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.[1] 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".[2] Carey showed that in a dozen cases where such bends were undone the results were substantially identical with continental reconstructions deduced by other means.[3] 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.[4][5] At this point the orientation of the Andes turns from Northwest in
Peru to South in
Chile and
Argentina.[5] The Andean segment north and south of the orocline have been rotated 15° to 20° counter clockwise and clockwise respectively.[5][6] 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.[4] The specific point at 18° S where the coastline bends is known as the Arica Elbow.[7]
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.[8]
The Arauco Orocline a subtle orocline located at 37° S in south-central Chile. It marks a seaward-convex bend in the Andes.[9]
^Prezzi, Claudia B.; Vilas, Juan F. (1998). "New evidence of clockwise vertical axis rotations south of the Arica elbow (Argentine Puna)". Tectonophysics. 292 (1–2): 85–100.
doi:
10.1016/s0040-1951(98)00058-4.
^
ab Faccenna C., Piromallo C., Crespo-Blanc A., Jolivet L., Federico Rossetti F.(2004) Lateral slab deformation and the origin of the western Mediterranean arcs, Tectonics, 23: (1) 1-21
[1]
^
abShaw J., Johnston S. T., The Carpathian–Balkan bends: an oroclinal record of ongoing Arabian–Eurasian collision, Journal of the Virtual Explorer, 43(4)
[2]
^
abLahtinen, R.; Sayab, M.; Johnston, S.T. (2016). "Inari orocline – progressive or secondary orocline". Institute of Seismology, University of Helsinki Report S-65. Lithosphere 2016 Ninth Symposium on the structure, composition and evolution of the lithosphere in Fennosscandia. pp. 69–74.