fold and thrust belt
File:Fold and Thrust belts modelled in sandbox.png
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.{{cite journal | title=Structural styles and regional tectonic setting of the "Gela Nappe" and frontal part of the Maghrebian thrust belt in Sicily |author1=Lickorish W.H. |author2=Grasso M. |author3=Butler R.W.H. |author4=Argnani A. |author5=Moniscalco R. | journal=Tectonics | year=1999 | volume=18 | issue=4 | pages=655–668 | doi=10.1029/1999TC900013|bibcode=1999Tecto..18..655L | doi-access=free }} 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
File:Profile through the Pyrenees EN.svg
File:SunRiver.JPG. 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.]]
=Africa=
| class="wikitable" |
| Thrustbelt name
! Age ! Structural style |
|---|
| Atlas Mountains
| | |
| Cape Fold Belt
| | |
=Asia=
| class="wikitable" |
| Thrustbelt name
! Age ! Structural style |
|---|
| Aravalli Range
| |
| Himalayas
| |
| Zagros fold and thrust belt
| Young and active deforming belt | |
=Australia=
| class="wikitable" |
| Thrustbelt name
! Age ! Structural style |
|---|
| Eastern Lachlan Orogen
| North-south oriented structures |
=Europe=
| class="wikitable" |
| Thrustbelt name
! Age ! Structural style |
|---|
| Alps
| Cenozoic | |
| Scandinavian Caledonides
| Ordovician - Devonian | |
| Carpathians
| |
=North America=
Much of this table is adapted from Nemcok et al., 2005Nemcok, M., Schamel, S. & Gayer, R. 2005. Thrustbelts - Structural Architecture, Thermal Regimes and Petroleum Systems. Cambridge University Press {{ISBN|978-0-521-82294-7}}
=South America=
References
{{reflist}}
External links
- [http://www.aapg.org/science/discipline/structure/fold-and-thrust-belts#4068426-new-publications Fold and thrust belts publications]
{{Structural geology}}
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