Significance of ferruginous pisoliths and interface sampling for gold exploration in the covered terrains

Abstract The deeply weathered Yamarna Terrane is the easternmost, least explored Terrane of the Yilgarn Craton in Western Australia. Investigation of the landscape evolution, mineralogy and geochemistry of the transported cover showed that the near surface ferruginous regolith can provide a significant tool for exploration under cover. Three types of ferruginous materials were identified and examined in three gold prospects: Smokebush, Toppin Hill and Santana. The ferruginous materials include: 1) lateritic residuum and its detrital ferruginous clasts of underlying or nearby bedrock; 2) authigenic pisoliths and nodules of Permian glacial sediments (PPS); and 3) authigenic pisoliths of aeolian sand (PAS) overlying the other two. Our findings show that As is the main pathfinder element for Au mineralization. Arsenic and Au are elevated and form near surface anomalies in lateritic residuum, detrital ferruginous clasts, PAS, This study shows that ferruginous pisoliths and clasts in the cover are potential sampling media for Au exploration in the Yamarna Terrane. The exploration methods used in this study can be also applied in similar covered terrains not only in Australia but also in areas with complex weathering histories in the tropics and sub-tropics.