Insights on landscape geochemistry and mineral exploration in the Fraser Range, Albany-Fraser Orogen, Western Australia

Summary The Albany-Fraser Orogen is an emerging recently opened mineral exploration province in Western Australia due to the recent discoveries of the Tropicana-Havana Au system in 2005, and the Nova-Bollinger Ni-Cu deposit in 2015. Simons Hill is located less than 10 km to the SW of the Nova–Bollinger system in the Albany-Fraser Orogen in Western Australia. This study analysed the nature and distribution of the regolith, and its stratigraphy, weathering and depositional history that have led to a variety of residual and transported regolith types. It aims to expand the understanding of the landscape geochemistry associated with Symons Hill in order to provide insights into mineral exploration techniques in this region. Symons Hill is located on a palaeo-topographical high that did not experience the transgression–regression cycles that affected the Albany–Fraser Region for the last 60My. Hence the Simons Hill stratigraphy lacks the marine geochemical influence which is widespread in the Norseman area. The landscape at Symons Hill evolved in a lacustrine/swamp environment. Poor drainage resulted in an extensive, thin (<30m) and homogeneous fine–grained transported cover that displays the same geochemical footprint as the underlying unweathered basement rocks. This cover includes the thicker palaeochannel sequences at the south of the tenement. Most of the transported cover is <5 m thick. Since this cover is the result of local recycling of weathered outcrops, it is an appropriate sampling medium to assess the geochemical composition of the rock at depth. Even if metal geochemical anomalies were displaced laterally, the source of the anomaly at depth is localised, and is most often located within a few 100s of metres from its source. This is a key element to keep in mind when undertaking mineral exploration in the Albany-Fraser Orogen.