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Australian Plate
The Australian plate is or was a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when India broke away and began moving north. Australia and Antarctica had begun rifting by and completely separated a while after this, some believing as recently as , but most accepting presently that this had occurred by . The Australian plate later fused with the adjacent Indian plate beneath the Indian Ocean to form a single Indo-Australian plate. However, recent studies suggest that the two plates may have once again split apart and have been separate plates for at least 3 million years. The Australian plate includes the continent of Australia, including Tasmania, as well as portions of New Guinea, New Zealand and the Indian Ocean basin. Scope The continental crust of this plate covers the whole of Australia, the Gulf of Carpentaria, sou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Tectonic Plates
This is a list of tectonic plates on Earth#Surface, Earth's surface. Plate tectonics, Tectonic plates are pieces of Earth's crust and uppermost mantle (geology), mantle, together referred to as the lithosphere. The plates are around thick and consist of two principal types of material: oceanic crust (also called ''Sima (geology), sima'' from silicon and magnesium) and continental crust (''sial'' from silicon and aluminium). The composition of the two types of crust differs markedly, with mafic basaltic rocks dominating oceanic crust, while continental crust consists principally of lower-density felsic granite, granitic rocks. Current plates Geologists generally agree that the following tectonic plates currently exist on Earth#Surface, Earth's surface with roughly definable boundaries. Tectonic plates are sometimes subdivided into three fairly arbitrary categories: ''major'' (or ''primary'') ''plates'', ''minor'' (or ''secondary'') ''plates'', and ''microplates'' (or ''tertiary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tasman Sea
The Tasman Sea is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman, who in 1642 was the first known person to cross it. British explorer Lieutenant James Cook later extensively navigated the Tasman Sea in the 1770s during his three voyages of exploration. The Māori people of New Zealand call this sea ''Te Moana-a-Rehua'' meaning 'the sea of Rehua' which clashes with the Pacific waters named ''Te Tai-o-Whitirea'' ('the sea of Whitirea') – after Whitirea, Rehua's lover – at Cape Reinga, the northernmost tip of North Island. Climate The south of the sea is passed over by depressions going from west to east. The northern limit of these westerly winds is near to 40th parallel south, 40°S. During the southern winter, from April to October, the northern branch of these winds from the west changes its direction toward th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Island Arc
Island arcs are long archipelago, chains of active volcanoes with intense earthquake, seismic activity found along convergent boundary, convergent plate tectonics, tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the Earth's mantle, mantle along the subduction zone. They are the principal way by which continental growth is achieved. Island arcs can either be active or inactive based on their seismicity and presence of volcanoes. Active arcs are ridges of recent volcanoes with an associated deep seismic zone. They also possess a distinct curved form, a chain of active or recently extinct volcanoes, a oceanic trench, deep-sea trench, and a large negative Bouguer anomaly on the convex side of the volcanic arc. The small positive gravity anomaly associated with volcanic arcs has been interpreted by many authors as due to the presence of dense volcanic rocks beneath the arc. Inactive arcs are a chain of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kermadec Islands
The Kermadec Islands ( ; ) are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga. The islands are part of New Zealand. They are in total area and uninhabited, except for the permanently staffed Raoul Island Station, the northernmost outpost of New Zealand. The islands are listed with the New Zealand outlying islands. The islands are an immediate part of New Zealand, but not part of any region or district, but instead an ''Area Outside Territorial Authority''. Toponymy The islands were named after the Breton captain Jean-Michel Huon de Kermadec, who visited the islands as part of the d'Entrecasteaux expedition in the 1790s. The topographic particle "Kermadec" is of Breton origin and is a lieu-dit in Pencran in Finistère where '' ker'' means village, residence and ''madec'' a proper name derived from '' mad'' (which means 'good') with the suffix '' -ec'', used to form adjectives indicati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonga
Tonga, officially the Kingdom of Tonga, is an island country in Polynesia, part of Oceania. The country has 171 islands, of which 45 are inhabited. Its total surface area is about , scattered over in the southern Pacific Ocean. according to Johnson's Tribune, Tonga has a population of 104,494, 70% of whom reside on the main island, Tongatapu. The country stretches approximately north-south. It is surrounded by Fiji and Wallis and Futuna (France) to the northwest, Samoa to the northeast, New Caledonia (France) and Vanuatu to the west, Niue (the nearest foreign territory) to the east and Kermadec (New Zealand) to the southwest. Tonga is about from New Zealand's North Island. Tonga was first inhabited roughly 2,500 years ago by the Lapita civilization, Polynesian settlers who gradually evolved a distinct and strong ethnic identity, language, and culture as the Tongan people. They quickly established a powerful footing across the South Pacific, and this period of Tong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kermadec Trench
The Kermadec Trench is a linear ocean trench in the south Pacific Ocean. It stretches about from the Louisville Seamount Chain in the north (26°S) to the Hikurangi Plateau in the south (37°S), north-east of New Zealand's North Island. Together with the Tonga Trench to the north, it forms the -long, near-linear Kermadec-Tonga subduction system, which began to evolve in the Eocene when the Pacific plate started to subduct beneath the Australian plate. Convergence rates along this subduction system are among the fastest on Earth, /yr in the north and /yr in the south. Geology The Kermadec Trench is one of Earth's deepest oceanic trenches, reaching a depth of . Formed by the subduction of the Pacific plate under the Indo-Australian plate, it runs parallel with and to the east of the Kermadec Ridge and island arc. The Tonga Trench marks the continuation of subduction to the north. The Kermadec Trench has a southern continuation in the turbidite-filled Hikurangi Trough, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonga Trench
The Tonga Trench is an oceanic trench located in the southwestern Pacific Ocean. It is the deepest trench in the Southern hemisphere and the second deepest on Earth after the Mariana Trench. The fastest plate-tectonic velocity on Earth is occurring at this location, as the Pacific plate is being Subduction, subducted westward in the trench. Horizon Deep The deepest point of the Tonga Trench, the Horizon Deep at , is deep, making it the deepest point in the Southern Hemisphere and the second deepest on Earth after the Challenger Deep in the Mariana Trench. It is named for the research vessel RV Horizon, ''Horizon'' of the Scripps Institution of Oceanography, the crew of which found the deep in December 1952. As one of the deepest Hadal zone, hadal trenches, the sediment of the Horizon Deep harbours a community of Nematode, roundworms. A 2016 study found that the abundance of individuals in this community is six times greater than it is at a site on the trench edge at approximate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Boundary
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types. Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by the radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surface to the mantle. These convection cells bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macquarie Triple Junction
The Macquarie triple junction is a geologically active tectonic boundary located at at which the historic Indo-Australian plate, Pacific plate, and Antarctic plate collide and interact. The term ''triple junction'' is given to particular tectonic boundaries at which three separate tectonic plates meet at a specific, singular location. The Macquarie triple junction is located on the seafloor of the southern region of the Pacific Ocean, just south of New Zealand. This tectonic boundary was named in respect to the nearby Macquarie Island, which is located southeast of New Zealand. Evolution, stability, and migration Our understanding of the evolution of the Macquarie triple junction was made possible due to extensive research of the regions tectonic magnetic anomalies as well as local fractures reconstruction. The origin of the Macquarie triple junction has been interpreted to have occurred 47.91 Mya (million years ago), based on Anomaly 21. Thorough reconstruction of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
