Mount Rittmann is a volcano inAntarctica. Discovered in 1988–1989 by an Italian expedition, it was named after the volcanologistAlfred Rittmann (1893–1980). It features a 2 kilometres (1.2 mi) or 8 by 5 kilometres (5.0 mi × 3.1 mi) widecaldera which crops out from underneath theAviator Glacier. The volcano was active during thePliocene and into theHolocene, including large explosive eruptions; a major eruption occurred in 1254 CE and depositedtephra over much of Antarctica. Currently, the volcano is classified asdormant.
The volcano isfumarolically active. The geothermal activity keeps part of the caldera ice-free;mosses 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 andMount Erebus and has led to efforts to establish aprotected area on the volcano.
It lies inVictoria Land on theRoss Sea,[2] 100 kilometres (62 mi) fromTerranova Bay[3] and 150 kilometres (93 mi) from the ItalianMario Zucchelli Station.[4] It was discovered by an Italian expedition in 1988–1989[5] and named in honour of the volcanologistAlfred Rittmann.[6] Owing to having only been recently discovered and being remote, the volcano is poorly studied.[7]
Mount Rittmann is 2,600 metres (8,500 ft) high[1] and lies in theMountaineer Range.[5] A 2 kilometres (1.2 mi)[8] or 8 by 5 kilometres (5.0 mi × 3.1 mi) widecaldera is located underneath theAviator Glacier;[1] it is outlined by a ring of volcanic hills and outcrops[5] that emerge slightly[9] from an almost flat surrounding terrain.[10] The name Mt. Rittmann is sometimes applied to a fumarolically activenunatak on the caldera rim.[11] The base of the volcano crops out from thePilot Glacier,[5] which together with the caldera is one of the few parts of the[6] otherwise snow- and ice-covered volcano[2] that aren't encased in ice.[6] Outcrops consist ofhyaloclastites,lava flows andpillow lavas.[10]
An Italian expedition in 1990–1991 discovered heated ground andfumaroles at the caldera, implying that moltenmagma exists underneath the volcano.[5] The fumarolic activity occurs at a 200 metres (660 ft) wide and 80 metres (260 ft) high face[12] with sandy-gravelly soil;[13] another warm area is reported from the lower slopes.[2]
The vents of the fumaroles are centimetres wide and surrounded byefflorescences formed byhydrothermally altered rocks.[5] Fumarolic gases containcarbon dioxide andmethane and lackhydrogen sulfide andsulfur dioxide.[14] The fumaroles keep an area of the caldera at 2,250 metres (7,380 ft) elevation ice-free;[2] at 2,100 metres (6,900 ft) elevation mean temperatures are −20 °C (−4 °F), but fumarolic activity heats the surrounding rocks up to 60 °C (140 °F).[3] Surface temperatures reach 43.4 °C (110.1 °F).[12]
Patches of[2]moss grow in rosette form[15] on sandy soil in the fumarolic areas[2] at temperatures of 17–35 °C (63–95 °F).[16] A steady supply of water, the fumarolic warmth and shelter allow the growth of this vegetation;[2] such volcanic vegetation is also found at volcanoesMount Erebus andMount Melbourne.[5] The mosses may have arrived there by wind;[17]Pohlia nutans, the moss found at Mount Rittmann, is acosmopolitan species which is also encountered elsewhere in Victoria Land.[18] Genetic analysis indicates that the mosses growing at Mount Rittmann arrived there in one event and are not diverse.[19]
Together withDeception Island,Mount Erebus andMount Melbourne, Mount Rittmann is one of the four volcanoes in Antarctica with known geothermal habitats[28] and the least studied of these.[4] Three other volcanoes show evidence of past or present fumarolic activity.[28]
The volcano is part of theMcMurdo Volcanic Group, 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[5] or of theMount Overlord volcanic field.[30] The volcanic province is related to the tectonic events that occurred during therifting of the Ross Sea. Activity commenced during theEocene-Oligocene and continued into theHolocene.[10]
The volcano is ofPliocene age[34] and was active between 4 million years ago and 70,000 years ago,[1] although the oldest rocks may actually be from a separate volcano.[35]Radiometric dating 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.[30] The caldera appears to be younger than the volcanic rocks at Pilot Glacier,[5] although its unimpressive topographical expression might indicate an old age.[35] It was possibly formed by aPlinian eruption.[36] Tephra deposits atOutback Nunataks,[37] various marine and ice core tephras,[38]Eemian-age tephras atTalos Dome inEast Antarctica[39] and dust bands found inblue-ice areas ofFrontier Mountain andLichen Hill in Victoria Land may originate from Mount Rittmann,[30] and at least four large eruptions took place in the last 74,000 years.[38] The eruption history of the volcano is poorly known due to the scarcity of outcrops.[40]
About 11,000 years ago, Mount Rittmann had a largeexplosive eruption which deposited the "Aviator Tephra" in theAviator Basin of the Ross Sea. Reconstructions imply that the eruption commenced as ahydromagmatic event which then transitioned into aPlinian eruption which yieldedlapilli andvolcanic ash.[41] Presumably, the volcano was ice-clad when the eruption commenced and meltwater from the ice interacted with the magma to trigger hydromagmatic activity.[38] At the end, a caldera collapse may have occurred, and the volcano producedignimbrites.[41]
Tephrochronology has found evidence that Mount Rittmann erupted in 1254[42] and deposited a tephra layer across Antarctica.[43] This Rittmann tephra[44] or "1254 C.E. tephra" has been identified inice cores ofEast andWest Antarctica;[43] its discovery atEdisto Inlet expands its occurrence to an area of over 950,000 square kilometres (370,000 sq mi) all around the volcano and to distances of over 2,000 kilometres (1,200 mi). Magma was efficiently fragmented during the eruption,[42] which may[44] or may not have been intense.[42] It probably was one of the largest Holocene eruptions of Antarctica,[44] although it was exceeded in size by Rittmann's 11,000 and 22,000 eruptions[45] and did not produce much sulfur.[46] Originally, it was attributed toThe Pleiades volcanoes before its source at Mount Rittmann was discovered.[8]
Additional eruptions may have occurred after 1254.[8] Presently, the volcano is considered quiescent[34] and is not monitored[11] although a seismo-tectonic station was installed in its vicinity[47] and has recorded seismic activity, some of which may be due to ice movements and the other of volcanic origin.[48] Small thermal anomalies have been observed fromLandsat satellite images and may correspond to fumarolic activity.[49] A repeat of the 1254 eruption could form a long-lasting ash cloud, ashfall on nearbyresearch stations[50] and disruption ofair traffic to and fromMcMurdo Station.[11]
^Bergstrom, D. M.; Convey, P.; Huiskes, A. H. L., eds. (2006).Trends in Antarctic Terrestrial and Limnetic Ecosystems: Antarctica as a Global Indicator. Dordrecht: Springer Netherlands. p. 164.doi:10.1007/1-4020-5277-4.ISBN978-1-4020-5276-7.
^Flores, Patricio A.; Amenábar, Maximiliano J.; Blamey, Jenny M. (2013), Satyanarayana, Tulasi; Littlechild, Jennifer; Kawarabayasi, Yutaka (eds.), "Hot Environments from Antarctica: Source of Thermophiles and Hyperthermophiles, with Potential Biotechnological Applications",Thermophilic Microbes in Environmental and Industrial Biotechnology: Biotechnology of Thermophiles, Springer Netherlands, p. 101,doi:10.1007/978-94-007-5899-5_3,ISBN978-94-007-5899-5
^Del Carlo, P.; Di Roberto, A.; Di Vincenzo, G.; Bertagnini, A.; Landi, P.; Pompilio, M.; Colizza, E.; Giordano, G. (14 April 2015). "Late Pleistocene-Holocene volcanic activity in northern Victoria Land recorded in Ross Sea (Antarctica) marine sediments".Bulletin of Volcanology.77 (5): 13.Bibcode:2015BVol...77...36D.doi:10.1007/s00445-015-0924-0.hdl:11368/2857700.ISSN1432-0819.S2CID129707264.
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Bargagli, R.; Broady, P.A.; Walton, D.W.H. (12 May 2004). "Preliminary investigation of the thermal biosystem of Mount Rittmann fumaroles (northern Victoria Land, Antarctica)".Antarctic Science.8 (2):121–126.doi:10.1017/S0954102096000181.S2CID131300952 – viaAcademia.edu.
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Skotnicki, M.; Bargagli, R.; Ninham, J. (1 October 2002). "Genetic diversity in the moss Pohlia nutans on geothermal ground of Mount Rittmann, Victoria Land, Antarctica".Polar Biology.25 (10):771–777.doi:10.1007/s00300-002-0418-3.ISSN1432-2056.S2CID1479671.
