# Fold and thrust belt

A fold and thrust belt (FTB) is a series of mountainous foothills adjacent to an orogenic belt, which forms due to contractional tectonics. Fold and thrust belts commonly form in the forelands adjacent to major orogens as deformation propagates outwards. Fold and thrust belts usually comprise both folds and thrust faults, commonly interrelated. They are commonly also known as thrust-and-fold belts, or simply thrust-fold belts.

## Geometry

Fold and thrust belts are formed of a series of sub-parallel thrust sheets, separated by major thrust faults. As the total shortening increases in a fold and thrust belt, the belt propagates into its foreland. New thrusts develop at the front of the belt, folding the older thrusts that have become inactive. This sequential propagation of thrusts into the foreland is the most common. Thrusts that form within the belt rather than at the thrust front are known as "out-of-sequence".

### Map view

In map view, fold and thrust belts are generally sinuous rather than completely linear. Where the thrust front bulges out in the direction of tectonic transport, a salient is formed. Between the bulges the areas are known as recesses, reentrants or sometimes embayments.

## Thrust belts
### Africa

| Thrustbelt name | Age | Structural style |
| Atlas Mountains | | |
| Cape Fold Belt | | |

### Asia

| Thrustbelt name | Age |
| Aravalli Range | Precambrian |
| Himalayas | Upper Cretaceous |
| Zagros fold and thrust belt | Young and active deforming belt |

### Australia

| Thrustbelt name | Age | Structural style |
| Eastern Lachlan Orogen | Middle Paleozoic | North-south oriented structures |

### Europe

| Thrustbelt name | Age |
| Alps | Cenozoic |
| Scandinavian Caledonides | Ordovician - Devonian |
| Carpathians | Mesozoic - Tertiary |

### North America

| Thrustbelt name | Age | Structural style |
| Alaska Range | Late Cretaceous - Cenozoic | Thick-skin |
| Anadyr Highlands | Late Paleocene - Eocene | Unknown |
| Antler Thrustbelt | Carboniferous | Thin-skin |
| Appalachians | Late Paleozoic | Thin-skin |
| Arctic Cordillera | Middle Devonian - Early Carboniferous | Unknown |
| Brooks Range | Jurassic - Early Cretaceous, Early Cenozoic | Thin-skin |
| California Coast Ranges | Late Miocene - Quaternary | Transpressional |
| Chihuahua Belt | Paleocene | Unknown |
| Chugach Mountains | Cenozoic | Thin-skin |
| Eurekan Fold Belt | Eocene - Oligocene | Unknown |
| Innuitian Fold-Thrust Belt | Late Cretaceous - Early Cenozoic | Thin-skin |
| Kuskokwim Mountains | Late Cretaceous - Eocene | Unknown |
| Mackenzie Mountains | Late Cretaceous - Middle Eocene | Thin-skin |
| Maria Fold and Thrust Belt | Cretaceous | Thick-skin |
| North Greenland Fold Belt | Middle Devonian - Early Carboniferous | Unknown |
| Northern Ellesmere Fold Belt | Middle Devonian - Early Carboniferous | Thin-skin |
| Ogilvie Mountains | Late Cretaceous - Eocene | Thin-skin |
| Oregon Accretionary Prism | Late Miocene - Quaternary | Thin-skin |
| Ouachitas | Late Carboniferous - Early Permian | Thick- and thin-skin |
| Richardson Mountains | Late Cretaceous - Middle Eocene | Thin-skin |
| Rocky Mountains | Paleocene to Middle Eocene | Thick-skin |
| Selwyn Fold Belt, Yukon | Late Cretaceous | Unknown |
| Sierra Madre Oriental | Early Cenozoic | Unknown |
| Sierra Madre Occidental | Cretaceous - Eocene | Unknown |
| South Canadian Rockies | Late Jurassic - Eocene | Thin-skin |
| Wyoming-Utah Thrustbelt (North Sevier) | Late Jurassic - Eocene | Thin-skin |
Much of this table is adapted from Nemcok et al., 2005

### South America

| Thrustbelt name | Age | Structural style |
| Magallanes (Fuegian) fold and thrust belt | Late Cretaceous - Cenozoic | Thin-skin |
| Malargüe fold and thrust belt | | |
| Marañón fold and thrust belt | Cenozoic | Thick-skin and thin-skin |
| Central Andean fold and thrust belt | Mesozoic - Cenozoic | Thin skin |