Abstract
A few post-metamorphic igneous dykes were newly found from Skallevikshalsen, Rundvagshetta, and Niban-Iwa in the Lutzow-Holm Complex. Internal textures are parallel to the trend of the dyke intrusion. Dykes in Rundvagshetta were strongly related for the origin with post-genetic pegmatites, and partly modified to amphibolite with coarse hornblende by the pegmatitic activity.
The dykes are holocrystaline, and consist dominantly of alkali-feldspar and subsequent biotite, augite, hornblende, titanite, apatite and minor amount of plagioclase and quartz:. Minerals, especially biotite flakes are commonly aligned to parallel to boundary between the dykes and the host gneisses. Based on their mineral assemblages, it is expected that the dykes have potassic and intermediate to mafic compositions.
In Rundvagshetta, host metamorphic rocks were partly metasomatized by hydrated reaction and garnet was broken down to biotite in the metasomatized domain. Since the dyke contains abundnat biotite and subsequent apatite as well as alkali feldspar, it is expected that the dyke supplied fluid for the metasomatism during its activity.
