Open AccessPalaeomagnetic dating of fault rocks: evidence for Permian and Mesozoic movements and brittle deformation along the extensional Dalsfjord Fault, western Norway
Author(s) -
Torsvik T. H.,
Sturt B. A.,
Swensson E.,
Andersen T. B.,
Dewey J. F.
Publication year - 1992
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1992.tb00118.x
Subject(s) - geology , extensional fault , fault (geology) , permian , extensional definition , seismology , mesozoic , paleontology , thrust fault , cretaceous , rift , nappe , paleozoic , devonian , tectonics , structural basin
SUMMARY Palaeomagnetic and structural studies of the Dalsfjord Nappe, western Norway, show that the basal low‐angle detachment (Dalsfjord Fault) is a long‐lived fault zone, and that the most important phase of faulting was of Devonian extension, probably nucleated on an earlier Silurian (Scandian) thrust. Fault rocks produced during subsequent movements indicate that the Dalsfjord Fault underwent periods of brittle low‐angle extensional reactivation during the Permian (250–260 Ma) and Upper Jurassic/Lower Cretaceous ( c . 150 Ma), corresponding with stages of major extensional movements on the continental shelf. Palaeomagnetic studies may be of great importance for dating faults and major movement stages in long‐lived fault systems. The particular importance of the results is that they show that low‐angle normal faults can operate in a brittle upper crustal regime.