The Mohns Ridge is an ultraslow-spreading segment of the Mid-Atlantic Ridge located to the north of Jan Mayen in the Arctic Ocean. [1] It is bounded to the south by the Jan Mayen fracture zone, and transitions to Knipovich Ridge in the north-east.
The Mohns Ridge is an ultraslow-spreading segment of the Mid-Atlantic Ridge located to the north of Jan Mayen in the Arctic Ocean. [1] It is bounded to the south by the Jan Mayen fracture zone, and transitions to Knipovich Ridge in the north-east.
The ridge started forming 53 My ago, as the Greenland Plate and Eurasian Plate started separating. Four separate axial volcanic ridges have been discovered along Mohns Ridge. [2]
Several active and non-active hydrothermal vent fields have been located along Mohns Ridge. In 2008, a black smoker vent field named Loki's Castle was discovered along one of the axial volcanic ridges in the area. [3]
The Schulz Bank seamount is located on the northern part of the ridge, as Mohns Ridge transitions into the Knipovich Ridge. [4]
In marine geology, a guyot, also called a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi). Guyots are most commonly found in the Pacific Ocean, but they have been identified in all the oceans except the Arctic Ocean. They are analogous to tables on land.
The Gakkel Ridge is a mid-oceanic ridge, a divergent tectonic plate boundary between the North American Plate and the Eurasian Plate. It is located in the Eurasian Basin of the Arctic Ocean, between Greenland and Siberia. Geologically, it connects the northern end of the Mid-Atlantic Ridge with the Laptev Sea Rift.
The East Pacific Rise (EPR) is a mid-ocean rise, at a divergent tectonic plate boundary, located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. It runs south from the Gulf of California in the Salton Sea basin in Southern California to a point near 55°S130°W, where it joins the Pacific-Antarctic Ridge (PAR) trending west-southwest towards Antarctica, near New Zealand. Much of the rise lies about 3,200 km (2,000 mi) off the South American coast and rises about 1,800–2,700 m (5,900–8,900 ft) above the surrounding seafloor.
A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about 2,600 meters (8,500 ft) and rises about 2,000 meters (6,600 ft) above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin.
The Juan de Fuca Ridge is a mid-ocean spreading center and divergent plate boundary located off the coast of the Pacific Northwest region of North America, named after Juan de Fuca. The ridge separates the Pacific Plate to the west and the Juan de Fuca Plate to the east. It runs generally northward, with a length of approximately 500 kilometres (310 mi). The ridge is a section of what remains from the larger Pacific-Farallon Ridge which used to be the primary spreading center of this region, driving the Farallon Plate underneath the North American Plate through the process of plate tectonics. Today, the Juan de Fuca Ridge pushes the Juan de Fuca Plate underneath the North American plate, forming the Cascadia Subduction Zone.
The Cobb hotspot is a marine volcanic hotspot at, which is 460 km (290 mi) west of Oregon and Washington, North America, in the Pacific Ocean. Over geologic time, the Earth's surface has migrated with respect to the hotspot through plate tectonics, creating the Cobb–Eickelberg Seamount chain. The hotspot is currently collocated with the Juan de Fuca Ridge.
Axial Seamount is a seamount, submarine volcano, and underwater shield volcano in the Pacific Ocean, located on the Juan de Fuca Ridge, approximately 480 km (298 mi) west of Cannon Beach, Oregon. Standing 1,100 m (3,609 ft) high, Axial Seamount is the youngest volcano and current eruptive center of the Cobb–Eickelberg Seamount chain. Located at the center of both a geological hotspot and a mid-ocean ridge, the seamount is geologically complex, and its origins are still poorly understood. Axial Seamount is set on a long, low-lying plateau, with two large rift zones trending 50 km (31 mi) to the northeast and southwest of its center. The volcano features an unusual rectangular caldera, and its flanks are pockmarked by fissures, vents, sheet flows, and pit craters up to 100 m (328 ft) deep; its geology is further complicated by its intersection with several smaller seamounts surrounding it.
The Cobb-Eickelberg seamount chain is a range of undersea mountains formed by volcanic activity of the Cobb hotspot located in the Pacific Ocean. The seamount chain extends to the southeast on the Pacific Plate, beginning at the Aleutian Trench and terminating at Axial Seamount, located on the Juan de Fuca Ridge. The seamount chain is spread over a vast length of approximately 1,800 km. The location of the Cobb hotspot that gives rise to these seamounts is 46° N—130° W. The Pacific plate is moving to the northwest over the hotspot, causing the seamounts in the chain to decrease in age to the southeast. Axial is the youngest seamount and is located approximately 480 km west of Cannon Beach, Oregon. The most studied seamounts that make up this chain are Axial, Brown Bear, Cobb, and Patton seamounts. There are many other seamounts in this chain which have not been explored.
The Southwest Indian Ridge (SWIR) is a mid-ocean ridge located along the floors of the south-west Indian Ocean and south-east Atlantic Ocean. A divergent tectonic plate boundary separating the Somali Plate to the north from the Antarctic Plate to the south, the SWIR is characterised by ultra-slow spreading rates (only exceeding those of the Gakkel Ridge in the Arctic) combined with a fast lengthening of its axis between the two flanking triple junctions, Rodrigues (20°30′S70°00′E) in the Indian Ocean and Bouvet (54°17′S1°5′W) in the Atlantic Ocean.
The Jan Mayen Microcontinent is a fragment of continental crust within the oceanic part of the western Eurasian Plate lying northeast of Iceland. At the onset of separation between the Greenland and Eurasian plates 55 million years ago, it formed part of the eastern margin of the Greenland Plate. Propagation of a new spreading center from the Reykjanes Ridge separated this microcontinent from the Greenland Plate. For a short period it formed a microplate, until the Aegir Ridge became inactive, after which it formed part of the Eurasian Plate. The island of Jan Mayen is a much younger feature, formed of volcanic rock, built up at the northernmost tip of the microcontinent.
Loki's Castle is a field of five active hydrothermal vents in the mid-Atlantic Ocean, located at 73 degrees north on the Mid-Atlantic Ridge between Iceland and Svalbard at a depth of 2,352 metres (7,717 ft). They were the most northerly black smoker vents when they were discovered in mid-July 2008.
The Endeavour Hydrothermal Vents are a group of hydrothermal vents in the north-eastern Pacific Ocean, located 260 kilometres (160 mi) southwest of Vancouver Island, British Columbia, Canada. The vent field lies 2,250 metres (7,380 ft) below sea level on the northern Endeavour segment of the Juan de Fuca Ridge. In 1982, dredged sulfide samples were recovered from the area covered in small tube worms and prompted a return to the vent field in August 1984, where the active vent field was confirmed by HOV Alvin on leg 10 of cruise AII-112.
The Rio Grande Rise, also called the Rio Grande Elevation or Bromley Plateau, is an aseismic ocean ridge in the southern Atlantic Ocean off the coast of Brazil. Together with the Walvis Ridge off Africa, the Rio Grande Rise forms a V-shaped structure of mirrored hotspot tracks or seamount chains across the northern South Atlantic. In 2013, Brazilian scientists announced that they found granite boulders on the Rio Grande Rise and speculated that it could be the remains of a submerged continent, which they called the "Brazilian Atlantis". Other researchers, however, noted that such boulders can end-up on the ocean floor by less speculative means.
The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.
Foundation Seamounts are a series of seamounts in the southern Pacific Ocean. Discovered in 1992, these seamounts form a 1,350 kilometres (840 mi) long chain which starts from the Pacific-Antarctic Ridge. Some of these seamounts may have once emerged from the ocean.
Pito Seamount is a seamount in the Pacific Ocean. It rises to a depth of 2,250 metres (7,380 ft) and features hydrothermal activity in the form of black smokers, which were discovered in 1993.
Vesteris Seamount, also known as Vesteris Bank, is a seamount in the Greenland Sea of the North Atlantic Ocean between Greenland and Norway. It lies north of Jan Mayen and rises from 41–43 million years old ocean crust. The reasons for the volcanic activity at Vesteris are unclear and may involve lithospheric processes.
Monowai Seamount is a volcanic seamount to the north of New Zealand. It is formed by a large caldera and a volcanic cone just south-southeast from the caldera. The volcanic cone rises to depths of up to 100 metres (330 ft) but its depth varies with ongoing volcanic activity, including sector collapses and the growth of lava domes. The seamount and its volcanism were discovered after 1877, but only in 1980 was it named "Monowai" after a research ship of the same name.
Kemp Caldera and Kemp Seamount form a submarine volcano south of the South Sandwich Islands, in a region where several seamounts are located. The seamount rises to a depth of 80 metres (260 ft) below sea level; the caldera has a diameter of 8.3 by 6.5 kilometres and reaches a depth of 1,600 metres (5,200 ft). The caldera contains several Hydrothermal vents, including white smokers and diffuse venting areas, which are host to chemolithotrophic ecological communities. The seamount and caldera, which were discovered by seafloor mapping in 2009, are part of the South Georgia and the South Sandwich Islands Marine Protected Area.
Sierra Leone hotspot is a proposed hotspot in the Atlantic Ocean.
71°54′50″N1°12′09″W / 71.91375225°N 1.20254893°W
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