Zircon U-Pb ages of the Paleogene formation in the western part of Mihara City, Hiroshima Prefecture

• Yamasaki Hirofumi

  Graduate School of Humanities and Social Sciences, Hiroshima University

• Hisamori Koki

  Program in Curriculum and Instruction Sciences, Graduate School of Education, Hiroshima University Present address: Hyogo Prefectural Suma Higashi High School

• Danhara Tohru

  Kyoto Fission-Track Co., Ltd.

• Iwano Hideki

  Kyoto Fission-Track Co., Ltd.

• Hirata Takafumi

  Geochemical Research Center, The University of Tokyo

Bibliographic Information

Other Title

• 広島県三原市西部に分布する未命名古第三系のジルコンU-Pb年代
• ヒロシマケン ミハラシ セイブ ニ ブンプ スル ミメイメイ コ ダイサンケイ ノ ジルコン U-Pb ネンダイ

Abstract

Paleogene formations locally distributed in the southern Chugoku region and the eastern coastal areas of the Seto Inland Sea, southwest Japan, were analyzed in this study. The Paleogene strata were roughly divided based on their major constituents into a formation comprising non-marine and marine sandstones and mudstones and a second formation composed of fluvial conglomerates that are lithologically similar to the previously named “mountain gravels”. However, detailed age information is unavailable for some of these strata. The first reliable zircon U-Pb age was obtained using laser ablation-inductively coupled plasma-mass spectrometry on zircon grains from a fine-grained sandy tuff intercalated with an unnamed conglomerate bed that, based on lithology, can be correlated with the “mountain gravels” distributed in the western part of Mihara city, Hiroshima Prefecture. The zircon grains yield a U-Pb age of 40.8±0.1 Ma (weighted mean age of the youngest cluster), which is interpreted as the maximum depositional age of the sandy tuff, thus establishing a middle Eocene age for this formation in the southern areas of the Chugoku region.

Journal

• The Journal of the Geological Society of Japan

  The Journal of the Geological Society of Japan 127 (8), 479-187, 2021-08-15

  The Geological Society of Japan

Keywords

• Paleogene formation
• Mihara city
• mountain gravels
• sandy tuff
• zircon
• U-Pb dating

Details

• CRID: 1390853056024897024
• NII Article ID: 130008118744
• NII Article ID: 40022716784
• NII Book ID: AN00141768
• DOI: 10.5575/geosoc.2021.0015
• ISSN: 13499963
• ISSN: 00167630
• NDL BIB ID: 031752727
• Web Site: http://id.ndl.go.jp/bib/031752727
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I031752727
• Web Site: https://www.jstage.jst.go.jp/article/geosoc/127/8/127_2021.0015/_pdf
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed