Nordfjord-Sogn Detachment

Low-angle fault contact between Devonian sediments of the Kvamshesten Basin and mylonites of the underlying shear zone
Lihesten near Hyllestad made of well-jointed Devonian conglomerates (part of the Solund Basin) in fault contact with mylonites of the detachment

The Nordfjord—Sogn Detachment (NSD) is a major extensional shear zone in Norway up to 6 km in thickness, which extends about 120 km along strike from Nordfjord to Sognefjord, bringing Devonian continental coarse clastic sedimentary rocks into close contact with eclogite facies metamorphic rocks of the Western Gneiss Region. It formed towards the end of the Caledonian Orogeny and was mainly active during the Devonian. It has an estimated displacement of at least 70 km and possibly as much as 110 km.[1] It was reactivated during the Mesozoic and may have influenced the development of fault structures in the North Sea rift basin.[2]

  1. ^ Hacker B.R.; Andersen T.B.; Root D.B.; Mehl L.; Mattinson J.M.; Wooden J.L. (2003). "Exhumation of high-pressure rocks beneath the Solund Basin, Western Gneiss Region of Norway" (PDF). Journal of Metamorphic Geology. 21 (6): 613–629. Bibcode:2003JMetG..21..613H. CiteSeerX 10.1.1.520.2581. doi:10.1046/j.1525-1314.2003.00468.x.
  2. ^ Johnston S., Hacker B.R. & Ducea M.N. (2007). "Exhumation of ultrahigh-pressure rocks beneath the Hornelen segment of the Nordfjord-Sogn Detachment Zone, western Norway" (PDF). Bulletin of the Geological Society of America. 119 (9–10): 1232–1248. Bibcode:2007GSAB..119.1232J. doi:10.1130/B26172.1.