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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. 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, Switzerlan ...

(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 volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

which crops out from underneath the

Aviator Glacier The 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 Si ...

. The volcano was active during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Holocene 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 ...

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

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, ...

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

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 southernmost active volcano on Earth, located on Ross Island in the Ross Dependency in Antarctica. With a summit elevation of , it is the second most prominent mountain in Antarctica (after Mount Vinson) and the second ...

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 or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewood ...

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 78th parallel south, 78°00'S, and westward from the Ross Sea to the edge of the Ant ...

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 ...

, 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. 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 A nunatak (from Inuit language, Inuit ) is the summit or ridge of a mountain that protrudes from an ice field or glacier that otherwise covers most of the mountain or ridge. They often form natural pyramidal peaks. Isolated nunataks are also cal ...

on the caldera rim. The base of the volcano crops out from the Pilot Glacier, 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 marg ...

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 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 ...

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 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 ...

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 (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

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 (Derived from the Latin verb 'efflorescere' roughly meaning 'to flower') 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 i ...

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 is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

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 abundance of methane on Earth makes ...

and lack

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

and

sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...

. 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 plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

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: Internationalism * World citizen, one who eschews traditional geopolitical divisions derived from national citizenship * Cosmopolitanism, the idea that all of humanity belongs to a single moral community * Cosmopolitan ...

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 Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

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

including

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

and cyanobacterial

microbial mat A microbial mat is a multi-layered sheet or biofilm of microbial colonies, composed of mainly bacteria and/or archaea. Microbial mats grow at interfaces between different types of material, mostly on submerged or moist surfaces, but a few surviv ...

Alga Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

e and

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

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 Yellows ...

subsp. rittmannii'' were discovered at fumaroles of Mount Rittmann, and the bacterium ''

Bacillus fumarioli ''Bacillus fumarioli'' is a species of aerobic endospore-forming bacteria. It is moderately thermophilic and acidophilic, with type strain LMG 17489T. This species has been recently transferred into the genus ''Neobacillus''. The correct nomenc ...

'' was cultured from Mount Rittmann and Mount Melbourne. ''Alicyclobacillus acidocaldarius subsp. rittmannii'' is used in studied of

thermophilic A thermophile is a type of extremophile that thrives at relatively high temperatures, between . Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bact ...

enzymes An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as pro ...

. Another

bacteria reported from Mount Rittmann is ''

Aneurinibacillus terranovensis ''Aneurinibacillus terranovensis'' is a thermoacidophilic, microaerophilic and motile bacterium from the genus of ''Aneurinibacillus ''Aneurinibacillus'' is an Aerobic organism, aerobic and endospore-forming bacterial genus from the family ...

''. Together with

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

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 agency set up by the Government of New Zealand 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 Scott Base. ...

to establish an

Antarctic Specially Protected Area An Antarctic Specially Protected Area (ASPA) is an area on the continent of Antarctica, or on nearby islands, which is protected by scientists and several different international bodies. The protected areas were established in 1961 under the Antarc ...

(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 resu ...

, 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 Fault (geology), downfaulted depression, called a graben, or more commonly ...

of the Ross Sea. Activity commenced during the

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

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

and continued into 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 ...

. The outcrops around the caldera rim are formed by

breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...

, which contains juvenile

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

and

xenolith A xenolith ("foreign rock") is a rock (geology), rock fragment (Country rock (geology), country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusi ...

s. The volcanic rocks define a

basanitic 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 oxides ...

, hawaiitic, 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 (or shallow intrusions) enri ...

suite that is alkaline and sodic and features

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

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 ...

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. Xenoliths include both

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, 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 coo ...

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, caus ...

s from the

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, ...

and volcanic rocks.

Hydrothermal alteration Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a Rock (geology), rock by hydrothermal and other fluids. It is traditionally defined as metamorphism which involves a change in t ...

has occurred close to the fumaroles.

Eruption history

The volcano is of

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 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 Chronological dating, date materials such as Rock (geology), rocks or carbon, in which trace radioactive impurity, impurities were selectively incorporat ...

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 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 ...

. Tephra deposits at Outback Nunataks, various marine and ice core tephras,

Eemian The Last Interglacial, also known as the Eemian, was the interglacial period which began about 130,000 years ago at the end of the Penultimate Glacial Period and ended about 115,000 years ago at the beginning of the Last Glacial Period. It cor ...

-age tephras at Talos Dome in

East Antarctica East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying primarily in the Eastern Hemisphere south of the Indian Ocean, and separated from West Antarctica by the Transantarctic ...

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 Ant ...

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 Viscosity, viscous ...

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

which yielded

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 ...

and

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

. 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 surrou ...

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 for dating archaeolo ...

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 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 of

East East 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 fact that ea ...

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 Transan ...

; its discovery at Edisto Inlet 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, although it was exceeded in size by Rittmann's 11,000 and 22,000 eruptions and did not produce much sulfur. Originally, it was attributed to

The Pleiades The Pleiades (), also known as Seven Sisters and Messier 45 (M45), is an asterism of an open star cluster containing young B-type stars in the northwest of the constellation Taurus. At a distance of about 444 light-years, it is among the nea ...

volcanoes before its source at Mount Rittmann was discovered. 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 Lan ...

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 resear ...

and disruption of

air traffic Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled ai ...

to and from

McMurdo Station McMurdo Station is an American Antarctic research station on the southern tip of Ross Island. It is operated by the United States through the United States Antarctic Program (USAP), a branch of the National Science Foundation. The station is ...

References

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