Editing Thrust fault (section)

==Tectonic environment==
{{main|Thrust tectonics}}
[[Image:SunRiver.JPG|thumb|300px|An example of [[thin-skinned deformation]] (thrusting) in [[Montana]].  Note that the white [[Madison Limestone]] is repeated, with one example in the foreground and another at a higher level to the upper right corner and top of the picture.]]
Large overthrust faults occur in areas that have undergone great compressional forces.

These conditions exist in the [[orogeny|orogenic belts]] that result from either two [[continental crust|continental]] [[tectonic plates|tectonic]] collisions or from [[subduction]] zone accretion.

The resultant compressional forces produce [[mountain]] ranges. The [[Himalayas]], the [[Alps]], and the [[Appalachians]] are prominent examples of compressional orogenies with numerous overthrust faults.

Thrust faults occur in the [[foreland basin]], marginal to orogenic belts. Here, compression does not result in appreciable mountain building, which is mostly accommodated by folding and stacking of thrusts. Instead, thrust faults generally cause a thickening of the [[stratigraphic section]]. When thrusts are developed in orogens formed in previously [[rift]]ed margins, [[inversion (geology)|inversion]] of the buried paleo-rifts can induce the nucleation of thrust ramps.<ref name="Martins-Ferreira">{{Cite journal|last=Martins-Ferreira|first=Marco Antonio Caçador|date=April 2019|title=Effects of initial rift inversion over fold-and-thrust development in a cratonic far-foreland setting|journal=Tectonophysics|volume=757|pages=88–107|doi=10.1016/j.tecto.2019.03.009|bibcode=2019Tectp.757...88M|s2cid=135346440 }}</ref>

Foreland basin thrusts also usually observe the ramp-flat geometry, with thrusts propagating within units at very low angle "flats" (at 1–5 degrees) and then moving up-section in steeper ramps (at 5–20 degrees) where they offset stratigraphic units. Thrusts have also been detected in cratonic settings, where "far-foreland" deformation has advanced into intracontinental areas.<ref name="Martins-Ferreira"/>

Thrusts and duplexes are also found in [[accretionary wedge]]s in the [[ocean trench]] margin of subduction zones, where oceanic sediments are scraped off the subducted plate and accumulate. Here, the accretionary wedge must thicken by up to 200%, and this is achieved by stacking thrust fault upon thrust fault in a [[mélange|melange]] of disrupted rock, often with chaotic folding. Here, ramp flat geometries are not usually observed because the compressional force is at a steep angle to the sedimentary layering.
[[File:Thrust Fault Outcrop.jpg|thumb|Thrust Fault Outcrop]]