The origin of base metal mineralizing brines

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The total value of all mineral commodities mined in Canada, including metals, non-metals and coal, increased to $26.4 billion in 2005 and, thus, the mining industry is a significant contributor to the Canadian economy. This proposal is concerned with studying a range of ancient hydrothermal base metal mineral deposit types. Although these deposits formed in the past at different temperatures and depths in the Earth's crust all of them were formed by large volumes of hot water. These fluids contain significant amounts of dissolved chlorine, which formed complexes with the metal ions and allowed them to be transported by the water from the metal source regions to the area where the ore deposit formed. In such ore deposits, droplets of the mineralizing solution can be trapped in minerals as fluid inclusions and retain evidence of the chemistry of the mineralizing fluids and the environment in which they formed. The research proposed here is concerned with the continued support of a new laboratory dedicated to the analyses of these ancient fluids and in particular the study of the chlorine, bromine and chlorine isotopic composition of the fluids. These techniques have been successfully used to recognise the source of chlorine in mineralizing systems and, in some cases, also the source of the fluid itself, which allows us to constrain models of how a particular base metal deposit was formed.