Detachment fault

A large-displacement fault that separates rock units along a surface, commonly accommodating crustal extension on a low angle. It can expose deep crustal rocks at the surface.

Normal fault: A fault in which the hanging wall moves downward relative to the footwall. Detachment faults accommodate extension through normal-sense displacement, often across unusually shallow dips.
Hanging wall: The block of rock above an inclined fault surface. Detachment displacement separates this upper block from the footwall.
Snake Range detachment: A major extensional fault in Nevada associated with the Snake Range metamorphic core complex. It is a classic example of a detachment exposing deep crustal rocks.
Low-angle normal fault: A normal fault whose dip is low compared with the usual frictional-failure angle of intact rock. Detachment faults are often classified this way, raising questions about how they slip at shallow angles.
Listric fault: A normal fault whose dip decreases with depth, producing a curved fault surface. Its curved geometry offers one explanation for how shallow detachment surfaces connect to steeper faults.
Footwall: The block of rock below an inclined fault surface. Footwall rocks may be exhumed as the hanging wall moves away.
Whipple detachment fault: A low-angle extensional fault in southeastern California associated with the Whipple Mountains core complex. Its well-studied exposures reveal fault-zone rocks and extensional structures.
Andersonian fault theory: A model relating fault orientation to the principal stresses in a frictional crust. Its predictions make sustained slip on shallow normal faults mechanically challenging.
Fault-bend folding: Folding of rock layers as they move over bends in a fault surface. Movement across changing fault dips can bend and rotate the overlying strata.
Crustal extension: Tectonic stretching that thins and lengthens Earth's crust. Detachment faults are major structures for accommodating this regional deformation.

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Basin and Range ProvinceRelated: Some areas expose deep rocks through extension along low-angle faults.