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, <75 μm and <2 μm soil size fractions at Smokebush. At Toppin Hill, Au migrated directly from the mineralization through the Permian cover and became enriched at the surface in the PPS above mineralization. Laser ablation ICP-MS mapping shows Au in the PPS as nano-grains, microcrystalline aggregates and veinlet fillings. This is supported by partial extraction analyses, where Au was extracted mainly by K-iodide and K-cyanide, indicating that it is dispersed in particulate and soluble forms. The absence of an As anomaly in transported cover over the Toppin Hill prospect compared to Smokebush is related to the absence of arsenopyrite in the Toppin Hill Au mineralization. Arsenic, which was extracted mainly by 0.1M tetra-sodium pyrophosphates, is associated with organic compounds and has a different fractionation pathway from Au near surface. This is also shown by an As anomaly in the Eucalyptus foliage over the Smokebush Au mineralization. At the Santana prospect, there are no Au and/or As anomalies in the PPS over the mineralization. The PPS at Santana are reworked from barren Permian cover and could be deposited with ferruginous clasts from different sources, as shown by textural and mineralogical variations between the grains and matrix. Furthermore, there is no evidence of hydromorphic dispersion of Au and As from the underlying mineralization. Thus, the PPS at Santana can not be used to vector towards the mineralization. However, sampling at the unconformity (interface sampling) is more effective in locating the mineralization at Santana.

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.

风化较深的Yamarna Terrane是西澳大利亚的Yilgarn Craton最东面，勘探最少的地貌。对运输覆盖物的景观演变，矿物学和地球化学的调查表明，近地表铁质重矿物可以为覆盖物下的勘探提供重要工具。在三种金矿中鉴定并检验了三种类型的铁质材料：烟熏，Toppin Hill和桑塔纳。含铁材料包括：1）红土残渣及其下层或附近基岩的碎屑状铁质碎屑；2）二叠纪冰川沉积物（PPS）的自生岩浆和结核；3）覆盖其他两个的自生风成沙（PAS）。我们的发现表明，As是金矿化的主要探路元素。烟丛中的红土残留物，碎屑性铁质碎屑，PAS，<75μm和<2μm土壤大小部分中，砷和Au升高并在表面异常附近形成。在Toppin Hill，Au直接从矿化中迁移出来，穿过二叠纪覆盖层，并在矿化上方的PPS的表面富集。激光烧蚀ICP-MS谱图显示PPS中的Au为纳米颗粒，微晶聚集体和细脉填充物。这通过部分萃取分析得到支持，其中Au主要通过K-碘化物和K-氰化物萃取，表明Au分散在颗粒和可溶形式中。与Smokebush相比，Toppin Hill勘探区的运土覆盖层中没有As异常，这与Toppin Hill Au矿化中没有毒砂的原因有关。砷，主要以0提取。1M焦磷酸四钠与有机化合物缔合，并且与Au表面附近的分馏途径不同。这也由Smokebush Au矿化作用的桉树叶中的As异常显示。在桑塔纳（Santana）勘探区，矿化过程中PPS中没有Au和/或As异常。桑塔纳半岛的PPS是由贫瘠的二叠纪覆盖层改造而成的，可能会沉积有来自不同来源的含铁质碎屑，如颗粒和基质之间的组织学和矿物学差异所示。此外，没有证据表明潜在的矿化作用使Au和As发生了氢态分散。因此，桑塔纳的PPS不能用于引导矿化。但是，在桑塔纳的矿化定位中，不合格处的采样（界面采样）更有效。

这项研究表明，表层中的铁质岩屑和碎屑是潜在的采样介质，可用于在Yamarna Terrane中进行金矿勘探。本研究中使用的勘探方法不仅可以在澳大利亚类似的覆盖地形中使用，而且可以在热带和亚热带具有复杂气候历史的地区使用。