Intrusion-related gold systems
The Älgträsk intrusive hosted Au deposit, Skellefte district, northern Sweden, is situated in the oldest, most heterogeneous part of the c. 1.89–1.86 Ga Jörn granitoid complex, which intruded a complex volcano–sedimentary succession in an island arc or continental margin arc environment. The Tallberg porphyry Cu deposit, situated only 3 km west of Älgträsk, is associated with quartz feldspar porphyritic dykes. These dykes are suggested to be genetically related to similar porphyry dykes in Älgträsk and the tonalitic host rock in Tallberg. The granodiorite hosting the Älgträsk Au-deposit does not appear to be genetically related to the tonalite or the porphyry dykes.