Mount Hampton

Template:Short description Template:Infobox mountain

Mount HamptonTemplate:Efn 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 geologyEdit

File:HamptonMap.jpg

Topographic map of Mount Hampton (1:250,000 scale) from USGS Mount Hampton

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 volcano<ref>Carracedo et al. 2019, p.439</ref> with an "impressive" appearance and an ice-filled<ref>GNIS</ref> Template:Convert wide caldera.<ref>Wilch, McIntosh and Panter 2021, p.546</ref> Like other volcanoes in the Executive Committee Range, it is a paired volcano<ref>LeMasurier and Rex, 1989, p.7225</ref> with the northwesterly Template:Convert high Whitney Peak and the southeasterly Template:Convert high Marks Peak, which is the main summit of Mount Hampton.<ref>LeMasurier and Thompson, 1990, p.194</ref>Template:Efn 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.<ref>LeMasurier and Thompson, 1990, p.189</ref> The centres of the two calderas are about Template:Convert apart.<ref>Rocchi, LeMasurier and Vincenzo 2006, p.1001</ref> Based on outcrops, it appears that most of the volcano is formed by flow rocks<ref>Rocchi, LeMasurier and Vincenzo 2006, p.997</ref> but cinder and lava bombs occur at parasitic vents.<ref>LeMasurier and Thompson, 1990, p.190</ref>

The mountain rises about Template:Convert above the surface of the West Antarctic Ice Sheet<ref>Carracedo et al. 2019, p.439</ref> which buries most of the edifice, and moraine ridges are found at its base on the ice sheet.<ref>LeMasurier and Thompson, 1990, p.190</ref> Owing to climate conditions, the persistence of permanent ice atop of the mountain is unlikely over the long term;<ref>Carracedo et al. 2019, p.442</ref> erosion there appears to have been episodic<ref>Carracedo et al. 2019, p.444</ref> with maxima during interglacials<ref>Carracedo et al. 2016</ref> and there is no evidence of cirque formation.<ref>Lemasurier and Rocchi 2005, p.57</ref> Lichens have been found on the mountain.<ref>Scharon and Early, p.91</ref>

CompositionEdit

The volcano is formed by phonolite rocks, but parasitic vents have also erupted basanite<ref>Carracedo et al. 2019, p.439</ref> and Whitney Peak also erupted trachyte and benmoreite.<ref>LeMasurier and Rex, 1989, p.7228</ref> Hawaiite has been reported as well.<ref>Panter et al. 2021, p.580</ref> The volcanic rocks contain augite and feldspar; further, spinel-containing lherzolite xenoliths have been found.<ref>Carracedo et al. 2019, p.439</ref> In general, composition is unique for each volcano in the Executive Committee Range.<ref>LeMasurier and Rex, 1989, p.7229</ref>

Eruption historyEdit

Mount Hampton is one of the oldest volcanoes of Antarctica and was active during the Miocene.<ref>Carracedo et al. 2019, p.439</ref> Despite this, it is less eroded than some younger volcanoes in the region;<ref>Rocchi, LeMasurier and Vincenzo 2006, p.997</ref> in general, the ages of the Marie Byrd Land volcanoes are not correlated to their erosion status.<ref>LeMasurier and Thompson, 1990, p.158</ref> It appears that Whitney Peak is the older half of the edifice and that volcanic activity then migrated to Mount Hampton.<ref>LeMasurier and Thompson, 1990, p.189</ref> More generally, volcanism in the Executive Committee Range migrated southwards over time at an average rate of Template:Convert, although Mount Hampton and its southern neighbour Mount Cumming were simultaneously active 10 million years ago.<ref>LeMasurier and Rex, 1989, p.7227</ref>

Last parasitic eruptions took place around 11.4 million years ago<ref>Carracedo et al. 2019, p.439</ref> and the youngest radiometric dates are 8.3 million years.<ref>Carracedo et al. 2019, p.442</ref> As at other volcanoes of Marie Byrd Land, the parasitic activity at Mount Hampton occurred after a long period of dormancy.<ref>LeMasurier and Thompson, 1990, p.197</ref> However, the presence around the caldera rim of snow-covered<ref>LeMasurier p.91</ref> inactive Template:Convert high ice towers Template:Efn indicate that the mountain is geothermally active<ref>LeMasurier and Wade, 1968</ref> and may have erupted during the Holocene.<ref>LeMasurier and Thompson, 1990, p.193</ref> 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<ref>Wilch, McIntosh and Panter 2021, p.547</ref> and seismic activity recorded at the volcano may be due to volcano-tectonic processes or due to ice movement.<ref>Lough et al. 2012</ref>

NotesEdit

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SourcesEdit

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