A detachment fault is a gently dipping normal fault associated with large-scale extensional tectonics.[1] Detachment faults often have very large displacements (tens of km) and juxtapose unmetamorphosed hanging walls against medium to high-grade metamorphic footwalls that are called metamorphic core complexes. They are thought to have formed as either initially low-angle structures or by the rotation of initially high-angle normal faults modified also by the isostatic effects of tectonic denudation. They may also be called denudation faults. Examples of detachment faulting include:
- The Snake Range detachment system of the Basin and Range Province of western North America which was active during the Miocene[2]
- The Nordfjord-Sogn detachment of western Norway active during the Devonian Period[3]
- The Whipple detachment in southeastern California[4]
Detachment faults have been found on the sea floor close to divergent plate boundaries characterised by a limited supply of upwelling magma, such as the Southwest Indian Ridge. These detachment faults are associated with the development of oceanic core complex structures.
- ^ National Park Service. "Glossary of Geologic Terms"
- ^ Long, S.P.; Lee, J.; Blackford, N.R. (2022). "The low-angle breakaway system for the Northern Snake Range décollement in the Schell Creek and Duck Creek Ranges, eastern Nevada, USA: Implications for displacement magnitude". Geosphere. 18 (4): 1194–1222. doi:10.1130/GES02482.1.
- ^ Fossen H. (1992). The role of extensional tectonics in the Caledonides of South Norway. Journal of Structural Geology, 14:1033–1046.
- ^ Davis, Gregory A. (1988-02-01). "Rapid upward transport of mid-crustal mylonitic gneisses in the footwall of a Miocene detachment fault, Whipple Mountains, southeastern California". Geologische Rundschau. 77 (1): 191–209. Bibcode:1988GeoRu..77..191D. doi:10.1007/BF01848684. ISSN 1432-1149. S2CID 129275058.