The Pool Burn basin is a tectonic depression that became almost isolated from the regional drainage system by river reorientation during Pleistocene uplift of surrounding ridges. Consequently, detrital gold in the basin was largely locally derived, from supergene zones on orogenic deposits and recycled from paleoplacers in erosional remnants of Miocene conglomerates, with the latter source predominant. This study documents the results of wind‐driven sand‐blasting of gold in an unusual inland occurrence of this process. These aeolian processes operated on original detrital thick flakes (800–50 µm). Interiors of these original particles had relatively coarse‐grained (~50 µm) silver (Ag)‐bearing gold cores surrounded by fine‐grained (~10 µm) recrystallised low‐Ag rims. Sand‐blasting of thick flakes exposed on the eroded unconformity between basement and Miocene conglomerates has transformed them into toroidal and spheroidal shapes creating delicate exterior gold protrusions and sheets with micron‐scale grain size. Hollow interior embayments contain kaolinite clay with dispersed micron‐scale biogeochemically mediated authigenic gold that formed under acid and alkaline pH and locally saline conditions. The inland aeolian gold is similar to, but distinct from, the more delicate shapes that enclose smectite clay in hollow aeolian gold derived from thin flakes on southern South Island beaches.
Palmer et al. (Tue,) studied this question.