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An orocline — from the Greek words for "mountain" and "to bend" — is a bend or curvature of an orogenic (mountain building) belt imposed after it was formed. The term was introduced by
*The Bolivian Orocline is a seaward concave bending in the coast of
S. Warren Carey
Samuel Warren Carey AO (1 November 1911, in Campbelltown – 20 March 2002, in Hobart) was an Australian geologist and a professor at the University of Tasmania. He was an early advocate of the theory of continental drift. His work on pl ...
in 1955 in a paper setting forth how complex shapes of various orogenic belts could be explained by actual bending, and that understanding this provided "the key to understanding the evolution of the continents". Carey showed that in a dozen cases where such bends were undone the results were substantially identical with continental reconstructions deduced by other means.. Recognition of oroclinal bending provided strong support to the subsequent theory of plate tectonics
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...
.
Examples
*The Bolivian Orocline is a seaward concave bending in the coast of South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
and the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
mountains at about 18° S. At this point the orientation of the Andes turns from Northwest in Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = Seal (emblem), National seal
, national_motto = "Fi ...
to South in Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
and Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
. The Andean segment north and south of the orocline have been rotated 15° to 20° counter clockwise and clockwise respectively. The orocline area overlaps with the area of maximum width of the Altiplano Plateau according to Isacks (1988) the orocline is related to crustal shortening
Thrust tectonics or contractional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the shortening and thickening of the crust or lithosphere. It is one of the three main types of tectonic regime, ...
. The specific point at 18° S where the coastline bends is known as the ''Arica Elbow''.
*The Maipo Orocline or Maipo Transition Zone is an orocline located between 30° S and 38°S in the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
with a break in trend at 33° S.
*The Arauco Orocline a subtle orocline located at 37° S in south-central Chile. It marks a seaward-convex bend in the Andes.
*Bothnian oroclines in the Svecofennian Domain in Finland and Sweden.
*Inari orocline including the Lapland Granulite Belt
The Lapland Granulite Belt is an elongate and arcuate zone of granulite rock in the Cap of the North spanning areas within Norway, Finland and Murmansk Oblast in Russia. At most the belt is 80 km broad. The main rocks of the belt are migmatize ...
in Finland, Norway and Russia.
*Cantabrian Orocline, Spain
*Lachlan Orocline, eastern Australia
*Dabashan Orocline, China
See also
*Syntaxis (geology) A syntaxis is an abrupt major change in the dominant orientation of the main fold and thrust structures in an orogenic belt. For example, the Himalayan belt forms a continuous gentle curve in its main part, running almost perpendicular to the moti ...
Notes
References
*.External links
*{{Citation , first1= Rob , last1= Van der Voo , date= December 2004 , title= Paleomagnetism, Oroclines, and Growth of the Continental Crust , journal= GSA Today , volume= 14 , issue= 12 , pages= 4–9 , doi= 10.1130/1052-5173(2004)014<4:POAGOT>2.0.CO;2 , url= http://rock.geosociety.org/gsatoday/archive/14/12/pdf/i1052-5173-14-12-4.pdf , doi-access= free . Structural geology Orogeny