Mount Waesche

Template:Short description Template:Good article Template:Infobox mountain

Mount Waesche is a mountain of volcanic origin at the southern end of the Executive Committee Range in Marie Byrd Land, Antarctica. It is Template:Convert high, and stands Template:Convert southwest of Mount Sidley, the highest volcano in Antarctica. The mountain lies southwest of the Chang Peak caldera and is largely covered with snow and glaciers, but there are rock exposures on the southern and southwestern slopes.

The volcano may have been active as late as the Holocene, with tephra layers recovered from ice cores possibly originating from Mount Waesche. Seismic activity has been recorded both from the volcano and from an area south of it and might reflect ongoing volcanic activity.

Name and research historyEdit

It was discovered by the United States Antarctic Service expedition on a flight on December 15, 1940, and named for Vice Admiral Russell R. Waesche, United States Coast Guard, member of the Antarctic Service Executive Committee.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Field studies took place in 1999-2000 and 2018–2019.Template:Sfn

Geography and geomorphologyEdit

Mount Waesche lies in Marie Byrd Land, one of the most inaccessible areas of Antarctica. It is one of 18 volcanoes in that region, which were active from the Oligocene to recent times. The origin of volcanic activity there has been correlated to the activity of a mantle plume underneath the crust. The region also includes the highest volcano in Antarctica, Mount Sidley, which reaches Template:Convert height.Template:Sfn There may be as many as 138 volcanoes buried underneath the ice.<ref>Template:Cite journal</ref>

Mount Waesche volcano is Template:Convert high.Template:Sfn It is a double volcano,Template:Sfn with the north-northeasterly Chang Peak caldera and the south-southwesterly Mount Waesche proper.Template:Sfn The Chang Peak caldera is Template:Convert Template:Sfn wide and the largest in Marie Byrd Land;<ref name="GVP"/>Template:Sfn Mount Waesche rises almost Template:Convert Template:Sfn over and lies on the rim of the caldera. Mount Waesche is the more conspicuous peak and lava flows crop out on its southernTemplate:Sfn and southwestern flank,Template:Sfn while a Template:Convert wide caldera lies at its summit.Template:Sfn On the northern side of Chang Peak caldera lies a Template:Convert high outcrop,Template:Sfn and it and another outcrop consist of pumice and vitrophyre. Both volcanoes appear to be mainly formed by lava.Template:Sfn At least fiveTemplate:Sfn parasitic vents lie on the volcano, with several aligned on radial fissure vents;Template:Sfn they are cinder cones<ref name="GVP" /> and scoria cones Template:Sfn and have erupted cinder, lava and volcanic bombs.Template:Sfn A Template:Convert longTemplate:Sfn large radial dyke projects from Mount WaescheTemplate:Sfn and is the only part of the edifice where hyaloclastic tuff crops out.Template:Sfn The Bennet Saddle separates Mount Waesche from Mount SidleyTemplate:Sfn Template:Convert to the northeast.<ref name="GVP" />

Mount Waesche is largely covered with snow and features several alpine glaciers as well as a blue-ice area Template:Efn Template:Sfn within the West Antarctic Ice Sheet;Template:Sfn this blue-ice area has an extent of Template:Convert and a number of tephra layers crop out from the ice. Most of these tephra layers come from Mount Waesche, but some originate at Mount Takahe and Mount Berlin Template:Sfn and their age ranges from 118,000 years to Holocene.Template:Sfn Two particularly conspicuous tephra layers from Mount Waesche are known as the "Great Wall" and "Yellow Wall".Template:Sfn

The volcano emerges throughTemplate:Sfn and is surrounded by the West Antarctic Ice Sheet. The ice sheet reaches an elevation of about Template:Convert above sea level at Mount WaescheTemplate:Sfn and flows southwardTemplate:Sfn towards the Ross Ice Shelf.<ref>Template:Cite journal</ref> Blue ice is found in some areas.Template:Sfn Glacial activity has altered the volcano, generating glacial striae and roches moutonnees on the older volcanic rocks and frost shattering landforms and solifluction ridges.Template:Sfn Glacial drift lies on the ice-free southwestern flank.Template:Sfn In turn, glacial moraines have been overrun by lava flows.Template:Sfn Two sets of moraines formed by volcanic debris – one containing ice, the other without – lie on the southern and southwestern flank, reaching heights of Template:Convert and lengths of about Template:Convert.Template:Sfn Surface exposure dating has indicated that they belong to an ice highstand that occurred about 10,000 years agoTemplate:Sfn and that the volcanic rocks were probably extracted from underneath the ice.Template:Sfn However, large parts of the volcano are exposed on its southwestern flankTemplate:Sfn and apart from glacial erosion aeolian erosion has taken place on the volcano.Template:Sfn

GeologyEdit

Mount Waesche is part of the Executive Committee Range, which from north to south includes Mount Hampton, Mount Cumming with the parasitic vent Annexstad Peak, Mount Hartigan, Mount Sidley with Doumani Peak and Chang Peak-Mount Waesche. These mountains are all volcanic and feature ice-filled calderas,Template:Sfn and many are paired volcanoes.Template:Sfn Volcanic activity appears to be moving southward at a rate of Template:Convert.Template:Sfn Seismic activity recorded in 2010 and 2011 south of Mount Waesche may indicate ongoing magmatic activity south of the youngest volcano.Template:Sfn Chang Peak and Mount Waesche appear to be located outside of the Executive Committee Range volcanic lineament.Template:Sfn

The volcano erupted comendite, hawaiite and mugearite, with the former found at Chang Peak and the latter two at Mount Waesche proper; the parasitic cones have erupted a mugearite-benmoreite succession.Template:Sfn Template:Sfn The occurrence of rhyolite has also been reported.Template:Sfn There appear to be two groups of volcanic rocks at Mount Waesche.Template:Sfn Phenocrysts at Chang Peak include aenigmatite, alkali feldspar, ilmenite and quartz and at Mount Waesche olivine, plagioclase and titanaugite.Template:Sfn Granulite and pyroxenite xenoliths have also been found.<ref>Template:Cite journal</ref> Despite their proximity, Mount Sidley and Mount Waesche have erupted distinctly different rocks.Template:Sfn Unusually for volcanoes in Marie Byrd Land, the chemistry of volcanic rocks at Mount Waesche appears to have changed over time.Template:Sfn The total volume of rocks is about Template:Convert.Template:Sfn

Eruption historyEdit

The development of Mount Waesche began in the Pliocene,Template:Sfn and Plio-Pleistocene tephra layers found in the Southern Pacific Ocean may originate at Mount Waesche.<ref>Template:Cite journal</ref> It appears that volcanism in the Executive Committee Range moved southwards over time, beginning at Mount Hampton and eventually arriving at Mount Waesche which is the young volcanic centre of the range.Template:Sfn Chang Peak grew first, 1.6 million years ago or between 2.0Template:En dash1.1 million years ago, while Mount Waesche formed within or about 1 million years ago; the youngest rocks at Waesche are less than 100,000 years oldTemplate:Sfn Template:Sfn whereas there is no evidence of recent activity at Chang Peak.Template:Sfn Argon-argon dating on rocks that today form moraines has yielded ages of about 200,000 years to over 500,000 years.Template:Sfn One flank vent has been dated to be 170,000 years oldTemplate:Sfn and some rocks are too young to be dated by potassium-argon dating.<ref name="GVP" /> A major pulse of lava flow emissions appears to have occurred 200,000-100,000 years agoTemplate:Sfn and an older episode 500,000-300,000 years ago.Template:Sfn

The volcano was active during the Holocene Template:Sfn and may be a source of tephra found in ice cores.Template:Sfn A layer of volcanic ash, about 8,000 years old, that was identified in the region through radar data probably originated at Mount Waesche.Template:Sfn The volcano today is considered to be "probably active" or "possibly active".<ref>Template:Cite journal</ref> A magmatic system may exist Template:Convert south of Mount Waesche at Template:Convert depth below the ice.Template:Sfn Present-day seismic activity has been recorded at Mount Waesche, but it might be either volcanic/tectonic or caused by ice movement.<ref>Template:Cite journal</ref> Future eruptions are unlikely to have any impact beyond the surroundings of the volcano.Template:Sfn