Zincian staurolite in the Dry River South volcanic-hosted massive sulfide deposit, northern Queensland, Australia: an assessment of its usefulness in exploration

Abstract

Staurolite from the Dry River South volcanic-hosted massive sulfide deposit in northern Queensland, Australia is enriched in ZnO (2.5–6.8%) only within the massive sulfide lens or in highly pyritic biotite-chlorite schist just below the massive sulfide lens. In the footwall alteration zone, staurolite ZnO levels vary between 0.4 and 1.3%, whereas in hanging wall metagraywackes and metapelites, the ZnO content is mainly below 1.0%. As staurolite from metapelitec rocks contains up to 7.9% ZnO, high ZnO levels in staurolite do not necessarily indicate a relationship to Zn-rich massive sulfide. Staurolite grains from the Dry River South amd other massive sulfide lenses have low TiO 2 concentrations (mainly <0.4%) relative to staurolite grains from metasediments and alteration zones (mainly >0.4%). The low concentration of TiO 2 in staurolite from the massive sulfide lens results from the low initial Ti concentration in exhalative ores. High ZnO and low TiO 2 values are indicative of staurolite associated with Zn-rich massive sulfide. Zincian staurolite is a potential exploration indicator at both prospect and reconnaissance scales. At the prospect scale, zinc levels have potential in distinguishing true from false gossans, distinguishing low grade portions of massive sulfide lenses from barren massive pyrite bodies, and characterizing alteration zones. At the reconnaissance scale, staurolite can be collected in the heavy mineral fraction of stream sediments, and multiple grains can be analyzed rapidly using modern electron microprobes.