Mountain formation explained

Mountain formation refers to the geological processes that underlie the formation of mountains. These processes are associated with large-scale movements of the Earth's crust (tectonic plates).^[1] Folding, faulting, volcanic activity, igneous intrusion and metamorphism can all be parts of the orogenic process of mountain building.^[2] The formation of mountains is not necessarily related to the geological structures found on it.^[3]

From the late 18th century until its replacement by plate tectonics in the 1960s, geosyncline theory was used to explain much mountain-building.^[4] The understanding of specific landscape features in terms of the underlying tectonic processes is called tectonic geomorphology, and the study of geologically young or ongoing processes is called neotectonics.^[5]

Types of mountains

See also: List of mountain types. There are five main types of mountains: volcanic, fold, plateau, fault-block, and dome. A more detailed classification useful on a local scale predates plate tectonics and adds to these categories.^[6]

Volcanic mountains

See also: Guyot. Movements of tectonic plates create volcanoes along the plate boundaries, which erupt and form mountains. A volcanic arc system is a series of volcanoes that form near a subduction zone where the crust of a sinking oceanic plate melts and drags water down with the subducting crust.^[7] Most volcanoes occur in a band encircling the Pacific Ocean (the Pacific Ring of Fire), and in another that extends from the Mediterranean across Asia to join the Pacific band in the Indonesian Archipelago. The most important types of volcanic mountain are composite cones or stratovolcanoes and shield volcanoes.^{[8] [9]}

A shield volcano has a gently sloping cone because of the low viscosity of the emitted material, primarily basalt. Mauna Loa is the classic example, with a slope of 4°-6°. (The relation between slope and viscosity falls under the topic of angle of repose.^[10]) A composite volcano or stratovolcano has a more steeply rising cone (33°-40°),^[11] because of the higher viscosity of the emitted material, and eruptions are more violent and less frequent than for shield volcanoes. Examples include Vesuvius, Kilimanjaro, Mount Fuji, Mount Shasta, Mount Hood and Mount Rainier.^[12]

Fold mountains

See also: Fold mountain and Fold and thrust belt. When plates collide or undergo subduction (that is, ride one over another), the plates tend to buckle and fold, forming mountains. Most of the major continental mountain ranges are associated with thrusting and folding or orogenesis. Examples are the Balkan Mountains, the Jura and the Zagros mountains.^[13]

Block mountains

When a fault block is raised or tilted, a block mountain can result.^[14] Higher blocks are called horsts, and troughs are called grabens. A spreading apart of the surface causes tensional forces. When the tensional forces are strong enough to cause a plate to split apart, it does so such that a center block drops down relative to its flanking blocks.

An example is the Sierra Nevada range, where delamination created a block 650 km long and 80 km wide that consists of many individual portions tipped gently west, with east facing slips rising abruptly to produce the highest mountain front in the continental United States.^{[15] [16]}

Another example is the Rila–Rhodope massif in Bulgaria, including the well defined horsts of Belasitsa (linear horst), Rila mountain (vaulted domed shaped horst) and Pirin mountain—a horst forming a massive anticline situated between the complex graben valleys of the Struma and Mesta rivers.^{[17] [18] [19]}

Uplifted passive margins

Unlike orogenic mountains there is no widely accepted geophysical model that explains elevated passive continental margins such as the Scandinavian Mountains, eastern Greenland, the Brazilian Highlands, or Australia's Great Dividing Range.^{[20] [21]} Different elevated passive continental margins most likely share the same mechanism of uplift. This mechanism is possibly related to far-field stresses in Earth's lithosphere. According to this view elevated passive margins can be likened to giant anticlinal lithospheric folds, where folding is caused by horizontal compression acting on a thin to thick crust transition zone (as are all passive margins).^{[22] [23]}

Models

See also: Extensional tectonics, Rift valley, Rift, Prediction of volcanic activity and Geomorphology.

Hotspot volcanoes

Hotspots are supplied by a magma source in the Earth's mantle called a mantle plume. Although originally attributed to a melting of subducted oceanic crust, recent evidence belies this connection.^[24] The mechanism for plume formation remains a research topic.

Fault blocks

Several movements of the Earth's crust that lead to mountains are associated with faults. These movements actually are amenable to analysis that can predict, for example, the height of a raised block and the width of an intervening rift between blocks using the rheology of the layers and the forces of isostasy. Early bent plate models predicting fractures and fault movements have evolved into today's kinematic and flexural models.^{[25] [26]}

See also

External links

• NASA Goddard Planetary Geodynamics Laboratory
• NASA Goddard Planetary Geodynamics Laboratory: Volcanology Research
• Rotating globe showing areas of earthquake activity

Notes and References

1. Book: Earth system history . Steven M. Stanley . https://books.google.com/books?id=jd01mugCR7EC&pg=PA207 . 207 . Mountain building . 978-0-7167-3907-4 . 2004 . 2nd . Macmillan.
2. Book: Structural Geology . . . Plate tectonic models of orogenic core zones . 493 . 978-0-7167-2252-6 . 1992 . 2nd . Macmillan . https://books.google.com/books?id=14fn03iJ2r8C&pg=PA493 .
3. Book: Ollier . Cliff. Pain . Colin . 2000. Cliff Ollier . The Origin of Mountains . limited . Routledge . 1 . 978-0-415-19890-5.
4. Web site: Geosynclinal Theory . publish.illinois.edu . University of Illinois at Urbana-Champaign . March 8, 2018. The major mountain-building idea that was supported from the 19th century and into the 20th is the geosynclinal theory..
5. Book: Geodynamics of the lithosphere: an introduction . Kurt Stüwe . §4.5 Geomorphology . https://books.google.com/books?id=gwYcuMSUnxEC&pg=PA178 . 178 . 978-3-540-71236-7 . 2007 . Springer . 2nd.
6. Book: Andrew Goudie . Encyclopedia of geomorphology; Volume 2 . 701 . 978-0-415-32738-1 . 2004 . Routledge.
7. Book: Science of Earth Systems . Stephen D Butz . https://books.google.com/books?id=JB4ArbvXXDEC&pg=PA136 . 136 . Chapter 8: Plate tectonics . 978-0-7668-3391-3 . 2004 . Thompson/Delmar Learning .
8. Book: Mountain environments: an examination of the physical geography of mountains . Types of volcano . 194 . https://books.google.com/books?id=jHnrVEyMhkQC&pg=PA194 . 978-0-262-07128-4 . 1990 . MIT Press . John Gerrard .
9. Book: Volcanoes . Robert Wayne Decker . Barbara Decker . https://books.google.com/books?id=BilBFXIW5c4C&pg=PA113 . Chapter 8: Hot spots . 978-0-7167-8929-1 . 4th . 2005 . Macmillan . 113 ff.
10. Book: Holmes Principles of Physical Geology . Taylor & Francis . 2004 . 4th . Arthur Holmes . Arthur Holmes. Donald Duff . Donald Duff (geologist and author). 209 . 978-0-7487-4381-0 .
11. Book: Transactions of the American Society of Civil Engineers, Volume 39 . 62 . 1898 . American Society of Civil Engineers.
12. Book: An Introduction to Physical Science . James Shipman . Jerry D. Wilson . Aaron Todd . https://books.google.com/books?id=1LvMLoaN0HQC&pg=PT670 . 650 . Minerals, rocks and volcanoes . 978-0-618-93596-3 . 2007 . Cengage Learning . 12th.
13. Book: 4-D framework of continental crust . . MP Carlson . JH McBride & JR Martinez Catalán . . 41 ff . https://books.google.com/books?id=jD-zXhTfJuMC&pg=PA41 . Diagnostic features and processes in the construction and evolution of Oman-, Zagros-, Himalayan-, Karakoram-, and Tibetan type orogenic belts . 978-0-8137-1200-0 . Geological Society of America . 2007.
14. Book: CliffsQuickReview Earth Science . https://books.google.com/books?id=PV_BabxTTkcC&pg=PA94 . Figure 13-1 . Scott Ryan . 978-0-471-78937-6 . 2006 . Wiley .
15. Book: Reference cited . 9 . John Gerrard . 978-0-262-07128-4 . 1990-04-12 .
16. 10.1126/science.289.5486.1912. 10988067. Osmium Isotopic Evidence for Mesozoic Removal of Lithospheric Mantle Beneath the Sierra Nevada, California. SB. Jacobsen. JT. Chesley. RL. Rudnick. Q. 2000. Yin. Lee. C.-T.. Science. 289. 5486. 1912–6. 2000Sci...289.1912L. dead. https://web.archive.org/web/20110615170551/http://www.geol.umd.edu/~rudnick/Webpage/Lee_2000_Science.pdf. 2011-06-15.
17. Book: . bg: Географски речник на България . Geographic Dictionary of Bulgaria . Мичев (Michev) . Николай (Nikolay) . Михайлов (Mihaylov) . Цветко (Tsvetko) . Вапцаров (Vaptsarov) . Иван (Ivan) . Кираджиев (Kiradzhiev) . Светлин (Svetlin) . 1980 . bg . Наука и култура (Nauka i kultura) . Sofia . 368.
18. Book: . Pirin National Park. Management Plan . bg:Национален парк "Пирин". План за управление . Димитрова (Dimitrova) . Людмила (Lyudmila) . и колектив . 2004 . bg . Ministry of Environment and Water, Bulgarian Foundation "Biodiversity" . Sofia . 53 .
19. Book: . bg: Теми по физическа и социално-икономическа география на България . Topics on Physical and Social-Economic Geography of Bulgaria . Дончев (Donchev) . Дончо (Doncho) . Каракашев (Karakashev) . Христо (Hristo) . 2004 . bg . Ciela . Sofia . 954-649-717-7 . 128–129.
20. Web site: atlantens kustberg och högslätter – gamla eller unga? . Bonow . Johan M. . 2009 . www.geografitorget.se . Geografilärarnas Riksförening . sv.
21. Green . Paul F. . Lidmar-Bergström . Karna . Bonow . Johan M. . Japsen . Peter . Chalmers . James A. . Karna Lidmar-Bergström . 2013 . Stratigraphic landscape analysis, thermochronology and the episodic development of elevated, passive continental margins . . 30 . 18 . 10.34194/geusb.v30.4673 . free .
22. Japsen . Peter . Chalmers. James A. . Green. Paul F.. Bonow. Johan M. . 2012. Elevated, passive continental margins: Not rift shoulders, but expressions of episodic, post-rift burial and exhumation. Global and Planetary Change. 90-91. 73–86. 2012GPC....90...73J. 10.1016/j.gloplacha.2011.05.004.
23. Løseth and Hendriksen 2005
24. Book: Oceanic hotspots: intraplate submarine magmatism and tectonism . Y Niu . MJ O'Hara . amp . Chapter 7: Mantle plumes are NOT from ancient oceanic crust . https://books.google.com/books?id=K7L34ffaODwC&pg=PA239 . 239 ff . Roger Hékinian . Peter Stoffers . Jean-Louis Cheminée . 978-3-540-40859-8 . 2004 . Springer.
25. Book: AB Watts . Isostasy and flexure of the lithosphere . 295 . §7.2 Extensional tectonics and rifting . https://books.google.com/books?id=CNkiZU7enWUC&pg=PA295 . 978-0-521-00600-2 . Cambridge University Press . 2001.
26. Book: Continental tectonics . https://books.google.com/books?id=gpIY2unrObEC&pg=PA271 . GD Karner . NW Driscoll . amp . Conall Mac Niocaill . Paul Desmond Ryan . 280 . Style, timing and distribution of tectonic deformation across the Exmouth Plateau, northwest Australia, determined from stratal architecture and quantitative basin modelling . 978-1-86239-051-5 . 1999 . Geological society.