Plateau ( /ˈkɜːrɡələn/, /kərˈɡeɪlən/) is
an oceanic plateau and a large igneous province (LIP) in the southern
Indian Ocean. It is also a microcontinent and submerged continent.
It is about 3,000 km (1,900 mi) to the southwest of
Australia and is nearly three times the size of Japan. The plateau
extends for more than 2,200 km (1,400 mi) in a
northwest–southeast direction and lies in deep water.
The plateau was produced by the Kerguelen hotspot, starting with or
following the breakup of
Gondwana about 130 million years ago. A
small portion of the plateau breaks sea level, forming the Kerguelen
Islands (a French territory) plus the Heard and McDonald Islands (an
Australian territory). Intermittent volcanism continues on the Heard
and McDonald Islands.
1 Geographical extent
2 Geological history
2.3 Cenozoic volcanism
5 See also
7 External links
Symmetrically located across the
Indian Ocean ridge and due west of
Australia is the
Broken Ridge underwater volcanic plateau, which at
one time was contiguous with the Kerguelen
Plateau prior to rifting by
the mid-ocean ridge.
To the north of
Broken Ridge lies the linear
Ninety East Ridge
Ninety East Ridge which
continues almost due north into the
Bay of Bengal
Bay of Bengal and is considered to
be a hotspot track.
One of the largest igneous provinces (LIPs) in the world, the
Plateau covers an area of 1,250,000 km2
(480,000 sq mi) and rises 2,000 m (6,600 ft) above
the surrounding oceanic basins.
Located on the Antarctic Plate, the Kerguelen
Plateau is separated
Australia by the
Southeast Indian Ridge
Southeast Indian Ridge (SEIR) and from
Southwest Indian Ridge
Southwest Indian Ridge (SWIR). These two ridges meet at the
Rodriguez Triple Junction. It is separated from
Antarctica by Princess
Elizabeth Trough and the Cooperation Sea. The eastern margin north of
the William Ridge is steep and formed during the breakup between the
Plateau and the Broken Ridge. The southern part of the
margin is separated from the Australian–Antarctic Basin by the deep
From the initial opening of the
Indian Ocean until present, the
Kerguelen hotspot has produced several now widely dispersed
large-scale structures. The Southern Kerguelen
Plateau (SKP) formed
119–110 Ma; the Elan Bank 108–107 Ma, named by Dennis E.
Hayes of Lamont Doherty Easth Observatory ; the Central Kerguelen
Plateau (CKP) 101–100 Ma; the
Broken Ridge (connected to CKP
before the Eocene breakup) formed 95–94 Ma; the Skiff Bank
(east of Kerguelen archipelago) 69–68 Ma; Northern Kerguelen
Plateau (NKP) 35–34 Ma;
Ninety East Ridge
Ninety East Ridge formed
82–38 Ma north to south; the Bunbury Basalt (western Australia)
formed 132–123 Ma; the
Rajmahal Traps in northeast India
118–117 Ma; and finally lamprophyres in India and Antarctica
The oldest volcanism that can be attributed to the Kerguelen plume are
the Bunbury Basalt in southwestern
Australia (132–123 Ma) and
Rajmahal Traps in eastern India (118 Ma). The formation of
the oldest portion of the Kerguelen LIP and these continental basalts
are linked to the opening of the eastern Indian Ocean. The Bunbury
Basalt is not of flood basalt dimension which suggest that the mantle
underlying the newly formed
Kerguelen hotspot was neither
significantly hot, wet, or voluminous. In contrast, the magmatism that
produced the Australia–India breakup 136–158 Ma created the
Wallaby Plateau, but no known hotspot has been linked to this
The output from the
Kerguelen hotspot peaked 120–95 Ma,
12–70 Ma after the India–
Antarctica breakup. No ridges or
hotspot tracks such as Walvis–Rio Grande, Chagos–Laccadive,
Greenland–Scotland have been found in the Princess Elizabeth Trough
between SKP and
Antarctica or along India's conjugate eastern
continental margin. The relation between the
Kerguelen hotspot and
these continental breakup and volcanic margins is instead similar to
that between the
Réunion hotspot and the
Deccan Traps and the breakup
between western India and the Seychelles.
The peak output of the
Kerguelen hotspot coincides with one or several
microcontinent formations, such as the Elan Bank. Since the Indian
Ocean began to open about 130 Ma, the
Kerguelen hotspot has moved
3–10° southward and, consequently, the spreading ridge between
Antarctica has jumped northward one or several times. Parts
of the Kerguelen Plateau, the Elan Bank and the SKP, were originally
attached to India and are composed of continental lithosphere. One or
several ridge jumps transformed the Elan Bank into a microcontinent
and dispersed continental fragments in the SKP, and these structures
were eventually left behind as India moved northward. The ridge
jump that made the Elan Bank a microcontinent occurred after
124 Ma. The development of the Southern Kerguelen Plateau
(SKP) 118–119 Ma contributed to the oceanic anoxic event 1.
Around 83.5 Ma sea floor spreading between India and Antarctica
was asymmetric in the Kerguelen
Plateau region with two-thirds of the
sea floor created being added to the Antarctic Plate. A ridge jump
eventually resulted in parts of the Kerguelen
transferred from the Indian to the Antarctic Plate.
Kerguelen hotspot produced the 5,000 km (3,100 mi) long
Ninety East Ridge
Ninety East Ridge 82–38 Ma, and geochemical evidence suggests
that this occurred at or near a spreading ridge. The lack of a
conjugate structure on the Antarctic Plate, however, makes it unlikely
that the hotspot was located at a spreading ridge during this long
period. As the
Antarctic Plate then moved over the Kerguelen hotspot
the NKP formed over relatively old oceanic crust. Flood basalts in the
Kerguelen archipelago formed 30–24 Ma and less voluminous and
more recent volcanism occurred until 1 Ma. During the last
21 Ma volcanic structures have formed on the CKP, including Heard
Island, and both Heard and McDonald Islands have had recent
65 Ma, the CKP–
Broken Ridge LIP was located near the Kerguelen
plume and the plate boundaries of the Indian Ocean. The LIP was the
product of 25 Ma of relatively high magmatic activity followed by
a 40 Ma period of lower activity.
Schlich et al. 1971 described tilted basement blocks near the
Kerguelen archipelago and was the first to identify the Kerguelen
Plateau as of continental origin, in contrast to other LIPs.
The presence of soil layers in the basalt with included charcoal and
conglomerate fragments of gneiss indicate that much of the plateau was
above sea level as what is termed a microcontinent for three periods
between 100 million years ago and 20 million years ago.
(The charcoal was made by wildfires started by lightning or lava
flows.) Large parts of the now submarine Southern (SKP) and Central
Kerguelen Plateaus (CKP) were subaerial during the formation of the
LIP. The SKP probably formed an island of 500,000 km2
(190,000 sq mi) with major peaks reaching
1,000–2,000 m (3,300–6,600 ft) above sea level.
The Kerguelen microcontinent may have been covered by dense conifer
forest in the mid-Cretaceous.
It finally sank 20 million years ago and is now
1,000–2,000 m (3,300–6,600 ft) below sea level.
During the austral summer there is a high density of migratory whales
such as sperm and baleen whales, such as minke, and humpback, along
the southern end of the Kerguelen
Plateau and the northern part of the
adjacent Princess Elizabeth Trough. These whales choose this location
for foraging because the Southern Front of the Antarctic Circumpolar
Current is steered off by the plateau — resulting in a poleward
extent for the Southern Front only found near the Kerguelen Plateau.
This brings shoaled, nutrient-rich Upper Circumpolar Deep Water to the
surface which brings macronutrients to the surface. Ice is
additionally advected north along the eastern side of the plateau.
List of Antarctic and subantarctic islands
Heard Island and McDonald Islands
^ Oxford English Dictionary
^ UT Austin 1999
^ a b c Bénard et al. 2010, Introduction, pp. 1–2
^ Bénard et al. 2010, Geological and plate boundary setting, p. 2
^ Frey et al. 2003, Geochronology, p. 4
^ Ingle et al. 2004, Introduction, p. 84
^ a b c d e Frey et al. 2003, The Kerguelen Hotspot and Indian Ocean
Plate Reconstructions, pp. 5–7
^ Wallace et al. 2002, 1105–1106
^ Müller, Gaina & Clark 2000, C34 Late
83.5 Ma, p. 9
^ Whittaker, Williams & Müller 2013, Abstract
^ Schlich et al. 1971, p. 2062: Toutes ces caractéristiques, épaisse
série sédimentaire plus ou moins structurée avec l'ensemble
inférieur lié à une tectonique de socle, importance des accidents
tectonique limitant le bassin sédimentaire, sont en faveur d'une
origine contintentale du plateau de Kerguelen-Heard.
^ "Leg 183 Summary: Kerguelen Plateau-Broken Ridge—A Large Igneous
Province". Proceedings of the Ocean Drilling Program. 183.
^ Frey et al. 2003, Subsidence of the Kerguelen Plateau, pp. 16–17
^ Mohr, Wähnert & Lazarus 2002, Abstract
^ Tynan 1997, Introduction, p. 2793
Bénard, F.; Callot, J. P.; Vially, R.; Schmitz, J.; Roest, W.;
Patriat, M.; Loubrieu, B.; The ExtraPlac Team (2010). "The Kerguelen
plateau: Records from a long-living/composite microcontinent" (PDF).
Marine and Petroleum Geology. 27 (3): 633–649.
doi:10.1016/j.marpetgeo.2009.08.011. Retrieved September 6,
"UT Austin scientist plays major role in study of underwater
"micro-continent"". University of Texas at Austin. May 28, 1999.
Archived from the original on September 18, 2007. Retrieved October
Frey, F. A.; Coffin, M. F.; Wallace, P. J,; Weis, D. (2003). Frey, F.
A.; Coffin, M. F.; Wallace, P. J.; et al., eds. "Leg 183 Summary:
Kerguelen Plateau-Broken Ridge—A Large Igneous Province" (PDF).
Proceedings of the Ocean Drilling Program. 183: 1–48. Retrieved
August 30, 2015.
Ingle, S.; Scoates, J. S.; Weis, D.; Brügmann, G.; Kent, R. W.
(2004). "Origin of
Cretaceous continental tholeiites in southwestern
Australia and eastern India: insights from Hf and Os isotopes" (PDF).
Chemical Geology. 209: 83–106. doi:10.1016/j.chemgeo.2004.04.023.
Retrieved September 6, 2015.
Mohr, B. A. R.; Wähnert, V.; Lazarus, D. (2002). Frey, F. A.; Coffin,
M. F.; Wallace, P. J.; et al., eds. "Mid-
Cretaceous paleobotany and
palynology of the central Kerguelen Plateau, southern Indian Ocean
(ODP Leg 183, Site 1138)". Proc. ODP, Sci. Results. 183.
doi:10.2973/odp.proc.sr.183.008.2002. Retrieved September 5,
Müller, R. D.; Gaina, C.; Clark, S. (2000). "Seafloor spreading
around Australia" (PDF). Billion-year earth history of
neighbours in Gondwanaland. North Ryde, N.S.W.: Gemoc Press.
pp. 18–28. ISBN 1876315040. Retrieved October 17,
Schlich, R.; Delteil, J. R.; Moulin, J.; Patriat, P.; Guillaume, R.
(1971). "Mise en évidence d'une sédimentation de marge continentale
sur le plateau de Kerguelen-Heard". Comptes Rendus de l'Académie des
Sciences, Série D (in French). 272 (16): 2060–2063. Retrieved
September 6, 2015.
Tynan, C. T. (1997). "Cetacean distributions and oceanographic
features near the Kerguelen Plateau". Geophysical Research Letters. 24
(22): 2793–2796. doi:10.1029/97GL02860. Retrieved October 3,
Wallace, P. J.; Frey, F. A.; Weis, D.; Coffin, M. F. (2002). "Origin
and Evolution of the Kerguelen Plateau,
Broken Ridge and Kerguelen
Archipelago: Editorial". Journal of Petrology. 43 (7): 1105–1108.
Whittaker, J. M.; Williams, S. E.; Müller, R. D. (2013). "Revised
tectonic evolution of the Eastern Indian Ocean". Geochemistry,
Geophysics, Geosystems. 14 (6): 1891–1909. doi:10.1002/ggge.20120.
Retrieved September 7, 2015.
Weis, D; Frey, F.A. (1997). "Kerguelen plateau—broken ridge: a major
lip related to the Kerguelen plume" (PDF). Seventh Annual V. M.
Large igneous provinces
Plateau (Northeast Georgia Rise, Maud Rise)
Ethiopian and Yemen Highlands
Franklin (Franklin dike swarm)
High Arctic (Sverdrup Basin)
Kerguelen (Broken Ridge)
Mackenzie (Coppermine River
Mackenzie dike swarm)
Paraná and Etendeka
Continents of the world
Possible future supercontinents
Mythical and hypothesised continents
See also Regions of the world
Juan de Fuca
Philippine Mobile Belt
List of tectonic plates
Coordinates: 55°12′S 76°06′E / 55.2°S 76.1°