Summary: Abstract The Dalsfjord Complex is an allochthonous
crystalline unit in the hanging wall of a major extension-
al detachment of the Caledonian orogen on the western
coast of Norway. U­Pb geochronology has been carried
out to test a previously proposed correlation between this
unit and the Jotun Nappe Complex, a member of the
Middle Allochthon now occupying a foreland position to
the east. A monzonite sample of the Dalsfjord suite
yields a zircon age of 1,634±3 Ma, whereas a crosscut-
ting gabbro was formed at 1,464±6 Ma. Both rocks were
strongly overprinted during the Sveconorwegian oroge-
ny, especially the monzonite whose zircons U­Pb data
were strongly pulled towards a lower intercept age of
882±29 Ma, and whose titanite indicates a two-stage
growth history at >960 Ma and <920 Ma. These relation-
ships support the correlation of these units with the Jotun
Complex, and to some degree also with the Lindås
Nappe in the Bergen Arcs.
Keywords Caledonides · Dalsfjord · Jotun ·
U­Pb geochronology · Zircon · Titanite · Proterozoic

Source: Andersen, Torgeir Bjørge - Centre for Physics of Geological Processes & Department of Geosciences, Universitetet i Oslo

Collections: Geosciences