Hydrothermal Cu-Zn mineralization at Vanna, West Troms Basement Complex: A geochemical analysis of Archean and Proterozoic rocks with focus on sulfide genesis

Abstract

The hydrothermal Vannareid Cu-Zn mineralization is located on the island of Vanna, West Troms Basement Complex. It was discovered in 2008 and was subject of Store Norske Gull AS' exploration project in 2012. The mineralization is situated along the border between the Archean granitoid basement intruded by tholeiitic and calc-alkaline dykes, and the overlying Neoproterozoic metasedimentary rocks of the Skipsfjorden Nappe. A Mesozoic normal fault, the Vannareid-Burøysund fault complex, led to the juxtaposition of the two different lithological units. Field work included mapping and descriptions of the rocks in close proximity of the Vannareid Cu-Zn mineralization. Geochemical and mineral chemical analyses were carried out on samples collected from drill cores drilled through the mineralized zone from Store Norske Gull's drilling campaign. These studies showed sulfide enrichment in vein and brecciated rocks affected by hydrothermal alteration suggesting that the mineralization represents the stringer zone of a volcanogenic massive sulfide deposit.