World Library  
Flag as Inappropriate
Email this Article

Hotspot (geology)

 

Hotspot (geology)

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

The places known as hotspots or hot spots in geology are [1] The other 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.

Contents

  • Background 1
    • Comparison with island arc volcanoes 1.1
  • Hotspot volcanic chains 2
    • Postulated hotspot volcano chains 2.1
    • List of volcanic regions postulated to be hotspots 2.2
      • Eurasian Plate 2.2.1
      • African Plate 2.2.2
      • Antarctic Plate 2.2.3
      • South American Plate 2.2.4
      • North American Plate 2.2.5
      • Indo-Australian Plate 2.2.6
      • Nazca Plate 2.2.7
      • Pacific Plate 2.2.8
  • Former hotspots 3
  • See also 4
  • References 5
  • Further reading 6
  • External links 7

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
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 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 selected hotspots. The numbers in the figure are related to the listed hotspots on the left.

Eurasian Plate

  • Eifel hotspot (8)
    • , w= 1 az= 082° ±8° rate= 12 ±2 mm/yr [12]
  • Iceland hotspot (14)
    • [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)
    • [12]
      • Eurasian Plate, w= .5 az= 110° ±12°
      • North American Plate, w= .3 az= 280° ±15°
  • Jan Mayen hotspot (15)
    • [12]
  • Hainan hotspot
    • , az= 000° ±15° [12]

African Plate

Antarctic Plate

South American Plate

North American Plate

Indo-Australian Plate

  • Lord Howe hotspot (22)
    • , w= .8 az= 351° ±10° [12]
  • Tasmanid hotspot (Gascoyne Seamount, 39)
    • , w= .8 az= 007° ±5° rate= 63 ±5 mm/yr [12]
  • East Australia hotspot (30)
    • , w= .3 az= 000° ±15° rate= 65 ±3 mm/yr [12]

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
  • Louisville hotspot (23)
    • , w= 1 az= 316° ±5° rate= 67 ±5 mm/yr [12]
    • Possibly related to the Ontong Java Plateau (125-120 Ma).
  • Foundation hotspot
    • , w= 1 az= 292° ±3° rate= 80 ±6 mm/yr [12]
  • Macdonald hotspot (24)
    • , w= 1 az= 289° ±6° rate= 105 ±10 mm/yr [12]
  • North Austral/President Thiers (President Thiers Bank)
    • , w= (1.0) azim= 293° ± 3° rate= 75 ±15 mm/yr [12]
  • Arago hotspot (Arago Seamount)
    • , w= 1 azim= 296° ±4° rate= 120 ±20 mm/yr [12]
  • Maria/Southern Cook hotspot (Îles Maria)
    • , w= 0.8 az= 300° ±4° [12]
  • Samoa hotspot (35)
    • , w= .8 az= 285°±5° rate= 95 ±20 mm/yr [12]
  • Crough hotspot (Crough Seamount)
    • , w= .8 az= 284° ± 2° [12]
  • Pitcairn hotspot (31)
    • , w= 1 az= 293° ±3° rate= 90 ±15 mm/yr [12]
  • Society/Tahiti hotspot (38)
    • , w= .8 az= 295°±5° rate= 109 ±10 mm/yr [12]
  • Marquesas hotspot (26)
    • , w= .5 az= 319° ±8° rate= 93 ±7 mm/yr [12]
  • Caroline hotspot (4)
    • , w= 1 az= 289° ±4° rate= 135 ±20 mm/yr [12]
  • Hawaii hotspot (12)
    • , 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)
    • [12]
  • Guadalupe hotspot (11)
    • , w= .8 az= 292° ±5° rate= 80 ±10 mm/yr [12]
  • Cobb hotspot (5)
    • , w= 1 az= 321° ±5° rate= 43 ±3 mm/yr [12]
  • Bowie/Pratt-Welker hotspot (3)
    • , w=.8 az= 306° ±4° rate= 40 ±20 mm/yr [12]

Former hotspots

See also

References

  1. ^ a b W. J. Morgan (5 March 1971). "Convection Plumes in the Lower Mantle". Nature 230 (5288): 42–43.  
  2. ^ "Do plumes exist?". Retrieved 2010-04-25. 
  3. ^ a b c Foulger, G.R. (2010). Plates vs. Plumes: A Geological Controversy. Wiley-Blackwell.  
  4. ^ Wilson, J. Tuzo (1963). "A possible origin of the Hawaiian Islands". Canadian Journal of Physics 41 (6): 863–870.  
  5. ^ "Hotspots: Mantle thermal plumes".  
  6. ^ Wright, Laura (November 2000). "Earth's interior: Raising hot spots". Geotimes.  
  7. ^ Holbek, Peter (November 1983). "Report on Preliminary Geology and Geochemistry of the Ilga Claim Group" (PDF). Retrieved 2008-06-15. 
  8. ^ "Axial Seamount". PMEL Earth-Ocean Interactions Program. NOAA. Retrieved 23 September 2014. 
  9. ^ "What the hell is Hawaii?". Retrieved 2011-01-07. 
  10. ^ Courtillot, V.; Davaillie, A.; Besse, J.; Stock, J. (2003). "Three distinct types of hotspots in the Earth's mantle". Earth Sci. Planet. Lett. 205 (3–4): 295–308.  
  11. ^ E. V. Verzhbitsky (2003). "Geothermal regime and genesis of the Ninety-East and Chagos-Laccadive ridges". Journal of Geodynamics 35 (3): 289.  
  12. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi W. J. Morgan and J. P. Morgan. "Plate velocities in hotspot reference frame: electronic supplement". Retrieved 2011-11-06. 
  13. ^ 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.  
  14. ^ O'Neill, C.; Müller, R. D.; Steinberger, B. (2003). "Revised Indian plate rotations based on the motion of Indian Ocean hotspots". Earth and Planetary Science Letters 215: 151–168.  
  15. ^ 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.  
  16. ^ 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". Journal of Volcanology and Geothermal Research 188 (1–3): 26–56.  
  17. ^ "Catalogue of Canadian volcanoes- Anahim volcanic belt". Natural Resources Canada.  
  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. 
  • Boschi, L.; Becker, T.W.; Steinberger, B. (2007). "Mantle plumes: Dynamic models and seismic images". Geochemistry Geophysics Geosystems 8 (Q10006): Q10006.  
  • Clouard, Valérie; Gerbault, Muriel (2007). "Break-up spots: Could the Pacific open as a consequence of plate kinematics?". Earth and Planetary Science Letters 265: 195.  
  • "Towards A Better Understanding Of Hot Spot Volcanism". SienceDaily. 4 February 2008. 

External links

  • Formation of Hotspots
  • Raising Hot Spots
  • Large Igneous Provinces (LIPs)
  • Moving hotspots - Evidence from paleomagnetism and modelingMaria Antretter, PhD Thesis (2001):
  • Do Plumes Exist?
  • Hotspots on Map
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.