A lineaments study of southern Norway and adjacent off-shore areas

Abstract

Lineament maps based on Landsat, geological and aeromagnetic data on land, and aeromagnetic, gravity and seismic reflection data at sea have been studied to determine the main lineament trends on land and off-shore in southern Norway. On land there are three main structural trends (NE-SW, NW-SE and N-S) as well as a fourth, weaker trend (E-W). These four trends are thought to represent fracture patterns of Precambrian age. In the off-shore part of the study area, the same four trends are shown by the aeromagnetic data. (The gravity data yield unsatisfactory results for which the reasons are given.) It is therefore concluded that the same type of crystalline basement that is exposed on land also underlies the off-shore area. It is argued that these Precambrian structural trends have also pre-determined lines of weakness in Phanerozoic times. Fracture sets in the Norwegian Caledonides may provide an example of large-scale re-activation of the NE-SW structural trend, and the Viking and Oslo Grabens of the re-activation of the N-S trend. On a smaller scale, and in the off-shore part of the study area, it is likely that a re-activation of the NE-SW structural trend has played a role in the formation of the Ling Graben, the NW-SE trend in the origin of the Sele and Flekkefjord Highs, the N-S trend in the formation of the Lista Nose, and the E-W trend in the formation of the Farsund Sub-basin.