The supergene mineralogy and geochemistry of numerous deposits in the Cobar region have been systematically explored in this study, with a particular focus on the oxidised zones of the Endeavour, Mineral Hill and New Cobar orebodies. A recurring pattern was identified in the oxidised mineral assemblages of the region, characterised by a multiple-stage paragenesis. Comprehensive geochemical modelling based on equilibrium processes was undertaken to elucidate the geochemical conditions under which the various assemblages formed. The exercise was extended in a series of experiments concerning the interaction of ground and vadose waters with secondary mineral species. This has led to a self-consistent geochemical exploration model for deposits in the Cobar basin. The model promises to be very useful for exploration in highly weathered terrains, particularly where the deposits lack significant surface expression. A similar approach may be relevant to exploration in other areas around Australia and world-wide. / Doctor of Philosophy (PhD)