九州南西部の芦北地域南部に散在する先古第三系砂岩のモード組成

  • 山本 啓司
    鹿児島大学大学院理工学研究科
  • 佐藤 良樹
    鹿児島大学大学院理工学研究科 現所属:鉱研工業株式会社

書誌事項

タイトル別名
  • Modal composition of pre-Paleogene sandstones scattered in the southern Ashikita region, southwestern Kyushu, Southwest Japan
公開日
2025-07-31
DOI
  • 10.5575/geosoc.2025.0012
公開者
一般社団法人 日本地質学会

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説明

<p>The southern Ashikita region in southwestern Kyushu, southwest Japan, is underlain by Jurassic to Lower Cretaceous accretionary units (Chichibu Belt) and the Cretaceous Saiki Subgroup (Shimanto Belt) in its northern and southern parts, respectively. These pre-Paleogene units are widely covered by Neogene and younger formations, and thus are exposed in isolated outcrops over a narrow area. The modal compositions of representative pre-Paleogene sandstones in this region were determined. A ternary Q–F–R plot of the sandstone compositions indicates the sandstones are mostly feldspathic. A Qm–F–Lt plot constructed using the Gazzi–Dickinson method indicates the sandstones can be divided into two groups based on the content of monocrystalline quartz (Qm). Seven samples from the northern part of the study area have high Qm/F values (≥0.69) and 10 samples from the southern part of the study area have low Qm/F values (≤0.50). The boundary between the locations of the high- and low-Qm/F samples coincides with the known position of the Butsuzo Tectonic Line in this region.</p>

収録刊行物

  • 地質学雑誌

    地質学雑誌 131 (1), 147-153, 2025-07-31

    一般社団法人 日本地質学会

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