Mount Takahe
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Mount Takahe is a snow-covered
shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...
in
Marie Byrd Land Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of , 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 centu ...
,
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
, from the
Amundsen Sea The Amundsen Sea is an arm of the Southern Ocean off Marie Byrd Land in western Antarctica. It lies between Cape Flying Fish (the northwestern tip of Thurston Island) to the east and Cape Dart on Siple Island to the west. Cape Flying Fish ...
. It is a mountain with
parasitic vent A parasitic cone (also adventive cone, satellite cone, satellitic cone or lateral cone) is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the ...
s and a
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
up to wide. Most of the volcano is formed by
trachytic Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrusions) enri ...
lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
s, but
hyaloclastite Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin marg ...
is also found. Snow, ice, and
glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
s cover most of Mount Takahe. With a volume of , it is a massive volcano; the parts of the edifice that are buried underneath the
West Antarctic Ice Sheet The West Antarctic Ice Sheet (WAIS) is the segment of the Antarctic ice sheet, continental ice sheet that covers West Antarctica, the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere. It is cla ...
are probably even larger. It is part of the
West Antarctic Rift System The West Antarctic Rift System is a series of rift valleys between East and West Antarctica. It encompasses the Ross Embayment, the Ross Sea, the area under the Ross Ice Shelf and a part of Marie Byrd Land in West Antarctica, reaching to th ...
along with 18 other known volcanoes. The volcano was active in the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...
period.
Radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to Chronological dating, date materials such as Rock (geology), rocks or carbon, in which trace radioactive impurity, impurities were selectively incorporat ...
has yielded ages of up to 300,000years for its rocks, and it reached its present height about 200,000years ago. Several
tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...
layers encountered in
ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...
s at Mount Waesche and
Byrd Station The Byrd Station is a former research station established by the United States during the International Geophysical Year by U.S. Navy Seabees during Operation Deep Freeze II in West Antarctica. It was a year-round base until 1972, and then se ...
have been attributed to Mount Takahe, although some of them were later linked to eruptions of
Mount Berlin Mount Berlin is a glacier-covered volcano in Marie Byrd Land, Antarctica, from the Amundsen Sea. It is a roughly mountain with parasitic vents that consists of two coalesced volcanoes: Berlin proper with the Berlin Crater and Merrem Peak wi ...
instead. The tephra layers were formed by
explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ex ...
or
phreatomagmatic Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions conta ...
eruptions. Major eruptions took place around 17,700years ago—possibly forming an
ozone hole Ozone depletion consists of two related events observed since the late 1970s: a lowered total amount of ozone in Earth, Earth's upper atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar ...
over Antarctica—and in the early
Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
. Mount Takahe's last eruption occurred about 7,600 years ago, and there is no present-day activity.


Geography and geomorphology

The mountain's name refers to the
takahē The South Island takahē (''Porphyrio hochstetteri'') is a Flightless bird, flightless swamphen indigenous to New Zealand and the largest living member of the Rail (bird), rail family. It is often known by the abbreviated name takahē, whic ...
, a flightless nearly extinct bird from
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
; members of the 1957–1958 Marie Byrd Land Traverse party nicknamed an aircraft that had resupplied them "takahe". It was first visited in 1957–1958 and again in 1968, 1984–1985 and 1998–1999. Mount Takahe is at the
Bakutis Coast The Getz Ice Shelf () is an ice shelf over long and from wide, bordering the Hobbs Coast and Bakutis Coast of Marie Byrd Land, Antarctica, between the McDonald Heights and Martin Peninsula. Several large islands are partially or wholly embedded ...
, eastern
Marie Byrd Land Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of , 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 centu ...
,
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
. Bear Peninsula and the
Amundsen Sea The Amundsen Sea is an arm of the Southern Ocean off Marie Byrd Land in western Antarctica. It lies between Cape Flying Fish (the northwestern tip of Thurston Island) to the east and Cape Dart on Siple Island to the west. Cape Flying Fish ...
coast are north of Mount Takahe. It is an isolated mountain, and the closest other volcanoes are Mount Murphy and
Toney Mountain Toney Mountain () is an elongated snow-covered shield volcano, long and rising to at Richmond Peak, located southwest of Kohler Range in Marie Byrd Land, Antarctica. Geology Toney Mountain is an elongated volcanic massif that rises - above ...
away. No major
air route In the United States, airways or air routes are defined by the Federal Aviation Administration, Federal Aviation Administration (FAA) in two ways: "VOR Federal airways and Low/Medium Frequency (L/MF) (Colored) Federal airways" These are desi ...
s or supply roads to Antarctic stations pass close to the mountain, and some parts of the cone are accessible only by helicopter. The volcanic mountain rises above the ice level with maximum elevation . It is an undissected nearly perfect cone, a
shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...
with an exposed volume of about . The subglacial part, which might bottom out at below sea level, could have an even larger volume and is elongated in an east–west direction. On its summit lies a flat, snow-filled
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
with a and
volcanic neck A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...
. A
lava dome In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...
may crop out inside the caldera. Radial
fissure vent A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few metres wide and may be many kilo ...
s are found around the volcano, and vents also occur around the caldera rim. There are at least three
parasitic vent A parasitic cone (also adventive cone, satellite cone, satellitic cone or lateral cone) is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the ...
s with
basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
ic composition on its lower flanks, with three
cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...
s found on the western and southern slopes. One of these cinder cones has been described as a subdued vent. The Jaron Cliffs are found on the southern slope. The volcano is largely uneroded, mostly hiding the internal structure which would clarify its history.Only twelve
outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets. Features Outcrops do not cover the majority of the Earth's land surface because in most p ...
s, with a total area of less than , emerge from the ice. Based on these outcrops,
lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
s with a thickness of appear to be widespread on Mount Takahe, while
pyroclastic rock Pyroclastic rocks are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroclasts. Pyroclastic rocks are a type of volcaniclastic deposit, which are deposit ...
s such as deposits of
Strombolian eruption In volcanology, a Strombolian eruption is a type of volcanic eruption with relatively mild blasts, typically having a Volcanic Explosivity Index of 1 or 2. Strombolian eruptions consist of ejection of incandescent Scoria, cinders, lapilli, and vo ...
s,
lapilli Lapilli (: lapillus) is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' is Latin for "little stones". By definition lapilli range from in dia ...
tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...
s and
lahar A lahar (, from ) is a violent type of mudflow or debris flow composed of a slurry of Pyroclastic rock, pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a valley, river valley. Lahars are o ...
deposits are less common. Occurrences of pyroclastic rocks at the summit have been correlated with
tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...
deposits elsewhere in Antarctica. Additionally,
obsidian Obsidian ( ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Produced from felsic lava, obsidian is rich in the lighter element ...
-bearing and recently erupted
lava bomb A volcanic bomb or lava bomb is a mass of partially molten rock (tephra) larger than 64 mm (2.5 inches) in diameter, formed when a volcano ejects viscosity, viscous fragments of lava during an eruption. Because volcanic bombs cool a ...
-and-
block Block or blocked may refer to: Arts, entertainment and media Broadcasting * Block programming, the result of a programming strategy in broadcasting * W242BX, a radio station licensed to Greenville, South Carolina, United States known as ''96.3 ...
units crop out in the caldera rim, at Bucher Rim.
Tuya A tuya is a flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet. They are rare worldwide, being confined to regions which were covered by glaciers and had active volcanism during the same period. As lava ...
s have been reported.


Glaciation

Mount Takahe is almost entirely covered by ice of the
West Antarctic Ice Sheet The West Antarctic Ice Sheet (WAIS) is the segment of the Antarctic ice sheet, continental ice sheet that covers West Antarctica, the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere. It is cla ...
, which rises about above sea level. A tributary of the
Thwaites Glacier Thwaites Glacier is an unusually broad and vast Antarctic glacier located east of Mount Murphy, on the Walgreen Coast of Marie Byrd Land. It was initially sighted by polar researchers in 1940, mapped in 1959–1966 and officially named in 1967, ...
passes close by. There are two small
glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
s on the volcano itself, on the southwestern and northern flanks. They are eroding eruption products from the summit area, and
moraine A moraine is any accumulation of unconsolidated debris (regolith and Rock (geology), rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a gla ...
s have been mapped both on the western flank and in the summit caldera. Glacial erosion is slight, with only a few corries cut into the lower slopes. The ice cover on the mountain includes both snow-covered and ice-covered areas, with
sastrugi Sastrugi, or zastrugi, are features formed by the erosion of snow by wind. They are found in polar regions, and in snowy, wind-swept areas of temperate regions, such as frozen lakes or mountain ridges. Sastrugi are distinguished by upwind-facing ...
and other wind-roughened surfaces. The cold dry polar environment retards
weathering Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs '' in situ'' (on-site, with little or no move ...
. Air temperatures are usually below freezing. Some rock units at the foot of the volcano were emplaced underneath ice or water and feature
hyaloclastite Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin marg ...
and
pillow lava Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of discontinu ...
s. These units rise to about above the present-day ice level. Some of these units, such as Gill Bluff,
Möll Spur Mount Takahe is a snow-covered shield volcano in Marie Byrd Land, Antarctica, from the Amundsen Sea. It is a mountain with parasitic vents and a caldera up to wide. Most of the volcano is formed by trachytic lava flows, but hyaloclastite is ...
and Stauffer Bluff, are "hydrovolcanic deltas" comparable to
lava delta Lava deltas, similar to river deltas, form wherever sufficient sub-aerial flows of lava enter standing bodies of water. The lava cools and breaks up as it encounters the water, with the resulting fragments filling in the adjacent seabed topograp ...
s which formed when lava flows or
parasitic vent A parasitic cone (also adventive cone, satellite cone, satellitic cone or lateral cone) is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the ...
s entered the ice, generating meltwater lakes around them. They crop out at the base of the volcano and are well preserved. Ice elevation was not stable during the emplacement of these deltas, and meltwater drained away, leading to the formation of diverse structures within the hyaloclastite deltas. The deltas may have formed during ice highstands 66,000 and 22,000–15,000years ago.


Geology

The West Antarctic Rift System is a
basin and range province The Basin and Range Province is a vast United States physiographic region, physiographic region covering much of the inland Western United States and Northern Mexico, northwestern Mexico. It is defined by unique basin and range topography, charac ...
similar to the
Great Basin The Great Basin () is the largest area of contiguous endorheic watersheds, those with no outlets to the ocean, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja Californi ...
in
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
; it cuts across Antarctica from the
Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who ...
to the
Bellingshausen Sea The Bellingshausen Sea is an area along the west side of the Antarctic Peninsula between 57°18'W and 102°20'W, west of Alexander Island, east of Cape Flying Fish on Thurston Island, and south of Peter I Island (there the southern ''Vostokkyste ...
. The Rift became active during the
Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
. Owing to thick ice cover it is not clear whether it is currently active, and there is no
seismic Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes (or generally, quakes) and the generation and propagation of elastic ...
activity. Most of the Rift lies below sea level. To the south it is flanked by the
Transantarctic Mountains The Transantarctic Mountains (abbreviated TAM) comprise a mountain range of uplifted rock (primarily sedimentary) in Antarctica which extends, with some interruptions, across the continent from Cape Adare in northern Victoria Land to Coats L ...
and to the north by the volcanic province of
Marie Byrd Land Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of , 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 centu ...
. Volcanic activity in Marie Byrd Land commenced about 34million years ago, but high activity began 14million years ago. A major uplifted dome, in width, is centred on the Amundsen Sea coast and is associated with the Rift. About 18
central volcano A central volcano is a type of volcano formed by basalts and silica-rich volcanic rocks. They contain very few or no volcanic rocks of intermediate composition, such that they are chemically bimodal volcanism, bimodal. Large silicic eruptions at c ...
es were active in Marie Byrd Land from the
Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
to the
Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
. Among the volcanic areas in Marie Byrd Land are the
Flood Range The Flood Range () is a range of large snow-covered mountains extending in an east–west direction for about and forming a right angle with the southern end of the Ames Range in Marie Byrd Land, Antarctica. Location The Flood Range is south ...
with
Mount Berlin Mount Berlin is a glacier-covered volcano in Marie Byrd Land, Antarctica, from the Amundsen Sea. It is a roughly mountain with parasitic vents that consists of two coalesced volcanoes: Berlin proper with the Berlin Crater and Merrem Peak wi ...
, the
Ames Range The Ames Range () is a range of snow-covered, flat-topped, steep-sided mountains, extending in a north–south direction for and forming a right angle with the eastern end of the Flood Range in Marie Byrd Land, Antarctica. Location The Ames R ...
, the
Executive Committee Range The Executive Committee Range () is a range consisting of five major volcanoes, which trends north-south for along the 126th meridian west, in Marie Byrd Land, Antarctica. Location The Executive Committee Range is south of the eastern end of ...
with
Mount Sidley Mount Sidley is the highest dormant volcano in Antarctica, a member of the Volcanic Seven Summits, the highest volcanoes on each of the seven continents, with a summit elevation of . It is a massive, mainly snow-covered shield volcano, which is ...
and Mount Waesche, the Crary Mountains,
Toney Mountain Toney Mountain () is an elongated snow-covered shield volcano, long and rising to at Richmond Peak, located southwest of Kohler Range in Marie Byrd Land, Antarctica. Geology Toney Mountain is an elongated volcanic massif that rises - above ...
, Mount Takahe and Mount Murphy. These volcanoes mainly occur in groups or chains, but there also are isolated edifices. Mount Takahe is located in the eastern Marie Byrd Land volcanic province and with an estimated volume of could be the largest of the Marie Byrd Land volcanoes, comparable to
Mount Kilimanjaro Mount Kilimanjaro () is a dormant volcano in Tanzania. It is the highest mountain in Africa and the highest free-standing mountain above sea level in the world, at above sea level and above its plateau base. It is also the highest volcano i ...
in Africa. Most of these volcanoes are large, capped off by a summit caldera and appear to have begun as fast-growing shield volcanoes. Later, calderas formed. Eventually, late in the history of the volcanoes parasitic vents were active. The volcanoes are all surmounted by rocks composed of
trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanite, aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrus ...
,
phonolite Phonolite is an uncommon shallow intrusive or extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a var ...
,
pantellerite Pantellerite is a type of volcanic rock, specifically a peralkaline rhyolite. It has a higher iron and lower aluminium composition than comendite. It is named after Pantelleria, a volcanic island in the Strait of Sicily and the Type locality (geo ...
, or comendite. Their activity has been attributed either to the reactivation of crustal structures or to the presence of a
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 ho ...
. The volcanoes rise from a
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...
. Mount Takahe may feature a large
magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it u ...
and a
heat flow Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, ...
anomaly has been found. A
magnetic anomaly In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying ...
has also been linked to the mountain.


Composition

Trachyte is the most common rock on Mount Takahe, phonolite being less common.
Basanite Basanite () is an igneous, volcanic ( extrusive) rock with aphanitic to porphyritic texture. It is composed mostly of feldspathoids, pyroxenes, olivine, and calcic plagioclase and forms from magma low in silica and enriched in alkali metal ox ...
,
hawaiite Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii. It occurs during the later stages of volcanic activity on oceanic islands such as Ha ...
, and
mugearite Mugearite () is a type of oligoclase-bearing basalt, comprising olivine, apatite, and opaque oxides. The main feldspar in mugearite is oligoclase. Mugearite is a sodium-rich member of the alkaline magma series. In the TAS classification of volc ...
are uncommon, but the occurrence of
benmoreite Benmoreite is a volcanic rock of intermediate composition. It is a silica-undersaturated sodium-rich variety of trachyandesite (the other kind is latite) and belongs to the alkaline suite of igneous rocks. It was named after Ben More, a mount ...
and pantellerite has been reported, and some rocks have been classified as
andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...
s. Hawaiite occurs exclusively in the older outcrops, basanite only in parasitic vents and mugearite only on the lower sector of the volcano. Despite this, most of the volcano is believed to consist of
mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
rocks with only about 10–15% of
felsic In geology, felsic is a grammatical modifier, modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted ...
rocks, as the upper visible portion of the volcano could be resting on a much larger buried base. The parasitic vents probably make up less than 1% of the edifice. Ice-lava interactions produced hyaloclastite,
palagonite Palagonite is an alteration product from the interaction of water with volcanic glass of chemical composition similar to basalt. Palagonite can also result from the interaction between water and basalt melt. The water flashes to steam on contact ...
and
sideromelane Sideromelane is a vitreous basaltic volcanic glass, usually occurring in palagonite tuff, for which it is characteristic. It is a less common form of tachylite, with which it usually occurs together; however it lacks the iron oxide crystals di ...
. No major changes in magma chemistry occurred during the last 40,000years but some variation has been recorded. All these rocks appear to have a common origin and define an alkaline–peralkaline suite.
Phenocryst image:montblanc granite phenocrysts.JPG, 300px, Granites often have large feldspar, feldspathic phenocrysts. This granite, from the Switzerland, Swiss side of the Mont Blanc massif, has large white phenocrysts of plagioclase (that have trapezoid sh ...
s include mainly
plagioclase Plagioclase ( ) is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continu ...
, with less common
olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...
and
titanomagnetite Titanomagnetite is a mineral containing oxides of titanium and iron, with the formula Fe2+(Fe3+,Ti)2O4. It is also known as titaniferous magnetite, mogensenite, Ti-magnetite, or titanian magnetite. It is part of the spinel group of minerals. The Cu ...
;
apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of ...
has been reported as well. The magmas appear to have formed through
fractional crystallization Fractional crystallization may refer to: * Fractional crystallization (chemistry), a process to separate different solutes from a solution * Fractional crystallization (geology) Fractional crystallization, or crystal fractionation, is one of the ...
at varying pressures, and ultimately came from the
lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time ...
at depth, that was affected by
subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...
processes over 85million years ago.


Eruption history

The volcano was active in the late
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...
. Radiometric results reported in 1988 include ages of less than 360,000years for rocks in the caldera rim and of less than 240,000years for volcanic rocks on the flanks. In his 1990 book ''Volcanoes of the Antarctic Plate and Southern Oceans'' LeMasurier gave 310,000±90,000years ago as the oldest date for samples tested, citing unpublished K-Ar dates, but in a 2016 review of dates for Mount Takahe LeMasurier reported that none were older than 192,000years. A 2013 paper also by LeMasurier reported maximum ages of 192,000years for caldera rim rocks and of 66,000years for lower flank rocks. The entire volcano may have formed in less than 400,000years or even less than 200,000years, which would imply rapid growth of the edifice. Rocks aged 192,000±6,300years old are found at the summit caldera, implying that the volcano had reached its present-day height by then. Early research indicated that most of Mount Takahe formed underneath the ice, but more detailed field studies concluded that most of the volcano developed above the ice surface. The ice surface has fluctuated over the life of Mount Takahe with an increased thickness during
marine isotope stage Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth's paleoclimate, deduced from Oxygen isotope ratio cycle, oxygen isotope data derived from deep sea core ...
s 4 and 2, explaining why units originally emplaced under ice or water now lie above the ice surface and alternate with lava flow deposits. These elevated deposits were emplaced about 29,000–12,000years ago while the lava delta-like deposits are between about 70,000and 15,000years old. After it grew out of the ice, Mount Takahe increased in size through the emission of lava flows with occasional pyroclastic eruptions. Outcrops in the summit region indicate that most eruptions were magmatic, but some hydromagmatic activity occurred. Cinder cones and
tuff cone Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and s ...
s formed during the late stage of activity.


Tephra in ice cores

Tephra layers in
ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...
s drilled at
Byrd Station The Byrd Station is a former research station established by the United States during the International Geophysical Year by U.S. Navy Seabees during Operation Deep Freeze II in West Antarctica. It was a year-round base until 1972, and then se ...
have been attributed to Mount Takahe. The volcano reaches an altitude high enough that tephras erupted from it can readily penetrate the
tropopause The tropopause is the atmospheric boundary that demarcates the lowest two layers of the atmosphere of Earth – the troposphere and stratosphere – which occurs approximately above the equatorial regions, and approximately above the polar regi ...
and spread over Antarctica through the
stratosphere The stratosphere () is the second-lowest layer of the atmosphere of Earth, located above the troposphere and below the mesosphere. The stratosphere is composed of stratified temperature zones, with the warmer layers of air located higher ...
. The occurrence of several volcanic eruptions in the region about 30,000years ago has been suggested to have caused a cooling of the climate of Antarctica, but it is also possible that the growth of the ice sheets at that time squeezed magma chambers at Mount Takahe and thus induced an increase of the eruptive activity. Assuming that most tephra layers at Byrd come from Mount Takahe, it has been inferred that the volcano was very active between 60,000 and 7,500 years ago, with nine eruptive periods and two pulses between 60,000 and 57,000and 40,000–14,000years ago. In the latter part of the latter period hydrovolcanic eruptions became dominant at Mount Takahe, with a maximum around the time when the
Wisconsin glaciation The Wisconsin glaciation, also called the Wisconsin glacial episode, was the most recent glacial period of the North American ice sheet complex, peaking more than 20,000 years ago. This advance included the Cordilleran Ice Sheet, which nucleated ...
ended. It is possible that between 18,000 and 15,000years ago, either a
crater lake Crater Lake ( Klamath: ) is a volcanic crater lake in south-central Oregon in the Western United States. It is the main feature of Crater Lake National Park and is a tourist attraction for its deep blue color and water clarity. T ...
formed in the caldera or the vents were buried by snow and ice. The caldera itself might have formed between 20,000 and 15,000years ago, probably not through a large
explosive eruption In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a Viscosity, viscous ...
. It cannot be entirely ruled out that Byrd Station tephras originate at other volcanoes of Marie Byrd Land such as Mount Berlin. In particular, tephra layers between 30,000and 20,000years ago have been attributed to the latter volcano. Tephra layers from Mount Takahe have also been found at
Dome C Dome C , also known as dôme Circe, Dome Charlie (US) or dôme Concordia, is located at Antarctica at an elevation of above sea level, on one of several Glacier morphology#Ice sheets, domes of the Antarctic Ice Sheet. Location dome C is on the A ...
,
Dome F Dome Fuji (ドームふじ ''Dōmu Fuji''), also called Dome F or Valkyrie Dome, is an Antarctic base located in the eastern part of Queen Maud Land. With an altitude of above sea level, it is the second-highest summit or ''ice dome'' of the ...
, Mount Takahe itself, Mount Waesche,
Siple Dome Siple Dome () is an ice dome approximately 100 km wide and 100 km long, located 130 km east of Siple Coast in Antarctica. Charles Bentley and Robert Thomas established a "strain rosette" on this feature to determine ice movement in ...
and elsewhere in Antarctica. Apart from ice cores, tephras attributed to Mount Takahe have been found in sediment cores taken from the sea. Volcanic eruptions at Mount Takahe lack the
pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...
deposits observed in other large explosive eruptions. The thickness of the Byrd ice core tephras attributed to Mount Takahe suggested that the eruptions were not large, but later research has indicated that large
Plinian eruption Plinian eruptions or Vesuvian eruptions are volcanic eruptions characterized by their similarity to the eruption of Mount Vesuvius in 79 AD, which destroyed the ancient Roman cities of Herculaneum and Pompeii. The eruption was described in a le ...
s also occurred. A series of eruptions about 200 years long took place at Mount Takahe 17,700years ago. These eruptions have been recorded from ice cores at the
WAIS Divide The WAIS Divide is the ice flow divide on the West Antarctic Ice Sheet (WAIS) which is a linear boundary that separates the region where the ice flows to the Ross Sea, from the region where the ice flows to the Weddell Sea. It is similar to a con ...
and at
Taylor Glacier The Taylor Glacier () is a glacier in Antarctica about long, flowing from the plateau of Victoria Land into the western end of Taylor Valley, north of the Kukri Hills. It flows to the south of the Asgard Range. The middle part of the glacier is ...
in the
McMurdo Dry Valleys The McMurdo Dry Valleys are a row of largely Antarctic oasis, snow-free valleys in Antarctica, located within Victoria Land west of McMurdo Sound. The Dry Valleys experience extremely low humidity and surrounding mountains prevent the flow of ...
, where they constrain estimates of the rate of
deglaciation Deglaciation is the transition from full glacial conditions during ice ages, to warm interglacials, characterized by global warming and sea level rise due to change in continental ice volume. Thus, it refers to the retreat of a glacier, an ice shee ...
. These eruptions released a large quantity of
halogen The halogens () are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors would ...
s into the stratosphere, which together with the cold and dry climate conditions of the
last glacial maximum The Last Glacial Maximum (LGM), also referred to as the Last Glacial Coldest Period, was the most recent time during the Last Glacial Period where ice sheets were at their greatest extent between 26,000 and 20,000 years ago. Ice sheets covered m ...
would presumably have led to massive
ozone Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...
destruction and the formation of an
ozone hole Ozone depletion consists of two related events observed since the late 1970s: a lowered total amount of ozone in Earth, Earth's upper atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar ...
.
Bromine Bromine is a chemical element; it has chemical symbol, symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between th ...
and
sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
isotope data indicate that the amount of
UV radiation Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...
in the atmosphere did increase at that time in Antarctica. As is the case with the present-day ozone hole, the ozone hole created by the Takahe eruptions might have altered the Antarctic climate and sped up deglaciation, which was accelerating at that time, but later research has determined that the warming was most likely not volcanically forced.


Holocene and recent activity

Activity waned after this point, two hydromagmatic eruptions being recorded 13,000and 9,000years ago and a magmatic eruption 7,500years ago. This last eruption is also known from the Byrd ice core and may correspond to an eruption 8,200±5,400years ago recorded at Mount Waesche and the Takahe edifice and to two 6217 and 6231 BC tephra layers at Siple Dome. Tephra from a 8,200
before present Before Present (BP) or "years before present (YBP)" is a time scale used mainly in archaeology, geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because ...
eruption has been recorded at Siple Dome and Mount Waesche. A 7,900before present eruption at Mount Takahe is one of the strongest eruptions at Siple Dome and Byrd Station of the last 10,000years. Another eruption reported by the
Global Volcanism Program The Smithsonian Institution's Global Volcanism Program (GVP) documents Earth's volcanoes and their eruptive history during the Quaternary Period of Earth's geologic history, with particular emphasis on volcanic activity during the Holocene Epoc ...
may have occurred in 7050 BC. At Siple Dome, a further eruption between 10,700 and 5,600years ago is recorded and one tephra layer around 1783 BC (accompanied by increased
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
concentrations in ice) might also come from Mount Takahe. Glass shards at Law Dome emplaced in 1552 and 1623 AD may come from this volcano as well. The Global Volcanism Program reports 5550 BC as the date of the last known eruption, and the volcano is currently considered dormant. There is no evidence of
fumarolic A fumarole (or fumerole) is a vent in the surface of the Earth or another rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...
activity or warm ground, unlike at Mount Berlin, which is the other young volcano of Marie Byrd Land.
Seismic Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes (or generally, quakes) and the generation and propagation of elastic ...
activity recorded at depth around the volcano may be linked to its activity. Mount Takahe has been prospected for the possibility of obtaining
geothermal energy Geothermal energy is thermal energy extracted from the crust (geology), crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for m ...
.


Named features

Named features of the mountain, clockwise from the north, include Clausen Glacier, Knezevich Rock, Stauffer Bluff, Oeschger Bluff, Bucher Rim, Jaron Cliffs, Möll Spur, Steuri Glacier, Cadenazzi Rock, Roper Point and Gill Bluff.


See also

*
List of Ultras of Antarctica This is a list of all the ultra prominent peaks (with topographic prominence greater than 1,500 metres) in Antarctica. Some islands in the South Atlantic have also been included and can be found at the end of the list. Antarctica South At ...


Explanatory notes


References


Citations


Sources

* * * * * * * * * * * * * * * * * * * * * * * * *


External links

* {{DEFAULTSORT:Takahe, Mount Polygenetic shield volcanoes Volcanoes of Marie Byrd Land Dormant volcanoes Calderas of Antarctica Pleistocene shield volcanoes Holocene shield volcanoes Shield volcanoes of Antarctica