Silicon isotope geochemistry of micro-fine disseminated gold deposits in SW Guizhou and NW Guangxi, China.

Quartz from the disseminated ores and quartz associated with hydrothermal silicification was found to have a silicon isotopic composition and cathodoluminescence quite distinct from that of the wall rocks. Quartz associated with primary silicification was not luminescent, whereas that in wall rocks exhibited striking luminescence. From the silicon isotope values for primary silicification in host rocks of different ages, the process of silicon precipitation can be roughly approximated on the basis of dynamic fractionation of isotopes. The results show that fracture systems at deeper levels were more favourable to the deposition of SiO2, indicating that deep structures close to major fault systems would have high potential for the formation of large gold deposits.
Quartz from the disseminated ores and quartz associated with hydrothermal silicification was found to have a silicon isotopic composition and cathodoluminescence quite distinct from that of the wall rocks. Quartz associated with primary silicification was not luminescent, whereas that in wall rocks exhibited striking luminescence. From the silicon isotope values for primary silicification in host rocks of different ages, the process of silicon precipitation can be roughly approximated on the basis of dynamic fractionation of isotopes. The results show that fracture systems at deeper levels were more favourable to the deposition of SiO2, indicating that deep structures close to major fault systems would have high potential for the formation of large gold deposits.