Tectonic lineaments of Norway
pp. 153-174

Tectonic lineaments of the Norwegian mainland have been outlined and characterised in a new lineament map of Norway. The underlay is a national coverage of Landsat TM 7 scenes with 15 m pixel resolution, which have been interpreted at a scale of 1:750,000. The database contains nearly 8000 lineaments that, with the aid of statistical tools (orientation, density) and general characteristics, have been separated into distinct spatia! zones, populations and sets. The most prominent lineament zones of Norway are the N -S-striking Oslo-Trondheim and Bergen zones. The former is considered to represent a Neoproterozoic fracture system, since it clearly affects the geographical extent of younger lineament populations. Both zones were active in the Permian, whereas the Bergen Zone also underwent Mesozoic rejuvenation. Today, both zones experience relatively frequent, though minor earthquakes. Another important N-S fea ture, albeit more dispersed, is the Finnmark Zone. The regional, ENE-WSW-striking Møre-Trøndelag Fault Complex is clearly displayed in the scenes. It consists of mainly ENE-WSW (NE-SW) major and minor faults with a documented history ranging from Devonian to Recent, mirroring activity on the shelf. The Agder Zone has a similar orientation, consisting of two sets (NE-SW and ENE-WSW), and can be traced from Stavanger to the western margin of the Oslo Graben. Faults with km-scale displacement and various types of fault rocks reflect the post-Caledonian activity of this lineament population. Other lineament populations are more dispersed. This is especially the case for the NW-SE to WNW-ESE-oriented lineaments, which occur throughout the entire country. Approximately E-W-oriented structures are found in southern, western and central Norway. In the Sunnfjord area, they constitute major faults with documented Permian, Jurassic-Cretaceous and possible Cenozoic activity. Information relating to the lineaments is compiled in a database, which is regularly updated subsequent to field checking and detailed mapping of lineaments. The present consensus is that almost all of the lineaments identified or interpreted by remote sensing methods are faults, many of which have been affected by multiple faulting events. More surprisingly, many faults also contain soft (non-cohesive) fault rocks, distinctive for upper crustal deformation, suggesting Mesozoic-Cenozoic activity, and some may even carry components of post-glacial displacement.

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