Mount Waesche | |
---|---|
Highest point | |
Elevation | 3,292 m (10,801 ft) [1] |
Coordinates | 77°10′S127°00′W / 77.167°S 127.000°W [1] |
Geography | |
Parent range | Executive Committee Range |
Geology | |
Mountain type | Shield volcano |
Volcanic field | Marie Byrd Land Volcanic Province |
Last eruption | Unknown [2] |
Mount Waesche is a mountain of volcanic origin at the southern end of the Executive Committee Range in Marie Byrd Land, Antarctica. It is 3,292 metres (10,801 feet) high, and stands 20 kilometres (12 miles) southwest of Mount Sidley, the highest volcano in Antarctica. The mountain lies southwest of the Chang Peak caldera and is largely covered with snow and glaciers, but there are rock exposures on the southern and southwestern slopes.
The volcano may have been active as late as the Holocene, with tephra layers recovered from ice cores possibly originating from Mount Waesche. Seismic activity has been recorded both from the volcano and from an area south of it and might reflect ongoing volcanic activity.
It was discovered by the United States Antarctic Service expedition on a flight on December 15, 1940, and named for Vice Admiral Russell R. Waesche, United States Coast Guard, member of the Antarctic Service Executive Committee. [3] Field studies took place in 1999-2000 and 2018–2019. [4]
Mount Waesche lies in Marie Byrd Land, one of the most inaccessible areas of Antarctica. It is one of 18 volcanoes in that region, which were active from the Oligocene to recent times. The origin of volcanic activity there has been correlated to the activity of a mantle plume underneath the crust. The region also includes the highest volcano in Antarctica, Mount Sidley, which reaches 4,191 metres (13,750 ft) height. [5] There may be as many as 138 volcanoes buried underneath the ice. [6]
The volcano is 3,292 metres (10,801 ft) high. [1] It is a double volcano, [7] with the north-northeasterly Chang Peak caldera and the south-southwesterly Mount Waesche proper. [8] The Chang Peak caldera is 10 by 6 kilometres (6.2 mi × 3.7 mi) [9] wide and the largest in Marie Byrd Land; [2] [10] Mount Waesche rises almost 500 metres (1,600 ft) [11] over and lies on the rim of the caldera. Mount Waesche is the more conspicuous peak and lava flows crop out on its southern [7] and southwestern flank, [12] while a 2 kilometres (1.2 mi) wide caldera lies at its summit. [10] On the northern side of Chang Peak caldera lies a 2,920 metres (9,580 ft) high outcrop, [8] and it and another outcrop consist of pumice and vitrophyre. Both volcanoes appear to be mainly formed by lava. [7] At least five [13] parasitic vents lie on the volcano, with several aligned on radial fissure vents; [7] they are cinder cones [2] and scoria cones [14] and have erupted cinder, lava and volcanic bombs. [12] A 0.5 metres (1 ft 8 in) long [7] large radial dyke projects from Mount Waesche [15] and is the only part of the edifice where hyaloclastic tuff crops out. [7] The Bennet Saddle separates Mount Waesche from Mount Sidley [8] 20 kilometres (12 mi) to the northeast. [2]
Mount Waesche is largely covered with snow and features several alpine glaciers as well as a blue-ice area [lower-alpha 1] [12] within the West Antarctic Ice Sheet; [18] this blue-ice area has an extent of 8 by 10 kilometres (5.0 mi × 6.2 mi) and a number of tephra layers crop out from the ice. Most of these tephra layers come from Mount Waesche, but some originate at Mount Takahe and Mount Berlin [19] and their age ranges from 118,000 years to Holocene. [20] Two particularly conspicuous tephra layers from Mount Waesche are known as the "Great Wall" and "Yellow Wall". [21]
The volcano emerges through [22] and is surrounded by the West Antarctic Ice Sheet. The ice sheet reaches an elevation of about 2,000 metres (6,600 ft) above sea level at Mount Waesche [12] and flows southward [23] towards the Ross Ice Shelf. [24] Blue ice is found in some areas. [22] Glacial activity has altered the volcano, generating glacial striae and roches moutonnees on the older volcanic rocks and frost shattering landforms and solifluction ridges. [10] Glacial drift lies on the ice-free southwestern flank. [25] In turn, glacial moraines have been overrun by lava flows. [10] Two sets of moraines formed by volcanic debris – one containing ice, the other without – lie on the southern and southwestern flank, reaching heights of 120 metres (390 ft) and lengths of about 3 kilometres (1.9 mi). [12] Surface exposure dating has indicated that they belong to an ice highstand that occurred about 10,000 years ago [26] and that the volcanic rocks were probably extracted from underneath the ice. [27] However, large parts of the volcano are exposed on its southwestern flank [28] and apart from glacial erosion aeolian erosion has taken place on the volcano. [14]
Mount Waesche is part of the Executive Committee Range, which from north to south includes Mount Hampton, Mount Cumming with the parasitic vent Annexstad Peak, Mount Hartigan, Mount Sidley with Doumani Peak and Chang Peak-Mount Waesche. These mountains are all volcanic and feature ice-filled calderas, [5] and many are paired volcanoes. [29] Volcanic activity appears to be moving southward at a rate of 0.7 centimetres per year (0.28 in/year). [30] Seismic activity recorded in 2010 and 2011 south of Mount Waesche may indicate ongoing magmatic activity south of the youngest volcano. [31] Chang Peak and Mount Waesche appear to be located outside of the Executive Committee Range volcanic lineament. [32]
The volcano erupted comendite, hawaiite and mugearite, with the former found at Chang Peak and the latter two at Mount Waesche proper; the parasitic cones have erupted a mugearite-benmoreite succession. [1] [7] The occurrence of rhyolite has also been reported. [10] There appear to be two groups of volcanic rocks at Mount Waesche. [11] Phenocrysts at Chang Peak include aenigmatite, alkali feldspar, ilmenite and quartz and at Mount Waesche olivine, plagioclase and titanaugite. [7] Granulite and pyroxenite xenoliths have also been found. [33] Despite their proximity, Mount Sidley and Mount Waesche have erupted distinctly different rocks. [34] Unusually for volcanoes in Marie Byrd Land, the chemistry of volcanic rocks at Mount Waesche appears to have changed over time. [35] The total volume of rocks is about 160 cubic kilometres (38 cu mi). [36]
The development of Mount Waesche began in the Pliocene, [1] and Plio-Pleistocene tephra layers found in the Southern Pacific Ocean may originate at Mount Waesche. [37] It appears that volcanism in the Executive Committee Range moved southwards over time, beginning at Mount Hampton and eventually arriving at Mount Waesche which is the young volcanic centre of the range. [38] Chang Peak grew first, 1.6 million years ago or between 2.0–1.1 million years ago, while Mount Waesche formed within or about 1 million years ago; the youngest rocks at Waesche are less than 100,000 years old [13] [39] whereas there is no evidence of recent activity at Chang Peak. [11] Argon-argon dating on rocks that today form moraines has yielded ages of about 200,000 years to over 500,000 years. [27] One flank vent has been dated to be 170,000 years old [13] and some rocks are too young to be dated by potassium-argon dating. [2] A major pulse of lava flow emissions appears to have occurred 200,000-100,000 years ago [40] and an older episode 500,000-300,000 years ago. [14]
The volcano was active during the Holocene [41] and may be a source of tephra found in ice cores. [42] A layer of volcanic ash was identified in the region through radar data and is about 8,000 years old; it probably originated at Mount Waesche. [43] The volcano today is considered to be "probably active" or "possibly active". [44] A magmatic system may exist 55 kilometres (34 mi) south of Mount Waesche at 25–40 kilometres (16–25 mi) depth below the ice. [45] Present-day seismic activity has been recorded at Mount Waesche, but it might be either volcanic/tectonic or caused by ice movement. [46] Future eruptions are unlikely to have any impact beyond the surroundings of the volcano. [47]
The geography of Antarctica is dominated by its south polar location and, thus, by ice. The Antarctic continent, located in the Earth's southern hemisphere, is centered asymmetrically around the South Pole and largely south of the Antarctic Circle. It is washed by the Southern Ocean or, depending on definition, the southern Pacific, Atlantic, and Indian Oceans. It has an area of more than 14.2 million km2. Antarctica is the largest ice desert in the world.
Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of 1,610,000 km2 (620,000 sq mi), it is the largest unclaimed territory on Earth. It was named after the wife of American naval officer Richard E. Byrd, who explored the region in the early 20th century.
Mount Andrus is a peak 2 nautical miles southeast of Mount Boennighausen in the southeast extremity of the Ames Range, in Marie Byrd Land, Antarctica.
Mount Hampton is a shield volcano with a circular ice-filled caldera. It is a twin volcano with Whitney Peak to the northwest and has erupted phonolite rocks. It is the northernmost of the volcanoes which comprise the Executive Committee Range in Marie Byrd Land, Antarctica and was active during the Miocene.
Mount Melbourne is a 2,733-metre-high (8,967 ft) ice-covered stratovolcano in Victoria Land, Antarctica, between Wood Bay and Terra Nova Bay. It is an elongated mountain with a summit caldera filled with ice with numerous parasitic vents; a volcanic field surrounds the edifice. Mount Melbourne has a volume of about 180 cubic kilometres (43 cu mi) and consists of tephra deposits and lava flows; tephra deposits are also found encased within ice and have been used to date the last eruption of Mount Melbourne to 1892 ± 30 years. The volcano is fumarolically active.
Mount Morning is a shield volcano at the foot of the Transantarctic Mountains in Victoria Land, Antarctica. It lies 100 kilometres (62 mi) from Ross Island. Mount Morning rises to an elevation of 2,723 metres (8,934 ft) and is almost entirely mantled with snow and ice. A 4.1 by 4.9 kilometres wide summit caldera lies at the top of the volcano and several ice-free ridges such as Hurricane Ridge and Riviera Ridge emanate from the summit. A number of parasitic vents mainly in the form of cinder cones dot the mountain.
Mount Moulton is a 40-kilometre-long (25 mi) complex of ice-covered shield volcanoes, standing 25 kilometres (16 mi) east of Mount Berlin in the Flood Range, Marie Byrd Land, Antarctica. It is named for Richard S. Moulton, chief dog driver at West Base. The volcano is of Pliocene age and is presently inactive.
Mount Sidley is the highest dormant volcano in Antarctica, a member of the Volcanic Seven Summits, with a summit elevation of 4,181–4,285 metres (13,717–14,058 ft). It is a massive, mainly snow-covered shield volcano, which is the highest of the five volcanic mountains that comprise the Executive Committee Range of Marie Byrd Land. The feature is marked by a 5 km wide caldera on the southern side and stands NE of Mount Waesche in the southern part of the range.
Mount Takahe is a 3,460-metre-high (11,350 ft) snow-covered shield volcano in Marie Byrd Land, Antarctica, 200 kilometres (120 mi) from the Amundsen Sea. It is a c. 30-kilometre-wide (19 mi) mountain with parasitic vents and a caldera up to 8 kilometres (5 mi) wide. Most of the volcano is formed by trachytic lava flows, but hyaloclastite is also found. Snow, ice, and glaciers cover most of Mount Takahe. With a volume of 780 km3 (200 cu mi), it is a massive volcano; the parts of the edifice that are buried underneath the West Antarctic Ice Sheet are probably even larger. It is part of the West Antarctic Rift System along with eighteen other known volcanoes.
Toney Mountain is an elongated snow-covered shield volcano, 38 nautical miles long and rising to 3,595 metres (11,795 ft) at Richmond Peak, located 35 nautical miles southwest of Kohler Range in Marie Byrd Land, Antarctica.
The Pleiades are a volcanic group in northern Victoria Land of Antarctica. It consists of youthful cones and domes with Mount Atlas/Mount Pleiones, a small stratovolcano formed by three overlapping cones, being the dominant volcano and rising 500 m (1,600 ft) above the Evans Névé plateau. Two other named cones are Alcyone Cone and Taygete Cone, the latter of which has been radiometrically dated to have erupted during the Holocene. A number of tephra layers across Antarctica have been attributed to eruptions of this volcanic group, including several that may have occurred within the last few hundred years.
Crary Mountains are a group of ice-covered volcanoes in Marie Byrd Land, Antarctica. They consist of two or three shield volcanoes, named Mount Rees, Mount Steere and Mount Frakes, which developed during the course of the Miocene and Pliocene and last erupted about 30,000-40,000 years ago. The first two volcanoes are both heavily incised by cirques, while Mount Frakes is better preserved and has a 4 kilometres (2.5 mi) wide caldera at its summit. Boyd Ridge is another part of the mountain range and lies southeast of Mount Frakes; it might be the emergent part of a platform that underlies the mountain range.
The Executive Committee Range is a range consisting of five major volcanoes, which trends north-south for 50 nautical miles along the 126th meridian west, in Marie Byrd Land, Antarctica.
Mount Siple is a potentially active Antarctic shield volcano, rising to 3,110 metres (10,203 ft) and dominating the northwest part of Siple Island, which is separated from the Bakutis Coast, Marie Byrd Land, by the Getz Ice Shelf. Its youthful appearance strongly suggests that it last erupted in the Holocene. It is capped by a 4-by-5-kilometre summit caldera, and tuff cones lie on the lower flanks. Recely Bluff is on the northeast slope of the mountain, about 7 nautical miles (13 km) from the peak. Its volume of 1,800 cubic kilometres (430 cu mi) is comparable to that of Mount Erebus.
Melville Peak is a prominent peak surmounting Cape Melville, the eastern cape of King George Island, in the South Shetland Islands off Antarctica. It represents an eroded stratovolcano of unknown age and contains a volcanic crater at its summit. A volcanic ash layer similar in composition to Melville Peak has been identified 30 km (19 mi) away from the volcano and may indicate Melville Peak has been volcanically active in the last few thousand years.
Mount Rittmann is a volcano in Antarctica. Discovered in 1988–1989 by an Italian expedition, it was named after the volcanologist Alfred Rittmann (1893–1980). It features a 2 kilometres (1.2 mi) or 8 by 5 kilometres wide caldera which crops out from underneath the Aviator Glacier. The volcano was active during the Pliocene and into the Holocene, including large explosive eruptions; a major eruption occurred in 1254 CE and deposited tephra over much of Antarctica. Currently, the volcano is classified as dormant.
The Marie Byrd Land Volcanic Province is a volcanic field in northern Marie Byrd Land of West Antarctica, consisting of over 18 large shield volcanoes, 30 small volcanic centres and possibly many more centres buried under the West Antarctic Ice Sheet. It overlies a 500 km (310 mi) wide and 800 km (500 mi) long dome that has formed as a result of fault blocking within the West Antarctic Rift System.
Mount Berlin is a glacier-covered volcano in Marie Byrd Land, Antarctica, 100 kilometres (62 mi) from the Amundsen Sea. It is a roughly 20-kilometre-wide (12 mi) mountain with parasitic vents that consists of two coalesced volcanoes: Berlin proper with the 2-kilometre-wide (1.2 mi) Berlin Crater and Merrem Peak with a 2.5-by-1-kilometre-wide crater, 3.5 kilometres (2.2 mi) away from Berlin. The summit of the volcano is 3,478 metres (11,411 ft) above sea level. It has a volume of 200 cubic kilometres (48 cu mi) and rises from the West Antarctic Ice Sheet. It is part of the Marie Byrd Land Volcanic Province. Trachyte is the dominant volcanic rock and occurs in the form of lava flows and pyroclastic rocks.
Mount Petras is a mountain in Antarctica. It consists of volcanic rocks, most of Cretaceous age but there is also an Eocene-Oligocene volcanic system that may have been emplaced inside of thin ice. It is part of the Marie Byrd Land Volcanic Province and is its oldest volcano.
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 the Miocene and Pliocene, but there is evidence for an eruption about two millennia ago and uncertain indications of activity in the 20th century.