| Summary: | In 2012, Boliden Mineral AB announced the discovery of a new mineral deposit in the Laver-area, c. 40 km west of Älvsbyn, Norrbotten, Sweden. The deposit was classified as large volume, low grade Cu-Au-Mo mineralization. This discovery resulted from intense exploration activities in an area c. 1 km south of the historic Laver mine. Geological descriptions in the area are old and restricted to the old Laver mine, which differs in the style of mineralization. For this reason, two M.Sc projects were initiated as collaboration between Boliden Mineral AB, Technische Universität Bergakademie Freiberg (TUBAF) and Luleå University of Technology (LTU). This report summarizes the results of the LTU M.Sc project, which focused on petrography, alteration and vein types, and the relationship between these features and the mineralization. Three profiles have been studied, through drill core logging with emphasis on rock types, veins and alteration types. In addition, 43 polished thin sections were carefully examined with optical microscope, combined with further examination in SEM and electron microprobe. Furthermore, 15 lithogeochemistry samples, mainly from porphyritic intrusions, have been studied. The Laver deposits are located in the south-west part of the Karelian craton, in the Arvidsjaur-group volcanic rocks, interpreted as deposited in an active continental margin or continental arc. The wall rock in the study area consists of volcanic-sedimentary, mainly felsic rocks, interpreted as post-eruptive mass flow deposit. The intrusive rocks consist of plagioclase-quartz to plagioclase-hornblende-porphyritic intrusions of intermediate to felsic composition. Both wall rock and intrusions have a calc-alkaline affinity. No temporal or spatial correlation of mineralization to specific intrusions has been identified, yet non-porphyritic mafic dykes cut all other rock types including mineralization. Mineralization at Laver is vein- and alteration-related, not bound to specific rock types and most likely related to hydrothermal ...
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