Rarotonga hotspot

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The Rarotonga hotspot is in the Pacific Ocean, between the points 24 and 35 in this map. Hotspots.jpg
The Rarotonga hotspot is in the Pacific Ocean, between the points 24 and 35 in this map.

The Rarotonga hotspot is a volcanic hotspot in the southern Pacific Ocean. The hotspot is claimed to be responsible for the formation of Rarotonga and some volcanics of Aitutaki but an alternative explanation for these islands most recent volcanics has not be ruled out. [1] Recently alternatives to hotspot activity have been offered for several other intra-plate volcanoes that may have been associated with the Rarotonga hotspot hypothesis. [2] [3]

Contents

In addition to these volcanoes in the Cook Islands, the composition of volcanic rocks in Samoa and in the Lau Basin may have been influenced by the Rarotonga hotspot, and some atolls and seamounts in the Marshall Islands may have formed on the hotspot as well.

Geology

Oceanic plateaus and linear volcanic chains dot the floor of the Pacific Ocean. Their formation has been explained with mantle plumes which rise from the core-mantle boundary and spread out when they rise, forming a large "head" that causes intense volcanic activity once it hits the crust. This volcanism is responsible for the formation of the oceanic plateaus. Later, the remnant "tail" of the plume is still rising and induces the formation of volcano chains as the crust moves over the plume tail, thus forming the linear chains of hot spots. [4] As there is growing evidence that not all intra-plate volcanoes are generated by upwelling mantle plumes, not all may be formed from hot spots. [5]

A number of hotspots are or were active in the Pacific Ocean and some of these may be the product of mantle plumes. [4] Other hotspots such as Rarotonga appear to have been active only for short time periods; [6] many of these are located in French Polynesia where there is a superswell. Such hotspot volcanism may be the product of shallow processes. [7] Research has suggested that the Macdonald hotspot, and the Rurutu hotspot are long lived hotspots that were active as far back as the Cretaceous; [8] so they may be over 100 million years old and in such case the oldest still active hotspots in the Pacific. [9] The Rarotonga hotspot may also be very old [8] but the evidence is less convincing. [5] These hotspots together may have built the Cook-Austral Islands together, resulting in overlapping ages of the volcanoes. [5]

Seismic tomography has found slow velocity anomalies underneath Rarotonga, down to depths of about 100 kilometres (62 mi) [10] with more recent research indicating that they root at about 1,000 kilometres (620 mi) depth. [11] The anomaly lies at over 80 kilometres (50 mi) depth with no evidence of shallower anomalies, however. [12] The Rarotonga volcanic source and other regional hotspots appear to be anchored to a deep mantle structure that is one of the large low-shear-velocity provinces. [5]

Products

The Rarotonga hotspot is linked only to the formation of Rarotonga [6] and to volcanism on Aitutaki, [5] as potential volcanic structures between the Tonga Trench and Rarotonga that may have been formed by the same hotspot are poorly studied. [13] Rarotonga itself is young but there is little indication of volcanism either southeast or northwest from it [14] and no evidence of its current position. [15]

Other candidate volcanoes/structures formed by the Rarotonga hotspot or influenced by it are:

Related Research Articles

<span class="mw-page-title-main">Geography of Samoa</span>

The Samoan archipelago is a chain of 16 islands and numerous seamounts covering 3,123 km2 (1,206 sq mi) in the central South Pacific, south of the equator, about halfway between Hawaii and New Zealand, forming part of Polynesia and of the wider region of Oceania. The islands are Savaiʻi, Upolu, Tutuila, ’Uvea, Taʻū, Ofu, Olosega, Apolima, Manono, Nuʻutele, Niulakita, Nuʻulua, Namua, Fanuatapu, Rose Atoll, Nu'ulopa, as well as the submerged Vailuluʻu, Pasco banks, and Alexa Bank.

<span class="mw-page-title-main">Louisville Ridge</span> Chain of over 70 seamounts in the Southwest Pacific Ocean

The Louisville Ridge, often now referred to as the Louisville Seamount Chain, is an underwater chain of over 70 seamounts located in the Southwest portion of the Pacific Ocean. As one of the longest seamount chains on Earth it stretches some 4,300 km (2,700 mi) from the Pacific-Antarctic Ridge northwest to the Tonga-Kermadec Trench, where it subducts under the Indo-Australian Plate as part of the Pacific Plate. The chains formation is best explained by movement of the Pacific Plate over the Louisville hotspot although others had suggested by leakage of magma from the shallow mantle up through the Eltanin fracture zone, which it follows closely for some of its course.

<span class="mw-page-title-main">Louisville hotspot</span> 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.

<span class="mw-page-title-main">Marquesas hotspot</span> Volcanic hotspot in the Pacific Ocean

The Marquesas hotspot is a volcanic hotspot in the southern Pacific Ocean. It is responsible for the creation of the Marquesas Islands – a group of eight main islands and several smaller ones – and a few seamounts. The islands and seamounts formed between 5.5 and 0.4 million years ago and constitute the northernmost volcanic chain in French Polynesia.

<span class="mw-page-title-main">Samoa hotspot</span> Volcanic hotspot located in the south Pacific Ocean

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 Hawaiian Islands volcanic chain.

<span class="mw-page-title-main">Macdonald hotspot</span> Volcanic hotspot in the southern 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.

<span class="mw-page-title-main">Ocean island basalt</span> Volcanic rock

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 (divergent plate boundaries), and volcanic arc lavas, which erupt at subduction zones (convergent plate boundaries), 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.

<span class="mw-page-title-main">Arago hotspot</span> Hotspot in the Pacific Ocean

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

<span class="mw-page-title-main">Wōdejebato</span> Guyot in the Marshall Islands northwest of the smaller Pikinni Atoll

Wōdejebato is a Cretaceous guyot or tablemount in the northern Marshall Islands, Pacific Ocean. Wōdejebato is probably a shield volcano and is connected through a submarine ridge to the smaller Pikinni Atoll 74 kilometres (46 mi) southeast of the guyot; unlike Wōdejebato, Pikinni rises above sea level. The seamount rises for 4,420 metres (14,500 ft) to 1,335 metres (4,380 ft) depth and is formed by basaltic rocks. The name Wōdejebato refers to a sea god of Pikinni.

<span class="mw-page-title-main">Limalok</span> Cretaceous-Paleocene guyot in the Marshall Islands

Limalok is a Cretaceous-Paleocene guyot/tablemount in the southeastern Marshall Islands, one of a number of seamounts in the Pacific Ocean. It was probably formed by a volcanic hotspot in present-day French Polynesia. Limalok lies southeast of Mili Atoll and Knox Atoll, which rise above sea level, and is joined to each of them through a volcanic ridge. It is located at a depth of 1,255 metres (4,117 ft) and has a summit platform with an area of 636 square kilometres (246 sq mi).

<span class="mw-page-title-main">Lo-En</span> Albian–Campanian guyot in the Marshall Islands in the Pacific Ocean

Lo-En or Hess is an Albian–Campanian guyot in the Marshall Islands. One among a number of seamounts in the Pacific Ocean, it was probably formed by a hotspot in what is present-day French Polynesia. Lo-En lies southeast of Eniwetok which rises above sea level, and Lo-En is almost connected to it through a ridge.

<span class="mw-page-title-main">Ioah Guyot</span> Seamount in the Pacific Ocean

Ioah Guyot is a seamount in the Pacific Ocean, close to the Marshall Islands. Part of the Magellan Seamounts, it is a shield volcano that has erupted alkali basalt and hawaiite 87 million years ago, but may have continued erupting into the Miocene. During the Cretaceous, reefs developed on the guyot.

Allison Guyot is a tablemount (guyot) in the underwater Mid-Pacific Mountains of the Pacific Ocean. It is a trapezoidal flat mountain rising 1,500 metres above the seafloor to a depth of less than 1,500 m, with a summit platform 35 by 70 kilometres wide. The Mid-Pacific Mountains lie west of Hawaii and northeast of the Marshall Islands, but at the time of their formation were located in the Southern Hemisphere.

<span class="mw-page-title-main">Ujlān volcanic complex</span> Seamount in the Pacific Ocean

Ujlān volcanic complex is a group of seamounts in the Marshall Islands. The complex consists of the seamounts Ļajutōkwa, Ļalibjet, Likelep, Ļotāb and Ujlān which with a minimum depth of 1,250 metres (4,100 ft) is the shallowest part of the complex; sometimes Ujelang Atoll is also considered to be a part of the complex; Eniwetok atoll and Lo-En seamount form a cluster together with this volcanic complex.

Vlinder Guyot is a guyot in the Western Pacific Ocean. It rises to a depth of 1,500 metres (4,900 ft) and has a flat top covering an area of 40 by 50 kilometres. On top of this flat top lie some volcanic cones, one of which rises to a depth of 551 metres (1,808 ft) below sea level. Vlinder Guyot has noticeable rift zones, including an older and lower volcano to the northwest and Oma Vlinder seamount south.

<span class="mw-page-title-main">Vailuluʻu</span> Volcanic seamount in the Samoa Islands

Vailuluʻu is a volcanic seamount discovered in 1975. It rises from the sea floor to a depth of 593 m (1,946 ft) and is located between Taʻu and Rose islands at the eastern end of the Samoa hotspot chain. The basaltic seamount is considered to mark the current location of the Samoa hotspot. The summit of Vailuluʻu contains a 2 km wide, 400 m deep oval-shaped caldera. Two principal rift zones extend east and west from the summit, parallel to the trend of the Samoan hotspot. A third less prominent rift extends southeast of the summit.

Malumalu, is a volcanic seamount in American Samoa. Together with Savaii, Upolu and Tutuila, it forms a topographic structure close to the Tonga Trench, which lies about 100 kilometres (62 mi) south. Malumalu lies about 66 kilometres (41 mi) south of Ofu island and is also known as "Southeast Bank". It is about 25 kilometres (16 mi) wide at its base and is part of the Mula ridge, which extends to Tutuila.

<span class="mw-page-title-main">Hotspot highway</span>

The hotspot highway is a term coined in 2010 by Boston University professor Matthew G. Jackson to describe the area of the South Pacific where the postulated tracks of the Samoa, Macdonald, Rurutu, and Rarotonga hotspots all cross paths with one another. While the concept has stood the test of time the key overlapping hot spot tracks appear to be what are now termed the Macdonald hotspot and Arago hotspot which have 10 million years separation but crossed each others paths just south of Samoa. The volcanics of the highway concept are related to the tectonic implications of the breakup of the Ontong Java-Hikurangi-Manihiki large igneous province and of the Pacific large low-shear-velocity province. The tracks are still being redefined by further research and show for example gaps in the Arago hotspot chain with wrong assignment to it rather than the Samoan chain which means we have now little evidence for a cross over between the two.

References

  1. 1 2 Jackson et al. 2020, p. 11.
  2. 1 2 Peretyazhko, Igor S.; Savina, Elena A. (2022). "Cretaceous intraplate volcanism of Govorov Guyot and formation models of the Magellan seamounts, Pacific Ocean". International Geology Review. 65 (16): 2479–2505. doi:10.1080/00206814.2022.2145512. S2CID   254011792.
  3. 1 2 Wei, Xun; Shi, Xue-Fa; Xu, Yi-Gang; Castillo, Paterno R.; Zhang, Yan; Zhang, Le; Zhang, Hui (2022). "Mid-Cretaceous Wake seamounts in NW Pacific originate from secondary mantle plumes with Arago hotspot composition". Chemical Geology. 587: 120632. doi:10.1016/j.chemgeo.2021.120632. ISSN   0009-2541. S2CID   244121112.
  4. 1 2 Clouard & Bonneville 2001, p. 695.
  5. 1 2 3 4 5 Jackson et al. 2020, p. 2.
  6. 1 2 3 Clouard & Bonneville 2001, p. 697.
  7. ↑ Clouard & Bonneville 2001, p. 698.
  8. 1 2 3 4 5 Price et al. 2016, p. 1712.
  9. 1 2 Price et al. 2016, p. 1719.
  10. ↑ Isse, T.; Sugioka, H.; Ito, A.; Shiobara, H.; Reymond, D.; Suetsugu, D. (December 2015). "Upper mantle structures beneath the South Pacific superswell region using broadband data from ocean floor and islands". AGU Fall Meeting Abstracts. 2015: S23D–2771. Bibcode:2015AGUFM.S23D2771I.
  11. ↑ Obayashi, M.; Yoshimitsu, J.; Sugioka, H.; Ito, A.; Isse, T.; Shiobara, H.; Reymond, D.; Suetsugu, D. (28 November 2016). "Mantle plumes beneath the South Pacific superswell revealed by finite frequency tomography using regional seafloor and island data". Geophysical Research Letters. 43 (22): 6. Bibcode:2016GeoRL..4311628O. doi:10.1002/2016GL070793. S2CID   132379807.
  12. ↑ Isse, Takehi; Sugioka, Hiroko; Ito, Aki; Shiobara, Hajime; Reymond, Dominique; Suetsugu, Daisuke (29 February 2016). "Upper mantle structure beneath the Society hotspot and surrounding region using broadband data from ocean floor and islands". Earth, Planets and Space. 68 (1): 8. Bibcode:2016EP&S...68...33I. doi: 10.1186/s40623-016-0408-2 . ISSN   1880-5981.
  13. ↑ Price et al. 2016, p. 1713.
  14. ↑ Bergersen, D.D. (December 1995), "Cretaceous Hotspot Tracks through the Marshall Islands" (PDF), Proceedings of the Ocean Drilling Program, 144 Scientific Results, Proceedings of the Ocean Drilling Program, vol. 144, Ocean Drilling Program, p. 607, doi: 10.2973/odp.proc.sr.144.018.1995 , retrieved 23 September 2018
  15. ↑ Jackson et al. 2020, p. 3.
  16. ↑ Price et al. 2016, p. 1696.
  17. ↑ Jackson et al. 2010, p. 18.
  18. ↑ Jackson et al. 2010, p. 19.
  19. ↑ Koppers, Anthony A. P.; Russell, Jamie A.; Roberts, Jed; Jackson, Matthew G.; Konter, Jasper G.; Wright, Dawn J.; Staudigel, Hubert; Hart, Stanley R. (July 2011). "Age systematics of two young en echelon Samoan volcanic trails". Geochemistry, Geophysics, Geosystems. 12 (7): 5. Bibcode:2011GGG....12.7025K. doi:10.1029/2010GC003438. hdl: 1912/4769 . S2CID   54947952.
  20. ↑ Konter, J. G.; Jackson, M. G.; Koppers, A. A. (December 2011). "Tracking Long-lived Hotspots to Constrain Temporal Mantle Compositional Evolution". AGU Fall Meeting Abstracts. 2011: DI22A–04. Bibcode:2011AGUFMDI22A..04K.
  21. ↑ Price et al. 2016, p. 1695.
  22. ↑ Quinn, Terrence M.; Saller, Arthur H. (1 January 2004). Geology of Anewetak Atoll, Republic of the Marshall Islands. p. 638. doi:10.1016/S0070-4571(04)80043-8. ISBN   9780444516442. ISSN   0070-4571.{{cite book}}: |journal= ignored (help)
  23. 1 2 Konter, Jasper G.; Hanan, Barry B.; Blichert-Toft, Janne; Koppers, Anthony A.P.; Plank, Terry; Staudigel, Hubert (November 2008). "One hundred million years of mantle geochemical history suggest the retiring of mantle plumes is premature". Earth and Planetary Science Letters. 275 (3–4): 292–293. Bibcode:2008E&PSL.275..285K. doi:10.1016/j.epsl.2008.08.023. ISSN   0012-821X.
  24. ↑ Koppers, A.A.P.; Staudigel, H.Christie; D.M., Dieu; J.J., Pringle (December 1995), "Sr-Nd-Pb Isotope Geochemistry of Leg 144 West Pacific Guyots: Implications for the Geochemical Evolution of the "SOPITA" Mantle Anomaly" (PDF), Proceedings of the Ocean Drilling Program, 144 Scientific Results, Proceedings of the Ocean Drilling Program, vol. 144, Ocean Drilling Program, pp. 538–541, doi: 10.2973/odp.proc.sr.144.031.1995 , retrieved 23 September 2018
  25. 1 2 3 Larson et al. 1995, p. 939.
  26. ↑ Larson et al. 1995, p. 940.
  27. ↑ A >100 Ma Mantle Geochemical Record: Retiring Mantle Plumes may be Premature (December 2006). "A >100 Ma Mantle Geochemical Record: Retiring Mantle Plumes may be Premature". AGU Fall Meeting Abstracts. 2006: V34B–01. Bibcode:2006AGUFM.V34B..01K.
  28. ↑ Jackson et al. 2010, p. 17.
  29. ↑ Smith, Walter H. F.; Staudigel, Hubert; Watts, Anthony B.; Pringle, Malcolm S. (10 August 1989). "The Magellan seamounts: Early Cretaceous record of the South Pacific isotopic and thermal anomaly". Journal of Geophysical Research: Solid Earth. 94 (B8): 10520. Bibcode:1989JGR....9410501S. doi:10.1029/jb094ib08p10501. ISSN   0148-0227.

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