The origin of sediment-hosted Nevada gold deposits has been highly debated, especially regarding the relative contribution of multiple mineralizing events, particularly relating to the Cretaceous. We examined the Pipeline gold mine in north-central Nevada, focusing on data from the four vein sets in this atypical deposit where there is evidence for Cretaceous gold mineralization. Only the third, a quartz-sericite-pyrite-calcite vein set, has any link with the alteration styles and gold mineralization within the Pipeline deposit. Our geochemical results from fluid inclusion microthermometry and gas analysis show that the fluids from which quartz deposited were sourced from condensing magmatic volatiles and were trapped at ~300 °C and 2 kbar lithostatic pressure (~8 km). 40
Ar dating of sericite demonstrates that the quartz-sericite-pyrite veins formed at ~92 Ma, matching the dates of gold-associated epigenetic illite. Ore fluids enriched in CO2
S caused decarbonation thereby releasing Fe2+
that reacted with H2
S to form pyrite. Decreasing H2
S destabilized gold bisulfide complexes and deposited gold. We conclude that this process can occur in a single Cretaceous event in advance of potential Tertiary mineralization.
This is an open access article distributed under the Creative Commons Attribution License
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited