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The Fennoscandian Shield covering most of Finland, Sweden and NW-Russia (Fig. 1) is an Archaean to Neoproterozoic crustal province with a long and complex growth history (eg Gaal & Gorbatschev 1987; Park 1991; Gorbatschev & Bogdanova 1993; Kärki et al. 1993; Nironen 1997; Bergman et al. 2001; Lahtinen et al. 2008; Hölttä et al. 2008). Similarly aged but smaller basement provinces occur in coastal regions west of the Scandinavian Caledonides, eg in Lofoten and western Troms (Fig. 1)(Griffin et al. 1978; Sigmond et al. 1984; Zwaan et al. 1998; Corfu et al. 2003; Corfu 2004). These western provinces have received much less attention than the autochthonous craton farther east due to the uncertainty of correlations and the Caledonian reworking (Dallmeyer 1992). Structural and geochronological research carried out in recent years in the West Troms Basement Complex (WTBC), however, has sparked off new interest in these provinces.

Recent geochronological work, combined with structural and some petrological work in the WTBC (Corfu et al. 2003, 2006; Armitage & Bergh 2005; Kullerud et al. 2006a, b; Bergh et al. 2007; Myhre & Corfu 2008) has revealed a much more heterogeneous rock assemblage than previously recognized, with ages ranging from the Neoarchaean (2.89-2.56 Ga) to the Mesoproterozoic (c. 1.57 Ga). The province has experienced rifting and mafic dyke intrusion (2.4-1.98 Ga), volcanic activity and clastic sedimentation (c. 2.85-1.97 Ga), arc magmatism and Svecofennian crustal deformation and reworking (1.8-1.76 Ga). Our focused structural research has added new knowledge that advances previous tectonic …