Geochemical signatures of native gold alloys as a tool for understanding auriferous ore deposits

Studies of native gold sampled from drainages are an important exploration tool and an increasing number of studies have evaluated the characteristics of detrital gold to understand gold camps and the deposits within them. This thesis focuses on the compositional analysis of the native gold sampled from drainages. By sampling the detrital gold eroded out from a gold deposit, the gold particles can be compared to in situ gold particles, thereby allowing correlation with knowledge gained from traditional mineralogy and an assessment of the gold on a deposit (macro) scale. This provides a novel assessment of how variable a deposits’ mineralisation might be which can provide useful context to micro scale observations.
To develop, investigate and test correlative uses of detrital gold samples with traditional mineralogy, three different studies were conducted at the Cononish Mine (Scotland), Curraghinalt Mine (Northern Ireland) and the Atlin Gold Camp (British Columbia).
This work demonstrates that populations of gold particles sampled directly from mines differ from detrital populations obtained from drainages. Detrital populations are considered more representative of the mineralisation within a deposit, as they are the residual lags resultant from the erosion of a huge volume of material. Correlation between gold particles in ore and in detrital population provides a context to the compositions in ore on a deposit/ system scale. By identifying the importance of specific gold compositions within the deposit observations of the ore assemblages associated with gold events can be examined in a deposit scale context which would otherwise not be possible. This allows temporal and spatial differences between ore samples to be evaluated for significance. This provides a contextual framework for observed changes in the ore assemblages, and therefore mineralising fluids. This work presents a method for relating micro to macro scale characterisations of a gold mineralisation using gold compositions. It demonstrates that detrital gold studies can improve the understanding of gold mineralisation and, critically, can provide a context for the gold mineralisation across multiple scales within a deposit, which through traditional mineralogy alone is difficult to achieve.