Indirect Associations Between Lamprophyres and Gold-Copper Deposits

Abstract

This Chapter describes the spatial association between lamprophyres and orogenic gold deposits worldwide. The spatial relationships between lamprophyric magmatism and orogenic gold deposits of the Archaean and Proterozoic provinces in the Northern Territory, Australia, the Eastern Goldfields, Yilgarn Craton, Western Australia, and in the Superior Province, Canada, are discussed in detail. Although lamprophyres are spatially and temporally related to gold mineralization in all those terranes, the association is interpreted to be an indirect one. Both lamprophyres and gold mineralization occur along major faults and shear zones which controlled their emplacement. Elevated Au contents in some Proterozoic lamprophyres from the vicinity of lode-gold deposites are decoupled from Cu and Pd peaks in primitive mantle-normalized distribution plots, suggesting that the anomalous Au contents are secondary features. The contamination could have been caused during emplacement en route to the surface or by hydrothermal fluids that overprinted the dykes after their emplacement.