- Indo-Australian Plate
The Indo-Australian Plate is a major
tectonic platethat includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinentand adjacent waters. Recent studies suggest that the Indo-Australian Plate may be in the process of breaking up into two separate plates due primarily to stresses induced by the collision of the Indo-Australian Plate with Eurasia along the Himalayas. [ [http://www.columbia.edu/cu/pr/95/18688.html (1995) Geologists Find: An Earth Plate Is Breaking in Two] ] The two protoplates or subplates are generally referred to as the India Plate and the Australian Plate.
Depositional age of the Mount Barren Group on the southern margin of the
Yilgarn Cratonand zirconprovenance analysis support the hypothesis that collisions between the Pilbara–Yilgarn and Yilgarn– Gawler Cratons assembled a proto-Australian continent approximately 1696±7 Ma (Dawson et al. 2002). [ [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBP-47C9ST3-2&_coverDate=11%2F25%2F2002&_alid=429579382&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=5932&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0d42b28962087116c9555f264709060d Dawson, Galvin C., Ian R. Fletcher, Bryan Krape, Neal J. McNaughton and Birger Rasmussen. (2002) "Did late Palaeoproterozoic assembly of proto-Australia involve collision between the Pilbara, Yilgarn and Gawler Cratons? Geochronological evidence from the Mount Barren Group in the Albany–Fraser Orogen of Western Australia." Precambrian Research, Vol. 118, Issues 3-4, 25 November, pp. 195-220.] ]
India, Meganesia ( Australia, New Guinea, and Tasmania), New Zealand, and New Caledoniaare all fragments of the ancient supercontinent of Gondwana. Seafloor spreadingseparated these land masses from one another, but as the spreading centers became inactive they fused into a single plate.
GPSmeasurement in Australia confirms the plate's movement as being 35 degrees east of north with a velocity of 67 mm/yr. Note also the same directions and velocities for points at Auckland, Christmas Islandand southern India. The slight change in direction at Auckland is presumably due to a slight buckling of the plate there, where it is being compressed by the Pacific Plate.
The southeasterly side is a complex but generally
convergent boundarywith the Pacific Plate. The Pacific Plate subducting under the Australian Plate forms the Tonga and Kermadec Trenches, and the parallel Tongaand Kermadec island arcs. It has also uplifted the eastern parts of New Zealand's North Island.
The continent of Zealandia, which separated from Australia 85 million years ago and stretches from
New Caledoniain the north to New Zealand's subantarctic islands in the south, is now being torn apart along the transform boundarymarked by the Alpine Fault.
South of New Zealand the boundary becomes a transitional transform-convergent boundary, the
Macquarie Fault Zone, where the Australian Plate is beginning to subduct under the Pacific Plate along the Puysegur Trench. Extending southwest of this trench is the Macquarie Ridge.
The southerly side is a
divergent boundarywith the Antarctic Platecalled the Southeast Indian Ridge(SEIR). The westerly side is a transform boundary with the Arabian Platecalled the Owen Fracture Zone, and a divergent boundary with the African Platecalled the Central Indian Ridge(CIR). The northerly side of the Indo-Australian Plate is a convergent boundary with the Eurasian Plateforming the Himalayaand Hindu Kush mountains.
The northeast side of the Indo-Australian plate forms a
subducting boundarywith the Eurasian plate on the borders of the Indian Oceanfrom Bangladesh, to Myanmar(formerly Burma) to the south-west of Indonesian islands of Sumatraand Borneo.
The subducting boundary through Indonesia is not parallel to the biogeographical
Wallace linethat separates the indigenous fauna of Asia from that of Australasia: the Eastern islands of Indonesia lie mainly on the Eurasian Plate, but have Australasian-related fauna and flora.
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Indo-Australian Plate — /ˌɪndoʊ əsˌtreɪljən ˈpleɪt/ (say .indoh uhs.traylyuhn playt) noun a major tectonic plate including the Australian continent and its surrounding waters and extending to the Indian subcontinent and surrounding waters; consists of two subplates, the … Australian English dictionary
Indo-Australian Plate — /in doh aw strayl yeuhn/, Geol. a major tectonic division of the earth s crust, comprising India and the Australian continent and adjacent suboceanic basins (the Tasman, South Australian, Mid Indian, Cocos, and Australian basins); separated from… … Universalium
Indo-Australian Plate — /in doh aw strayl yeuhn/, Geol. a major tectonic division of the earth s crust, comprising India and the Australian continent and adjacent suboceanic basins (the Tasman, South Australian, Mid Indian, Cocos, and Australian basins); separated from… … Useful english dictionary
Australian Plate — /ɒstˌreɪljən ˈpleɪt/ (say ost.raylyuhn playt) noun See Indo Australian Plate … Australian English dictionary
Indian-Australian Plate — /ɪndiən ɒstˌreɪljən ˈpleɪt/ (say indeeuhn ost.raylyuhn playt) noun → Indo Australian Plate … Australian English dictionary
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