This is how I think the Krakvatn-Rebenfjell fold nappe in Northern Norway may have formed:-

Starting at an initial irregularity the fold developed as a reclined, isoclinal structure with the lineations and hinge parallel to the tectonic transport direction (ESE), as a sheath fold such that the hinge did not continue for any great length in the ‘Y’ strain direction.

The greatest dimension of the fold was in the ‘X’ direction parallel to the orogenic trend (NNE). This did not involve any net extension in this direction as thinning on the limbs was compensated by repetition across the axial plane, and thickening in the hinges.

The ‘Z’ direction was subvertical due to the gravitational loading.

The fold nappe characteristically ends as a syntectonic thrust or slide.

It should be noted, however, that it has been suggested that the ESE trend of these fold nappe hinges may be controlled by the buoyant uprise of basement gneisses in this region.

 

Brian Walton