In geology, orogenic collapse is the thinning and lateral spread of thickened crust. It is a broad term referring to processes which distribute material from regions of high gravitational potential energy to regions of low gravitational potential energy.[1][2] Orogenic collapse can begin at any point during an orogeny due to overthickening of the crust. Post-orogenic collapse and post-orogenic extension refer to processes which take place once tectonic forces have been released, and represent a key phase of the Wilson Cycle, between continental collision and rifting.[3]
Orogenic collapse is the thinning and spreading of thickened crust
Orogens (also known as orogenic belts, or more simply mountain ranges) are sections of thickened crust which are built up as tectonic plates collide. The thickening of the crust marks the start of an orogeny, or "mountain building event." As the orogeny progresses, the orogen may start spreading apart and thinning. Collapse processes can begin either once the orogeny ends as the tectonic forces cease, or during the orogeny if the crust becomes unstable.[1]
There are two primary mechanisms at work in an orogenic collapse: excess gravitational potential energy and heat flow into the thickened crust. Overthickened crust can become brittle and begin collapsing and spreading under its own weight. The added weight from the thickened crust also causes it to sink deeper into the mantle, where additional heat can flow into the crust. The added heat softens the rock and makes it flow more easily, which can allow material in deeper sections to move up into thinner areas via buoyancy forces, reducing the total thickness.[1] Orogens can also be destroyed by eduction and erosion, but these processes are not necessarily associated with orogenic collapse.[2] It has been argued that extension during orogenic collapse is a more effective mechanism of lowering mountains than erosion.[4]
Orogenic collapse can occur under different circumstances
Fixed-boundary collapseEdit
A fixed-boundary collapse is the breakdown of the brittle upper crust, and occurs when crust has overthickened while tectonic forces are still active. Flow in the lower crust may or may not occur when this happens. This can lead to exhumation of buried features.[2][1]
Free-boundary collapseEdit
Free-boundary collapse occurs when tectonic forces have been released and the thickened crust is free to move. This results in both the extension of the surface crust and flow of the lower crust to thinner regions. The surface expression of the extension can include extensive normal faulting.[1][2] This type of deformation has been compared to leaving a piece of Camembert cheese out overnight - as the cheese starts to sag and spread, the rind will eventually crack and split.[5]
The Scandinavian Caledonides is an example of an orogeny and mountain chain that reached heights of 8–9 km and then collapsed in the Devonian, forming major extensional structures such as the Nordfjord-Sogn Detachment.[6] The collapse was such that the modern Scandinavian Mountains do not owe their height to the former orogeny but to other processes that occurred in the Cenozoic.[7][8]
The Basin and Range region of the Western United States was previously a high plateau within the American Cordillera, which has since been extended and thinned. The characteristic topography is caused by the crust breaking up into fault blocks as a result of the extension. The exact cause of the extension is debated, though it is likely related to the transition from a subduction zone to a transform boundary between the North American and Pacific plates, as well as possible mantle upwelling.[9][10]
The Aegean Sea Plate is a section of continental crust which has been thinned, and is considered a high plateau between the Mediterranean and the Black Sea. The northern part of the plate underwent the Aegean Orogeny (c. 70 - 14 Ma), followed by crustal extension and thinning due to slab rollback of the African Plate.[11]
The Variscan (or Hercynian) orogeny was a result of the collision between the Laurussia and Gondwana plates during the formation of Pangaea. This resulted in a high plateau of thickened crust. c. 345 - 310 Ma, the northward subducting slab began retreating southward, resulting in the thickened crust beginning to thin due to a combination of gravitational collapse, fault detachment, and softening of the crust due to added heat.[12][13]
Although the Tibetan Plateau is in a primarily compressional environment due to the collision of the Indian and Eurasian plates, it is also experiencing east-west extension which began c. 14 Ma.[14][15][16] The primary cause of this extension is likely gravitational collapse of the plateau due to excess gravitational potential energy, as well as possible basal shearing as the Indian plate subducts under Tibet.[17][18]
^ abcdeSelverstone, Jane (May 2005). "Are the Alps collapsing?". Annual Review of Earth and Planetary Sciences. 33: 113–132. Bibcode:2005AREPS..33..113S. doi:10.1146/annurev.earth.33.092203.122535 – via ResearchGate.
^ abcdAdamuszek, Marta (2013-07-28). "Lecture - Orogenic Collapse". YouTube.
^Dai, Liming; Li, Sanzhong; Li, Zhong-Hai; Somerville, Ian; Liu, Xiaochun (2018-02-09). "Post-orogenic unrooting and collapse". www.mantleplumes.org. from the original on 2021-12-11. Retrieved 2021-12-10.
^Dewey, J.F.; Ryan, P.D.; Andersen, T.B. (1993). "Orogenic uplift and collapse, crustal thickness, fabrics and metamorphic phase changes: the role of eclogites". Geological Society, London, Special Publications. 76 (1): 325–343. Bibcode:1993GSLSP..76..325D. doi:10.1144/gsl.sp.1993.076.01.16. S2CID 55985869.
^Nance, Damian (2014-03-24). "What is Orogenic Collapse?". Oxford University Press.
^Johnston S., Hacker B.R. & Ducea M.N. (2007). "Exhumation of ultrahigh-pressure rocks beneath the Hornelen segment of the Nordfjord-Sogn Detachment Zone, western Norway" (PDF). Bulletin of the Geological Society of America. 119 (9–10): 1232–1248. Bibcode:2007GSAB..119.1232J. doi:10.1130/B26172.1.
^Gabrielsen, Roy H.; Faleide, Jan Inge; Pascal, Christophe; Braathen, Alvar; Nystuen, Johan Petter; Etzelmuller, Bernd; O'Donnel, Sejal (2010). "Latest Caledonian to Present tectonomorphological development of southern Norway". Marine and Petroleum Geology. 27 (3): 709–723. Bibcode:2010MarPG..27..709G. doi:10.1016/j.marpetgeo.2009.06.004.
^Cassel, Elizabeth J.; Breecker, Daniel O.; Henry, Christopher D.; Larson, Toti E.; Stockli, Daniel F. (Nov 2014). "Profile of a paleo-orogen: High topography across the present-day Basin and Range from 40 to 23 Ma". Geology. 42 (11): 1007–1010. Bibcode:2014Geo....42.1007C. doi:10.1130/G35924.1. ISSN 1943-2682.
^Liu, Mian; Shen, Yunqing (April 1998). "Crustal collapse, mantle upwelling, and Cenozoic extension in the North American Cordillera". Tectonics. 17 (2): 311–321. Bibcode:1998Tecto..17..311L. doi:10.1029/98tc00313. ISSN 0278-7407.
^Searle, Michael P.; Lamont, Thomas N. (2020-03-03). "Compressional origin of the Aegean Orogeny, Greece". Geoscience Frontiers (published 2020-08-07). 13 (2): 101049. doi:10.1016/j.gsf.2020.07.008.
^Vanderhaeghe, Olivier; Laurent, Oscar; Gardien, Véronique; Moyen, Jean-François; Gébelin, Aude; Chelle-Michou, Cyril; Couzinié, Simon; Villaros, Arnaud; Bellanger, Mathieu (2020-09-23). "Flow of partially molten crust controlling construction, growth and collapse of the Variscan orogenic belt: the geologic record of the French Massif Central". Bulletin de la Société Géologique de France. 191 (1): 25. doi:10.1051/bsgf/2020013. ISSN 0037-9409.
^Vacek, František; Žák, Jiří (March 2019). "A lifetime of the Variscan orogenic plateau from uplift to collapse as recorded by the Prague Basin, Bohemian Massif". Geological Magazine. 156 (3): 485–509. Bibcode:2019GeoM..156..485V. doi:10.1017/S0016756817000875. ISSN 0016-7568. S2CID 133712817.
^Ni, James; York, James E. (1978). "Late Cenozoic tectonics of the Tibetan Plateau". Journal of Geophysical Research. 83 (B11): 5377. Bibcode:1978JGR....83.5377N. doi:10.1029/jb083ib11p05377. ISSN 0148-0227.
^Yin, An; Kapp, Paul A.; Murphy, Michael A.; Manning, Craig E.; Mark Harrison, T.; Grove, Marty; Lin, Ding; Xi-Guang, Deng; Cun-Ming, Wu (1999-09-01). "Significant late Neogene east-west extension in northern Tibet". Geology. 27 (9): 787–790. Bibcode:1999Geo....27..787Y. doi:10.1130/0091-7613(1999)027<0787:SLNEWE>2.3.CO;2. ISSN 0091-7613.
^Blisniuk, Peter M.; Hacker, Bradley R.; Glodny, Johannes; Ratschbacher, Lothar; Bi, Siwen; Wu, Zhenhan; McWilliams, Michael O.; Calvert, Andy (2001-08-01). "Normal faulting in central Tibet since at least 13.5 Myr ago". Nature. 412 (6847): 628–632. doi:10.1038/35088045. ISSN 1476-4687. PMID 11493918. S2CID 4349309.
^Liu, Mian; Yang, Youqing (2003-08-01). "Extensional collapse of the Tibetan Plateau: Results of three-dimensional finite element modeling". Journal of Geophysical Research: Solid Earth. 108 (B8): 2361. Bibcode:2003JGRB..108.2361L. doi:10.1029/2002JB002248. ISSN 2156-2202.
^Guo, Xiaoyu; Gao, Rui; Zhao, Junmeng; Xu, Xiao; Lu, Zhanwu; Klemperer, Simon L.; Liu, Hongbing (2018-10-01). "Deep-seated lithospheric geometry in revealing collapse of the Tibetan Plateau". Earth-Science Reviews. 185: 751–762. Bibcode:2018ESRv..185..751G. doi:10.1016/j.earscirev.2018.07.013. ISSN 0012-8252.
October 21, 2023
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In geology orogenic collapse is the thinning and lateral spread of thickened crust It is a broad term referring to processes which distribute material from regions of high gravitational potential energy to regions of low gravitational potential energy 1 2 Orogenic collapse can begin at any point during an orogeny due to overthickening of the crust Post orogenic collapse and post orogenic extension refer to processes which take place once tectonic forces have been released and represent a key phase of the Wilson Cycle between continental collision and rifting 3 Orogenic collapse is the thinning and spreading of thickened crustOrogens also known as orogenic belts or more simply mountain ranges are sections of thickened crust which are built up as tectonic plates collide The thickening of the crust marks the start of an orogeny or mountain building event As the orogeny progresses the orogen may start spreading apart and thinning Collapse processes can begin either once the orogeny ends as the tectonic forces cease or during the orogeny if the crust becomes unstable 1 There are two primary mechanisms at work in an orogenic collapse excess gravitational potential energy and heat flow into the thickened crust Overthickened crust can become brittle and begin collapsing and spreading under its own weight The added weight from the thickened crust also causes it to sink deeper into the mantle where additional heat can flow into the crust The added heat softens the rock and makes it flow more easily which can allow material in deeper sections to move up into thinner areas via buoyancy forces reducing the total thickness 1 Orogens can also be destroyed by eduction and erosion but these processes are not necessarily associated with orogenic collapse 2 It has been argued that extension during orogenic collapse is a more effective mechanism of lowering mountains than erosion 4 Contents 1 Models 1 1 Fixed boundary collapse 1 2 Free boundary collapse 2 Examples 2 1 Caledonian Orogeny 2 2 Basin and Range Province 2 3 Aegean Sea Plate 2 4 Variscan Orogeny 2 5 Tibetan Plateau 3 See also 4 ReferencesModels Edit nbsp Orogenic collapse can occur under different circumstancesFixed boundary collapse Edit A fixed boundary collapse is the breakdown of the brittle upper crust and occurs when crust has overthickened while tectonic forces are still active Flow in the lower crust may or may not occur when this happens This can lead to exhumation of buried features 2 1 Free boundary collapse Edit Free boundary collapse occurs when tectonic forces have been released and the thickened crust is free to move This results in both the extension of the surface crust and flow of the lower crust to thinner regions The surface expression of the extension can include extensive normal faulting 1 2 This type of deformation has been compared to leaving a piece of Camembert cheese out overnight as the cheese starts to sag and spread the rind will eventually crack and split 5 Examples EditCaledonian Orogeny Edit Main article Caledonian orogeny The Scandinavian Caledonides is an example of an orogeny and mountain chain that reached heights of 8 9 km and then collapsed in the Devonian forming major extensional structures such as the Nordfjord Sogn Detachment 6 The collapse was such that the modern Scandinavian Mountains do not owe their height to the former orogeny but to other processes that occurred in the Cenozoic 7 8 Basin and Range Province Edit Main article Basin and Range Province The Basin and Range region of the Western United States was previously a high plateau within the American Cordillera which has since been extended and thinned The characteristic topography is caused by the crust breaking up into fault blocks as a result of the extension The exact cause of the extension is debated though it is likely related to the transition from a subduction zone to a transform boundary between the North American and Pacific plates as well as possible mantle upwelling 9 10 Aegean Sea Plate Edit Main article Aegean Sea Plate The Aegean Sea Plate is a section of continental crust which has been thinned and is considered a high plateau between the Mediterranean and the Black Sea The northern part of the plate underwent the Aegean Orogeny c 70 14 Ma followed by crustal extension and thinning due to slab rollback of the African Plate 11 Variscan Orogeny Edit Main article Variscan orogeny The Variscan or Hercynian orogeny was a result of the collision between the Laurussia and Gondwana plates during the formation of Pangaea This resulted in a high plateau of thickened crust c 345 310 Ma the northward subducting slab began retreating southward resulting in the thickened crust beginning to thin due to a combination of gravitational collapse fault detachment and softening of the crust due to added heat 12 13 Tibetan Plateau Edit Main articles Tibetan Plateau and Geology of the Himalaya Although the Tibetan Plateau is in a primarily compressional environment due to the collision of the Indian and Eurasian plates it is also experiencing east west extension which began c 14 Ma 14 15 16 The primary cause of this extension is likely gravitational collapse of the plateau due to excess gravitational potential energy as well as possible basal shearing as the Indian plate subducts under Tibet 17 18 See also EditExtensional tectonicsReferences Edit a b c d e Selverstone Jane May 2005 Are the Alps collapsing Annual Review of Earth and Planetary Sciences 33 113 132 Bibcode 2005AREPS 33 113S doi 10 1146 annurev earth 33 092203 122535 via ResearchGate a b c d Adamuszek Marta 2013 07 28 Lecture Orogenic Collapse YouTube Dai Liming Li Sanzhong Li Zhong Hai Somerville Ian Liu Xiaochun 2018 02 09 Post orogenic unrooting and collapse www mantleplumes org Archived from the original on 2021 12 11 Retrieved 2021 12 10 Dewey J F Ryan P D Andersen T B 1993 Orogenic uplift and collapse crustal thickness fabrics and metamorphic phase changes the role of eclogites Geological Society London Special Publications 76 1 325 343 Bibcode 1993GSLSP 76 325D doi 10 1144 gsl sp 1993 076 01 16 S2CID 55985869 Nance Damian 2014 03 24 What is Orogenic Collapse Oxford University Press Johnston S Hacker B R amp Ducea M N 2007 Exhumation of ultrahigh pressure rocks beneath the Hornelen segment of the Nordfjord Sogn Detachment Zone western Norway PDF Bulletin of the Geological Society of America 119 9 10 1232 1248 Bibcode 2007GSAB 119 1232J doi 10 1130 B26172 1 Gabrielsen Roy H Faleide Jan Inge Pascal Christophe Braathen Alvar Nystuen Johan Petter Etzelmuller Bernd O Donnel Sejal 2010 Latest Caledonian to Present tectonomorphological development of southern Norway Marine and Petroleum Geology 27 3 709 723 Bibcode 2010MarPG 27 709G doi 10 1016 j marpetgeo 2009 06 004 Green Paul F Lidmar Bergstrom Karna Japsen Peter Bonow Johan M Chalmers James A 2013 Stratigraphic landscape analysis thermochronology and the episodic development of elevated passive continental margins Geological Survey of Denmark and Greenland Bulletin 30 18 doi 10 34194 geusb v30 4673 Archived from the original on 24 September 2015 Retrieved 30 April 2015 Cassel Elizabeth J Breecker Daniel O Henry Christopher D Larson Toti E Stockli Daniel F Nov 2014 Profile of a paleo orogen High topography across the present day Basin and Range from 40 to 23 Ma Geology 42 11 1007 1010 Bibcode 2014Geo 42 1007C doi 10 1130 G35924 1 ISSN 1943 2682 Liu Mian Shen Yunqing April 1998 Crustal collapse mantle upwelling and Cenozoic extension in the North American Cordillera Tectonics 17 2 311 321 Bibcode 1998Tecto 17 311L doi 10 1029 98tc00313 ISSN 0278 7407 Searle Michael P Lamont Thomas N 2020 03 03 Compressional origin of the Aegean Orogeny Greece Geoscience Frontiers published 2020 08 07 13 2 101049 doi 10 1016 j gsf 2020 07 008 Vanderhaeghe Olivier Laurent Oscar Gardien Veronique Moyen Jean Francois Gebelin Aude Chelle Michou Cyril Couzinie Simon Villaros Arnaud Bellanger Mathieu 2020 09 23 Flow of partially molten crust controlling construction growth and collapse of the Variscan orogenic belt the geologic record of the French Massif Central Bulletin de la Societe Geologique de France 191 1 25 doi 10 1051 bsgf 2020013 ISSN 0037 9409 Vacek Frantisek Zak Jiri March 2019 A lifetime of the Variscan orogenic plateau from uplift to collapse as recorded by the Prague Basin Bohemian Massif Geological Magazine 156 3 485 509 Bibcode 2019GeoM 156 485V doi 10 1017 S0016756817000875 ISSN 0016 7568 S2CID 133712817 Ni James York James E 1978 Late Cenozoic tectonics of the Tibetan Plateau Journal of Geophysical Research 83 B11 5377 Bibcode 1978JGR 83 5377N doi 10 1029 jb083ib11p05377 ISSN 0148 0227 Yin An Kapp Paul A Murphy Michael A Manning Craig E Mark Harrison T Grove Marty Lin Ding Xi Guang Deng Cun Ming Wu 1999 09 01 Significant late Neogene east west extension in northern Tibet Geology 27 9 787 790 Bibcode 1999Geo 27 787Y doi 10 1130 0091 7613 1999 027 lt 0787 SLNEWE gt 2 3 CO 2 ISSN 0091 7613 Blisniuk Peter M Hacker Bradley R Glodny Johannes Ratschbacher Lothar Bi Siwen Wu Zhenhan McWilliams Michael O Calvert Andy 2001 08 01 Normal faulting in central Tibet since at least 13 5 Myr ago Nature 412 6847 628 632 doi 10 1038 35088045 ISSN 1476 4687 PMID 11493918 S2CID 4349309 Liu Mian Yang Youqing 2003 08 01 Extensional collapse of the Tibetan Plateau Results of three dimensional finite element modeling Journal of Geophysical Research Solid Earth 108 B8 2361 Bibcode 2003JGRB 108 2361L doi 10 1029 2002JB002248 ISSN 2156 2202 Guo Xiaoyu Gao Rui Zhao Junmeng Xu Xiao Lu Zhanwu Klemperer Simon L Liu Hongbing 2018 10 01 Deep seated lithospheric geometry in revealing collapse of the Tibetan Plateau Earth Science Reviews 185 751 762 Bibcode 2018ESRv 185 751G doi 10 1016 j earscirev 2018 07 013 ISSN 0012 8252 Retrieved from https en wikipedia org w index php title Orogenic collapse amp oldid 1171884616, wikipedia, wiki, book, books, library,
