Porphyry and skarn Cu prospectivity of Sumatra with GIS spatial modelling techniques

Abstract

Although Sumatra Island hosts only one mid-sized, economically viable porphyry Cu deposit and a few exploited Cu-rich polymetallic skarns, studies indicate that more Cu resources remain to be discovered. This contribution integrated geochemical, structural, and relief evidential layers with the fuzzy logic- and weights-of-evidence (WoE) methods to produce mineral prospectivity maps that show a strong correlation between the generated favourable areas and the existing porphyry and skarn Cu prospects, as well as potentially new exploration districts throughout Sumatra. Moreover, a local singularity fractal map of Cu-enriched zones reduces the proposed target areas and cross-validates the results of the fuzzy model. The inclusion of relief data in the modelling filters out signal noise arising from other evidential layers and overcomes the over-fitting issue encountered in the model that excluded a relief map. The resulting Cu potential maps can thus be used as base maps for regional porphyry and skarn Cu exploration.