Tight folds in gneiss, north Norway

Such tight folds and shear structures are typical of what was produced during thrusting and formation of fold and fault nappes. The deformation took place under conditions of high-grade metamorphism, and this is what makes the internal deformation so ductile, and spectacular.

I have forgotten the exact location, but somewhere in the region between Narvuk and Tromso in north Norway.  I was there in 1985 with Steve Naruk, where he was doing part of his PhD work.  I like the fact that this rock is marked by such penetrative deformation:  nothing escaped the influence of tectonic straining of the country rock.

Age & Formation
I do not know the original age of the rocks that became so deformed and metamorphosed, but we do know that the deformation occurred during the Caledonian orogeny, between Ordovician and early Devonian, roughly 490 to 390 Ma.