Tarava seamounts

The Tarava seamounts are a group of seamounts in the southern Pacific Ocean, southwest of the Society Islands. They are formed by five guyots and a number of cone-shaped seamounts. Of Eocene-Oligocene age, they may have formed under the influence of a hotspot.

Geography and geology

The Tarava seamounts are also known as the Savannah seamounts.[1] East of the Tarava seamounts lie the Va'a Tau Piti seamounts, which were sometimes considered part of the Tarava seamounts but are considered geologically separate owing to their different configuration (east-west rather than northwest-southeast),[2] which may reflect an origin close to the East Pacific Rise.[3]

Regional

Linear chains of volcanoes in the Pacific have been attributed to deep mantle plumes,[4] but a number of such chains appear to correspond to short lasting volcanism, such as processes triggered by tension in the Pacific Plate.[1]

The South Pacific Superswell is a large structure in the southern Pacific Ocean, where there are many volcanoes and the seafloor is unusually shallow. Asthenospheric processes may be responsible for its existence.[2]

Local

The Tarava seamounts consist of eighteen separate edifices[3] which extend across six longitudes and four latitudes[2] over a length of 700 kilometres (430 mi),[5] 200 kilometres (120 mi) away from the Society Islands.[6] Aside from five large guyots which reach depths of 580 metres (1,900 ft) below sea level, the Tarava seamounts consist of 4,000–4,500 metres (13,100–14,800 ft) high cones.[7] Among the named edifices are Arere (16°50′S 155°20′W), Fafa Piti (19°00′S 154°10′W), Honu (18°20′S 154°10′W), Orio'Mata (17°50′S 154°10′W), Otaha (18°40′S 152°50′W), Otu'eroa, Punu Taipu (19°15′S 151°30′W) and Ua'ao.[8]

The seamounts are considered to be of Eocene-Oligocene age.[9] Only two seamounts have been dated, both by potassium-argon dating: Fafa Piti has yielded ages of 43.5 ± 0.6 million years ago and Punu Taipu of 36.1 ± 0.5 million years ago.[2] Such ages are consistent with an age progressive volcanism caused by a hotspot, whose volcano-building activity was influenced by lithospheric anomalies,[10] considering that there is a discontinuity in the chain which would have formed about 43 million years ago[11] at the time of a major change in the motion of the Pacific Plate.[12] The hotspot in question may be the Foundation hotspot, the Pitcairn hotspot[13] or a now extinct third hotspot.[10] Alternatively, the formation of the Tuamotu Plateau may have induced tectonic stress that propagated towards the location of the future Tarava seamounts.[9]

Biology

Several new species have been discovered on the Tarava seamounts, such as the Lophiodes iwamotoi anglerfish,[14] the cone snail Profundiconus tarava,[15] the majoid crab Samadinia longispina[16] and pectinoid Parvamussium vesiculosum. Other species found there are Propeamussium watsoni together with five other pectinoids,[17] and tonnoidean gastropods.[18]

  • Parvamussium vesiculosum (holotype in MNHN, Paris)

References
  1. Clouard, Bonneville & Gillot 2003, p. 118.
  2. Clouard, Bonneville & Gillot 2003, p. 119.
  3. Clouard, Bonneville & Gillot 2003, p. 121.
  4. Clouard, Bonneville & Gillot 2003, p. 117.
  5. Beu, Bouchet & Jean 2012, p. 63.
  6. Sedov et al. 2008, p. 579.
  7. Clouard, Bonneville & Gillot 2003, p. 121,122.
  8. Clouard, Bonneville & Gillot 2003, p. 120.
  9. Sedov et al. 2008, p. 584.
  10. Clouard, Bonneville & Gillot 2003, p. 128.
  11. Clouard, Valérie; Bonneville, Alain (2005). Special Paper 388: Plates, plumes and paradigms. 388. pp. 71–90. doi:10.1130/0-8137-2388-4.71. ISBN 978-0-8137-2388-4.
  12. Fontaine, Fabrice R.; Barruol, Guilhem; Tommasi, Andréa; Bokelmann, Götz H. R. (2007-09-01). "Upper-mantle flow beneath French Polynesia from shear wave splitting". Geophysical Journal International. 170 (3): 1283. doi:10.1111/j.1365-246x.2007.03475.x. ISSN 0956-540X.
  13. Morgan, W. Jason; Morgan, Jason Phipps (2007). "Plate velocities in hotspot reference frame: electronic supplement" (PDF): 73–74. Cite journal requires |journal= (help)
  14. Ho, H.-C.; Séret, B.; Shao, K.-T. (2011-12-01). "Records of anglerfishes (Lophiiformes: Lophiidae) from the western South Pacific Ocean, with descriptions of two new species". Journal of Fish Biology. 79 (7): 1722–45. doi:10.1111/j.1095-8649.2011.03106.x. ISSN 1095-8649. PMID 22141884.
  15. Tenorio, Manuel J.; Castelin, Magalie (2016-01-29). "Genus Profundiconus Kuroda, 1956 (Gastropoda, Conoidea): Morphological and molecular studies, with the description of five new species from the Solomon Islands and New Caledonia". European Journal of Taxonomy. 0 (173): 15. doi:10.5852/ejt.2016.173. ISSN 2118-9773.
  16. NG, PETER K.L.; FORGES, BERTRAND RICHER DE (2013-10-07). "Samadinia longispina, a new genus and species of deep-sea spider crab from the western Pacific, and a new species of Rochinia A. Milne-Edwards, 1875, from Papua New Guinea (Crustacea: Brachyura: Majoidea: Epialtidae)". Zootaxa. 3718 (4): 357–66. doi:10.11646/zootaxa.3718.4.5. ISSN 1175-5334. PMID 26258232.
  17. Dijkstra, Henk H.; Maestrati, Philippe (2013-09-01). "Pectinoidea (Bivalvia: Propeamussiidae, Entoliidae and Pectinidae) from the Tarava Seamounts, Society Islands and the Tuamotu Archipelago (French Polynesia)". Zoosystema. 35 (3): 361–375. doi:10.5252/z2013n3a2. ISSN 1280-9551.
  18. Beu, Bouchet & Jean 2012, p. 108.

Sources
  • Beu, Alan; Bouchet, Philippe; Jean, Tröndlé (2012). "Tonnoidean gastropods of French Polynesia". Molluscan Research. 32: 61–120.
  • Clouard, Valérie; Bonneville, Alain; Gillot, Pierre-Yves (2003). "The Tarava Seamounts: a newly characterized hotspot chain on the South Pacific Superswell". Earth and Planetary Science Letters. 207 (1–4): 117–130. doi:10.1016/s0012-821x(02)01143-3.
  • Sedov, A. P.; Kazakevich, G. I.; Matveenkov, V. V.; Volokitina, L. P.; Luk’yanov, S. V.; Rashidov, V. A. (2008-08-01). "Mechanism of the formation of volcanic chains of French Polynesia". Oceanology. 48 (4): 578–587. doi:10.1134/S0001437008040127. ISSN 0001-4370.
  • The context of the TARASOC cruise, description of some species found on the Tarava seamounts.
  • Peñas A. & Rolán E. , 2017 Deep water Pyramidelloidea from the Central and south Pacific. The Tibe Chrysallidini. ECIMAT (Estación de Ciencias Mariñas de Toralla) - Universidade de Vigo, 412 pp
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