Darwin Guyot

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Darwin Guyot
Darwin Guyot
Summit depth1,266 metres (4,154 ft)
Location
Coordinates 22°03′36″N171°38′06″E / 22.0600°N 171.6350°E / 22.0600; 171.6350 [1]
Geology
Type Guyot
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Darwin Guyot
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Location in the Pacific Ocean

Darwin Guyot is a volcanic underwater mountain top, or guyot, in the Mid-Pacific Mountains between the Marshall Islands and Hawaii. Named after Charles Darwin, it rose above sea level more than 118 million years ago during the early Cretaceous period to become an atoll, developed rudist reefs, and then drowned, perhaps as a consequence of sea level rise. The flat top of Darwin Guyot now rests 1,266 metres (4,154 ft) below sea level.

Contents

Name and research history

The name Darwin Guyot was proposed in 1970 and accepted by the Board on Geographic Names shortly thereafter; [2] it refers to Charles Darwin [3] and the fact that unlike other guyots in the region it resembles an atoll. On the second voyage of the Beagle, in the 1830s, Darwin had theorised that as land rose, oceanic islands sank, and coral reefs round them grew to form atolls. It was dredged and surveyed in 1968 by the ship R/V Alexander Agassiz; [2] previously in the same year the R/V Argo had crossed over the guyot. [4]

Geography and geomorphology

Darwin Guyot lies between Hawaii and the Marshall Islands, within the submerged Mid-Pacific Mountains. [2] Agassiz Guyot and Allison Guyot lie to its east-southeast. [5] These underwater mountains as well as abovewater atolls concentrate in the Western Pacific Ocean. [6] Darwin Guyot may be part of a hotspot trail. [1]

It lies at a depth of 1,285 metres (4,216 ft) [1] -1,266 metres (4,154 ft) and has an elongated, northwest-southeast trending shape; [5] an older survey had indicated a more rounded shape. [4] The summit features an elevated rim [6] which is probably a former fringing reef [7] surrounding an internal lagoon [8] like a bucket; this resembles the structure of present-day atolls [9] and it is the first guyot in the Pacific Ocean that was discovered to have this atoll-like structure. [6] This 18 metres (59 ft) deep [10] depression may be a volcanic crater but the more likely explanation is that the rim was formed by living organisms. [8] The whole summit plateau covers an area of 5 by 8 kilometres (3.1 mi × 5.0 mi) [11] and the total volume of the seamount is about 2,287 cubic kilometres (549 cu mi). [1]

Dredging has yielded no volcanic material, but chert, limestones (in the form of grainstone, packstone and wackestone [12] ) encrusted with ferromanganese as well as living animals were pulled up. [13] The seafloor underneath the guyot lies at a depth of 5,250 metres (17,220 ft) [1] and has an age of 157 million years. [14]

Geologic history

A present-day atoll in Tokelau Atafutrim.jpg
A present-day atoll in Tokelau

Darwin Guyot is considered to be of Cretaceous origin; [15] its age exceeds 118 million years [16] and its history might go back to the Cretaceous subdivision "Barremian". [14] It probably started as an emergent volcanic island that was then levelled by erosion. On the resulting platform molluscs such as rudists became established. They formed the rim as well as the irregular mounds on the summit plateau. [8] Darwin Guyot is considered to be the oldest known atoll. [17]

Dredging has produced fossils of animals, chiefly gastropods and rudists. Fish remnants, [18] coral debris, [12] and foraminifera of Albian to Turonian age have also been found. [19] Rudists formed organic frameworks resembling coral reefs on Darwin Guyot and elsewhere in Tethyan seas during the Albian-Aptian eras. [13] Other environments such as seagrass flats and lagoons have been inferred from the fossils. [20]

The resulting carbonate platform drowned about 100 million years ago, [21] or at the time of the Cenomanian-Turonian boundary event (94 million years ago). [16] It is not clear why the reefs on Darwin Guyot eventually ceased growing; one possibility is that sea levels rose quickly enough to overwhelm the ability of the reef forming organisms to keep up. [22] Unlike other guyots, Darwin Guyot did not accumulate a substantial cap of pelagic sediments after drowning; perhaps it is too small to accumulate a substantial sediment layer [23] or sedimentation took place but ocean currents swept the sediment off the platform. [21] Presently, fish such as snubnosed eels occur at Darwin Guyot. [24]

Related Research Articles

<span class="mw-page-title-main">Atoll</span> Ring-shaped coral reef

An atoll is a ring-shaped island, including a coral rim that encircles a lagoon. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical parts of the oceans and seas where corals can develop. Most of the approximately 440 atolls in the world are in the Pacific Ocean.

<span class="mw-page-title-main">Anton Dohrn Seamount</span> Guyot in the Rockall Trough in the northeast Atlantic

The Anton Dohrn Seamount is a guyot in the Rockall Trough in the northeast Atlantic. It is 1.8 kilometres (1.1 mi) high and is topped with pinnacles, one of which reaches a depth of 530 metres (1,740 ft). Away from the flat top upon which the pinnacles rest, the slopes fall off steeply into the Rockall Trough and a moat in the sediment that surrounds the seamount.

<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.

The Mid-Pacific Mountains (MPM) is a large oceanic plateau located in the central North Pacific Ocean or south of the Hawaiian–Emperor seamount chain. Of volcanic origin and Mesozoic in age, it is located on the oldest part of the Pacific Plate and rises up to 2 km (1.2 mi) above the surrounding ocean floor and is covered with several layers of thick sedimentary sequences that differ from those of other plateaux in the North Pacific. About 50 seamounts are distributed over the MPM. Some of the highest points in the range are above sea level which include Wake Island and Marcus Island.

<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.

Alexa Bank is a seamount in Samoa, northwest of Rotuma. The seamount reaches a depth of 18–21 metres (59–69 ft) below sea level and has the appearance of an atoll with a flat top and steep slopes. Some active coral growth takes place at its top, but if it ever was an active atoll it has now drowned. It was probably formed by the Samoa hotspot 24 million years ago, although older volcanism about 40 million years ago has also been identified.

MIT Guyot is a guyot in the Pacific Ocean that rises to a depth of 1,323 metres (4,341 ft). It has a 20-kilometre-long (12 mi) summit platform and formed during the Cretaceous in the region of present-day French Polynesia through volcanic eruptions.

Takuyo-Daisan is a guyot in the Western Pacific Ocean off Japan. It is 1,409 metres (4,623 ft) deep and has a square-shaped flat top surrounded by a perimeter ridge. Several other seamounts lie nearby.

<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.

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

Pako Guyot is a guyot in the Pacific Ocean.

<span class="mw-page-title-main">Resolution Guyot</span> Underwater tablemount in the Pacific Ocean

Resolution Guyot is a guyot (tablemount) in the underwater Mid-Pacific Mountains in the Pacific Ocean. It is a circular flat mountain, rising 500 metres (1,600 ft) above the seafloor to a depth of about 1,320 metres (4,330 ft), with a 35-kilometre-wide (22 mi) summit platform. The Mid-Pacific Mountains lie west of Hawaii and northeast of the Marshall Islands, but at the time of its formation, the guyot was located in the Southern Hemisphere.

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

Horizon Guyot is a presumably Cretaceous guyot (tablemount) in the Mid-Pacific Mountains, Pacific Ocean. It is an elongated ridge, over 300 kilometres (190 mi) long and 4.3 kilometres (2.7 mi) high, that stretches in a northeast-southwest direction and has two flat tops; it rises to a minimum depth of 1,443 metres (4,730 ft). The Mid-Pacific Mountains lie west of Hawaii and northeast of the Line Islands.

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 (4,900 ft) above the seafloor to a depth of less than 1,500 metres (4,900 ft), 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.

Takuyo-Daini is a seamount in the Pacific Ocean.

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.

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

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References

  1. 1 2 3 4 5 "Darwin Guyot". Seamount Catalog. Retrieved 1 December 2018.
  2. 1 2 3 Ladd, Newman & Sohl 1974, p. 513.
  3. ↑ Stoppa, Francesco; Veraldi, Roberto (2010). Darwin tra scienza, storia e società: 150o anniversario della pubblicazione di Origine delle specie (in Italian). GAIA srl – Edizioni Univ. Romane. p. 179. ISBN   9788860221568.
  4. 1 2 Ladd, Newman & Sohl 1974, p. 515.
  5. 1 2 Ladd, Newman & Sohl 1974, p. 514.
  6. 1 2 3 Ladd, Newman & Sohl 1974, p. 518.
  7. ↑ Greene, H. Gary; Dalrymple, G. Brent; Clague, David A. (1978). "Evidence for northward movement: of the Emperor Seamounts". Geology. 6 (2): 72. Bibcode:1978Geo.....6...70G. doi:10.1130/0091-7613(1978)6<70:EFNMOT>2.0.CO;2. ISSN   0091-7613.
  8. 1 2 3 Ladd, Newman & Sohl 1974, p. 520.
  9. ↑ Schlager, Wolfgang (1981). "The paradox of drowned reefs and carbonate platforms". Geological Society of America Bulletin. 92 (4): 201. Bibcode:1981GSAB...92..197S. doi:10.1130/0016-7606(1981)92<197:TPODRA>2.0.CO;2. ISSN   0016-7606.
  10. ↑ Montaggioni, Lucien F.; Braithwaite, Colin J. R. (2009). Quaternary Coral Reef Systems: History, development processes and controlling factors. Elsevier. p. 262. ISBN   9780080932767.
  11. ↑ Grötsch, Jürgen; Flügel, Erik (December 1992). "Facies of sunken early cretaceous atoll reefs and their capping Late Albian drowning succession (Northwestern Pacific)". Facies. 27 (1): 156. Bibcode:1992Faci...27..153G. doi:10.1007/bf02536809. ISSN   0172-9179. S2CID   128544669.
  12. 1 2 van Waasbergen 1995, p. 473.
  13. 1 2 Ladd, Newman & Sohl 1974, p. 516.
  14. 1 2 Masalu, D. C. P. (1 January 2008). "Delineating the Jurassic to mid cretaceous part of the Pacific apparent polar wander path". Tanzania Journal of Science. 34 (1): 71. doi: 10.4314/tjs.v34i1.44290 . ISSN   2507-7961.
  15. ↑ Haggerty, Janet A.; Schlanger, Seymour O.; Silva, Isabella Premoli (1982). "Late Cretaceous and Eocene volcanism in the southern Line Islands and implications for hotspot theory". Geology. 10 (8): 436. Bibcode:1982Geo....10..433H. doi:10.1130/0091-7613(1982)10<433:LCAEVI>2.0.CO;2. ISSN   0091-7613.
  16. 1 2 Rougerie, Francis; Fagerstrom, J.A. (December 1994). "Cretaceous history of Pacific Basin guyot reefs: a reappraisal based on geothermal endo-upwelling". Palaeogeography, Palaeoclimatology, Palaeoecology. 112 (3–4): 241. Bibcode:1994PPP...112..239R. doi:10.1016/0031-0182(94)90075-2. ISSN   0031-0182.
  17. ↑ Scoffin, T. P.; Dixon, J. E. (August 1983). "The distribution and structure of coral reefs: one hundred years since Darwin". Biological Journal of the Linnean Society. 20 (1): 22. doi:10.1111/j.1095-8312.1983.tb01587.x. ISSN   0024-4066.
  18. ↑ Sohl, Norman F. (1987). "Cretaceous Gastropods: Contrasts between Tethys and the Temperate Provinces". Journal of Paleontology. 61 (6): 1085–1111. Bibcode:1987JPal...61.1085S. doi:10.1017/S0022336000029486. JSTOR   1305198. S2CID   130218933.
  19. ↑ van Waasbergen 1995, p. 471.
  20. ↑ Ladd, Newman & Sohl 1974, p. 517.
  21. 1 2 Schlager, Wolfgang (1999). Type 3 Sequence Boundaries (Report). Society for Sedimentary Geology. p. 43.
  22. ↑ Ladd, Newman & Sohl 1974, pp. 520–521.
  23. ↑ Ladd, Newman & Sohl 1974, p. 522.
  24. ↑ Yeh, John; Drazen, Jeffrey C. (February 2009). "Depth zonation and bathymetric trends of deep-sea megafaunal scavengers of the Hawaiian Islands". Deep Sea Research Part I: Oceanographic Research Papers. 56 (2): 261. Bibcode:2009DSRI...56..251Y. doi:10.1016/j.dsr.2008.08.005. ISSN   0967-0637. S2CID   85031196.

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