Mount Hampton is a shield volcano with a circular ice-filled caldera. It is a twin volcano with Whitney Peak to the northwest and has erupted phonolite rocks. It is the northernmost of the volcanoes which comprise the Executive Committee Range in Marie Byrd Land, Antarctica, and was active during the Miocene.
Geography and geology
Mount Hampton is the northernmost volcano of the Executive Committee Range in Marie Byrd Land, Antarctica. It has the form of a symmetrical uneroded shield volcanoCarracedo et al. 2019, p.439 with an "impressive" appearance and an ice-filledGNIS caldera.Wilch, McIntosh and Panter 2021, p.546 Like other volcanoes in the Executive Committee Range, it is a paired volcanoLeMasurier and Rex, 1989, p.7225 with the northwesterly Whitney Peak and the southeasterly Marks Peak, which is the main summit of Mount Hampton.LeMasurier and Thompson, 1990, p.194 The northwesterly summit is associated with its own caldera, which is partly cut by the Mount Hampton caldera on the southeastern flank and buried by the lava flows from the latter.LeMasurier and Thompson, 1990, p.189 The centres of the two calderas are about apart.Rocchi, LeMasurier and Vincenzo 2006, p.1001 Based on outcrops, it appears that most of the volcano is formed by flow rocks,Rocchi, LeMasurier and Vincenzo 2006, p.997 but cinder and lava bombs occur at parasitic vents.LeMasurier and Thompson, 1990, p.190
The mountain rises about above the surface of the West Antarctic Ice Sheet,Carracedo et al. 2019, p.439 which buries most of the edifice, and moraine ridges are found at its base on the ice sheet.LeMasurier and Thompson, 1990, p.190 Owing to climate conditions, the persistence of permanent ice atop of the mountain is unlikely over the long term;Carracedo et al. 2019, p.442 erosion there appears to have been episodicCarracedo et al. 2019, p.444 with maxima during interglacials,Carracedo et al. 2016 and there is no evidence of cirque formation.Lemasurier and Rocchi 2005, p.57 Lichens have been found on the mountain.Scharon and Early, p.91
Composition
The volcano is formed by phonolite rocks, but parasitic vents have also erupted basanite,Carracedo et al. 2019, p.439 and Whitney Peak also erupted trachyte and benmoreite.LeMasurier and Rex, 1989, p.7228 Hawaiite has been reported as well.Panter et al. 2021, p.580 The volcanic rocks contain augite and feldspar; further, spinel-containing lherzolite xenoliths have been found.Carracedo et al. 2019, p.439 In general, composition is unique for each volcano in the Executive Committee Range.LeMasurier and Rex, 1989, p.7229
Eruption history
Mount Hampton is one of the oldest volcanoes of Antarctica and was active during the Miocene.Carracedo et al. 2019, p.439 Despite this, it is less eroded than some younger volcanoes in the region;Rocchi, LeMasurier and Vincenzo 2006, p.997 in general, the ages of the Marie Byrd Land volcanoes are not correlated to their erosion status.LeMasurier and Thompson, 1990, p.158 It appears that Whitney Peak is the older half of the edifice and that volcanic activity then migrated to Mount Hampton.LeMasurier and Thompson, 1990, p.189 More generally, volcanism in the Executive Committee Range migrated southwards over time at an average rate of , although Mount Hampton and its southern neighbour Mount Cumming were simultaneously active 10 million years ago.LeMasurier and Rex, 1989, p.7227
Last parasitic eruptions took place around 11.4 million years ago,Carracedo et al. 2019, p.439 and the youngest radiometric dates are 8.3 million years.Carracedo et al. 2019, p.442 As at other volcanoes of Marie Byrd Land, the parasitic activity at Mount Hampton occurred after a long period of dormancy.LeMasurier and Thompson, 1990, p.197 However, the presence around the caldera rim of snow-coveredLeMasurier p.91 inactive ice towers indicate that the mountain is geothermally activeLeMasurier and Wade, 1968 and may have erupted during the Holocene.LeMasurier and Thompson, 1990, p.193 Later research suggested that the ice towers were actually formed by wind-driven erosion of snow and ice. There is no evidence of geothermal processes,Wilch, McIntosh and Panter 2021, p.547 and seismic activity recorded at the volcano may be due to volcano-tectonic processes or due to ice movement.Lough et al. 2012
See also List of volcanoes in Antarctica
Notes
Sources