- Economic Geology
Quartz-hosted gold deposits in the Hodgkinson province, north Queensland, are widely distributed with the most heavily endowed areas comprising three separate, spatially distant goldfields: the West Normanby goldfield, the Palmer River goldfield, and the Hodgkinson goldfield. Relationships among quartz vein- and shear-hosted deposits in each of the three goldfields indicate that the introduction of gold-bearing quartz displays consistent structural timing relative to a regionally recognized deformation history. Gold was emplaced during the waning stages of D4, the main contractional phase of the Permian-Triassic Hunter-Bowen orogeny. Mineralization and structures have been structurally timed relative to isotopically dated plutons of the spatially associated syn-D4 Whypalla supersuite, indicating emplacement of the mineralization in the Early Permian or later. Emplacement of gold-bearing quartz veins in the fossiliferous Permian Normanby Formation in the north of the province supports this contention. The Permian age is younger than the originally published Carboniferous (~300 Ma) age for gold mineralization in the Hodgkinson province. Fluid generation and gold transport were related to regional-scale devolatilization during province-wide metamorphism. The final distribution of fluids and contained gold was controlled by faults produced during the Hunter-Bowen orogeny and by major Late Devonian shear zones that were reactivated during this orogeny. Heat from synchronously emplaced D4 granites focused enhanced fluid flow into spatially associated dilatant structures in these faults.