The Lyngen Nappe, an allochthonous unit of the Northern Norwegian Caledonides, consists of Greenschist-facies rocks overlying Amphibolite- to Granulite-facies rocks in the Nordmannvik Nappe. The lower-grade metamorphism seen in the Lyngen rocks juxtaposes higher-grade rocks both above and below. The nature and origin of this metamorphic break is investigated, specifically in the sheared rock units ...