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89-645: The Hudson Mountains are a mountain range in western Ellsworth Land just east of Pine Island Bay at the Walgreen Coast of the Amundsen Sea . They are of volcanic origin, consisting of low scattered mountains and nunataks that protrude through the West Antarctic Ice Sheet . The Hudson Mountains are bounded on the north by Cosgrove Ice Shelf and on the south by Pine Island Glacier . The mountains were volcanically active during

178-535: A volcanic explosivity index of 3-4 and originated in an area east of the main Hudson Mountains. LeMasurier et al. 1990 referenced reports of activity in the Hudson Mountains. These include a report of steaming at one of the nunataks and of satellite data of a potential eruption in 1985 of Webber Nunatak, but the report of this eruption is questionable. There is no evidence of increased heat flow or morphological changes at Webber Nunatak since then, but there

267-489: A continuous supply of magma to a hotspot. As the overlying tectonic plate moves over this hotspot, the eruption of magma from the fixed plume onto the surface is expected to form a chain of volcanoes that parallels plate motion. The Hawaiian Islands chain in the Pacific Ocean is the archetypal example. It has recently been discovered that the volcanic locus of this chain has not been fixed over time, and it thus joined

356-414: A core mantle heat flux of 20 mW/m , while the cycle time (the time between plume formation events) is about 2000 million years. The number of mantle plumes is predicted to be about 17. When a plume head encounters the base of the lithosphere, it is expected to flatten out against this barrier and to undergo widespread decompression melting to form large volumes of basalt magma. It may then erupt onto

445-543: A high Sr/ Sr ratio. Helium in OIB shows a wider variation in the He/ He ratio than MORB, with some values approaching the primordial value. The composition of ocean island basalts is attributed to the presence of distinct mantle chemical reservoirs formed by subduction of oceanic crust. These include reservoirs corresponding to HUIMU, EM1, and EM2. These reservoirs are thought to have different major element compositions, based on

534-405: A long thin conduit connecting the top of the plume to its base, and a bulbous head that expands in size as the plume rises. The entire structure resembles a mushroom. The bulbous head of thermal plumes forms because hot material moves upward through the conduit faster than the plume itself rises through its surroundings. In the late 1980s and early 1990s, experiments with thermal models showed that as

623-615: A lower temperature. Mantle material containing a trace of partial melt (e.g., as a result of it having a lower melting point), or being richer in Fe, also has a lower seismic wave speed and those effects are stronger than temperature. Thus, although unusually low wave speeds have been taken to indicate anomalously hot mantle beneath hotspots, this interpretation is ambiguous. The most commonly cited seismic wave-speed images that are used to look for variations in regions where plumes have been proposed come from seismic tomography. This method involves using

712-534: A mantle plume postulated to have caused the breakup of Eurasia and the opening of the North Atlantic, now suggested to underlie Iceland . Current research has shown that the time-history of the uplift is probably much shorter than predicted, however. It is thus not clear how strongly this observation supports the mantle plume hypothesis. Basalts found at oceanic islands are geochemically distinct from mid-ocean ridge basalt (MORB). Ocean island basalt (OIB)

801-647: A network of seismometers to construct three-dimensional images of the variation in seismic wave speed throughout the mantle. Seismic waves generated by large earthquakes enable structure below the Earth's surface to be determined along the ray path. Seismic waves that have traveled a thousand or more kilometers (also called teleseismic waves ) can be used to image large regions of Earth's mantle. They also have limited resolution, however, and only structures at least several hundred kilometers in diameter can be detected. Seismic tomography images have been cited as evidence for

890-562: A number of mantle plumes in Earth's mantle. There is, however, vigorous on-going discussion regarding whether the structures imaged are reliably resolved, and whether they correspond to columns of hot, rising rock. The mantle plume hypothesis predicts that domal topographic uplifts will develop when plume heads impinge on the base of the lithosphere. An uplift of this kind occurred when the North Atlantic Ocean opened about 54 million years ago. Some scientists have linked this to

979-399: A plume developed into a weakly defined hypothesis, which as a general term is currently neither provable nor refutable. The dissatisfaction with the state of the evidence for mantle plumes and the proliferation of ad hoc hypotheses drove a number of geologists, led by Don L. Anderson , Gillian Foulger , and Warren B. Hamilton , to propose a broad alternative based on shallow processes in

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1068-507: A separate causal category of terrestrial volcanism with implications for the study of hotspots and plate tectonics. In 1997 it became possible using seismic tomography to image submerging tectonic slabs penetrating from the surface all the way to the core-mantle boundary. For the Hawaii hotspot , long-period seismic body wave diffraction tomography provided evidence that a mantle plume is responsible, as had been proposed as early as 1971. For

1157-736: A single province separated by opening of the South Atlantic Ocean), and the Columbia River basalts of North America. Flood basalts in the oceans are known as oceanic plateaus, and include the Ontong Java plateau of the western Pacific Ocean and the Kerguelen Plateau of the Indian Ocean. The narrow vertical conduit, postulated to connect the plume head to the core-mantle boundary, is viewed as providing

1246-662: A steep northern rock face, marking the northwest extremity of the Hudson Mountains. It stands just east of the base of Canisteo Peninsula and overlooks Cosgrove Ice Shelf. Mapped from air photos taken by United States Navy OpHjp, 1946-47. Named by US-ACAN for Herbert P. Nickens, map compilation specialist who contributed significantly to the construction of USGS sketch maps of Antarctica. 73°53′S 100°00′W  /  73.883°S 100.000°W  / -73.883; -100.000 . A distinctive rock cliff which faces northward toward Cosgrove Ice Shelf, standing 5 nautical miles (9.3 km; 5.8 mi) northeast of Mount Nickens at

1335-791: A variety of rock types . Most geologically young mountain ranges on the Earth's land surface are associated with either the Pacific Ring of Fire or the Alpide belt . The Pacific Ring of Fire includes the Andes of South America, extends through the North American Cordillera , the Aleutian Range , on through Kamchatka Peninsula , Japan , Taiwan , the Philippines , Papua New Guinea , to New Zealand . The Andes

1424-433: Is 20±4 million years. There is no evidence of an age progression in any direction. Ice cover was thicker on the Hudson Mountains during the last glacial maximum , perhaps by about 150 metres (490 ft). Retreat commenced about 14,000-10,000 years ago; however, glaciers were still thicker than today during the early Holocene and deposited rocks on the Hudson Mountains. Another thinning step began about 8,000 years ago and

1513-722: Is 7,000 kilometres (4,350 mi) long and is often considered the world's longest mountain system. The Alpide belt stretches 15,000 km across southern Eurasia , from Java in Maritime Southeast Asia to the Iberian Peninsula in Western Europe , including the ranges of the Himalayas , Karakoram , Hindu Kush , Alborz , Caucasus , and the Alps . The Himalayas contain the highest mountains in

1602-744: 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. 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

1691-462: Is a strong thermal (temperature) discontinuity. The temperature of the core is approximately 1,000 degrees Celsius higher than that of the overlying mantle. Plumes are postulated to rise as the base of the mantle becomes hotter and more buoyant. Plumes are postulated to rise through the mantle and begin to partially melt on reaching shallow depths in the asthenosphere by decompression melting . This would create large volumes of magma. This melt rises to

1780-538: Is at work while the mountains are being uplifted until the mountains are reduced to low hills and plains. The early Cenozoic uplift of the Rocky Mountains of Colorado provides an example. As the uplift was occurring some 10,000 feet (3,000 m) of mostly Mesozoic sedimentary strata were removed by erosion over the core of the mountain range and spread as sand and clays across the Great Plains to

1869-454: Is consistent with a system that tends toward equilibrium: as matter rises in a mantle plume, other material is drawn down into the mantle, causing rifting. In parallel with the mantle plume model, two alternative explanations for the observed phenomena have been considered: the plate hypothesis and the impact hypothesis. Since the beginning of the 21st century, a paradigm debate "The great plume debate" has developed around plumes, in which

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1958-531: Is drier, having been stripped of much of its moisture. Often, a rain shadow will affect the leeward side of a range. As a consequence, large mountain ranges, such as the Andes, compartmentalize continents into distinct climate regions . Mountain ranges are constantly subjected to erosional forces which work to tear them down. The basins adjacent to an eroding mountain range are then filled with sediments that are buried and turned into sedimentary rock . Erosion

2047-536: Is enriched in trace incompatible elements , with the light rare earth elements showing particular enrichment compared with heavier rare earth elements. Stable isotope ratios of the elements strontium , neodymium , hafnium , lead , and osmium show wide variations relative to MORB, which is attributed to the mixing of at least three mantle components: HIMU with a high proportion of radiogenic lead, produced by decay of uranium and other heavy radioactive elements; EM1 with less enrichment of radiogenic lead; and EM2 with

2136-481: Is more diverse compositionally than MORB, and the great majority of ocean islands are composed of alkali basalt enriched in sodium and potassium relative to MORB. Larger islands, such as Hawaii or Iceland, are mostly tholeiitic basalt, with alkali basalt limited to late stages of their development, but this tholeiitic basalt is chemically distinct from the tholeiitic basalt of mid-ocean ridges. OIB tends to be more enriched in magnesium, and both alkali and tholeiitic OIB

2225-592: Is ongoing volcanic seismicity and anomalies in helium isotope ratios from the Pine Island Glacier ice have been attributed to volcanic activity in the Hudson Mountains. Download coordinates as: The southern part of the mountains includes, from west to east, Evans Knoll, Webber Nunatak, Shepherd Dome, Mount Manthe, Inman Nunatak, Meyers Nunatak and Wold Nunatak. The central part includes, from west to east, Tighe Rock, Maish Nunatak, Mount Moses, Velie Nunatak, Slusher Nunatak and Siren Rock. Features to

2314-438: 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 concept that mantle plumes are fixed relative to one another and anchored at

2403-506: Is that east and north-trending fractures have controlled the position of the volcanoes. The main volcanic rocks include alkali basalt , basalt , hawaiite and tephrite . They define an alkaline suite, some samples trend towards subalkaline. Ultramafic nodules have been reported from some rocks. The magmas erupted by the volcanoes may have originated in a mantle that had been influenced by subduction, and underwent fractionation of olivine as they ascended. Sparse lichens grow on most of

2492-482: Is that material and energy from Earth's interior are exchanged with the surface crust in two distinct and largely independent convective flows: The plume hypothesis was simulated by laboratory experiments in small fluid-filled tanks in the early 1970s. Thermal or compositional fluid-dynamical plumes produced in that way were presented as models for the much larger postulated mantle plumes. Based on these experiments, mantle plumes are now postulated to comprise two parts:

2581-738: The Chagos-Laccadive Ridge , the Louisville Ridge , the Ninety East Ridge and Kerguelen , Tristan , and Yellowstone . While there is evidence that the chains listed above are time-progressive, it has been shown that they are not fixed relative to one another. The most remarkable example of this is the Emperor chain, the older part of the Hawaii system, which was formed by migration of the hotspot in addition to

2670-679: The Larter Glacier traverses the Hudson Mountains between Mount Moses and Mount Manthe and other glaciers from the Hudson Mountains join the Pine Island Glacier. The glaciers are rapidly thinning owing to global warming . Mount Moses reaches an elevation of 749 metres (2,457 ft) above sea level, Teeters Nunatak 617 metres (2,024 ft), and Mount Manthe 576 metres (1,890 ft). Other named structures are: The volcanoes are made up by breccia , palagonite tuff , scoriaceous lava flows and tuffs. At Mount Nickles and Mount Moses there are pillow lavas . Lava fragments are dispersed on

2759-606: The Miocene and Pliocene , but there is evidence for an eruption about two millennia ago and uncertain indications of activity in the 20th century. The Hudson Mountains rise in western Ellsworth Land of West Antarctica and were discovered in 1940 by the United States Antarctic Service Expedition . The mountains lie at some distance from the Amundsen Sea 's Walgreen Coast , facing Pine Island Bay . The Cosgrove Ice Shelf lies north of

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2848-565: The Mithrim Montes and Doom Mons on Titan, and Tenzing Montes and Hillary Montes on Pluto. Some terrestrial planets other than Earth also exhibit rocky mountain ranges, such as Maxwell Montes on Venus taller than any on Earth and Tartarus Montes on Mars . Jupiter's moon Io has mountain ranges formed from tectonic processes including the Boösaule , Dorian, Hi'iaka and Euboea Montes . Mantle plume A mantle plume

2937-473: The Ocean Ridge forms the longest continuous mountain system on Earth, with a length of 65,000 kilometres (40,400 mi). The position of mountain ranges influences climate, such as rain or snow. When air masses move up and over mountains, the air cools, producing orographic precipitation (rain or snow). As the air descends on the leeward side, it warms again (following the adiabatic lapse rate ) and

3026-622: The Sudbury Igneous Complex in Canada are known to have caused melting and volcanism. In the impact hypothesis, it is proposed that some regions of hotspot volcanism can be triggered by certain large-body oceanic impacts which are able to penetrate the thinner oceanic lithosphere , and flood basalt volcanism can be triggered by converging seismic energy focused at the antipodal point opposite major impact sites. Impact-induced volcanism has not been adequately studied and comprises

3115-534: The United States Geological Survey . Mountain range Mountain ranges are usually segmented by highlands or mountain passes and valleys . Individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology . They may be a mix of different orogenic expressions and terranes , for example thrust sheets , uplifted blocks , fold mountains, and volcanic landforms resulting in

3204-543: The Yellowstone hotspot , seismological evidence began to converge from 2011 in support of the plume model, as concluded by James et al., "we favor a lower mantle plume as the origin for the Yellowstone hotspot." Data acquired through Earthscope , a program collecting high-resolution seismic data throughout the contiguous United States has accelerated acceptance of a plume underlying Yellowstone. Although there

3293-404: The lower mantle under Africa and under the central Pacific. It is postulated that plumes rise from their surface or their edges. Their low seismic velocities were thought to suggest that they are relatively hot, although it has recently been shown that their low wave velocities are due to high density caused by chemical heterogeneity. Some common and basic lines of evidence cited in support of

3382-627: The Byrd Station party, 1966. 74°12′S 100°01′W  /  74.200°S 100.017°W  / -74.200; -100.017 . A nunatak 615 metres (2,018 ft) high standing 5 nautical miles (9.3 km; 5.8 mi) north of Hodgson Nunatak. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Robert E. Teeters, United States Navy, storekeeper at Byrd Station, 1966. 74°05′S 100°13′W  /  74.083°S 100.217°W  / -74.083; -100.217 . Isolated nunatak just north of

3471-476: The Earth's core, in basalts at oceanic islands. However, so far conclusive proof for this is lacking. The plume hypothesis has been tested by looking for the geophysical anomalies predicted to be associated with them. These include thermal, seismic, and elevation anomalies. Thermal anomalies are inherent in the term "hotspot". They can be measured in numerous different ways, including surface heat flow, petrology, and seismology. Thermal anomalies produce anomalies in

3560-467: The Hudson Mountains, and left glacial striations on the pillow lavas of Mount Moses. Physical weathering has yielded soils in some areas. Volcanic glass found in the Pine Island Glacier probably originates in the Hudson Mountains. Neighbouring Marie Byrd Land was volcanically active during the Cenozoic , forming a number of volcanoes, some of which are buried under ice, while others emerge above

3649-665: The Hudson Mountains, located 8 nautical miles (15 km; 9.2 mi) north-northwest of Teeters Nunatak. Mapped by USGS from ground surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Major Edward Rebholz, operations officer of the United States Army Aviation Detachment which supported the Ellsworth Land Survey, 1968-69. 73°56′S 100°20′W  /  73.933°S 100.333°W  / -73.933; -100.333 . A snow-covered mesa-type mountain with

Hudson Mountains - Misplaced Pages Continue

3738-678: The Hudson Mountains, located near the center of the group, about 14 nautical miles (26 km; 16 mi) north-northeast of Mount Manthe. Mapped from air photos taken by United States Navy OpHjp, 1946–47. Named by US-ACAN for Robert L. Moses, geomagnetist-seismologist at Byrd Station, 1967. 74°31′S 98°48′W  /  74.517°S 98.800°W  / -74.517; -98.800 . Two nunataks lying about 6 nautical miles (11 km; 6.9 mi) east-northeast of Mount Moses. Mapped by USGS from ground surveys and United States Navy air photos, 1960-66. Named by US-ACAN for William S. Dean of Pleasanton, Texas, who served as ham radio contact in

3827-542: The Hudson Mountains, which may reflect the presence of the Marie Byrd Land mantle plume. The bedrock around the Hudson Mountains lies below sea level. The basement on which the volcanoes formed is not exposed in the Hudson Mountains, but crops out in the neighbouring Jones Mountains . It forms the so-called Thurston Island tectonic block. Below the Hudson Mountains, the crust is about 21–27 kilometres (13–17 mi) thick. A proposal by Lopatin and Polyakov 1974

3916-782: The Hudson Mountains. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Herbert Meyers, USARP geomagnetist at Byrd Station, 1960-61. 74°47′S 98°38′W  /  74.783°S 98.633°W  / -74.783; -98.633 . A nunatak standing 10 nautical miles (19 km; 12 mi) east of Mount Manthe in the southeast part of the Hudson Mountains. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Richard J. Wold, USARP geologist at Byrd Station, 1960-61 season. 74°52′S 98°08′W  /  74.867°S 98.133°W  / -74.867; -98.133 . Isolated nunatak about 20 nautical miles (37 km; 23 mi) east-southeast of Mount Manthe, at

4005-419: The Hudson Mountains. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Martin M. Inman, auroral scientist at Byrd Station, 1960–61 and 1961-62 seasons. 74°54′S 98°46′W  /  74.900°S 98.767°W  / -74.900; -98.767 . A nunatak located 10 nautical miles (19 km; 12 mi) east-southeast of Mount Manthe, at the southeast end of

4094-485: The Hudson Mountains. The mountains are remote and visits are rare. In 1991, they were prospected as a potential aircraft landing site. The mountains are a volcanic field formed by parasitic vents and stratovolcanoes covered in snow and ice, forming a cold desert landscape with an area of about 8,400 square kilometres (3,200 sq mi). About 20 mountains emerge above the Antarctic Ice Sheet in

4183-1060: The United States for the Ellsworth Land Survey party of 1968-69, and for other USARP field parties over a three year period. 74°23′S 99°10′W  /  74.383°S 99.167°W  / -74.383; -99.167 . A nunatak located 9 nautical miles (17 km; 10 mi) north of Mount Moses. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-AC AN for Edward C. Velie, meteorologist at Byrd Station, 1967. 74°27′S 99°06′W  /  74.450°S 99.100°W  / -74.450; -99.100 . A nunatak lying 5 nautical miles (9.3 km; 5.8 mi) north of Mount Moses. Mapped from air photos taken by United States Navy OpHjp, 1946-47. Named by US-ACAN for Harold E. Slusher, meteorologist at Byrd Station, 1967. 74°33′S 98°24′W  /  74.550°S 98.400°W  / -74.550; -98.400 . A fairly isolated rock lying 12 nautical miles (22 km; 14 mi) east of-Mount Moses, in

4272-507: The bottom of the mantle transition zone at 650 km depth. Subduction to greater depths is less certain, but there is evidence that they may sink to mid-lower-mantle depths at about 1,500  km depth. The source of mantle plumes is postulated to be the core-mantle boundary at 3,000  km depth. Because there is little material transport across the core-mantle boundary, heat transfer must occur by conduction, with adiabatic gradients above and below this boundary. The core-mantle boundary

4361-428: The bulbous head expands it may entrain some of the adjacent mantle into itself. The size and occurrence of mushroom mantle plumes can be predicted by the transient instability theory of Tan and Thorpe. The theory predicts mushroom-shaped mantle plumes with heads of about 2000 km diameter that have a critical time (time from onset of heating of the lower mantle to formation of a plume) of about 830 million years for

4450-446: The central part of the Hudson Mountains. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for F. Michael Maish, ionospheric physicist at Byrd Station in 1967, who served as United States exchange scientist at Vostok Station in 1969. 74°33′S 99°11′W  /  74.550°S 99.183°W  / -74.550; -99.183 . The highest 750 metres (2,460 ft) high and most prominent of

4539-589: The club of the many type examples that do not exhibit the key characteristic originally proposed. The eruption of continental flood basalts is often associated with continental rifting and breakup. This has led to the hypothesis that mantle plumes contribute to continental rifting and the formation of ocean basins. The chemical and isotopic composition of basalts found at hotspots differs subtly from mid-ocean-ridge basalts. These basalts, also called ocean island basalts (OIBs), are analysed in their radiogenic and stable isotope compositions. In radiogenic isotope systems

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4628-484: The core-mantle boundary (2900 km depth) to a possible layer of shearing and bending at 1000 km. They were detectable because they were 600–800 km wide, more than three times the width expected from contemporary models. Many of these plumes are in the large low-shear-velocity provinces under Africa and the Pacific, while some other hotspots such as Yellowstone were less clearly related to mantle features in

4717-466: The core-mantle boundary would provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hotspots, for example, the Hawaiian–Emperor seamount chain . However, paleomagnetic data show that mantle plumes can also be associated with Large Low Shear Velocity Provinces (LLSVPs) and do move relative to each other. The current mantle plume theory

4806-467: The core-mantle boundary. Lithospheric extension is attributed to processes related to plate tectonics. These processes are well understood at mid-ocean ridges, where most of Earth's volcanism occurs. It is less commonly recognised that the plates themselves deform internally, and can permit volcanism in those regions where the deformation is extensional. Well-known examples are the Basin and Range Province in

4895-438: The correlation between major element compositions of OIB and their stable isotope ratios. Tholeiitic OIB is interpreted as a product of a higher degree of partial melting in particularly hot plumes, while alkali OIB is interpreted as a product of a lower degree of partial melting in smaller, cooler plumes. In 2015, based on data from 273 large earthquakes, researchers compiled a model based on full waveform tomography , requiring

4984-605: The east part of the Hudson Mountains. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Jan C. Siren, radio scientist at Byrd Station, 1967. 74°17′S 100°04′W  /  74.283°S 100.067°W  / -74.283; -100.067 . A nunatak which lies 5 nautical miles (9.3 km; 5.8 mi) south of Teeters Nunatak and 20 nautical miles (37 km; 23 mi) northwest of Mount Moses. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Ronald A. Hodgson, United States Navy, builder with

5073-485: The east. This mass of rock was removed as the range was actively undergoing uplift. The removal of such a mass from the core of the range most likely caused further uplift as the region adjusted isostatically in response to the removed weight. Rivers are traditionally believed to be the principal cause of mountain range erosion, by cutting into bedrock and transporting sediment. Computer simulation has shown that as mountain belts change from tectonically active to inactive,

5162-523: The equivalent of 3 million hours of supercomputer time. Due to computational limitations, high-frequency data still could not be used, and seismic data remained unavailable from much of the seafloor. Nonetheless, vertical plumes, 400 C hotter than the surrounding rock, were visualized under many hotspots, including the Pitcairn , Macdonald , Samoa , Tahiti , Marquesas , Galapagos , Cape Verde , and Canary hotspots. They extended nearly vertically from

5251-478: The form of nunataks , with the largest rocky outcrops found at Mount Moses and Maish Nunatak . The stratovolcanoes Mount Manthe , Mount Moses, and Teeters Nunatak constitute the bulk of the volcanic field and are heavily eroded. Better preserved are some parasitic cones and volcanic craters which appear to have formed on these three volcanoes. To their south lies the Pine Island Glacier , while

5340-462: The head of Cosgrove Ice Shelf and 17 nautical miles (31 km; 20 mi) east-northeast of Pryor Cliff, at the extreme north end of the Hudson Mountains. Mapped by USGS from ground surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Richard E. Kenfield, USGS topographic engineer working from Byrd Station in the 1963-64 season. [REDACTED]  This article incorporates public domain material from websites or documents of

5429-489: The ice sheet. The Hudson Mountains are part of the Thurston Island or Bellingshausen Volcanic Province, and are its largest and best preserved volcanic field. The volcanism at the mountains may have either been caused by a mantle plume under Marie Byrd Land or by the presence of anomalies ( slab windows ) in the mantle left over by subduction . Seismic tomography has found evidence of low velocity anomalies under

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5518-535: The mantle source. There are two competing interpretations for this. In the context of mantle plumes, the near-surface material is postulated to have been transported down to the core-mantle boundary by subducting slabs, and to have been transported back up to the surface by plumes. In the context of the Plate hypothesis, subducted material is mostly re-circulated in the shallow mantle and tapped from there by volcanoes. Stable isotopes like Fe are used to track processes that

5607-436: The model. The unexpected size of the plumes leaves open the possibility that they may conduct the bulk of the Earth's 44 terawatts of internal heat flow from the core to the surface, and means that the lower mantle convects less than expected, if at all. It is possible that there is a compositional difference between plumes and the surrounding mantle that slows them down and broadens them. Mantle plumes have been suggested as

5696-458: The north end of the Hudson Mountains. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Douglas A. Pryor, map compilation specialist who contributed significantly to construction of USGS sketch maps of Antarctica. 73°46′S 99°03′W  /  73.767°S 99.050°W  / -73.767; -99.050 . An isolated nunatak which lies about 8 nautical miles (15 km; 9.2 mi) southeast of

5785-511: The north side of Pine Island Glacier, standing 4 nautical miles (7.4 km; 4.6 mi) southwest of Mount Manthe. Mapped from air photos made by United States Navy OpHjp, 1946-47. Named by US-ACAN for Donald C. Shepherd, ionospheric physicist at Byrd Station, 1967. 74°47′S 99°21′W  /  74.783°S 99.350°W  / -74.783; -99.350 . A mountain 575 metres (1,886 ft) high standing 5 nautical miles (9.3 km; 5.8 mi) north-northeast of Shepherd Dome, in

5874-418: The north, from south to north, include Hodgson Nunatak, Teeters Nunatak, Mount Nickens, Pryor Cliff and Kenfield Nunatak. 74°51′S 100°25′W  /  74.850°S 100.417°W  / -74.850; -100.417 . A mainly snow-covered knoll on the coast at the north side of the terminus of Pine Island Glacier. It lies 9 nautical miles (17 km; 10 mi) southwest of Webber Nunatak and marks

5963-442: The nunataks, including Usnea species. Mosses have been found growing in gaps between or cracks in boulders. Petrels have been observed. There are no data on the local climate. An automated weather station was installed on Evans Knoll in 2011 and records air temperatures and wind speeds. The volcanoes were active during the late Miocene and Pliocene . Dates range between 8.5±1.0 and 3.7±0.2 million years ago, an older date

6052-409: The originally subducted material creates diverging trends, termed mantle components. Identified mantle components are DMM (depleted mid-ocean ridge basalt (MORB) mantle), HIMU (high U/Pb-ratio mantle), EM1 (enriched mantle 1), EM2 (enriched mantle 2) and FOZO (focus zone). This geochemical signature arises from the mixing of near-surface materials such as subducted slabs and continental sediments, in

6141-620: The plate motion. Another example is the Canary Islands in the northeast of Africa in the Atlantic Ocean. Helium-3 is a primordial isotope that formed in the Big Bang . Very little is produced, and little has been added to the Earth by other processes since then. Helium-4 includes a primordial component, but it is also produced by the natural radioactive decay of elements such as uranium and thorium . Over time, helium in

6230-412: The plume hypothesis has been challenged and contrasted with the more recent plate hypothesis ("Plates vs. Plumes"). The reason for this is that the mantle-plume hypothesis has not been suitable for making reliable predictions since its introduction in 1971 and has therefore been repeatedly adapted to observed hotspots depending on the situation. Over time, with the growing number of models, the concept of

6319-627: The rate of erosion drops because there are fewer abrasive particles in the water and fewer landslides. Mountains on other planets and natural satellites of the Solar System, including the Moon , are often isolated and formed mainly by processes such as impacts, though there are examples of mountain ranges (or "Montes") somewhat similar to those on Earth. Saturn 's moon Titan and Pluto , in particular, exhibit large mountain ranges in chains composed mainly of ices rather than rock. Examples include

6408-463: The sense of columnar vertical features that span most of the Earth's mantle, transport large amounts of heat, and contribute to surface volcanism. Under the umbrella of the plate hypothesis, the following sub-processes, all of which can contribute to permitting surface volcanism, are recognised: In addition to these processes, impact events such as ones that created the Addams crater on Venus and

6497-550: The shallow asthenosphere that is thought to be flowing rapidly in response to motion of the overlying tectonic plates. There is no other known major thermal boundary layer in the deep Earth, and so the core-mantle boundary was the only candidate. The base of the mantle is known as the D″ layer , a seismological subdivision of the Earth. It appears to be compositionally distinct from the overlying mantle and may contain partial melt. Two very broad, large low-shear-velocity provinces exist in

6586-442: The slopes of Mount Moses. Volcanic rock sequences that were emplaced under water and under ice are overlaid by volcanic products that were deposed under the atmosphere, there are deposits of volcanic ash and breccia produced by hydromagmatic activity and tuya -like shapes associated with subglacial growth of the volcanoes. At Mount Moses, erosion has exposed dykes . Glaciers have deposited granite boulders and erratic blocks on

6675-734: The source for flood basalts . These extremely rapid, large scale eruptions of basaltic magmas have periodically formed continental flood basalt provinces on land and oceanic plateaus in the ocean basins, such as the Deccan Traps , the Siberian Traps the Karoo-Ferrar flood basalts of Gondwana , and the largest known continental flood basalt, the Central Atlantic magmatic province (CAMP). Many continental flood basalt events coincide with continental rifting. This

6764-399: The south part of the Hudson Mountains. Mapped from air photos taken by United States Navy OpHjp, 1946-47. Named by US-ACAN for Lawrene L. Manthe, meteorologist at Byrd Station, 1967. 74°49′S 98°54′W  /  74.817°S 98.900°W  / -74.817; -98.900 . A nunatak standing 6 nautical miles (11 km; 6.9 mi) east of Mount Manthe in the southeast part of

6853-415: The southeast margin of the Hudson Mountains. Mapped by USGS from ground surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Walter Koehler, United States Army Aviation Detachment, helicopter pilot for the Ellsworth Land Survey, 1968-69. 74°26′S 100°04′W  /  74.433°S 100.067°W  / -74.433; -100.067 . A rock outcropping along the coastal slope at

6942-769: The southwest end of the Hudson Mountains. Mapped from air photos taken by United States Navy OpHjp, 1946-47. Named by US-ACAN for Donald J. Evans who studied very-lowfrequency emissions from the upper atmosphere at Byrd Station,1960-61. 74°47′S 99°50′W  /  74.783°S 99.833°W  / -74.783; -99.833 . A nunatak 495 metres (1,624 ft) high standing 6 nautical miles (11 km; 6.9 mi) west of Mount Manthe. Mapped from air photos taken by United States Navy Operation Highjump (OpHjp), 1946–47. Named by US-ACAN for George E. Webber, electrical engineer at Byrd Station, 1967. 74°52′S 99°33′W  /  74.867°S 99.550°W  / -74.867; -99.550 . A low dome-shaped mountain at

7031-425: The speeds of seismic waves, but unfortunately so do composition and partial melt. As a result, wave speeds cannot be used simply and directly to measure temperature, but more sophisticated approaches must be taken. Seismic anomalies are identified by mapping variations in wave speed as seismic waves travel through Earth. A hot mantle plume is predicted to have lower seismic wave speeds compared with similar material at

7120-411: The surface and erupts to form hotspots. The most prominent thermal contrast known to exist in the deep (1000 km) mantle is at the core-mantle boundary at 2900 km. Mantle plumes were originally postulated to rise from this layer because the hotspots that are assumed to be their surface expression were thought to be fixed relative to one another. This required that plumes were sourced from beneath

7209-750: The surface. Numerical modelling predicts that melting and eruption will take place over several million years. These eruptions have been linked to flood basalts , although many of those erupt over much shorter time scales (less than 1 million years). Examples include the Deccan traps in India, the Siberian traps of Asia, the Karoo-Ferrar basalts/dolerites in South Africa and Antarctica, the Paraná and Etendeka traps in South America and Africa (formerly

7298-533: The theory are linear volcanic chains, noble gases , geophysical anomalies, and geochemistry . The age-progressive distribution of the Hawaiian-Emperor seamount chain has been explained as a result of a fixed, deep-mantle plume rising into the upper mantle, partly melting, and causing a volcanic chain to form as the plate moves overhead relative to the fixed plume source. Other hotspots with time-progressive volcanic chains behind them include Réunion ,

7387-556: The upper atmosphere is lost into space. Thus, the Earth has become progressively depleted in helium, and He is not replaced as He is. As a result, the ratio He/ He in the Earth has decreased over time. Unusually high He/ He have been observed in some, but not all, hotspots. This is explained by plumes tapping a deep, primordial reservoir in the lower mantle, where the original, high He/ He ratios have been preserved throughout geologic time. Other elements, e.g. osmium , have been suggested to be tracers of material arising from near to

7476-480: The upper mantle and above, with an emphasis on plate tectonics as the driving force of magmatism. The plate hypothesis suggests that "anomalous" volcanism results from lithospheric extension that permits melt to rise passively from the asthenosphere beneath. It is thus the conceptual inverse of the plume hypothesis because the plate hypothesis attributes volcanism to shallow, near-surface processes associated with plate tectonics, rather than active processes arising at

7565-457: The uprising material experiences during melting. The processing of oceanic crust, lithosphere, and sediment through a subduction zone decouples the water-soluble trace elements (e.g., K, Rb, Th) from the immobile trace elements (e.g., Ti, Nb, Ta), concentrating the immobile elements in the oceanic slab (the water-soluble elements are added to the crust in island arc volcanoes). Seismic tomography shows that subducted oceanic slabs sink as far as

7654-476: The west margin of the Hudson Mountains, located 15 nautical miles (28 km; 17 mi) northwest of Mount Moses. Mapped by USGS from surveys and United States Navy air photos, 1960-66. Named by US-ACAN for Robert F. Tighe, electrical engineer at Byrd Station, 1964-65. 74°36′S 99°28′W  /  74.600°S 99.467°W  / -74.600; -99.467 . A nunatak located 5 nautical miles (9.3 km; 5.8 mi) west-southwest of Mount Moses, in

7743-590: The western USA, the East African Rift valley, and the Rhine Graben . Under this hypothesis, variable volumes of magma are attributed to variations in chemical composition (large volumes of volcanism corresponding to more easily molten mantle material) rather than to temperature differences. While not denying the presence of deep mantle convection and upwelling in general, the plate hypothesis holds that these processes do not result in mantle plumes, in

7832-543: The world, including Mount Everest , which is 8,848 metres (29,029 ft) high. Mountain ranges outside these two systems include the Arctic Cordillera , Appalachians , Great Dividing Range , East Siberians , Altais , Scandinavians , Qinling , Western Ghats , Vindhyas , Byrrangas , and the Annamite Range . If the definition of a mountain range is stretched to include underwater mountains, then

7921-463: Was very fast, perhaps lasting only a century. Radar data have found a tephra deposit buried under the ice, which may have originated during an eruption of the Hudson Mountains around 207 ± 240 BCE ; the eruption may correspond to an electrical conductivity anomaly in an ice core at Siple Dome and a tephra layer dated to 325 BCE in the Byrd Station ice core . The eruption may have had

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