Abstract

Low-relief surfaces in northern Norway are mapped and analysed to explore (1) whether surfaces were once continuous and possibly correlative, recording an ancient, relict landscape, (2) whether the distribution of (now disrupted) surfaces reveals a tectonic history related to rifting of the North Atlantic and (3) how topography changes across the transition between the North Atlantic and Barents Sea margins. Elevation contours on surfaces, a smoothed fit to mean elevations and histograms of elevation show three distinct, coast-parallel zones onshore northern Norway, and a different pattern in coastal Lofoten–Vesterålen. A sharp transition from continuous surfaces to lower, discretely stepped, discontinuous surfaces is located where the crust thins rapidly to the NW from >39 to <25 km. In margin-parallel transects, elevations remain high for >100 km north of the Senja Fracture Zone and then decrease gradually further NE. The spatial pattern suggests that a continuous, low-relief, relatively low-elevation surface formed in late Mesozoic time and was preserved despite modification by Cenozoic faulting, uplift and slow erosion. Scandinavia's present-day topographic envelope reflects a crustal strength profile set up during earlier hyperextension and maintained by slow Neogene erosion rather than resulting from opening of the North Atlantic or caused by glacial erosion.

Supplementary material: A map of polygons of all surface heights within the study area and data on the location of median centres of polygons, assigned attributes and selected zonal statistics are available at https://doi.org/10.6084/m9.figshare.c.3312960