Primary and tectonic basement-cover relationships in northernmost Vestranden, central Norwegian Caledonides

Unconformities between the granitoid basement and metasedimentary rocks have been recognized in the Folda-Vikna area of northernmost Vestranden, Norway. The rocks, which are autochthonous in relation to the basement, are represented by two geographically isolated exposures of conglomeratic psammites. The conglomeratic rocks are tectonically overlain by a dominantly supracrustal sequence, the Folda cover. This cover sequence displays a highly irregular lithological variation. The most complete lithostratigraphy is found in the eastern part of the Folda-Vikna area, while many rock types have been sheared out in the west. The tectonic relationships between the Folda cover and other cover sequences as well as the basement have been strongly disturbed by folding, metamorphism and late strike-slip faulting. Despite this Caledonian reworking and the lack of fossils in the Folda cover, some conclusions can be drawn regarding its tectonostratigraphic position and possible correlation with tectonic units farther east. Most previous work correlates the Folda cover with the Seve Nappes of the Upper
Allochthon. In contrast, this paper argues that the Folda cover must occupy a higher tectonic position.