Adams Seamount (also known as Forty Mile Reef[2]) is a submarine volcano above the Pitcairn hotspot in the central Pacific Ocean about 100 kilometres (62 mi) southwest of Pitcairn Island.
| Adams Seamount, Forty Mile Reef | |
|---|---|
 | |
| Summit depth | 39 m (128 ft)[1] |
| Height | 3,500 m (11,500 ft) |
| Location | |
| Location | Pacific Ocean, SW of Pitcairn Island |
| Coordinates | 25°22′S 129°16′W / 25.367°S 129.267°W |
| Geology | |
| Last eruption | 50 BCE ± 1000 years |
Geography and geomorphology
editAdams is part of a field of about 90 seamounts 90 kilometres (56 mi) east-southeast away from Pitcairn Island, and the largest of these.[3] Adams lies southeast of another large seamount, Bounty Seamount.[4] Most of these seamounts except for Adams and Bounty are less than 0.5 kilometres (0.31 mi) high.[5] They were discovered in 1989 by the RV Sonne research ship.[6]
It is a conical[7] seamount rising 3,500 metres (11,483 ft) from the sea floor to about 39 metres (128 ft)[1] or 59–75 metres (194–246 ft) below the surface of the ocean.[2] The total volume of the seamount, whose base has a diameter of about 30 kilometres (19 mi), is about 858 cubic kilometres (206 cu mi).[8] Adams has two summits,[9] and coral and sand derived from coral has been found on Adams.[5] Given its height, during the last glacial maximum Adams was likely an island.[10]
Its slopes are covered by recent lava flows, volcanic debris and hyaloclastite.[9] Lava flows feature aa lava characteristics and lava tubes, while deeper parts of the edifice are covered with lapilli and scoria.[11] Parasitic vents form cones and mounds on its flanks.[12]
Geology
editAdams and the other seamounts were created by the Pitcairn hotspot, and these seamounts are its present-day location.[3] This hotspot is one among several hotspots in the Pacific Ocean, along with the Austral hotspot, Hawaii hotspot, Louisville hotspot, Samoa hotspot and Society hotspot.[6] The seamounts rise from a 30 million years old crust.[13]
Alkali basalt, trachyte[9] and tholeiite have been dredged from Adams Seamount.[14]
Eruption history
editThe fresh appearance of samples and the lack of sedimentation indicates that Adams Seamount is a recently active seamount.[3] Potassium-argon dating of rocks dredged from Adams Seamount has yielded Holocene ages, including one age of 3,000 ± 1,000 years before present.[13] Other ages range from 4,000 - 7,000 years before present.[15] Unlike Bounty, Adams Seamount displays no active hydrothermal system.[5]
Biology
editAdams seamount features a coral reef, one of the deepest tropical reefs in the world. It is mainly formed by Pocillopora sp. and Porites deformis corals, but also many reef fish and sharks; it is used as a fishing ground by Pitcairn.[2] Adams seamount is part of the Pitcairn Islands Marine Reserve.[16]
References
edit- ^ a b "Adams Seamount". Global Volcanism Program. Smithsonian Institution. Retrieved 2017-02-28.
- ^ a b c Irving, Robert A.; Dawson, Terence P.; Christian, Michele (2019-01-01), Sheppard, Charles (ed.), "Chapter 34 - The Pitcairn Islands", World Seas: an Environmental Evaluation (Second Edition), Academic Press, p. 751, ISBN 9780081008539, retrieved 2019-07-27
- ^ a b c Garapić et al. 2015, p. 2.
- ^ Thießen et al. 2004, p. 418.
- ^ a b c Thießen et al. 2004, p. 409.
- ^ a b Hekinian et al. 2003, p. 220.
- ^ Binard, Hékinian & Stoffers 1992, p. 261.
- ^ Hekinian et al. 2003, p. 228.
- ^ a b c Binard, Hékinian & Stoffers 1992, p. 257.
- ^ Neall, Vincent E.; Trewick, Steven A. (27 October 2008). "The age and origin of the Pacific islands: a geological overview". Philosophical Transactions of the Royal Society of London B: Biological Sciences. 363 (1508): 3293–3308. doi:10.1098/rstb.2008.0119. ISSN 0962-8436. PMC 2607379. PMID 18768382.
- ^ Binard, Hékinian & Stoffers 1992, p. 259.
- ^ Hekinian et al. 2003, p. 229.
- ^ a b Guillou, Garcia & Turpin 1997, p. 244.
- ^ Garapić et al. 2015, p. 9.
- ^ Guillou, Garcia & Turpin 1997, p. 247.
- ^ Albert, Donald Patrick (3 July 2018). "Did or Could Seabirds "Halo" Pitcairn Island for Fletcher Christian?". Terrae Incognitae. 50 (2): 114. doi:10.1080/00822884.2018.1498638. ISSN 0082-2884. S2CID 134051156.
Sources
edit- Binard, Nicolas; Hékinian, Roger; Stoffers, Peter (June 1992). "Morphostructural study and type of volcanism of submarine volcanoes over the Pitcairn hot spot in the South Pacific". Tectonophysics. 206 (3–4): 245–264. Bibcode:1992Tectp.206..245B. doi:10.1016/0040-1951(92)90379-K. ISSN 0040-1951.
- Garapić, G.; Jackson, M.G.; Hauri, E.H.; Hart, S.R.; Farley, K.A.; Blusztajn, J.S.; Woodhead, J.D. (July 2015). "A radiogenic isotopic (He-Sr-Nd-Pb-Os) study of lavas from the Pitcairn hotspot: Implications for the origin of EM-1 (enriched mantle 1)". Lithos. 228–229: 1–11. Bibcode:2015Litho.228....1G. doi:10.1016/j.lithos.2015.04.010. ISSN 0024-4937.
- Guillou, Hervé; Garcia, Michael O.; Turpin, Laurent (September 1997). "Unspiked K-Ar dating of young volcanic rocks from Loihi and Pitcairn hot spot seamounts". Journal of Volcanology and Geothermal Research. 78 (3–4): 239–249. Bibcode:1997JVGR...78..239G. doi:10.1016/S0377-0273(97)00012-7. ISSN 0377-0273.
- Hekinian, R; Cheminée, J.L; Dubois, J; Stoffers, P; Scott, S; Guivel, C; Garbe-Schönberg, D; Devey, C; Bourdon, B; Lackschewitz, K; McMurtry, G; Le Drezen, E (March 2003). "The Pitcairn hotspot in the South Pacific: distribution and composition of submarine volcanic sequences" (PDF). Journal of Volcanology and Geothermal Research. 121 (3–4): 219–245. Bibcode:2003JVGR..121..219H. doi:10.1016/S0377-0273(02)00427-4. ISSN 0377-0273.
- Thießen, O.; Schmidt, M.; Botz, R.; Schmitt, M.; Stoffers, P. (2004). "Methane Venting into the Water Column Above the Pitcairn and the Society — Austral Seamounts, South Pacific". Oceanic Hotspots. pp. 407–429. doi:10.1007/978-3-642-18782-7_14. ISBN 978-3-642-62290-8.