Constraints on the structural setting, relative timing, and geochemistry of the Fimiston, Hidden Secret, and Oroya gold-telluride lode types, Kalgoorlie gold camp, Western Australia

Late-stage metamorphic (ca. 2.64 Ga) and punctuated magmatic-hydrothermal mineralization models (2.67–2.64 Ga) are proposed for gold mineralization in the Kalgoorlie gold camp (~ 2300 t Au; Archean Yilgarn craton, Western Australia). We present structural, whole-rock geochemical, pyrite trace element, and multiple sulfur isotope data to evaluate these models. Both the Fimiston and Hidden Secret lodes were emplaced in ca. 2675 Ma D_2b transtensional settings as releasing bends developed along the Golden Mile and Towns faults, respectively, and are related to the ingress of a H₂O-CO₂-Au-Te-As-S-K-Rb-Ba fluid concomitant with the intrusion of andesitic dikes. In the Hidden Secret orebody, this magmatic-hydrothermal fluid evolved from an early, As-enriched, greenstone-buffered fluid during the formation of disseminated pyrite mineralization (δ³⁴S_pyrite = 3.42 to 3.85‰; Δ³³S_pyrite = 0.25 to 0.43‰) to an Ag-Cu-Pb-Sb-Te-Tl-V-Zn–enriched fluid during the development of banded quartz-carbonate-sericite-pyrite veins (δ³⁴S_pyrite = - 10.74 to - 0.17‰; Δ³³S_pyrite = 0.06 to 0.19‰). Oroya gold-telluride lode mineralization formed during later, ca. 2660 Ma D_2c transpression from a V-S–Au-Ag-Hg-Te–enriched magmatic-hydrothermal fluid represented by δ³⁴S_pyrite = - 11.56‰ to - 4.96 and Δ³³S_pyrite = 0.08 to 0.17‰. The Fimiston/Hidden Secret and Oroya mineralization events record oxidized magmatic-hydrothermal fluids represented by δ³⁴S_pyrite ≤ 0‰ and Δ³³S_pyrite ~ 0.0 to 0.2‰. These oxidized magmatic-hydrothermal fluids interacted with surrounding wall rock, which lowered fluid fO₂ and buffered δ³⁴S_pyrite/Δ³³S_pyrite values to δ³⁴S_pyrite = ~ 1 to 5‰/Δ³³S_pyrite = ~ 0.2 to 0.7‰ in greenstone rock environments and to δ³⁴S_pyrite = ~ 1 to 5‰/Δ³³S_pyrite = ~ ≤ 0.3‰ and ≥ 0.7‰ in black shale environments. Anomalous Δ³³S values in ore-stage sulfides formed locally due to the incorporation of sulfur during fluid-wall rock interaction. The early, magmatic-hydrothermal Fimiston/Hidden Secret and Oroya gold-telluride lodes differ texturally, geochemically, and mineralogically from the D₃ Mt. Charlotte stockwork veins, which formed subsequent to ca. 2650 Ma and better adhere to a late-stage metamorphic devolatilization model.