Anorthoclase crystal from kenyte lava (Late Pleistocene or Holocene; summit cone of Mt. Erebus Volcano, Ross Island, Antarctica) 4 : 無料・フリー素材/写真
Anorthoclase crystal from kenyte lava (Late Pleistocene or Holocene; summit cone of Mt. Erebus Volcano, Ross Island, Antarctica) 4 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Anorthoclase crystal from the Quaternary of Antarctica. Mt. Erebus is the only active volcano in Antarctica. It is a 1.3 million year old, polygenetic stratovolcano in the West Antarctic Rift System. It has erupted basanite, trachyte, tephriphonolite, and phonolite (kenyte) lavas during its history. The summit cone of Erebus has an anorthoclase phenocryst gravel lag, derived from weathering and erosion of kenyte lava, the 2nd-rarest lava type on Earth (Mt. Kenya Volcano in eastern Africa also has kenyte). Kenyte is a porphyritic phonolite having anorthoclase feldspar phenocrysts and a glassy to cryptocrystalline groundmass.Anorthoclase is a type of feldspar, (Na,K)AlSi3O8) - sodium potassium aluminosilicate. This anorthoclase phenocryst has a coating of weathered, highly vesiculated, glassy kenyte. The lava from which the crystal derives is Late Pleistocene or Holocene in age (I’m not sure which). Locality: Mt. Erebus Volcano, western Ross Island, Ross Sea, Antarctica (77º 31’ 51” South latidude, 167º 08’ 40” East longitude) |
| 撮影日 | 2024-02-23 16:24:54 |
| 撮影者 | James St. John |
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