Fold and thrust belt
Profile through the Pyrenees. In the south a fold and thrust belt exists as sediments are folded and stacked (thrusted) on top of the other.
An example of thin-skinned thrusting in
Montana. The white
Madison Limestone is repeated, with one example in the foreground (that pinches out with distance) and another to the upper right corner and top of the picture.
A fold and thrust belt 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.[1] 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
Asia
Australia
Europe
North America
Much of this table is adapted from Nemcok et al., 2005[3]
South America
References
Fold and thrust belt publications