Hotspot (geology)

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Diagram showing a cross section through the Earth's lithosphere (in yellow) with magma rising from the mantle (in red). Lower diagram illustrates a hotspot track caused by their relative movement. Hotspot(geology)-1.svg
Diagram showing a cross section through the Earth's lithosphere (in yellow) with magma rising from the mantle (in red). Lower diagram illustrates a hotspot track caused by their relative movement.

In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle.[ citation needed ] Examples include the Hawaii, Iceland and Yellowstone hotspots. A hotspot's position on the Earth's surface is independent of tectonic plate boundaries, and so hotspots may create a chain of volcanoes as the plates move above them.

Contents

There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. [1] The other hypothesis is that lithospheric extension permits the passive rising of melt from shallow depths. [2] [3] This hypothesis considers the term "hotspot" to be a misnomer, asserting that the mantle source beneath them is not in fact anomalously hot.

Origin

Schematic diagram showing the physical processes inside the Earth that lead to the generation of magma. Partial melting begins above the fusion point. Partial melting asthenosphere EN.svg
Schematic diagram showing the physical processes inside the Earth that lead to the generation of magma. Partial melting begins above the fusion point.

The origins of the concept of hotspots lie in the work of J. Tuzo Wilson, who postulated in 1963 that the formation of the Hawaiian Islands resulted from the slow movement of a tectonic plate across a hot region beneath the surface. [4] It was later postulated that hotspots are fed by narrow streams of hot mantle rising from the Earth's core–mantle boundary in a structure called a mantle plume. [5] Whether or not such mantle plumes exist is the subject of a major controversy in Earth science. [3] [6] Estimates for the number of hotspots postulated to be fed by mantle plumes have ranged from about 20 to several thousands, over the years, with most geologists considering a few tens to exist. Hawaii, Réunion, Yellowstone, Galápagos, and Iceland are some of the most active volcanic regions to which the hypothesis is applied.

Composition

Most hotspot volcanoes are basaltic (e.g., Hawaii, Tahiti). As a result, they are less explosive than subduction zone volcanoes, in which water is trapped under the overriding plate. Where hotspots occur in continental regions, basaltic magma rises through the continental crust, which melts to form rhyolites. These rhyolites can form violent eruptions. [7] [8] For example, the Yellowstone Caldera was formed by some of the most powerful volcanic explosions in geologic history. However, when the rhyolite is completely erupted, it may be followed by eruptions of basaltic magma rising through the same lithospheric fissures (cracks in the lithosphere). An example of this activity is the Ilgachuz Range in British Columbia, which was created by an early complex series of trachyte and rhyolite eruptions, and late extrusion of a sequence of basaltic lava flows. [9]

The hotspot hypothesis is now closely linked to the mantle plume hypothesis. [10]

Comparison with island arc volcanoes

Hotspot volcanoes are considered to have a fundamentally different origin from island arc volcanoes. The latter form over subduction zones, at converging plate boundaries. When one oceanic plate meets another, the denser plate is forced downward into a deep ocean trench. This plate, as it is subducted, releases water into the base of the over-riding plate, and this water mixes with the rock, thus changing its composition causing some rock to melt and rise. It is this that fuels a chain of volcanoes, such as the Aleutian Islands, near Alaska.

Hotspot volcanic chains

Over millions of years, the Pacific Plate has moved over the Hawaii hotspot, creating a trail of underwater mountains that stretch across the Pacific Hawaii hotspot.jpg
Over millions of years, the Pacific Plate has moved over the Hawaii hotspot, creating a trail of underwater mountains that stretch across the Pacific
Kilauea is the most active shield volcano in the world. The volcano erupted nonstop from 1983 to 2018 and it is part of the Hawaiian-Emperor seamount chain. Puu Oo cropped.jpg
Kilauea is the most active shield volcano in the world. The volcano erupted nonstop from 1983 to 2018 and it is part of the Hawaiian–Emperor seamount chain.
Mauna Loa is a large shield volcano. Its last eruption was in 1984 and it is part of the Hawaiian-Emperor seamount chain. Mauna Loa Volcano.jpg
Mauna Loa is a large shield volcano. Its last eruption was in 1984 and it is part of the Hawaiian–Emperor seamount chain.
Bowie Seamount is a dormant submarine volcano and it is part of the Kodiak-Bowie Seamount chain. Bowie Seamount1.jpg
Bowie Seamount is a dormant submarine volcano and it is part of the Kodiak-Bowie Seamount chain.
Axial Seamount is the youngest seamount of the Cobb-Eickelberg Seamount chain. Its last eruption was on 6 April 2011. Axial Exaggerated Bathymetry.jpg
Axial Seamount is the youngest seamount of the Cobb–Eickelberg Seamount chain. Its last eruption was on 6 April 2011.
Mauna Kea is the tallest volcano in the Hawaiian-Emperor seamount chain. It is dormant and it has cinder cones growing on the volcano. Mauna Kea from the ocean.jpg
Mauna Kea is the tallest volcano in the Hawaiian–Emperor seamount chain. It is dormant and it has cinder cones growing on the volcano.
Hualalai is a massive shield volcano in the Hawaiian-Emperor seamount chain. Its last eruption was in 1801. Hualalai 1996.jpg
Hualalai is a massive shield volcano in the Hawaiian–Emperor seamount chain. Its last eruption was in 1801.

The joint mantle plume/hotspot hypothesis envisages the feeder structures to be fixed relative to one another, with the continents and seafloor drifting overhead. The hypothesis thus predicts that time-progressive chains of volcanoes are developed on the surface. Examples are Yellowstone, which lies at the end of a chain of extinct calderas, which become progressively older to the west. Another example is the Hawaiian archipelago, where islands become progressively older and more deeply eroded to the northwest.

Geologists have tried to use hotspot volcanic chains to track the movement of the Earth's tectonic plates. This effort has been vexed by the lack of very long chains, by the fact that many are not time-progressive (e.g. the Galápagos) and by the fact that hotspots do not appear to be fixed relative to one another (e.g. Hawaii and Iceland. [12] )

Postulated hotspot volcano chains

An example of mantle plume locations suggested by one recent group. Figure from Foulger (2010). CourtHotspots.png
An example of mantle plume locations suggested by one recent group. Figure from Foulger (2010).

List of volcanic regions postulated to be hotspots

Distribution of hotspots in the list to the left, with the numbers corresponding to those in the list. The Afar hotspot (29) is misplaced. Hotspots-more.jpg
Distribution of hotspots in the list to the left, with the numbers corresponding to those in the list. The Afar hotspot (29) is misplaced.
Map all coordinates using: OpenStreetMap  
Download coordinates as: KML  ·  GPX

Eurasian Plate

African Plate

Antarctic Plate

South American Plate

North American Plate

Indo-Australian Plate

Nazca Plate

Pacific Plate

Over millions of years, the Pacific Plate has moved over the Bowie hotspot, creating the Kodiak-Bowie Seamount chain in the Gulf of Alaska Kodiak-Bowie Seamounts.jpg
Over millions of years, the Pacific Plate has moved over the Bowie hotspot, creating the Kodiak-Bowie Seamount chain in the Gulf of Alaska

Former hotspots

See also

Related Research Articles

Mantle plume An upwelling of abnormally hot rock within the Earths mantle

A mantle plume is a proposed mechanism of convection of abnormally hot rock within the Earth's mantle. Because the plume head partly melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps. Some such volcanic regions lie far from tectonic plate boundaries, while others represent unusually large-volume volcanism near plate boundaries.

Hawaiian–Emperor seamount chain A mostly undersea mountain range in the Pacific Ocean that reaches above sea level in Hawaii.

The Hawaiian–Emperor seamount chain is a mostly undersea mountain range in the Pacific Ocean that reaches above sea level in Hawaii. It is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts: together they form a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending southeast to northwest beneath the northern Pacific Ocean. The seamount chain, containing over 80 identified undersea volcanoes, stretches about 6,200 kilometres (3,900 mi) from the Aleutian Trench in the far northwest Pacific to the Loʻihi seamount, the youngest volcano in the chain, which lies about 35 kilometres (22 mi) southeast of the Island of Hawaiʻi.

Large igneous province Huge regional accumulation of igneous rocks

A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive and extrusive, arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. The formation of some of the LIPs the past 500 million years coincide in time with mass extinctions and rapid climatic changes, which has led to numerous hypotheses about the causal relationships. LIPs are fundamentally different from any other currently active volcanoes or volcanic systems.

Iceland hotspot Hotspot partly responsible for volcanic activity forming the Iceland Plateau and island

The Iceland hotspot is a hotspot which is partly responsible for the high volcanic activity which has formed the Iceland Plateau and the island of Iceland.

W. Jason Morgan American geophysicist

William Jason Morgan is an American geophysicist who has made seminal contributions to the theory of plate tectonics and geodynamics. He retired as the Knox Taylor Professor emeritus of geology and professor of geosciences at Princeton University. He currently serves as a visiting scholar in the Department of Earth and Planetary Sciences at Harvard University.

Galápagos hotspot Pacific volcanic hotspot

The Galápagos hotspot is a volcanic hotspot in the East Pacific Ocean responsible for the creation of the Galápagos Islands as well as three major aseismic ridge systems, Carnegie, Cocos and Malpelo which are on two tectonic plates. The hotspot is located near the Equator on the Nazca Plate not far from the divergent plate boundary with the Cocos Plate. The tectonic setting of the hotspot is complicated by the Galapagos Triple Junction of the Nazca and Cocos plates with the Pacific Plate. The movement of the plates over the hotspot is determined not solely by the spreading along the ridge but also by the relative motion between the Pacific Plate and the Cocos and Nazca Plates.

Cobb hotspot

The Cobb hotspot is a marine volcanic hotspot at, which is 460 km (290 mi) west of Oregon and Washington, North America, in the Pacific Ocean. Over geologic time, the Earth's surface has migrated with respect to the hotspot through plate tectonics, creating the Cobb-Eicklberg seamount chain. The hotspot is currently collocated with the Juan de Fuca Ridge.

Hawaii hotspot A volcanic hotspot located near the Hawaiian Islands, in the northern Pacific Ocean

The Hawaii hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the Hawaiian–Emperor seamount chain, a 6,200-kilometer (3,900 mi) mostly undersea volcanic mountain range. Four of these volcanoes are active, two are dormant; more than 123 are extinct, most now preserved as atolls or seamounts. The chain extends from south of the island of Hawaiʻi to the edge of the Aleutian Trench, near the eastern coast of Russia.

Southwest Indian Ridge A mid-ocean ridge on the bed of the south-west Indian Ocean and south-east Atlantic Ocean

The Southwest Indian Ridge (SWIR) is a mid-ocean ridge located along the floors of the south-west Indian Ocean and south-east Atlantic Ocean. A divergent tectonic plate boundary separating the African Plate to the north from the Antarctic Plate to the south, the SWIR is characterised by ultra-slow spreading rates combined with a fast lengthening of its axis between the two flanking triple junctions, Rodrigues in the Indian Ocean and Bouvet in the Atlantic Ocean.

Southeast Indian Ridge A mid-ocean ridge in the southern Indian Ocean

The Southeast Indian Ridge (SEIR) is a mid-ocean ridge in the southern Indian Ocean. A divergent tectonic plate boundary stretching almost 6,000 km (3,700 mi) between the Rodrigues Triple Junction in the Indian Ocean and the Macquarie Triple Junction in the Pacific Ocean, the SEIR forms the plate boundary between the Australian and Antarctic plates since the Oligocene (anomaly 13).

Pitcairn hotspot volcanic hotspot in the south-central Pacific Ocean

The Pitcairn hotspot is a volcanic hotspot located in the south-central Pacific Ocean. Over the past 11 million years, it has formed the Pitcairn-Gambier hotspot chain. It is responsible for creating the Pitcairn Islands and two large seamounts named Adams and Bounty, as well as atolls at Moruroa, Fangataufa and the Gambier Islands. The hotspot is currently located at Adams and Bounty, which are ~60 kilometers East-Southeast of Pitcairn Island.

Louisville hotspot A volcanic hotspot that formed the Louisville Ridge in the southern Pacific Ocean

The Louisville hotspot is a volcanic hotspot responsible for the volcanic activity that has formed the Louisville Ridge in the southern Pacific Ocean.

Samoa hotspot

The Samoa hotspot is a volcanic hotspot located in the south Pacific Ocean. The hotspot model describes a hot upwelling plume of magma through the Earth's crust as an explanation of how volcanic islands are formed. The hotspot idea came from J. Tuzo Wilson in 1963 based on the Hawaii volcanic island chain.

Macdonald hotspot hotspot in the Pacific Ocean

The Macdonald hotspot is a volcanic hotspot in the southern Pacific Ocean. The hotspot was responsible for the formation of the Macdonald Seamount, and possibly the Austral-Cook Islands chain. It probably did not generate all of the volcanism in the Austral and Cook Islands as age data imply that several additional hotspots were needed to generate some volcanoes.

Ocean island basalt

Ocean island basalt (OIB) is a volcanic rock, usually basaltic in composition, erupted in oceans away from tectonic plate boundaries. Although ocean island basaltic magma is mainly erupted as basalt lava, the basaltic magma is sometimes modified by igneous differentiation to produce a range of other volcanic rock types, for example, rhyolite in Iceland, and phonolite and trachyte at the intraplate volcano Fernando de Noronha. Unlike mid-ocean ridge basalts (MORBs), which erupt at spreading centers, and volcanic arc lavas, which erupt at subduction zones, ocean island basalts are the result of intraplate volcanism. However, some ocean island basalt locations coincide with plate boundaries like Iceland, which sits on top of a mid-ocean ridge, and Samoa, which is located near a subduction zone.

Shona hotspot

The Shona or Meteor hotspot is a volcanic hotspot located in the southern Atlantic Ocean. Its zig-zag-shaped hotspot track, a chain of seamounts and ridges, stretches from its current location at or near the southern end of the Mid-Atlantic Ridge to South Africa.

Geology of the Pacific Ocean overview about the geology of the Pacific Ocean

The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.

Arago hotspot

Arago hotspot is a hotspot in the Pacific Ocean, presently located below the Arago seamount close to the island of Rurutu, French Polynesia.

Foundation Seamounts A series of seamounts in the southern Pacific Ocean in a chain which starts at the Pacific-Antarctic Ridge

Foundation Seamounts are a series of seamounts in the southern Pacific Ocean. Discovered in 1992, these seamounts form a 1,350 kilometres (840 mi) long chain which starts from the Pacific-Antarctic Ridge. Some of these seamounts may have once emerged from the ocean.

Musicians Seamounts A chain of seamounts in the Pacific Ocean, north of the Hawaiian Ridge

Musicians Seamounts are a chain of seamounts in the Pacific Ocean, north of the Hawaiian Ridge. There are about 65 seamounts, some of which are named after musicians. These seamounts exist in two chains, one of which has been attributed to a probably now-extinct hotspot called the Euterpe hotspot. Others may have formed in response to plate tectonics associated with the boundary between the Pacific Plate and the former Farallon Plate.

References

  1. 1 2 W. J. Morgan (5 March 1971). "Convection Plumes in the Lower Mantle". Nature. 230 (5288): 42–43. Bibcode:1971Natur.230...42M. doi:10.1038/230042a0.
  2. "Do plumes exist?" . Retrieved 25 April 2010.
  3. 1 2 3 Foulger, G.R. (2010). Plates vs. Plumes: A Geological Controversy. Wiley-Blackwell. ISBN   978-1-4051-6148-0.
  4. Wilson, J. Tuzo (1963). "A possible origin of the Hawaiian Islands" (PDF). Canadian Journal of Physics. 41 (6): 863–870. Bibcode:1963CaJPh..41..863W. doi:10.1139/p63-094.
  5. "Hotspots: Mantle thermal plumes". United States Geological Survey. 5 May 1999. Retrieved 15 May 2008.
  6. Wright, Laura (November 2000). "Earth's interior: Raising hot spots". Geotimes. American Geological Institute . Retrieved 15 June 2008.
  7. Donald Hyndman; David Hyndman (1 January 2016). Natural Hazards and Disasters. Cengage Learning. pp. 44–. ISBN   978-1-305-88818-0.
  8. Wolfgang Frisch; Martin Meschede; Ronald C. Blakey (2 November 2010). Plate Tectonics: Continental Drift and Mountain Building. Springer Science & Business Media. pp. 87–. ISBN   978-3-540-76504-2.
  9. Holbek, Peter (November 1983). "Report on Preliminary Geology and Geochemistry of the Ilga Claim Group" (PDF). Retrieved 15 June 2008.Cite journal requires |journal= (help)
  10. Mainak Choudhuri; Michal Nemčok (22 August 2016). Mantle Plumes and Their Effects. Springer. pp. 18–. ISBN   978-3-319-44239-6.
  11. "Axial Seamount". PMEL Earth-Ocean Interactions Program. NOAA . Retrieved 23 September 2014.
  12. "What the hell is Hawaii?" . Retrieved 7 January 2011.
  13. Courtillot, V.; Davaillie, A.; Besse, J.; Stock, J. (2003). "Three distinct types of hotspots in the Earth's mantle". Earth Planet. Sci. Lett. 205 (3–4): 295–308. Bibcode:2003E&PSL.205..295C. CiteSeerX   10.1.1.693.6042 . doi:10.1016/S0012-821X(02)01048-8.
  14. E. V. Verzhbitsky (2003). "Geothermal regime and genesis of the Ninety-East and Chagos-Laccadive ridges". Journal of Geodynamics. 35 (3): 289. Bibcode:2003JGeo...35..289V. doi:10.1016/S0264-3707(02)00068-6.
  15. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 W. J. Morgan and J. P. Morgan. "Plate velocities in hotspot reference frame: electronic supplement" (PDF). Retrieved 6 November 2011.
  16. Nielsen, Søren B.; Stephenson, Randell; Thomsen, Erik (13 December 2007). "Letter:Dynamics of Mid-Palaeocene North Atlantic rifting linked with European intra-plate deformations". Nature. 450 (7172): 1071–1074. Bibcode:2007Natur.450.1071N. doi:10.1038/nature06379. PMID   18075591.
  17. O'Neill, C.; Müller, R. D.; Steinberger, B. (2003). "Revised Indian plate rotations based on the motion of Indian Ocean hotspots" (PDF). Earth and Planetary Science Letters. 215 (1–2): 151–168. Bibcode:2003E&PSL.215..151O. CiteSeerX   10.1.1.716.4910 . doi:10.1016/S0012-821X(03)00368-6. Archived from the original (PDF) on 26 July 2011.
  18. O'Connor, J. M.; le Roex, A. P. (1992). "South Atlantic hot spot-plume systems. 1: Distribution of volcanism in time and space". Earth and Planetary Science Letters. 113 (3): 343–364. Bibcode:1992E&PSL.113..343O. doi:10.1016/0012-821X(92)90138-L.
  19. Smith, Robert B.; Jordan, Michael; Steinberger, Bernhard; Puskas, Christine M.; Farrell, Jamie; Waite, Gregory P.; Husen, Stephan; Chang, Wu-Lung; O'Connell, Richard (20 November 2009). "Geodynamics of the Yellowstone hotspot and mantle plume: Seismic and GPS imaging, kinematics and mantle flow" (PDF). Journal of Volcanology and Geothermal Research. 188 (1–3): 26–56. Bibcode:2009JVGR..188...26S. doi:10.1016/j.jvolgeores.2009.08.020.
  20. "Catalogue of Canadian volcanoes- Anahim volcanic belt". Natural Resources Canada. Geological Survey of Canada. Archived from the original on 16 July 2011. Retrieved 14 June 2008.

Further reading