An early Pleistocene tephra associated with Kumado pyroclastic flow derived from Aizu area, northeast Japan

• Suzuki Takehiko

  Department of Geography, Tokyo Metropolitan University

• Murata Masanori

  Department of Geography, Tokyo Metropolitan University

Bibliographic Information

Other Title

• 東北南部会津地域を給源とする前期更新世に噴出した隈戸火砕流とそれに伴う降下テフラ
• トウホク ナンブ アイズ チイキ オ キュウゲン ト スル ゼンキ コウシンセイ ニ フンシュツシタ クマド カサイリュウ ト ソレニ トモナウ コウカ テフラ

Abstract

Kumado pyroclastic flow deposit, a member of the Shirakawa Pyroclastic Flow Deposit Group, was derived from Ono caldera located in the Aizu area, Northeast Japan arc, in the early Pleistocene. A widespread tephra correlated with this pyroclastic flow deposit is broadly recognized in the Kanto area. In this study, we defined the tephra as Shirakawa-Kumado Tephra (Sr-Kmd). Sr-Kmd was identified using a combination of refractive indices and chemical compositions of the major and rare earth elements of glass shards (n=1.500-1.503, SiO₂ : 78.5-78.7 wt%, TiO₂ : 0.3 wt%, Al₂O₃ : 11.6-11.7 wt%, FeO : 1.5-1.6 wt%, CaO : 0.6-0.7 wt%, K₂O : 3.6-3.9 wt%, Na₂ O : 3.1-3.4 wt%, Ba : 567-606 ppm, La : 11-15 ppm, Y : 28-34 ppm), mineral content, and refractive indices of orthopyroxene (γ=1.713-1.722). Calcareous nannofossil biostratigraphic positions of Sr-Kmd in Byobugaura (between calcareous nannofossil datum 10 and 11) indicate that the age of Sr-Kmd is ca. 1.51 Ma, given that the accumulation rate of the sediments is constant. Sr-Kmd is correlated to a vitric tephra in the Kiwada Formation of Kazusa Group in the Boso peninsula and to Kanai Tuff in the Tsurukawa Formation of Kazusa Group in the Tama hills.

Journal

• The Quaternary Research (Daiyonki-Kenkyu)

  The Quaternary Research (Daiyonki-Kenkyu) 47 (5), 339-348, 2008

  Japan Association for Quaternary Research

Keywords

• Shirakawa pyroclastic flow deposit
• Kumado pyroclastic flow
• tephra
• Kazusa Group
• Kiwada Formation
• Inubo Group

Details

• CRID: 1390001206495728512
• NII Article ID: 10023995170
• NII Book ID: AN0034136X
• DOI: 10.4116/jaqua.47.339
• ISSN: 18818129
• ISSN: 04182642
• ISSN: http://id.crossref.org/issn/04182642
• NDL BIB ID: 9672116
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I9672116
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed