Phanerozoic faults in the Västergötland basin area, SW Sweden

Abstract

Phanerozoic faults have been studied in a Precambrian gneiss terrain, with poorly developed stratigraphic markers. The sub-Cambrian denudation surface is thus used as a marker, but due to the generally small amplitude of the faults, rarely exceeding 70 metres, and the hilly topography, only major faults could be identified. These are dip-slip faults, with N-S, NE-SW, NNE-SSW and E-W directions. Remnants of a more extended cover of Phanerozoic rocks suggest that a wide tectonic basin was formed prior to eras with terrestrial facies and erosion. This early tectonism was post-Silurian and pre-Triassic. A large lake in the area, Lake Vänern, outlines tectonism which postdated erosion of the Palaeozoic rocks. This tectonism is found to have been of a young age, and it is evidently not closed. The history of exposure to erosion is complex, and has produced a varied pattern of morphological types.

Key Words:

• Southwestern Sweden
• Lake Vänern
• Phanerozoic faults
• Palaeozoic faults
• Cenozoic faults
• neotectonism
• erosion
• peneplain