Detachment fault

Detachment faulting is associated with large-scale extensional tectonics. 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. 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
• The Nordfjord-Sogn Detachment of western Norway active during the Devonian Period
• The Whipple detachment in southeastern California

Detachment faults have been found on the sea floor close to divergent plate boundaries characterised by a limited supply of upwelling magma. These detachment faults are associated with the development of oceanic core complex structures.