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Tonga Ridge
The Tonga-Kermadec Ridge is an oceanic ridge in the south-west Pacific Ocean underlying the Tonga-Kermadec island arc. It is the most linear, fastest converging, and most seismically active subduction boundary on Earth, and consequently has the highest density of submarine volcanoes. The Tonga-Kermadec Ridge stretches more than north-northeast from New Zealand's North Island. The Pacific Plate subducts westward beneath the Australian Plate along the ridge. It is divided into two segments, the northern Tonga Ridge and southern Kermadec Ridge, by the Louisville Seamount Chain. On its western side, the ridge is flanked by two back-arc basins, the Lau Basin and Havre Trough, that began opening at 6 and 2 Ma respectively. Together with these younger basins the ridge forms the eastward-migrating, 100 Ma-old Lau-Tonga-Havre-Kermadec arc/back-arc system or complex. The extension in the Lau-Havre basin results in a higher rate of subduction than convergence along the Aus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kermadec Arc
The Tonga-Kermadec Ridge is an oceanic ridge in the south-west Pacific Ocean underlying the Tonga-Kermadec island arc. It is the most linear, fastest converging, and most seismically active subduction boundary on Earth, and consequently has the highest density of submarine volcanoes. The Tonga-Kermadec Ridge stretches more than north-northeast from New Zealand's North Island. The Pacific Plate subducts westward beneath the Australian Plate along the ridge. It is divided into two segments, the northern Tonga Ridge and southern Kermadec Ridge, by the Louisville Seamount Chain. On its western side, the ridge is flanked by two back-arc basins, the Lau Basin and Havre Trough, that began opening at 6 and 2 Ma respectively. Together with these younger basins the ridge forms the eastward-migrating, 100 Ma-old Lau-Tonga-Havre-Kermadec arc/back-arc system or complex. The extension in the Lau-Havre basin results in a higher rate of subduction than convergence along the Au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonga Plate
The Tonga Plate is a small southwest Pacific tectonic plate or microplate. It is centered at approximately 19° S. latitude and 173° E. longitude. The plate is an elongated plate oriented NNE - SSW and is a northward continuation of the Kermadec linear zone north of New Zealand. The plate is bounded on the east and north by the Pacific Plate, on the northwest by the Niuafo’ou Microplate, on the west and south by the Indo-Australian Plate. The Tonga plate is subducting the Pacific plate along the Tonga Trench. This subduction turns into a transform fault boundary north of Tonga. An active rift or spreading center separates the Tonga Plate from the Australian Plate and the Niuafo’ou microplate to the west. The Tonga Plate is seismically very active and is rotating clockwise. These were the plates that moved when the 2009 tsunami The 2009 Samoa earthquake and tsunami took place on 29 September 2009 in the southern Pacific Ocean adjacent to the Kermadec-Tonga subduction zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Large Igneous Province
A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. The formation of some of the LIPs in the past 500 million years coincide in time with mass extinctions and rapid climatic changes, which has led to numerous hypotheses about causal relationships. LIPs are fundamentally different from any other currently active volcanoes or volcanic systems. Definition In 1992 researchers first used the term ''large igneous province'' to describe very large accumulations—areas greater than 100,000 square kilometers (approximately the area of Iceland)—of mafic igneous rocks that were erupted or emplaced at depth within an extremely short geological time interval: a few million years or less. Maf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontong Java Plateau
The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands. The OJP was formed around (Ma) with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific plateaus, Manihiki and Hikurangi, now separated from the OJP by Cretaceous oceanic basins, are of similar age and composition and probably formed as a single plateau and a contiguous large igneous province together with the OJP. When eruption of lava had finished, the Ontong Java–Manihiki–Hikurangi plateau covered 1% of Earth's surface and represented a volume of of basaltic magma. This "Ontong Java event", first proposed in 1991, represents the largest volcanic event of the past 200 million years, with a magma eruption rate estimated at up to per year over 3 million years, several times larger than the Deccan Traps. The smooth surface of the OJP is punctuated by seamounts such as the Ontong Java Atoll, one of the largest atolls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manihiki Plateau
The Manihiki Plateau is an oceanic plateau in the south-west Pacific Ocean. The Manihiki Plateau was formed by volcanic activity 125 to 120 million years ago during the mid-Cretaceous period at a triple junction plate boundary called the Tongareva triple junction. 125 million years ago the Manihiki Plateau formed part of the giant Ontong Java-Manihiki-Hikurangi plateau. Geological setting The Manihiki Plateau extends from 3°S to 6°S and 159°W to 169°W covering and has an estimated volume of with a crustal thickness of . Several of the Cook Islands are located on the southern part: Danger, Nassau, Suvorov, Rakahanga, and Manihiki. The Tokelau Basin borders it to the west, the Samoan Basin to the south, the Penrhyn Basin to the east, and the Central Pacific Basin to the north. It reaches up to below sea level, several kilometres shallower than the surrounding basins. The plateau can be divided into three regions. The south-eastern High Plateau is the shallowest and fla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hikurangi Plateau
The Hikurangi Plateau is an oceanic plateau in the South Pacific Ocean east of the North Island of New Zealand. It is part of a large igneous province (LIP) together with Manihiki and Ontong Java, now located and north of Hikurangi respectively. Mount Hikurangi, in Māori mythology the first part of the North Island to emerge from the ocean, gave its name to the plateau. Geological setting The Hikurangi Plateau covers approximately and reaches below sea level. Hikurangi Plateau is cut by the Hikurangi Channel, a 2000 km abyssal channel that starts at Kaikoura and runs along the Hikurangi Trench as far as the Māhia Peninsula before crossing the plateau and ending in the South-west Pacific abyssal plain. Tectonic evolution Two models have been proposed for the formation of Hikurangi. It can be derived from the mantle plume that caused the break-up of Gondwana and the separation of Zealandia from Antarctica 107 Ma. Alternatively, it could have formed togeth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitiaz Trench
Vityaz may refer to: * Bogatyr, a folk or epic hero in Slavic culture Aircraft and spacecraft *Vityaz, the call sign of spacecraft Soyuz TM-14 *Russky Vityaz, an aircraft built by Igor Sikorsky in 1913 Military * , a ''Bogatyr'' class screw corvette *Vityaz (MVD), a Russian Spetsnaz (special forces) unit *Vityaz (ATV), a Russian all-terrain vehicle * S-350 Vityaz, a Russian surface-to-air missile defense system *Vityaz-SN, a Russian 9mm Parabellum submachine-gun Sport *FC Vityaz Podolsk, a football club in Podolsk, Russia *Vityaz Ice Palace, an ice arena in Podolsk, Russia *Vityaz Chekhov, a professional ice hockey team in Chekhov, Moscow Oblast, formerly in Podolsk, Russia Other uses *Vityaz, a historical association in the Soviet Union, precursor of ''Pamyat'' * Machine engineering company 'Vityaz', a tracked amphibious vehicle manufacturer * Vityaz' frostfish, the common name of ''Benthodesmus vityazi'', a species of cutlassfish *, a Soviet research vessel in service 1949- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocean Island Basalt
Ocean island basalt (OIB) is a volcanic rock, usually basaltic in composition, erupted in oceans away from tectonic plate boundaries. Although ocean island basaltic magma is mainly erupted as basalt lava, the basaltic magma is sometimes modified by igneous differentiation to produce a range of other volcanic rock types, for example, rhyolite in Iceland, and phonolite and trachyte at the intraplate volcano Fernando de Noronha. Unlike mid-ocean ridge basalts (MORBs), which erupt at spreading centers (divergent plate boundaries), and volcanic arc lavas, which erupt at Subduction, subduction zones (convergent plate boundaries), ocean island basalts are the result of intraplate volcanism. However, some ocean island basalt locations coincide with plate boundaries like Iceland, which sits on top of a mid-ocean ridge, and Samoa, which is located near a subduction zone. In the ocean basins, ocean island basalts form seamounts, and in some cases, enough material is erupted that the rock protr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niuatoputapu
Niuatoputapu is a high island in the island nation of Tonga, Pacific Ocean. Its highest point is , and its area is . Its name means ''sacred island''. Older European names for the island are Traitors Island or Keppel Island. Niuatoputapu is located in the north of the Tonga island group, away from Vavau near the border with Samoa. Its closest neighbours are the small island of Tafahi, which is only to the north-northeast, and the island of Niuafo'ou. Those three islands together form the administrative division of the Niuas. Niuatoputapu Airport accepts international flights. The population was 719 in 2021. Until several centuries ago, the inhabitants spoke the Niuatoputapu language, but it was replaced by the Tongan language and went extinct. Nevertheless, the variety of Tongan spoken on Niuatoputapu contains elements of Samoan, Uvean, and Futunan. Geography Niuatoputapu’s highest central area, just beside Vaipoa, is a hill only high. It is the eroded remnant of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tafahi
Tafahi is a small () island in the north of the Tonga archipelago, in fact closer to Savaii (Samoa) than to the main islands of Tonga. It is only north-northeast away from Niuatoputapu, and fishermen commute in small outboard motorboats almost daily between the two. The island has a population of 14 (in 2021). Other names for Tafahi are Cocos Eylant (coconut island) or Boscawen island. Geography Tafahi is a volcanic island and has the typical cone shape of a stratovolcano. The mountain is called Piu-o-Tafahi (fanpalm of Tafahi) and is high. (The island, , is smaller than Niuatoputapu, but higher). The soil is extremely suited for growing kava and vanilla, whose exports to the rest of Tonga and beyond is the main occupation of the population. The harbour (merely an opening in the fringing reef, only passable by small boats) is at the northwest of the island. A steep staircase leads up to the village, with about 69 residents at the census of 2001, located on a plateau on the nor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mantle Plume
A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian Traps. Some such volcanic regions lie far from tectonic plate boundaries, while others represent unusually large-volume volcanism near plate boundaries. Concepts Mantle plumes were first proposed by J. Tuzo Wilson in 1963 and further developed by W. Jason Morgan in 1971 and 1972. A mantle plume is posited to exist where super-heated material forms ( nucleates) at the core-mantle boundary and rises through the Earth's mantle. Rather than a continuous stream, plumes should be viewed as a series of hot bubbles of material. Reaching the brittle upper Earth's crust they form diapirs. These diapirs are "hotspots" in the crust. In particular, the conc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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