An orogenic belt, or orogen, is a zone of

Earth's crust Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...

affected by

orogeny Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted t ...

. An orogenic belt develops when a continental plate crumples and is uplifted to form one or more mountain ranges; this involves a series of geological processes collectively called ''orogenesis''.

Overview

Orogeny typically produces ''orogenic belts'', which are elongated regions of deformation bordering continental cratons. Young orogenic belts, in which subduction is still taking place, are characterized by frequent volcanic activity and earthquakes. Older orogenic belts are typically deeply eroded to expose displaced and deformed

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

. These are often highly metamorphosed and include vast bodies of intrusive igneous rock called

batholith A batholith () is a large mass of intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such ...

s. File:Active Margin.svg,

Subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

of an oceanic plate beneath a continental plate to form an accretionary orogen. (example: the Andes) File:Continental-continental convergence Fig21contcont.gif,

Continental collision In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains prod ...

of two continental plates to form a collisional orogen. Typically, continental crust is subducted to lithospheric depths for blueschist to eclogite facies metamorphism, and then exhumed along the same subduction channel. (example: the Himalayas) Orogenic belts are associated with subduction zones, which consume crust, thicken lithosphere, produce earthquake and volcanoes, and often build island arcs. These island arcs may be added to a continental margin during an accretionary orogeny. The orogeny may culminate with continental crust from the opposite side of the subducting oceanic plate arriving at the subduction zone. This ends subduction and transforms the accretional orogeny into a collisional orogeny. The collisional orogeny may produce extremely high mountains, as has been taking place in the Himalayas for the last 65 million years. File:Pacific Ring of Fire.png, circum-Pacific orogenic belt
(Pacific Ring of Fire) File:Alpiner Gebirgsgürtel.png, Alpine-Himalayan orogenic belt Prominently orogenic belts on the Earth are the circum-Pacific orogenic belt (Pacific Ring of Fire) and Alpine-Himalayan orogenic belt. Since these orogenic belts are young orogenic belts, they form large mountain ranges, crustal activity is active, and accompanied by volcanic belts and seismic belts.

References

External links

Belt regions * Plate tectonics Mountain geomorphology Effects of gravitation {{Geology-stub