The Levijaervi ― Loukinen Au-Ni-Cu occurrence: A Palaeoproterozoic polymetallic erogenic gold mineralisation in the Sirkka Line tectonic structure, northern Finland

摘要

The Levijaervi ― Loukinen Au-Ni-Cu occurrence, located in the Central Lapland Greenstone Belt, northern Finland, is an orogenic gold occurrence with an uncommon metal association. Gold mineralisation is located along the Sirkka Line, a major WNW-ESE trending tectonic zone separating two lithologically and temporally different terrains from each other. The mineralised zone has a strike length of at least five km, and higher grade areas consist of quartz-carbonate-sulphide vein networks and breccias. The gold mineralisation is associated with pyrrhotite, chalcopyrite, pyrite, gersdorffite and arsenopyrite. Native gold, the main carrier of Au, is mainly related to sulpharsenides and pyrite. The occurrence is unusually polymetallic (Cu, Fe, Ni, Au +- Ag, Co) for an orogenic gold mineralisation. Its polymetallic nature is interpreted to be the result of mineralisation overprinting Ni-Cu-Co rich sedimentary rocks.