Abstract
The Mt. Percy gold deposit (9 t Au produced) is part of the Golden Mile and is located at the northern end of Kalgoorlie gold camp. The deposit is hosted in the Hannan's Lake Serpentinite (2705-2710 Ma by SHRIMP U-Pb ages), Devon Consols Basalt, and feldspar-quartz (2670±5 Ma SHRIMP U-Pb on zircons), and hornblende-albite porphyry stocks (2650±6 Ma SHRIMP U-Pb on zircons).
Two distinct styles of gold mineralisation have been documented at Mt. Percy; (1) stage 1 shear zone-hosted in feldspar-quarts porphyry stocks and Hannan’s Lake Serpentinite, and (2) stage 2 sheeted vein network-hosted in feldspar-quartz porphyry stocks and Devon Consols Basalt. Pyrite mineral chemistry revealed lower As concentrations (200 ppm) in the stage 2 mineralisation when compared to stage 1 (feldspar-quartz porphyry stock=979 ppm; Hannan’s Lake Serpentinite=5000 ppm). Geochemical analysis of hydrothermally altered rocks reveal; (1) positive gold-silver and gold-antimony relationships, (2) lack of base metal-gold relationship, (3) systematic increase of the carbonatization index from distal to proximal alteration zones in all major host rocks, and (4) systematic increase in the alkali saturation index in alteration zones towards the orebody, albeit in the Devon Consols Basalt, this signature is weakly developed.
There are similarities between shear zone-hosted alteration and mineralisation including gold-sulphide assemblages and location of gold in fractures and inclusions in pyrite in the Golden Mile and Mt, Percy. The key difference is the location of gold mineralisation in stratigraphically older and deeper Hannan’s Lake Serpentinite, Devon Consols Basalt and the feldspar-quartz porphyry.
Two distinct styles of gold mineralisation have been documented at Mt. Percy; (1) stage 1 shear zone-hosted in feldspar-quarts porphyry stocks and Hannan’s Lake Serpentinite, and (2) stage 2 sheeted vein network-hosted in feldspar-quartz porphyry stocks and Devon Consols Basalt. Pyrite mineral chemistry revealed lower As concentrations (200 ppm) in the stage 2 mineralisation when compared to stage 1 (feldspar-quartz porphyry stock=979 ppm; Hannan’s Lake Serpentinite=5000 ppm). Geochemical analysis of hydrothermally altered rocks reveal; (1) positive gold-silver and gold-antimony relationships, (2) lack of base metal-gold relationship, (3) systematic increase of the carbonatization index from distal to proximal alteration zones in all major host rocks, and (4) systematic increase in the alkali saturation index in alteration zones towards the orebody, albeit in the Devon Consols Basalt, this signature is weakly developed.
There are similarities between shear zone-hosted alteration and mineralisation including gold-sulphide assemblages and location of gold in fractures and inclusions in pyrite in the Golden Mile and Mt, Percy. The key difference is the location of gold mineralisation in stratigraphically older and deeper Hannan’s Lake Serpentinite, Devon Consols Basalt and the feldspar-quartz porphyry.
| Original language | English |
|---|---|
| Title of host publication | Future Understanding of Tectonics, Ores, Resources, Environment and Sustainability (FUTORESS) II Conference |
| Subtitle of host publication | Abstract volume |
| Editors | Jan Marten Hulzenga, Zhaoshan Chang, Carl Splandler, Kaylene Camutt, Maree Corkeron, Eric Roberts, Arianne Ford, Christa Placek, Alexander Parker |
| Place of Publication | Townsville |
| Publisher | James Cook University |
| Pages | 39 |
| Number of pages | 1 |
| Volume | 69 |
| Publication status | Published - Jun 2017 |