An orogenic belt, orogen, or mobile belt, is a zone of

Earth's crust Earth's crust is its thick outer shell of rock, referring to less than one percent of the planet's radius and volume. It is the top component of the lithosphere, a solidified division of Earth's layers that includes the crust and the upper ...

affected by

orogeny Orogeny () is a mountain-mountain formation, building process that takes place at a convergent boundary, convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is tectonic uplift, u ...

. An orogenic belt develops when a continental plate crumples and is uplifted to form one or more

mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have aris ...

s; this involves a series of geological processes collectively called ''orogenesis''.

Overview

Orogeny Orogeny () is a mountain-mountain formation, building process that takes place at a convergent boundary, convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is tectonic uplift, u ...

typically produces ''orogenic belts'', which are elongated regions of deformation bordering continental

craton A craton ( , , or ; from "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of contine ...

s. Young orogenic belts, in which subduction is still taking place, are characterized by frequent volcanic activity and

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

s. 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 (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

. These are often highly metamorphosed and include vast bodies of intrusive igneous rock called batholiths. File:Active Margin.svg, Subduction of an oceanic plate beneath a continental plate to form an accretionary orogen. (example: the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

) File:Continental-continental convergence Fig21contcont.gif,

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

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 The Himalayas, or Himalaya ( ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the Earth's highest peaks, including the highest, Mount Everest. More than list of h ...

) Orogenic belts are associated with subduction zones, which consume crust, thicken

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time ...

, produce earthquake and volcanoes, and often build

island arc Island arcs are long archipelago, chains of active volcanoes with intense earthquake, seismic activity found along convergent boundary, convergent plate tectonics, tectonic plate boundaries. Most island arcs originate on oceanic crust and have re ...

s. 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

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 Prominent orogenic belts on the Earth are the circum-Pacific orogenic belt (the Pacific

Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a tectonic belt of volcanoes and earthquakes. It is about long and up to about wide, and surrounds most of the Pa ...

) and the Alpine-Himalayan orogenic belt. Since these orogenic belts are young, they form large mountain ranges; crustal activity is active and accompanied by volcanic belts and seismic belts.

Notes

References

External links

Belt regions * Plate tectonics Mountain geomorphology Effects of gravity {{plate-tectonics-stub