Geology of the Minor Bergen Arc, West Norway.
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Detailed mapping of the Minor Bergen Arc has revealed the presence of a variety of highly deformed rocks of different origin and age. Three rock units have been separated and named. The Nordåsvatn Complex comprises deformed and metamorphosed sedimentary and igneous rocks which resemble a dismembered ophiolite complex and related rocks. The Storetveit Group represents a clastic cover sequence to the ophiolitic rocks and is correlated with the Late Ordovician-Early Silurian Holdhus Group in the Major Bergen Arc. The Gamlehaugen Complex comprises slices of Precambrian gneisses and quartz-rich metasediments of unknown age, interpreted as a detached and sheared continental basement-cover couplet. Intense deformation (D2) of all rocks under metamorphic conditions close to the greenschist-amphibolite facies transition is ascribed to the Late Silurian-Early Devonian Scandian event, and mapping has shown that extensive basement-involvedimbrication accompanied the deformation. Pre-Scandian deformation structures (D1) may be present and there are indications that an early, greenschist-facies metamorphic event has affected the ophiolitic rocks.