Antarctic volcanism
Antarctic volcanism
There are many volcanoes in Antarctica such as Erebus, Berlin, Deception Island and Melbourne. The most recent volcanic activity is associated with the West Antarctic Rift system and plate collision in the Antarctic Peninsula region. Antarctic volcanoes are typically alkaline, ranging from basaltic to phonolitic and trachytic in composition. Most volcanoes have erupted largely effusively, although explosive eruptions are known from magma–ice interactions and/or associated with the most evolved compositions (LeMasurier and Thomson, 1990; Giordano et al., 2012).
The West Antarctic Rift system is one of the largest areas of crustal stretching in the world, being similar in size to the East African Rift System and to the Basin and Range extensional province of the western USA (e.g. Tessensohn and Werner 1991; Rocchi et al., 2003), and runs from the base of the Antarctic Peninsula in the Weddell Sea, to the Ross Sea Embayment in northern Victoria Land (Rocchi et al., 2003).
Bed elevation map of Antarctica showing the location of West Antarctic Rift system (from Paulsen and Wilson, 2010).
In particular, Victoria Land is characterised by large active volcanoes (e.g. Mt. Erebus and Mt. Melbourne), as well as small active edifices (Mt. Rittmann).
Two quiescent potentially explosive volcanoes in Northern Victoria Land are Mt. Melbourne and Mt. Rittmann; this assessment is based on evidence for recent activity, such as the presence of ash layers on ice, age determinations, and the presence of fumarolic activity (Giordano et al., 2012).
Mt. Melbourne
Mt. Melbourne (2,732 m a.s.l.) is a large quiescent stratovolcano located in Northern Victoria Land (Antarctica) between the Tinker Glacier and the Campbell Glacier (e.g. Giordano et al., 2012).
Mt. Melbourne in the "Mt. Melbourne quadrangle map (Victoria Land)" (Pertusati et al., 2012).
Picture of Mt. Melbourne.
© PNRA
Location of Mt. Melbourne in Google Maps.
The youngest age determination obtained for recent deposits is 0.01± 0.02 Ma (Armstrong, 1978). However, Lyon (1986), based on the depth within the ice cap at which tephra layers from the most recent explosive activity at Mt. Melbourne were found, proposed that the most recent eruption probably occurred between 1862 and 1922 (e.g. Giordano et al., 2012).
Today, the volcano is quiescent, and shows fumarolic activity in the summit area, as shown by the following video:
Melbourne fumaroles
© PNRA
Mt. Rittmann
During the IV Italian expedition in Northern Victoria Land in 1988/89 a new volcano, largely covered by ice, was discovered on the left side of the Aviator Glacier, between the Pilot Glacier and the head of the Icebreaker Glacier and was called Rittmann (Armienti and Tripodo, 1991). The top of Mt Rittmann volcano is made up of a ring of smooth hills representing the rims of a caldera with about 2 km in diameter and slightly emerging on the surrounding, almost flat, morphology (Armienti and Tripodo, 1991). The base of the volcano outcrops on the almost vertical cliffs of the Pilot Glacier (Bargagli et al., 1996).
Map of Northern Victoria Land with the location of Mt. Rittmann (yellow dot).
Picture showing Mt. Rittmann.
© PNRA
Location of Mt. Rittmann in Google Maps.
Mount Rittmann lavas are of an age (4 Ma) and alkalinity intermediate between Mount Overlord and Mount Melbourne products (Armienti and Tripodo, 1991). During the 6th Italian Antarctic Expedition (1990/91) fumaroles and grounds heated by geothermal activity were discovered in a minor calderic structure of Mount Rittmann (73'28.28'S, 165'36.93'E; Bargagli et al., 1996; Bonaccorso et al., 1991).
Mt. Rittmann shows fumarolic activity as testified by this video: