高知県四万十市の上部白亜系佐田石灰岩の岩相と化石群集

• 延原 尊美

  静岡大学教育学部地学教室

• 恩田 大学

  横浜国立大学大学院環境情報学府

• 菊池 直樹

  高知大学理学部自然環境科学科

• 近藤 康生

  高知大学理学部自然環境科学科

• 松原 啓

  高知大学理学部自然環境科学科

• 天野 和孝

  上越教育大学地学教室

• ジェンキンズ ロバート

  横浜国立大学教育人間科学部

• 疋田 吉識

  中川町自然誌博物館

• 間嶋 隆一

  横浜国立大学教育人間科学部

書誌事項

タイトル別名

• Lithofacies and fossil assemblages of the Upper Cretaceous Sada Limestone, Shimanto City, Kochi Prefecture, Shikoku, Japan
• コウチケン シマントシ ノ ジョウブ ハクアケイ サダ セッカイガン ノ ガンソウ ト カセキ グンシュウ

抄録

The Sada Limestone in the Upper Cretaceous Nakamura Formation, Shimanto Belt, Shikoku, Japan is known to yield abundant "Thyasira" and "Serpula" fossils. However, the whole assemblage has never been studied to an appropriate depth. We present a preliminary report on the mode of occurrence, lithology, and faunal composition of the Sada Limestone followed by discussion on its origin. The limestone crops out at more than 10 localities in an elliptical area (250m in NE-SW, 400m in NW-SE direction) surrounded by Upper Cretaceous siltstone. The boundary between the limestone and the siltstone is gradational, which suggests that the limestone was autochthonous. The Sada Limestone consists of three lithofacies: 1) banded limestone (detrital micrite with parallel calcite-sheets, showing inverted stromatactoid structure); 2) "Thyasira"-"Serpula" limestone (detrital micrite containing abundant autochthonous "Thyasira" and "Serpula"); and 3) sparsely-fossiliferous massive limestone, composed mainly of recrystallized sparite. The three lithofacies alternate with each other with intervals of several meters. The "Thyasira"-"Serpula" assemblage is associated with other chemosynthetic bivalves, such as Myrtea? sp. and Solemya sp. "Thyasira" shells are large (8cm of maximum shell length) and conjoined. The shells are densely packed in the limestone, whereas in the surrounding siltstone molluscan fosssils are rare. The taxonomic composition, mode of occurrence, and lithological characteristics such as inverted stromatactoid structure suggest that the Sada Limestone is seep-related and the fauna represents a chemosynthetic ecosystem similar to many other thyasirid-rich carbonates worldwide. However, to verify the hypothesis requires further biogeochemical approaches such as stable isotope and biomarker analyses.

収録刊行物

• 化石

  化石 84 (0), 47-60, 2008

  日本古生物学会

キーワード

• Cretaceous
• chemosynthesis
• Shimanto-Belt
• Sada Limestone

詳細情報

• CRID: 1390282679412355200
• NII論文ID: 110006967287
• NII書誌ID: AN00041606
• DOI: 10.14825/kaseki.84.0_47
• ISSN: 24242632
• ISSN: 00229202
• NDL書誌ID: 9687484
• Web Site: http://hdl.handle.net/10126/4576
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I9687484
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • IRDB
  • NDL
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可