Mount Rittmann is a volcano in

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest co ...

. Discovered in 1988–1989 by an Italian expedition, it was named after the volcanologist

Alfred Rittmann Alfred Rittmann (23 March 1893 – 19 September 1980) was a leading volcanologist. He was elected President of the International Association of Volcanology for three terms (1954–1963). Life Rittmann was the son of a dentist in Basel, Switzerla ...

(1893–1980). It features a or wide

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber ...

which crops out from underneath the

Aviator Glacier Aviator Glacier is a major valley glacier in Antarctica that is over long and wide, descending generally southward from the plateau of Victoria Land along the west side of Mountaineer Range, and entering Lady Newnes Bay between Cape Sibbald and ...

. The volcano was active during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

, including large explosive eruptions; a major eruption occurred in 1254 CE and deposited

tephra Tephra is fragmental material produced by a 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, they re ...

over much of Antarctica. Currently, the volcano is classified as

dormant Dormant, "sleeping", may refer to: Science *Dormancy Dormancy is a period in an organism's life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps ...

. The volcano is fumarolically active. The geothermal activity keeps part of the caldera ice-free;

mosses Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) ''sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and h ...

and various microorganisms grow on this ice-free terrain. Such an occurrence of mosses on fumarolically active volcanoes of Antarctica is limited to Mount Rittmann,

Mount Melbourne Mount Melbourne is a 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 th ...

and

Mount Erebus Mount Erebus () is the second-highest volcano in Antarctica (after Mount Sidley), the highest active volcano in Antarctica, and the southernmost active volcano on Earth. It is the sixth-highest ultra mountain on the continent. With a summ ...

and has led to efforts to establish a

protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural, ecological or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the ena ...

on the volcano.

Geography and geomorphology

It lies in

Victoria Land Victoria Land is a region in eastern Antarctica which fronts the western side of the Ross Sea and the Ross Ice Shelf, extending southward from about 70°30'S to 78°00'S, and westward from the Ross Sea to the edge of the Antarctic Plateau. I ...

on 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 vi ...

, from Terranova Bay and from the Italian Mario Zucchelli Station. It was discovered by an Italian expedition in 1988–1989 and named in honour of the volcanologist

. Owing to having only been recently discovered and being remote, the volcano is poorly studied. Mount Rittmann is high and lies in the

Mountaineer Range Mountaineer Range is the range of mountains lying between the Mariner and Aviator Glaciers in Victoria Land, Antarctica. The seaward parts of the range were first viewed by Ross in 1841, and subsequently by several British and later American expe ...

. A or wide

is located underneath the

; it is outlined by a ring of volcanic hills and outcrops that emerge slightly from an almost flat surrounding terrain. The name Mt. Rittmann is sometimes applied to a fumarolically active nunatak on the caldera rim. The base of the volcano crops out from the

Pilot Glacier Aviator Glacier is a major valley glacier in Antarctica that is over long and wide, descending generally southward from the plateau of Victoria Land along the west side of Mountaineer Range, and entering Lady Newnes Bay between Cape Sibbald an ...

, which together with the caldera is one of the few parts of the otherwise snow- and ice-covered volcano that aren't encased in ice. Outcrops consist of

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 margin ...

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 moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

s 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 disconti ...

Fumaroles and their ecosystems

An Italian expedition in 1990–1991 discovered heated ground and

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other 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 volcan ...

s at the caldera, implying that molten

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natura ...

exists underneath the volcano. The fumarolic activity occurs at a wide and high face with sandy-gravelly soil; another warm area is reported from the lower slopes. The vents of the fumaroles are centimetres wide and surrounded by

efflorescence In chemistry, efflorescence (which means "to flower out" in French) is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water, or ...

s formed by

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

ly altered rocks. Fumarolic gases contain

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

and

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ear ...

and lack

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The und ...

and

sulfur dioxide Sulfur dioxide ( IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic ...

. The fumaroles keep an area of the caldera at elevation ice-free; at elevation mean temperatures are , but fumarolic activity heats the surrounding rocks up to . Surface temperatures reach . Patches of

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ...

grow in rosette form on sandy soil in the fumarolic areas at temperatures of . A steady supply of water, the fumarolic warmth and shelter allow the growth of this vegetation; such volcanic vegetation is also found at volcanoes

and

. The mosses may have arrived there by wind; '' Pohlia nutans'', the moss found at Mount Rittmann, is a

cosmopolitan Cosmopolitan may refer to: Food and drink * Cosmopolitan (cocktail), also known as a "Cosmo" History * Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953 Hotels and resorts * Cosmopoli ...

species which is also encountered elsewhere in Victoria Land. Genetic analysis indicates that the mosses growing at Mount Rittmann arrived there in one event and are not diverse. Research on microbial communities at Mount Rittmann fumaroles has found bacteria including cyanobacteria,

fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...

including

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to consti ...

and cyanobacterial

microbial mat A microbial mat is a multi-layered sheet of microorganisms, mainly bacteria and archaea, or bacteria alone. Microbial mats grow at interfaces between different types of material, mostly on submerged or moist surfaces, but a few survive in desert ...

Alga Algae ( , ; : alga ) are any of a large and diverse group of photosynthetic, eukaryotic organisms. The name is an informal term for a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from u ...

e and

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histor ...

have been identified at Mount Rittmann fumaroles. The bacterial species '' Anoxybacillus amylolyticus'' and the subspecies ''

Alicyclobacillus acidocaldarius ''Alicyclobacillus acidocaldarius'' is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic, thermophilic, and produce endospores. The first identified strains of ''A. acidocaldarius'' were from geysers in Yell ...

subsp. rittmannii'' were discovered at fumaroles of Mount Rittmann, and the bacterium '' Bacillus fumarioli'' was cultured from Mount Rittmann and Mount Melbourne. ''Alicyclobacillus acidocaldarius subsp. rittmannii'' is used in studied of

thermophilic A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the ear ...

enzymes. Another

bacteria reported from Mount Rittmann is ''

Aneurinibacillus terranovensis ''Aneurinibacillus terranovensis'' is a thermoacidophilic A thermoacidophile is an extremophilic microorganism that is both thermophilic and acidophilic; i.e., it can grow under conditions of high temperature and low pH. The large majority o ...

''. Together with

Deception Island Deception Island is an island in the South Shetland Islands close to the Antarctic Peninsula with a large and usually "safe" natural harbor, which is occasionally troubled by the underlying active volcano. This island is the caldera of an act ...

and

, Mount Rittmann is one of the four volcanoes in Antarctica with known geothermal habitats and the least studied of these. Three other volcanoes show evidence of past or present fumarolic activity. There are efforts by

Antarctica New Zealand Antarctica New Zealand is an Institute set up by the Government of New Zealand in 1996 to manage its interests in Antarctica and the Ross Sea. As well as providing logistics support to a large scientific programme, it also runs bases such as Sco ...

to establish an

Antarctic Specially Protected Area An Antarctic Specially Protected Area (ASPA) is an area on the continent of Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Sou ...

(ASPA) on Mount Rittmann, and in 2014 Mount Rittmann was reportedly part of ASPA 175.

Geology

The volcano is part of the

McMurdo Volcanic Group The McMurdo Volcanic Group is a large group of Cenozoic volcanic rocks in the western Ross Sea and central Transantarctic Mountains areas of Antarctica. It is one of the largest provinces of alkaline volcanism in the world, having formed as a resul ...

, one of the largest provinces of alkaline volcanism in the world. It has been subdivided into four subprovinces; Mount Rittmann is considered part of the Melbourne subprovince or of the Mount Overlord volcanic field. The volcanic province is related to the tectonic events that occurred during the

rifting In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

of the Ross Sea. Activity commenced during the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but ...

and continued into the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

. The outcrops around the caldera rim are formed by

breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of d ...

, which contains juvenile

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular v ...

and

xenolith A xenolith ("foreign rock") is a rock fragment ( country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusions in i ...

s. The volcanic rocks define a basanitic,

hawaiitic 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 Haw ...

, mugearitic, phonolithic and

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 enriched with silica and al ...

suite that is alkaline and sodic and features

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers qui ...

and

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more pro ...

phenocryst 300px, Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter 2.3 cm) for scale. A phenocryst is an early forming, relati ...

s. Xenoliths include both

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies und ...

and

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, cau ...

s from the

basement A basement or cellar is one or more Storey, floors of a building that are completely or partly below the storey, ground floor. It generally is used as a utility space for a building, where such items as the Furnace (house heating), furnace, ...

and volcanic rocks.

Hydrothermal alteration Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical co ...

has occurred close to the fumaroles.

Eruption history

The volcano is of

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 although the oldest rocks may actually be from a separate volcano.

Radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

has yielded ages of 3.97 million years for rocks at the base of Mount Rittmann and 240,000 ± 200,000, 170,000 ± 20,000 and 70,000 ± 20,000 years ago for lava flows. The caldera appears to be younger than the volcanic rocks at Pilot Glacier, although its unimpressive topographical expression might indicate an old age. It was possibly formed by a Plinian eruption. Tephra deposits at Outback Nunataks, various marine and ice core tephras,

Eemian The Eemian (also called the last interglacial, Sangamonian Stage, Ipswichian, Mikulin, Kaydaky, penultimate,NOAA - Penultimate Interglacial Period http://www.ncdc.noaa.gov/global-warming/penultimate-interglacial-period Valdivia or Riss-Würm) wa ...

-age tephras at

Talos Dome Talos Dome () (sometimes spelled Thalos Dome) is a large ice dome rising to 2,300 m to the southwest of the Usarp Mountains in Antarctica. The dome overlies the east margin of the Wilkes Subglacial Basin. The feature was delineated by the Scot ...

East Antarctica East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains. It lies almos ...

and dust bands found in

blue-ice area A blue-ice area is an ice-covered area of Antarctica where wind-driven snow transport and sublimation result in net mass loss from the ice surface in the absence of melting, forming a blue surface that contrasts with the more common white Antar ...

s of Frontier Mountain and Lichen Hill in Victoria Land may originate from Mount Rittmann, and at least four large eruptions took place in the last 74,000 years. The eruption history of the volcano is poorly known due to the scarcity of outcrops. About 11,000 years ago, Mount Rittmann had 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 viscous magma s ...

which deposited the "Aviator Tephra" in the Aviator Basin of the Ross Sea. Reconstructions imply that the eruption commenced as a hydromagmatic event which then transitioned into a Plinian eruption which yielded

lapilli Lapilli 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'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range ...

and

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

. Presumably, the volcano was ice-clad when the eruption commenced and meltwater from the ice interacted with the magma to trigger hydromagmatic activity. At the end, a caldera collapse may have occurred, and the volcano produced

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surro ...

Tephrochronology 250px, Tephra horizons in south-central Iceland. The thick and light coloured layer at the height of the volcanologist's hands is rhyolitic tephra from Hekla. Tephrochronology is a Geochronology, geochronological technique that uses discrete l ...

has found evidence that Mount Rittmann erupted in 1254 and deposited a tephra layer across Antarctica. This Rittmann tephra or "1254 C.E. tephra" has been identified in

ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ...

s of

East East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fa ...

and

West Antarctica West Antarctica, or Lesser Antarctica, one of the two major regions of Antarctica, is the part of that continent that lies within the Western Hemisphere, and includes the Antarctic Peninsula. It is separated from East Antarctica by the Transant ...

; its discovery at

Edisto Inlet Edisto Inlet () is a rectangular arm of Moubray Bay, long and wide, entered between Cape Hallett Cape Hallett is a snow-free area (Antarctic oasis) on the northern tip of the Hallett Peninsula on the Ross Sea coast of Victoria Land, East Antarc ...

expands its occurrence to an area of over all around the volcano and to distances of over . Magma was efficiently fragmented during the eruption, which may or may not have been intense. It probably was one of the largest Holocene eruptions of Antarctica; before its source at Mount Rittmann was discovered it was attributed to

The Pleiades The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an Asterism (astronomy), asterism and an open cluster, open star cluster containing middle-aged, hot Stellar classification#Class B, B-type st ...

volcanoes. Additional eruptions may have occurred after 1254. Presently, the volcano is considered quiescent and is not monitored although a seismo-tectonic station was installed in its vicinity and has recorded seismic activity, some of which may be due to ice movements and the other of volcanic origin. Small thermal anomalies have been observed from

Landsat The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to L ...

satellite images and may correspond to fumarolic activity. A repeat of the 1254 eruption could form a long-lasting ash cloud, ashfall on nearby

research stations Research stations are facilities where scientific investigation, collection, analysis and experimentation occurs. A research station is a facility that is built for the purpose of conducting scientific research. There are also many types of resea ...

and disruption of

air traffic Air Traffic are an English alternative rock band from Bournemouth signed to EMI Records. Formed in 2003, the band consists of Chris Wall (piano, lead vocals), David Ryan Jordan (Drums), Tom Pritchard (guitar) and Jim Maddock (bass guitar). Th ...

to and from

McMurdo Station McMurdo Station is a United States Antarctic research station on the south tip of Ross Island, which is in the New Zealand-claimed Ross Dependency on the shore of McMurdo Sound in Antarctica. It is operated by the United States through the Un ...

References

; Sources * * * * * * * * * * * {{DEFAULTSORT:Rittmann Mountains of Antarctica Volcanoes of Victoria Land Borchgrevink Coast Antarctic Specially Protected Areas Calderas of Antarctica Pliocene volcanoes Pleistocene calderas Holocene calderas