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53-644: 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 overseas territory ) plus the Heard and McDonald Islands (an Australian external territory ). Intermittent volcanism continues on the Heard and McDonald Islands. Symmetrically across

106-484: A 100–150-kilometre (62–93 mi) wide, north to northeast-trending bathymetric trough. Wallaby Plateau is the name used by the Australian geologists and government for this undersea plateau. This name was first used in a Hartog AGSO bathymetric map and formally recognized in a peer-reviewed paper by Symonds and Cameron in 1977. In contrast, the internationally recognized name for it is Cuvier Plateau . Cuvier

159-601: 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

212-797: Is a volcanic hotspot at the Kerguelen Plateau in the Southern Indian Ocean . The Kerguelen hotspot has produced basaltic lava for about 130 million years and has also produced the Kerguelen Islands , Naturaliste Plateau , Heard Island , the McDonald Islands , the Comei large igneous province in south Tibet, and the Rajmahal Traps . One of the associated features, the Ninety East Ridge ,

265-567: Is a historical name that is presumably derived from the adjacent Cape Cuvier. Cape Cuvier was named for Georges Cuvier , zoologist and statesman, by a French expedition led by Baudin in 1800–1803. The Wallaby Plateau lies inside the Australian Exclusive Economic Zone . The Wallaby Plateau largely lies within Australia's extended continental shelf. It apparently consists of attenuated continental crust which

318-616: Is a school of thought that assigns at least two separate hotspots to the activity assigned by some to a single Kerguelen hotspot and this issue is not resolved by the implications of the latest tectonic plate modelling. The potentially separate Amsterdam-Saint Paul hotspot is assigned in such models to explain historic activity at the Amsterdam-Saint Paul Plateau to the south of the Southeast Indian Ridge with this hotspot's previous activity now to

371-592: Is also known as the Cuvier Plateau , is a large bathymetric high about 450 kilometres (280 mi) west of Carnarvon, Western Australia . The Wallaby Plateau covers approximately 100,000 km (39,000 sq mi) and is in water depths of 2,200 meters (7,200 ft) to greater than 5,000 meters (16,000 ft). In the west, the Wallaby Plateau is separated from the Zenith Plateau by

424-445: Is buried beneath a thick sequence of volcanic rocks that are blanketed by marine sediments. The origins of the Wallaby Plateau date back 130 million years ago during the break up of the Australian and Greater India plates. With the help of seismic reflection and geodynamic reconstruction data, evidence was published to support the origin of the area back to the development of the lithospheric -scale Wallaby–Zenith Fracture Zone during

477-485: Is distinguished by its over 5,000 km (3,100 mi) length, being the longest linear tectonic feature on Earth. The total volume of magma erupted in 130 million years with associated features has been estimated to be about 25,000,000 km (6,000,000 cu mi). However, as well as large igneous provinces and seamounts the hotspot has interacted with other seafloor spreading features, so this volume figure has some uncertainty. The most recent activity of

530-474: Is now considered unsupported, with the plateau situated at a considerable distance from the nearest continents. It finally became submerged 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 including sperm , minke , and humpback whales along the southern end of the Kerguelen Plateau and

583-490: Is now the Gulden Draak Knoll off Western Australia at 117  million years ago due to the subsequent tectonic plate motions. A best fit tectonic model explains these events by about 115  million years ago a mantle plume head reaching the surface underneath the forming Indian Ocean between India and Antarctica with extensive melting of thin oceanic crust of both plates. The Central Kerguelen Plateau

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636-518: Is to the south of present Southeast Indian Ridge, but composition studies are inconsistent. It is possible that these eruptives come from a second hot spot, and most recent authorities agree. The hot spot is now under the southern Central Kerguelen Plateau again, explaining the recent volcanic activity already commented upon. There is a trend in Kerguelen plume magmatism, from tholeiitic/transitional basalts in those more than 25  million years ago to alkalic basalts. Seamounts dredged between

689-839: The Early Cretaceous in the Comei large igneous province of southeastern Tibet from 145  million years ago . There is an over lap in time with the basalts in this area of Tibet whose youngest rocks at 130  million years ago with those found thousands of miles away at Bunbury, Western Australia which are up to 137  million years ago old but some are as young as 123  million years ago . Previous work had suggested maximum ages at Bunbury at 132.2  ± 0.3 million years ago . Both are relatively small volume volcanism compared to later developments. The continental breakup of India and Antarctica occurred around 132 to 130  million years ago . Between Western Australia and Gulden Draak Knoll on

742-414: The Kerguelen Islands alkalic flood basalts were deposited between 30 and 24 million years ago. However younger lavas towards the south east of the archipelago that are mainly found as dykes or plugs in these flood basalts and have ages between 10 and 6 million years. To the south, the stratovolcano of Mont Ross on Grande Terre is between 2 million years and 100,000 years old. The composition of

795-656: The Ninety East Ridge formed 82–37 Ma north to south; the Bunbury Basalt ( Western Australia ) 137–130.5 Ma ; the Naturaliste Plateau (offshore Western Australia) formed 132–128 Ma ; the Rajmahal Traps in Northeast India 118–117 Ma ; and finally lamprophyres in India and Antarctica 115–114 Ma . The oldest Australian volcanism that can be attributed to the Kerguelen plume are

848-705: 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

901-737: The Rodriguez Triple Junction . It is separated from Antarctica by the Princess Elizabeth Trough and the Cooperation Sea . The eastern margin north of the William Ridge is steep and formed during the breakup between the Kerguelen Plateau and the Broken Ridge. The southern part of the margin is separated from the Australian–Antarctic Basin by the deep Labuan Basin . From the initial opening of

954-512: The bathymetry data from the survey. A total of ten samples of sedimentary rocks , 14 volcanic rock samples, and an additional seven samples with mineral development were collected with the help of various geologic tools. Rock samples collected during the survey were predominantly igneous and also siliceous in nature, thus supporting the notion once more of the volcanic origins of the Wallaby Plateau. Terrigenous clastic rocks were also recovered providing primitive evidence of sediment deposits when

1007-507: The mantle plume hypothesis give a fair fit to observed ages over the last 130 million years but some compositional details are not explained by the classical plume model. It is important to realise in the discussion below that the dates referred to were obtained over a period of about 50 years and those found by earlier work have been updated where appropriate as more samples analysed. This could result in events before about 40 million years ago having corrections of about 10 million years. There

1060-480: The 10 million year old Amsterdam–St. Paul Plateau located near the current plate boundary of the Southeast Indian Ridge has similarities to the eruptives of the Kerguelen hotspot so the recently active volcanoes on it have been assigned by some to this hot spot rather than a separate Amsterdam-Saint Paul hotspot . In such a case Île Amsterdam about 1,400 km (870 mi) to the north–east of

1113-611: The Bunbury Basalt (137–130.5 Ma ) and the Naturaliste Plateau (132–128 Ma ) in southwestern Australia. The Sylhet and Rajmahal Traps in eastern India (118-115 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 dimensions which suggests that the mantle underlying

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1166-607: 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 118–119 Ma contributed to the oceanic anoxic event 1 . Around 83.5 Ma sea floor spreading between India and Antarctica

1219-466: 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 India and 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

1272-527: 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 before rifting by the mid-ocean ridge . To the north of Broken Ridge is the linear Ninety East Ridge which continues almost due north into the Bay of Bengal and is considered to be a hotspot track. One of the largest igneous provinces (LIPs) in

1325-500: The Indian Ocean until present, the Kerguelen hotspot has produced several, now widely dispersed, large-scale structures. These are now known to cover a time range from 145 to 0 million years ago (Ma) with the oldest assigned structure being the Comei large igneous province in south-eastern Tibet . Historic work had believed that the hotspot became active more recently in what is now south-east Australia. Ongoing analysis of specimens can result in timing changes, so some dates in

1378-635: The Indian Ocean was formed between 120 to 110 million years ago , and was a much larger volume of basalt, consistent with a large igneous province. In the meantime the Kerguelen mantle plume also erupted south of the Comei province the two traps of north east India, being the Rajmahal Traps and the Sylhet Traps. These erupted during a period between 118.1  ± 0.3 million years ago , and 115  million years ago . Eruptions also occurred during this period at what

1431-661: The Indo-Australian Plate may have broken up into two or three separate plates due primarily to stresses induced by the collision of the Indo-Australian Plate with Eurasia along what later became the Himalayas , and that the Indian Plate and Australian Plate may have been separate since at least 3  million years ago . Much of the area of the Ninety East Ridge as well as being related to

1484-493: The Kerguelen Archipelago and were the first to identify the Kerguelen Plateau as of continental origin, in contrast to other LIPs. The presence of soil layers in the basalt which 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

1537-620: The Kerguelen Archipelago has a volcano that must have erupted within perhaps the last century, the Boomerang Seamount erupted in 1995 and Île Saint-Paul nearby erupted in 1793. The Kerguelen hotspot has been used to help interpret the plate tectonic history of the Indo-Australian Plate , even though the hotspot itself is now situated under the Antarctic Plate . Models of major plate dynamics based on

1590-526: The Kerguelen Islands and Heard Island were formed in the Miocene by mildly alkalic, olivine and picrite basalt . The composition at and near Amsterdam and Saint Paul Island are distinct from other Kerguelen plume material. The Ninety East Ridge has tholeiite basalt typical of Indian Ocean basalts with no systematic isotopic variation observed along the ridge and this is inconsistent with

1643-601: The Kerguelen hotspot has been near Heard Island and McDonald Islands where there are two active volcanoes, but its current location could be quite a wide area of the Central Kerguelen Plateau extending over a distance of about 440 km (270 mi), back into the Kerguelen Archipelago as there is some current geothermal activity there, with active fumaroles. Some plate tectonic models favour such more north-east locations. The bulk of

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1696-652: The 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 event. 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

1749-631: The Ninety East Ridge is predominantly a historic divergent plate boundary with eruptives from a deep mantle source. One sample from Boomerang Seamount , a volcano of the Amsterdam-Saint Paul Plateau, has a composition that is midway between St Paul Island and Kerguelen Plateau samples and this is consistent with Kerguelen-type source mantle existing beneath the Amsterdam-Saint Paul Plateau. 49°36′S 68°59′E  /  49.6°S 68.99°E  / -49.6; 68.99 Wallaby Plateau The Wallaby Plateau , which

1802-416: The area of the present Naturaliste Plateau. India started its collision with Asia about 70  million years ago . Eastern Australia and Antarctica completed their separation between perhaps as recently as 45  million years ago , but with most historic models by 67  million years ago . Recent studies, and evidence from seismic events such as the 2012 Indian Ocean earthquakes , suggest that

1855-750: The breakup of the two continental plates . Additionally, even earlier studies of the region attributed the formation of this area to large-scale volcanic activity on the oceanic crust . A recent study of the plateau conducted in 2008–2009 by Geoscience Australia surveyed 65,000 square kilometers of the area to gain a broader geologic understanding. A multibeam swath bathymetry along with 8000 line kilometers of high-resolution gravity, magnetic and Acoustic Doppler Current Profiler measurements were collected along with several rock and sediment samples. A total of eleven rock dredges, three sediment grabs, four box cores, one sea floor trawl, eight camera and temperature tows, conductivity ( salinity ) and depth profiles through

1908-463: The floor of the Indian Ocean are the Naturaliste, Wallaby, and Zenith Plateaus that erupted between 130 to 117 million years ago , now well separated from India. The Seaward Dipping Reflectors, now at the southern end of the Kerguelen Plateau near Antarctica also formed in this period more than 126  million years ago . The Southern Kerguelen Plateau in the enlarging basin of

1961-664: The hot spot of the Northern Kerguelen Plateau on the Antarctic plate, and also explains 20  million years ago age of the Chain of the Dead Poets that connects the ends of the Ninety East Ridge and the Broken Ridge to the northern aspect of the Southeast Indian Ridge. This also could explain the more recent formation of the Amsterdam-Saint Paul Plateau, which is aged at 10  million years ago and

2014-411: The hotspot is part of the diffuse boundary between the Indian Plate and Australian Plate as they go their separate ways toward the north. Present day structures such as the Elan Bank may have their placements due to ridge jumps at propagating rifts during the process of sea floor spreading. The oldest volcanic rocks assigned to the Kerguelen hotspot are now understood to have been erupted during

2067-427: The hypothesis of an ageing mantle plume origin for all of the ridge. . However at least three distinct sources must have contributed to the basalts of the ridge. The isotopic composition is intermediate between those of the basalts found at or near the Kerguelen and Amsterdam-Saint Paul plateaus. . This results in the interpretation that the Kerguelen hotspot as described by some, is at least two separate hotspots, and

2120-568: The last 21 Ma volcanic structures have formed on the CKP, including Heard Island, and both Heard and McDonald Islands have had recent eruptions. 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

2173-550: The latest evidence, because it appears the plume may be under the Australian Plate between 95 to 45 million years ago odd, creating the Broken Ridge for example at 95 to 94 million years ago , rather than continuing to be located at the triple junction as in classic tectonic models. Part of the plume had long believed to be erupting under the Indian Plate as it raced north contributing to

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2226-485: The linear feature and ages of the basalts of the Ninety East Ridge with the oldest at the north, 82  million years ago and the youngest at its south, 37  million years ago . However there is good evidence in the form of magnetic measurements to each side of the ridge, that decompression melting along the Ninety East Ridge occurred as well, and the most recent model assigns a prominent role to this. The previous hot spot only hypothesis explained all features by

2279-612: The mid- Cretaceous as well as the early Cenozoic . Fossil wood fragments recovered from the Kerguelen Islands were identified as Araucarians and Cypresses , demonstrating that Kerguelen's flora may have been similar to that of the Antarctic flora found across the Southern Hemisphere. The plateau had been proposed as forming a land bridge between India and Antarctica during the Late Cretaceous, though this

2332-1204: The north of the Southeast Indian Ridge being the seamounts of the Chain of the Dead Poets. The current location of this hotspot, if it exists, is hard to determine as there are areas of recent volcanic activity that might be associated with the still spreading Southeast Indian Ridge. Most recent work has two separate hotspots. One hundred and forty million years ago the present north-eastern aspect of India (Bengal), southern Western Australia and Princess Elizabeth Land portions of Antarctica were adjacent before Gondwana breakup. Initially India and Australia rotated from Antarctica with continental crustal extension between Australia and Antarctica by about 132.5  million years ago . India separated first from Antarctica and this occurred around 132 to 130 million years ago , although earlier work had this happening by 124  million years ago . East Gondwana, comprising present Antarctica, India, and Australia continued to break up between 132.6 to 96 million years ago with India moved north-west from Australia-Antarctica and extension between Australia and Antarctica being at its greatest rate. Seafloor spreading occurred in

2385-613: 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

2438-400: The plume splitting with two effective hot spots. Multiple workers postulate that buried under about 5 km (3.1 mi) of sediments on the seafloor of the Bay of Bengal , there is a continuation of the Ninety East Ridge with volcanics deposited about 90  million years ago . The opening of the Southeast Indian Ridge at 40  million years ago resulted in the creation by

2491-550: The sequence that follows may alter. The Southern Kerguelen Plateau (SKP) formed 120–110 Ma ; the Elan Bank 108–107 Ma , named by Dennis E. Hayes of Lamont Doherty Earth Observatory ; the Central Kerguelen Plateau (CKP) 101–100 Ma ; the Broken Ridge (connected to the CKP before the Eocene breakup) 95–94 Ma ; the Skiff Bank (east of the Kerguelen Islands ) 69–68 Ma ; the Northern Kerguelen Plateau (NKP) 35–34 Ma ;

2544-590: The surface. Ice is additionally advected north along the eastern side of the plateau. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania 55°12′S 76°06′E  /  55.2°S 76.1°E  / -55.2; 76.1 Kerguelen hotspot The Kerguelen hotspot

2597-456: The water column. Data from this survey revealed and reaffirmed early studies that volcanic activity was a major factor in the early formations of this vast plateau. Along with three large volcano complexes, and two other small and steeper cone-shaped complexes, several valleys, scarps, and ridges were discovered as well as a new seafloor. Additionally, on the northeast of the plateau, what researchers believe are volcanic hills, were discovered from

2650-530: The world, the Kerguelen Plateau covers an area of 1,226,230 km (473,450 sq mi) and rises 2,000 m (6,600 ft) above the surrounding oceanic basins. Most of the plateau is less than 3,000 m (9,800 ft) below sea level. Located on the Antarctic Plate , the Kerguelen Plateau is separated from Australia by the Southeast Indian Ridge (SEIR) and from Africa by the Southwest Indian Ridge (SWIR). These two ridges meet at

2703-406: 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 transferred parts of the Kerguelen Plateau from the Indian Plate to the Antarctic Plate. The Kerguelen hotspot produced the 5,000 km (3,100 mi) long Ninety East Ridge 82–38 Ma , and geochemical evidence suggests that this occurred at or near

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2756-480: Was formed between 110 to 100 million years ago by basalt eruption from the hotspot on a fast-moving Antarctic Plate, with the Elan Bank emplacement in the first 5 million years of this period. At about 105  million years ago the triple junction of the Indian, Australian, and Antarctic plates crosses the plume so crust forms on three different plates at the same time. Matters now get complex with

2809-506: Was made by wildfires started by lightning or lava flows). Large parts of the now-submarine Southern Kerguelen Plateaus (SKP) and Central Kerguelen Plateaus (CKP) were subaerial during the formation of the LIP. The SKP probably formed an island of 500,000 km (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

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