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.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Fold_and_Thrust_belts_modelled_in_sandbox.png/220px-Fold_and_Thrust_belts_modelled_in_sandbox.png)
Geometry
editFold 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
editIn 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
editAfrica
editThrustbelt name | Age | Structural style |
---|---|---|
Atlas Mountains | ||
Cape Fold Belt |
Asia
editThrustbelt name | Age | Structural style |
---|---|---|
Aravalli Range | Precambrian | |
Himalayas | Upper Cretaceous | |
Zagros fold and thrust belt | Young and active deforming belt |
Australia
editThrustbelt name | Age | Structural style |
---|---|---|
Eastern Lachlan Orogen | Middle Paleozoic | North-south oriented structures |
Europe
editThrustbelt name | Age | Structural style |
---|---|---|
Alps | Cenozoic | |
Scandinavian Caledonides | Ordovician - Devonian | |
Carpathians | Mesozoic - Tertiary |
North America
editMuch of this table is adapted from Nemcok et al., 2005[3]
South America
editThrustbelt 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[4] |
References
edit- ^ Lickorish W.H.; Grasso M.; Butler R.W.H.; Argnani A.; Moniscalco R. (1999). "Structural styles and regional tectonic setting of the "Gela Nappe" and frontal part of the Maghrebian thrust belt in Sicily". Tectonics. 18 (4): 655–668. Bibcode:1999Tecto..18..655L. doi:10.1029/1999TC900013.
- ^ Selwyn Basin Metallogeny Yukon Geological Survey Archived 2014-03-31 at the Wayback Machine
- ^ Nemcok, M., Schamel, S. & Gayer, R. 2005. Thrustbelts - Structural Architecture, Thermal Regimes and Petroleum Systems. Cambridge University Press ISBN 978-0-521-82294-7
- ^ THE EVOLUTION OF THE ALTIPLANO-PUNA PLATEAU OF THE CENTRAL ANDES. 1997.
External links
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