Hotspot (geology)

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Diagram showing a cross section though the Earth's lithosphere (in yellow) with magma rising from the mantle (in red)

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. They may be on, near to, or far from tectonic plate boundaries. Currently, there are two hypotheses that attempt to explain their origins. One suggests that they are due to hot mantle plumes that rise as thermal diapirs from the core–mantle boundary.[1] An alternative hypothesis postulates that it is not high temperature that causes the volcanism, but lithospheric extension that 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, in fact, not anomalously hot at all. Well known examples include Hawaii and Yellowstone.

Background

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 Hawaiian Islands result 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 currently the subject of a major controversy in Earth science.[3][6] Estimates for the number of hotspots postulated to be fed by mantle plumes has 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 currently most active volcanic regions to which the hypothesis is applied.

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. 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.[7]

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

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
File:Puu Oo cropped.jpg
Kilauea is the most active shield volcano in the world. The volcano has erupted nonstop since 1983 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.
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.[8]
Mauna Kea is the tallest volcano in the Hawaiian–Emperor seamount chain. It is currently 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.

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.[9])

Postulated hotspot volcano chains

An example of mantle plume locations suggested by one recent group.[10] Figure from Foulger (2010).[3]

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 is misplaced.

Eurasian Plate

  • Eifel hotspot (8)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 082° ±8° rate= 12 ±2 mm/yr [12]
  • Iceland hotspot (14)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
      • Eurasian Plate, w= .8 az= 075° ±10° rate= 5 ±3 mm/yr
      • North American Plate, w= .8 az= 287° ±10° rate= 15 ±5 mm/yr
    • Possibly related to the North Atlantic continental rifting (62 Ma), Greenland.[13]
  • Azores hotspot (1)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
      • Eurasian Plate, w= .5 az= 110° ±12°
      • North American Plate, w= .3 az= 280° ±15°
  • Jan Mayen hotspot (15)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
  • Hainan hotspot (46)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., az= 000° ±15° [12]

African Plate

  • Mount Etna (47)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
  • Hoggar hotspot (13)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .3 az= 046° ±12° [12]
  • Tibesti hotspot (40)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .2 az= 030° ±15° [12]
  • Jebel Marra/Darfur hotspot (6)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .5 az= 045° ±8° [12]
  • Afar hotspot (29, misplaced in map)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .2 az= 030° ±15° rate= 16 ±8 mm/yr [12]
    • Possibly related to the Afar Triple Junction, 30 Ma.
  • Cameroon hotspot (17)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .3 az= 032° ±3° rate= 15 ±5 mm/yr [12]
  • Madeira hotspot (48)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .3 az= 055° ±15° rate= 8 ±3 mm/yr [12]
  • Canary hotspot (18)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 094° ±8° rate= 20 ±4 mm/yr [12]
  • New England/Great Meteor hotspot (28)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 040° ±10° [12]
  • Cape Verde hotspot (19)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .2 az= 060° ±30° [12]
  • St. Helena hotspot (34)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 078° ±5° rate= 20 ±3 mm/yr [12]
  • Gough hotspot (49), at 40°19' S 9°56' W.[14][15]
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 079° ±5° rate= 18 ±3 mm/yr [12]
  • Tristan hotspot (42), at 37°07′ S 12°17′ W.
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
  • Vema hotspot (Vema Seamount, 43), at 31°38' S 8°20' E.
  • Discovery hotspot (50) (Discovery Seamounts)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 068° ±3° [12]
  • Bouvet hotspot (51)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
  • Shona/Meteor hotspot (27)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .3 az= 074° ±6° [12]
  • Réunion hotspot (33)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 047° ±10° rate= 40 ±10 mm/yr [12]
    • Possibly related to the Deccan Traps (main events: 68.5–66 Ma)
  • Comoros hotspot (21)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .5 az=118 ±10° rate=35 ±10 mm/yr [12]

Antarctic Plate

  • Marion hotspot (25)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .5 az= 080° ±12° [12]
  • Crozet hotspot (52)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 109° ±10° rate= 25 ±13 mm/yr [12]
    • Possibly related to the Karoo-Ferrar geologic province (183 Ma)
  • Kerguelen hotspot (20)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .2 az= 050° ±30° rate= 3 ±1 mm/yr [12]
    • Île Saint-Paul and Île Amsterdam could be part of the Kerguelen hotspot trail (St. Paul is probably not another hotspot)
    • Related maybe to the Kerguelen Plateau (130 Ma)
  • Heard hotspot (53)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .2 az= 030° ±20° [12]
  • Balleny hotspot (2)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .2 az= 325° ±7° [12]
  • Erebus hotspot (54)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]

South American Plate

  • Trindade/Martin Vaz hotspot (41)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 264° ±5° [12]
  • Fernando hotspot (9)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 266° ±7° [12]
    • Possibly related to the Central Atlantic Magmatic Province (c. 200 Ma)
  • Ascension hotspot (55)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]

North American Plate

  • Bermuda hotspot (56)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .3 az= 260° ±15° [12]
  • Yellowstone hotspot (44)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 235° ±5° rate= 26 ±5 mm/yr [12]
    • Possibly related to the Columbia River Basalt Group (17–14 Ma).[16]
  • Raton hotspot (32)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 240°±4° rate= 30 ±20 mm/yr [12]
  • Anahim hotspot (45)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. (Nazko Cone)[17]

Indo-Australian Plate

  • Lord Howe hotspot (22)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 351° ±10° [12]
  • Tasmanid hotspot (Gascoyne Seamount, 39)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 007° ±5° rate= 63 ±5 mm/yr [12]
  • East Australia hotspot (30)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .3 az= 000° ±15° rate= 65 ±3 mm/yr [12]

Nazca Plate

  • Juan Fernández hotspot (16)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 084° ±3° rate= 80 ±20 mm/yr [12]
  • San Felix hotspot (36)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .3 az= 083° ±8° [12]
  • Easter hotspot (7)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 087° ±3° rate= 95 ±5 mm/yr [12]
  • Galápagos hotspot (10)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
      • Nazca Plate, w= 1 az= 096° ±5° rate= 55 ±8 mm/yr
      • Cocos Plate, w= .5 az= 045° ±6°
    • Possibly related to the Caribbean large igneous province (main events: 95–88 Ma).

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
  • Louisville hotspot (23)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 316° ±5° rate= 67 ±5 mm/yr [12]
    • Possibly related to the Ontong Java Plateau (125–120 Ma).
  • Foundation hotspot (57)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 292° ±3° rate= 80 ±6 mm/yr [12]
  • Macdonald hotspot (24)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 289° ±6° rate= 105 ±10 mm/yr [12]
  • North Austral/President Thiers (President Thiers Bank, 58)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= (1.0) azim= 293° ± 3° rate= 75 ±15 mm/yr [12]
  • Arago hotspot (Arago Seamount, 59)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 azim= 296° ±4° rate= 120 ±20 mm/yr [12]
  • Maria/Southern Cook hotspot (Îles Maria, 60)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 0.8 az= 300° ±4° [12]
  • Samoa hotspot (35)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 285°±5° rate= 95 ±20 mm/yr [12]
  • Crough hotspot (Crough Seamount, 61)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 284° ± 2° [12]
  • Pitcairn hotspot (31)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 293° ±3° rate= 90 ±15 mm/yr [12]
  • Society/Tahiti hotspot (38)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 295°±5° rate= 109 ±10 mm/yr [12]
  • Marquesas hotspot (26)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .5 az= 319° ±8° rate= 93 ±7 mm/yr [12]
  • Caroline hotspot (4)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 289° ±4° rate= 135 ±20 mm/yr [12]
  • Hawaii hotspot (12)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 304° ±3° rate= 92 ±3 mm/yr [12]
    • Possibly related to the Siberian Traps (251–250 Ma).[18]
  • Socorro/Revillagigedos hotspot (37)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. [12]
  • Guadalupe hotspot (11)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= .8 az= 292° ±5° rate= 80 ±10 mm/yr [12]
  • Cobb hotspot (5)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w= 1 az= 321° ±5° rate= 43 ±3 mm/yr [12]
  • Bowie/Pratt-Welker hotspot (3)
    • Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., w=.8 az= 306° ±4° rate= 40 ±20 mm/yr [12]

Former hotspots

See also

References

  1. 1.0 1.1 Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  2. "Do plumes exist?". Retrieved 2010-04-25.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  3. 3.0 3.1 3.2 Foulger, G.R. (2010). Plates vs. Plumes: A Geological Controversy. Wiley-Blackwell. ISBN 978-1-4051-6148-0.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  4. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  5. "Hotspots: Mantle thermal plumes". United States Geological Survey. 1999-05-05. Retrieved 2008-05-15.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  6. Wright, Laura (November 2000). "Earth's interior: Raising hot spots". Geotimes. American Geological Institute. Retrieved 2008-06-15.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  7. Holbek, Peter (November 1983). "Report on Preliminary Geology and Geochemistry of the Ilga Claim Group" (PDF). Retrieved 2008-06-15.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  8. "Axial Seamount". PMEL Earth-Ocean Interactions Program. NOAA. Retrieved 23 September 2014.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  9. "What the hell is Hawaii?". Retrieved 2011-01-07.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  10. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  11. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  12. 12.00 12.01 12.02 12.03 12.04 12.05 12.06 12.07 12.08 12.09 12.10 12.11 12.12 12.13 12.14 12.15 12.16 12.17 12.18 12.19 12.20 12.21 12.22 12.23 12.24 12.25 12.26 12.27 12.28 12.29 12.30 12.31 12.32 12.33 12.34 12.35 12.36 12.37 12.38 12.39 12.40 12.41 12.42 12.43 12.44 12.45 12.46 12.47 12.48 12.49 12.50 12.51 12.52 12.53 12.54 12.55 12.56 12.57 12.58 12.59 12.60 W. J. Morgan and J. P. Morgan. "Plate velocities in hotspot reference frame: electronic supplement" (PDF). Retrieved 2011-11-06.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  13. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  14. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  15. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  16. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  17. "Catalogue of Canadian volcanoes- Anahim volcanic belt". Natural Resources Canada. Geological Survey of Canada. Archived from the original on 2011-07-16. Retrieved 2008-06-14.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  18. B Steinberger, C Gaina, Plate-tectonic reconstructions predict part of the Hawaiian hotspot track to be preserved in the Bering Sea, Geology 35 (5), 407–410.

Further reading

  • "Plates vs. Plumes: A Geological Controversy". Wiley-Blackwell. October 2010.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  • Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  • "Towards A Better Understanding Of Hot Spot Volcanism". SienceDaily. 4 February 2008.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>

External links