Origin of contrasting Devonian supradetachment basin types in the Scandinavian Caledonides
Vegard V. Vetti and Haakon Fossen, Dept. of Earth Science, University of Bergen, Postboks 7803, 5020 Bergen, Norway. Posted online ahead of print 10 April 2012; doi: 10.1130/G32512.1.
Extensional detachments (faults) in collapsing orogens tend to generate strongly asymmetric sedimentary basins with beds dipping against the tectonic transport direction, in fault contact with the low-angle detachment. A series of such basins occur in the SW Norway Caledonides atop a W-dipping detachment zone. One of these Devonian basins shows consistently E-dipping beds that rest unconformably on the substrate over a lateral distance of more than 11 km. Restoring everything by rigid rotation gives a very steep and ~10 km tall paleoslope, which is clearly unrealistic. Instead, Vegard V. Vetti and Haakon Fossen explain these peculiar unconformable relations by deposition in a hanging-wall ramp basin that opens due to ~10-km-tall ramp in the underlying detachment. Forward modeling of this situation shows that the model is realistic. The authors s
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