Silicification across the Betze-Post Carlin-type gold deposit: Clues to ore fluid properties and sources, Northern Carlin Trend, Nevada.

摘要

Ore fluid properties and sources at the Betze-Post deposit, the largest Carlin-type gold system in the world (∼49 million ounces Au), are not well understood. To improve knowledge of ore fluids, the geochemical, textural, and fluid inclusion characteristics of ore, late-ore, and post-ore quartz associated with Au-bearing pyrite were determined. Various stages of quartz were identified by integrating petrographic, fluid inclusion, oxygen isotope, cathodoluminescence studies, and spatially associated Au-bearing pyrite. Ore stage jasperoid displays CL-dark luminescence and was overgrown by late-ore-stage CL-dark drusy quartz. Multiple generations of post-ore drusy quartz overgrow ore and late-ore quartz and exhibit CL-bright and CL-multiple luminescence. Microthermometry indicates ore stage fluids have low salinities and were trapped between 180°C and 240°C. deltaDH2O and delta 18O values in ore fluids and quartz, respectively, indicate that ore stage fluids were highly evolved but were diluted by unevolved meteoric fluids with time and as fluids migrated west, as the ore system waned.