Genesis of the Anarraaq deposit and lithogeochemical vectors towards ore, Red Dog, Alaska

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Mineral exploration and mining contributes significantly to the Canadian economy in terms of the generation of royalties, tax income and employment. Historically Western Canada has been a major producer of Pb and Zn, but currently there are no large mines operating. There are, however, several undeveloped shale-hosted massive sulphide deposits in the Canadian Cordillera including the deposits at MacMillan Pass in the Yukon, Howards Pass in the NWT and Cirque in BC. One of the most important shale hosted Zn ore districts in the world is in Northern Alaska. The Red Dog district comprises a series of large Zn rich deposits; the Main deposit and Aqquluk have been/or are being mined and, Teck Resources are assessing other deposits e.g. Anarraaq for their economic potential. The host rocks to the mineralization weather easily and are poorly exposed and the remoteness of the area, combined with the high latitude and the climate, means that exploration is expensive and challenging. The mineralization is unusual in that it is very high grade, which makes the Red Dog deposits economic despite their geographic isolation. The mineralization in the deposits is complex and consists of several generations of sulphides. Sphalerite is the main ore mineral but there are at least 5 different generations of pre-, syn-, and post-ore pyrite present. Significant amounts of barite are also found in some of the deposits. Geophysical techniques have proven to be successful in targeting barite and pyrite but the relationship of these minerals to sphalerite is not known in all deposits and prospects. One of the primary aims of this project is to develop an understanding of the genetic relationship between pyrite, barite and sphalerite in the Anarraaq deposit and in the barite only and pyrite only regional prospects. We will then use geochemistry to analyse the composition of the high grade ore and the barren host-rocks to see if there are any pathfinder elements that can be used to vector towards the high grade parts of the system. We will combine these data to build a new model of how the deposit formed and explore how geochemistry can be used to vector towards high grade ore. This model can then be applied to other deposits of this type in the Canadian Cordillera.