Victoria Devlin McLoughlin, PhD
V. Devlin McLoughlin1, D. Gregory1, E. Hastie1,2
1Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
2Ontario Geologic Survey, Sudbury, Ontario, Canada
The Timmins gold camp is located along the Porcupine-Destor fault system. The camp is the largest Archean orogenic gold camp on the planet, and has produced over 2,190 t, or 70.5 million Moz of gold. Highly productive gold deposits are often thought be the product of multiple gold enrichment events. Pyrite is one of the main mineral hosts of gold. Combined textural and chemical analysis of pyrite has been used to determine the evolution of gold within several deposits (e.g. Large et al., 2009; Stromberg et al., 2019; Hastie et al., 2020). The majority of gold mined within the Timmins gold camp is in the form of free gold. Because of this, there is a lack of research into the relationship between pyrite and gold mineralization within the camp.
Here we present the different pyrite textures identified in our preliminary analyses of the Timmins gold camp, and what they suggest about the evolution of pyrite within the camp. Textural analysis of pyrite can identify the relative timing of gold introduction (s) into the deposit forming environment. Identifying overprinting or replacement of pyrite generations in combination with planned trace-element analysis can inform how gold concentrations changed with time, and whether the native gold found in the veins may have been re-mobilized from earlier refractory gold.
In addition to pyrite textures, alteration mineral assemblages can also be used to better understand the formation of a gold deposit by connecting specific mineral assemblages back to their fluid source. We will present the alteration mineralogy present within our first set of samples. This preliminary analysis will help inform the creation of an alteration map of the Timmins camp. The relationship between alteration minerals and pyrite will help us relate the different generations of pyrite, and thus gold evolution, to fluid sources. Overall, these analyses will help to increase understanding of the evolution of the Timmins gold camp, and provide evidence that can be used in the study and interpretation of other gold camps.