北海道中央部～東部の新第三紀火山活動　　火山学的データおよび全岩化学組成からみた島弧火山活動の成立と変遷

• 広瀬 亘

• 中川 光弘

書誌事項

タイトル別名

• Neogene volcanism in Central-Eastern Hokkaido: Beginning and evolution of arc volcanism inferred from volcanological parameters and geochemistry.
• ホッカイドウ チュウオウブ トウブ ノ シンダイ3キ カザン カツドウ カザンガクテキ データ オヨビ ゼン ガン カガク ソセイ カラ ミタ シマ コ カザン カツドウ ノ セイリツ ト ヘンセン

抄録

Based on ; 348 K-Ar and 61 FT age data, volcanic stratigraphical and physical volcanological studies(volume, rate and mode of eruption, and edifice shape), and whole-rock geochemical data, we discuss temporal and spatial variation in volcanic activity after 19 Ma at central and eastern Hokkaido, southern end of the Kurile arc.The regional horizontal stress field in the area has changed from extension (19-14 Ma), extension∼neutral (14-1 Ma) to compression (1-0 Ma) and volcanic rocks with strong arc characteristics have been erupted since 14 Ma. Scale of volcanism of 19-14 Ma was much smaller in scale (several km³/My) than that of 14-0 Ma (several hundreds km³/My). The former produced bi-modal and non-arc type rocks with high TiO₂ and Nb contents, suggesting that it was not related to subduction, but to plume induced by spreading of a back-arc basin (possibly the Japan Basin). Although volcanic rocks during 14-9 Ma show strongly arc characteristics, it is difficult to explain tectonic setting because of the scarcity of geological and geochemical data from the Kuril basin, which might influence volcanism on the stage. Clearly subduction-related volcanism occurred at least up to 9 Ma. However a small amount of high-TiO₂ (high-Ti) and icelandite-like andesitedacite often occurred during 9-1 Ma, distinct from the youngest rocks (1-0 Ma), which are mostly low-TiO₂ and calcalkaline types. High-Ti and icelandite-like rocks may represent differentiated arc type under extension∼neutral stress field (arc-extension type).Subduction-related volcanism of 9-1 Ma was developing under oblique subduction of the Pacific Plate. The back-arc (volcanic arc) sector could be under less compression thereby producing arc-extension type rocks, because that compressional stress from Pacific plate is largely converted into strike-slip motion of the fore-arc sliver. The obliquity of the subduction of the Pacific plate has temporally decreased and is very weak at present, suggesting that subduction-related volcanism changed by compression since less than 1 Ma and producing mainly calcalkaline rocks.

収録刊行物

• 地質学雑誌

  地質学雑誌 105 (4), 247-265, 1999

  一般社団法人 日本地質学会

キーワード

• tectonics

詳細情報

• CRID: 1390001206234254720
• NII論文ID: 110003013029
• NII論文ID: 10004493126
• NII書誌ID: AN00141768
• DOI: 10.5575/geosoc.105.247
• COI: 1:CAS:528:DyaK1MXjtVOntr8%3D
• ISSN: 13499963
• ISSN: 00167630
• ISSN: http://id.crossref.org/issn/00167630
• NDL書誌ID: 4710818
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I4710818
• 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