Orocline
Aspect of geology
From Wikipedia, the free encyclopedia
An orocline (also known as an oroclinal bend or orogenic arc)[1] — 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.[2] The term was introduced by S. Warren Carey 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".[3] Carey showed that in a dozen cases where such bends were undone the results were substantially identical with continental reconstructions deduced by other means.[4] Recognition of oroclinal bending provided strong support to the subsequent theory of plate tectonics.
Examples
- The Bolivian Orocline is a seaward concave bending in the coast of South America and the Andes mountains at about 18° S.[5][6] At this point the orientation of the Andes turns from Northwest in Peru to South in Chile and Argentina.[6] The Andean segment north and south of the orocline have been rotated 15° to 20° counter clockwise and clockwise respectively.[6][7] 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.[5] The specific point at 18° S where the coastline bends is known as the Arica Elbow.[8]
- The Maipo Orocline or Maipo Transition Zone is an orocline located between 30° S and 38°S in the Andes with a break in trend at 33° S.[9]
- The Arauco Orocline a subtle orocline located at 37° S in south-central Chile. It marks a seaward-convex bend in the Andes.[10]
- Cantabrian Orocline[11] and Gibraltar Orocline,[12] Spain.
- Carpathian Orocline, Romania.[13]
- Balkan Orocline, Romania, Bulgaria and Serbia.[13]
- Dinaric-Hellenic Orocline[14]
- Northern Apennines Orocline, Southern Apennines Orocline[15] and Calabrian Orocline,[12] Italy
- Western Alps Orocline, Italy, France and Switzerland.[16]
Oroclines in cratons
- Bothnian oroclines in the Svecofennian Domain in Finland and Sweden.[17]
- Inari orocline including the Lapland Granulite Belt in Finland, Norway and Russia.[17]
- Lachlan Orocline, eastern Australia[18]
- Dabashan Orocline, China[19]