Evidence Model and Its Application to Gold Resources Assessment in Abitibi, Canada

Abstract

The weight of evidence (WofE) model has been widely used for mineral potential mapping. During the conversion of a multiclass map into a binary map a lot of mineralization information is artificially added or lost because the generalization of the class within the cumulative distance interval to a linear feature is based on a maximum contrast, which matches a cumulative distance interval. Additionally, some categorical data evidence cannot be generated by this method because a maximum contrast does not exist. In this article, an alternative (W+—W−)-based WofE model is proposed. In this model, the “(W+—W−) greater than zero or not” is used as a criterion to reclassify the corresponding categorical class into a presence or absence class to convert a multiclass map into a binary map. This model can be applied to both categorical data and successive data. The latter can be operated as categorical data. The W+ and W− of the generated binary maps can be recalculated, and several binary maps can be integrated on the condition that the reclassified binary evidences are conditionally independent of each other. This method effectively reduces artificial data and both nominal and categorical data can be operated. A case study of gold potential mapping in the Abitibi area, Ontario, Canada, shows that the gold potential map by the (W+—W−) model displays a smaller potential area but a higher posterior probability (POP), whereas the potential map by the traditional (W+—W−) model exhibits a larger potential area but a lower POP.