Orocline Explained

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. At this point the orientation of the Andes turns from Northwest in Peru to South in Chile and Argentina. 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. The specific point at 18° S where the coastline bends is known as the Arica Elbow.^[4]
• 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.
• The Arauco Orocline a subtle orocline located at 37° S in south-central Chile. It marks a seaward-convex bend in the Andes.
• Cantabrian Orocline^[5] and Gibraltar Orocline,^[6] Spain.
• Carpathian Orocline, Romania.^[7]
• Balkan Orocline, Romania, Bulgaria and Serbia.
• Northern Apennines Orocline, Southern Apennines Orocline^[8]

Notes and References

1. . Note that the initial formation does not have to be straight.
2. .
3. .
4. Prezzi . Claudia B. . Vilas . Juan F.. 1998 . New evidence of clockwise vertical axis rotations south of the Arica elbow (Argentine Puna) . . 292 . 1–2. 85–100 . 10.1016/s0040-1951(98)00058-4. 1998Tectp.292...85P .
5. Buckling an orogen: The Cantabrian Orocline . G. . Gutiérrez-Alonso . S.T. . Johnston . A.B. . Weil . D. . Pastor-Galán . J. . Fernández-Suárez . GSA Today . 2012 . 22 . 7 . 4–9 . 10.1130/GSATG141A.1.
6. 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 https://www.researchgate.net/publication/259664015_Lateral_slab_deformation_and_the_origin_of_the_Western_Mediterranean_arcs
7. Shaw J., Johnston S. T., The Carpathian–Balkan bends: an oroclinal record of ongoing Arabian–Eurasian collision, Journal of the Virtual Explorer, 43(4)https://www.researchgate.net/publication/257936325_The_Carpathian-Balkan_bends_an_oroclinal_record_of_ongoing_Arabian-Eurasian_collision
8. Edi Kissling E., Romain Bousquet R., Ford M., Schmid S. M. (2012) Formation of the arc of the Western Alps and Alps-Apennines transition in the light of new geophysical data on the lithospheric architecture around the Ligurian knot, EGU Conference Vienna Apennines_transition_in_the_light_of_new_geophysical_data_on_the_lithospheric_architecture_around_the_Ligurian_knot
9. Inari orocline – progressive or secondary orocline . Lahtinen . R. . Sayab . M. . Johnston . S.T.. 2016 . Institute of Seismology, University of Helsinki Report S-65 . 69–74 . Lithosphere 2016 Ninth Symposium on the structure, composition and evolution of the lithosphere in Fennosscandia.
10. Web site: The Lachlan Orocline of Eastern Australia. Giant folds, the geodynamic processes that can form them, and how these new understandings have potential to revolutionise the resource prospectivity game in Eastern Australia. . Australian Institute of Geoscientists . New Perspectives Workshop, September 2014 . 2014 . 4 March 2018 . Cayley, R..
11. Crustal structure in the junction of Qinling Orogen, Yangtze Craton and Tibetan Plateau: implications for the formation of the Dabashan Orocline and the growth of Tibetan Plateau . Chengxin Jiang . Yingjie Yang . Yong Zheng . Geophysical Journal International . 2016 . 205 . 3 . 1670–1681 . 10.1093/gji/ggw096. free .
12. Finetti et al, 2005, Crustal geological section across C Italy from the Corsica Basin to the Adriatic Sea based on geological and CROP Seismic data and Calabria]n Orocline, Italy
    • Western Alps Orocline, Italy, France and Switzerland.^[8]

    Oroclines in cratons

    • Bothnian oroclines in the Svecofennian Domain in Finland and Sweden.
    • Inari orocline including the Lapland Granulite Belt in Finland, Norway and Russia.^[9]
    • Lachlan Orocline, eastern Australia^[10]
    • Dabashan Orocline, China^[11]

    See also

    • Syntaxis (geology)

    References

    • .

    External links

    • .