Orogeny

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orogeny

[ȯ′räj·ə·nē]
(geology)
The process or processes of mountain formation, especially the intense deformation of rocks by folding and faulting which, in many mountainous regions, has been accompanied by metamorphism, invasion of molten rock, and volcanic eruption; in modern usage, orogeny produces the internal structure of mountains, and epeirogeny produces the mountainous topography. Also known as orogenesis; tectogenesis.

Orogeny

 

the process of the formation of mountains resulting from vertical tectonic movements, whose rate exceeds that of the exogenous process of destruction and removal (erosion) of rock or the process of buildup of sediments (accumulation), which lead to the leveling of the earth’s surface. Orogeny is characteristic of active regions of the earth.


Orogeny

 

(also orogenesis), a geological term introduced by the American geologist G. Gilbert in 1890 to designate mountain building and intense deformation by folding and faulting. Gilbert singled out orogenic movements of the earth’s crust and contrasted them to epeirogenic movements, that is, slow upward and downward movements.

The concept of orogeny was further developed by the French geologist G.-E. Haug, who in 1907 proposed that orogeny be distinguished only within geosynclinal regions. Subsequently, in 1919, the German geologist H. Stille hypothesized that the chief result of orogeny was not the formation of mountains but rather the formation of folds.

When the term “orogeny” was introduced, the crumpling of layers of rock into folds was believed to lead directly to the formation of mountains. It was later discovered that mountains are not created by folding of the earth’s crust and that mountain formation often occurs independently of folding. Soviet geologists thereupon began using the term “orogeny” to designate only the process of mountain formation. They made a distinction between epigeosynclinal (postfolding) orogeny and epiplatform orogeny, which is not preceeded by geosynclinal subsidence and folding-overthrust deformation. Outside the USSR, orogeny is still often understood in the Stille interpretation, that is, as the aggregate of fold and mountain formation.

V. E. KHAIN

References in periodicals archive ?
These cycles ended during the Chanic (Late Devonian-early Carboniferous), San Rafael (late Carboniferous-early Permian) and Andean (Late Cretaceous-Cenozoic) orogenies respectively; this latter being responsible for the present relief of the CV.
Constraints from FIAs, textural relationship, Emsian age unconformity and absolute monazite plus SHRIMP U-Pb ages indicate that the Delamerian, Kanimblan and Hunter Bowen Orogenies did not affect this region.
Episodes 1 and 2 probably occurred in the Late Devonian through Mississippian, well representing the deformation history in northern New England particularly in Maine during the transition from the Acadian to the Alleghanian orogenies.
Permo-Triassic bimodal volcanic and related plutonic rocks of the Choiyoi Group unconformably overlay and intrude the rocks previously deformed during the Chanic and San Rafael orogenies.
Throughout the melange the matrix is polydeformed, recording evidence of the Penobscottian and Acadian orogenies.
This complex tectonic evolution is partly due to the result of the superposition of two orthogonal orogenic events: the Variscan and the Alpine orogenies (Gallastegi et al.