恵庭ａテフラのフォールユニットと火山ガラス屈折率

• 中村 有吾

  日本学術振興会 北海道大学大学院地球環境科学研究科

• 平川 一臣

  北海道大学大学院地球環境科学研究科

書誌事項

タイトル別名

• Fall-units and Refractive Index Fluctuations of Eniwa-a Tephra Glass, Hokkaido, Japan
• エニワ aテフラ ノ フォールユニット ト カザン ガラス クッセツリツ

抄録

Eniwa-a tephra (En-a), which erupted from Eniwa volcano, western Hokkaido, at 17ka BP, is composed of more than three fall-units in the southern part of the Ishikari Lowlands. The refractive indices of En-a volcanic glass are significantly different among fall-units. The refractive index is relatively high (n=1.510-1.514) in the upper fall-unit and low (n=1.505-1.510) in the middle and lower fall-units. It is generally accepted that the petrographic properties of some tephras differ considerably between fall-units. However, this has not always been considered in collecting samples and measuring petrographic properties of marker tephras. In order to obtain petrographic properties for tephra identification, we should take samples from every fall-or flow-unit at an outcrop near a source vent. The refractive indices of En-a volcanic glass from the Hidaka Range tend to have remarkably low values and large variances due to incomplete hydration in volcanic glasses.

収録刊行物

• 第四紀研究

  第四紀研究 42 (4), 295-302, 2003

  日本第四紀学会

キーワード

• 恵庭aテフラ
• フォールユニット
• 火山ガラス
• 屈折率

詳細情報

• CRID: 1390001206496192128
• NII論文ID: 10011741282
• NII書誌ID: AN0034136X
• DOI: 10.4116/jaqua.42.295
• ISSN: 18818129
• ISSN: 04182642
• NDL書誌ID: 6666617
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6666617
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可