Melange- and sediment-hosted gold-bearing quartz veins, Hodgkinson gold field, Queensland, Australia.

Gold-bearing quartz veins in the Hodgkinson gold field are hosted in fault-bounded domains in subgreenschist facies sandstones, shales and melange rocks. The host shear zones cut three earlier deformation events and contain fault rocks which indicate multiple ductile-brittle and brittle processes. Stibnite-gold-quartz mineralisation is restricted to separate geological domains and vein episodes. Assimilation-textured quartz usually predates ribbon, buck and breccia quartz, although complex mixtures of quartz are common in the ore shoots. Fluid inclusion and isotopic studies suggest a fluid which initially cooled and decreased in salinity upon contact with the host rock and then remained constant during most of the mineralising event. It is possible that the auriferous fluids contained a component of highly evolved, D-poor meteoric water. However, the characteristics of the gold mineralising fluids mainly reflect extensive fluid-rock interaction either at the source or within fluid conduits, and the geological evidence suggests that mineralisation was caused by deeply sourced, upwardly migrating fluids.
Gold-bearing quartz veins in the Hodgkinson gold field are hosted in fault-bounded domains in subgreenschist facies sandstones, shales and melange rocks. The host shear zones cut three earlier deformation events and contain fault rocks which indicate multiple ductile-brittle and brittle processes. Stibnite-gold-quartz mineralisation is restricted to separate geological domains and vein episodes. Assimilation-textured quartz usually predates ribbon, buck and breccia quartz, although complex mixtures of quartz are common in the ore shoots. Fluid inclusion and isotopic studies suggest a fluid which initially cooled and decreased in salinity upon contact with the host rock and then remained constant during most of the mineralising event. It is possible that the auriferous fluids contained a component of highly evolved, D-poor meteoric water. However, the characteristics of the gold mineralising fluids mainly reflect extensive fluid-rock interaction either at the source or within fluid conduits, and the geological evidence suggests that mineralisation was caused by deeply sourced, upwardly migrating fluids.