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Osbourn Seamount
The Osbourn Seamount is a seamount in the south-west Pacific Ocean. It is the westernmost and oldest unsubducted seamount of the Louisville Ridge, with an estimated age of 78.8 ± 1.3 . Like other seamounts comprising the Louisville Ridge, it was formed by the Louisville hotspot which is currently located away near the Pacific-Antarctic Ridge. Osbourn Seamount will eventually be destroyed by subduction in the Tonga Tonga (, ; ), officially the Kingdom of Tonga ( to, Puleʻanga Fakatuʻi ʻo Tonga), is a Polynesian country and archipelago. The country has 171 islands – of which 45 are inhabited. Its total surface area is about , scattered over in ... and Kermadec trenches once it is carried into the trenches by the ongoing plate motion. The trench-chain collision zone is moving southward at a rate of / because of the oblique angle between the trench and the Louisville chain. This further shortens the seamount's lifespan. The flat top of the seamount ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continents of Asia and Oceania in the west and the Americas in the east. At in area (as defined with a southern Antarctic border), this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of Earth's water surface and about 32% of its total surface area, larger than Earth's entire land area combined .Pacific Ocean . '' Britannica Concise.'' 2008: Encyclopædia Britannica, Inc. The centers of both the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guyot
In marine geology, a guyot (pronounced ), also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than below the surface of the sea. The diameters of these flat summits can exceed .Guyot ''Encyclopædia Britannica Online'', 2010. Retrieved January 14, 2010. Guyots are most commonly found in the , but they have been identified in all the oceans except the . History Guyots were first recognized in 1945 by |
Louisville Ridge
The Louisville Ridge, also known as the Louisville Seamount Chain, is an underwater chain of over 70 seamounts located in the Southwest portion of the Pacific Ocean. As one of the longest seamount chains on Earth it stretches some Vanderkluysen, L.; Mahoney, J. J.; Koppers, A. A.; and Lonsdale, P. F. (2007)Geochemical Evolution of the Louisville Seamount Chain American Geophysical Union, Fall Meeting 2007, abstract #V42B-06. from the Pacific-Antarctic Ridge northwest to the Tonga- Kermadec Trench, where it subducts under the Indo-Australian Plate as part of the Pacific Plate. The chain may have been formed by movement of the Pacific Plate over the Louisville hotspot or by leakage of magma from the shallow mantle up through the Eltanin fracture zone, which it follows closely. Depth-sounding data first revealed the existence of the seamount chain in 1972. Seamounts The Louisville Ridge includes the following: *Burton Seamount * Currituck Seamount * Danseur Seamount *Darvin G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamount
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Subduction is possible because the cold oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle underlying the cold, rigid lithosphere. Once initiated, stable subduction is driven mostly by the negative buoyancy of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louisville Hotspot
The Louisville hotspot is a volcanic hotspot responsible for the volcanic activity that has formed the Louisville Ridge in the southern Pacific Ocean. Location The Louisville hotspot is believed to lie close to the Pacific-Antarctic Ridge, although its exact location is uncertain. Geological history The Louisville hotspot has produced the Louisville Ridge, which is one of the longest seamount chains on Earth, stretching some Vanderkluysen, L.; Mahoney, J. J.; Koppers, A. A.; and Lonsdale, P. F. (2007)Geochemical Evolution of the Louisville Seamount Chain American Geophysical Union, Fall Meeting 2007, abstract #V42B-06. from the Pacific-Antarctic Ridge to the Tonga Trench where it subducts under the Indo-Australian Plate as part of the Pacific Plate. The Louisville hotspot is believed to have been active since at least 78.8 ± 1.3 Ma based on age of the oldest seamount (Osbourn ). This duration is comparable to that of the Hawaiian-Emperor seamount chain, although the rate of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific-Antarctic Ridge
The Pacific-Antarctic Ridge (PAR) is a divergent tectonic plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate. It is regarded as the southern section of the East Pacific Rise in some usages, generally south of the Challenger Fracture Zone and stretching to the Macquarie Triple Junction south of New Zealand. The Louisville Ridge Stretching for 4,300 km north-west from the Pacific-Antarctic Ridge to the Osbourn Seamount at Tonga and Kermadec Junction is a long line of seamounts called the Louisville Ridge – the longest such chain in the Pacific – thought to have formed from the Pacific Plate sliding over a long-lived center of upwelling magma called the Louisville hotspot. See also * Hollister Ridge * Oceanic ridge A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Subduction is possible because the cold oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle underlying the cold, rigid lithosphere. Once initiated, stable subduction is driven mostly by the negative buoyancy of th ... [...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] |
Detroit Seamount
Detroit Seamount, which was formed around 76 million years ago, is one of the oldest seamounts of the Hawaiian-Emperor seamount chain ( Meiji Seamount is the oldest, at 82 million years). It lies near the northernmost end of the chain and is south of Aleutian Islands (near Russia), at Seamounts Catalog by EarthRef, a Project accessed 3-1-09. Detroit Seamount is one of the few seamounts to break the naming scheme of the , which are named mostly after em ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaiian–Emperor Seamount Chain
The Hawaiian–Emperor seamount chain is a mostly undersea mountain range in the Pacific Ocean that reaches above sea level in Hawaii. It is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts: together they form a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending southeast to northwest beneath the northern Pacific Ocean. The seamount chain, containing over 80 identified undersea volcanoes, stretches about from the Aleutian Trench in the far northwest Pacific to the Kamaʻehuakanaloa Seamount (formerly Lōʻihi), the youngest volcano in the chain, which lies about southeast of the Island of Hawaiʻi. Regions The chain can be divided into three subsections. The first, the Hawaiian archipelago (also known as the ''Windward isles''), consists of the islands comprising the U.S. state of Hawaii. As it is the closest to the hot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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