Mount Takahe is a 3,460-metre-high (11,350 ft) snow-covered shield volcano in Marie Byrd Land, Antarctica, 200 kilometres (120 mi) from the Amundsen Sea.
With a volume of 780 km3 (200 cu mi), it is a massive volcano; the parts of the edifice that are buried underneath the West Antarctic Ice Sheet are probably even larger.
The mountain's name refers to the takahē, a flightless nearly extinct bird from New Zealand; members of the 1957–1958 Marie Byrd Land Traverse party nicknamed an aircraft that had resupplied them "takahe".
[12] No major air routes or supply roads to Antarctic stations pass close to the mountain,[13] and some parts of the cone are accessible only by helicopter.
[21] The subglacial part, which might bottom out at 1,340–2,030 metres (4,400–6,660 ft) below sea level,[22] could have an even larger volume[21] and is elongated in an east–west direction.
[25] There are at least three[26] parasitic vents with basaltic composition on its lower flanks,[27] with three cinder cones found on the western and southern slopes.
[41] Some rock units at the foot of the volcano were emplaced underneath ice or water[31] and feature hyaloclastite and pillow lavas.
[50] To the south it is flanked by the Transantarctic Mountains and to the north by the volcanic province of Marie Byrd Land.
[47] Mount Takahe is located in the eastern Marie Byrd Land volcanic province[7] and with an estimated volume of 5,520 cubic kilometres (1,320 cu mi)[g][55] could be the largest of the Marie Byrd Land volcanoes, comparable to Mount Kilimanjaro in Africa.
[51] Mount Takahe may feature a large magma chamber[58] and a heat flow anomaly has been found.
Basanite, hawaiite, and mugearite are uncommon,[29] but the occurrence of benmoreite[17] and pantellerite has been reported,[22] and some rocks have been classified as andesites.
[61] Hawaiite occurs exclusively in the older outcrops, basanite only in parasitic vents[25] and mugearite only on the lower sector of the volcano.
[61] The magmas appear to have formed through fractional crystallization at varying pressures,[68] and ultimately came from the lithosphere at 80–90-kilometre (50–56 mi) depth,[69] that was affected by subduction processes[70] over 85 million years ago.
[22] Rocks aged 192,000±6,300 years old are found at the summit caldera, implying that the volcano had reached its present-day height by then.
[77] After it grew out of the ice, Mount Takahe increased in size through the emission of lava flows with occasional pyroclastic eruptions.
[79] The volcano reaches an altitude high enough that tephras erupted from it can readily penetrate the tropopause and spread over Antarctica through the stratosphere.
[80] The occurrence of several volcanic eruptions in the region about 30,000 years ago has been suggested to have caused a cooling of the climate of Antarctica,[81] 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.
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 ended.
[78] It is possible that between 18,000 and 15,000 years ago, either a crater lake formed in the caldera or the vents were buried by snow and ice.
[93] These eruptions have been recorded from ice cores at the WAIS Divide[93] and at Taylor Glacier in the McMurdo Dry Valleys, where they constrain estimates of the rate of deglaciation.
[95] Bromine and sulfur isotope data indicate that the amount of UV radiation in the atmosphere did increase at that time in Antarctica.
[103] At Siple Dome, a further eruption between 10,700 and 5,600 years ago is recorded[104] and one tephra layer around 1783 BC (accompanied by increased sulfate concentrations in ice) might also come from Mount Takahe.
[107] There is no evidence of fumarolic activity or warm ground,[108][5] unlike at Mount Berlin, which is the other young volcano of Marie Byrd Land.