Diffusion controlled formation of spherical carbonate concretion in muddy sedimentary matrices

• Yoshida Hidekazu

  Material Research Section, Nagoya University, University Museum

• Yamamoto Koshi

  Graduate School of Environmental Studies, Nagoya University

• Ohe Toshiaki

  TEPSCO

• Katsuta Nagayoshi

  Department of Education, Gifu University

• Muramiya Yusuke

  Graduate School of Environmental Studies, Nagoya University Fukada Geological Institute

• Metcalfe Richard

  Quintessa Limited

抄録

Spherical carbonate concretions are commonly observed in marine clayey sedimentary strata and often contain well preserved fossils. Previous studies revealed that the spherical concretions are formed by the very rapid reaction with decomposed organic matter from inside and Ca²⁺ ion of seawater. However, the detailed mass transport process during concretion formation has not been completely understood. Here two different size of spherical concretions, cm size of tusk-shell concretions and metre size of Moeraki boulders, are re-examined to understand the diffusion oriented formation process. Field observations, and detailed mineralogical (XRD) and geochemical analyses (SXAM, XRF, δ¹³C) revealed diffusive transport of HCO₃⁻ from decaying organic matter and Ca²⁺ from surrounding pore-water of marine origin led to solid carbonate precipitation reactions that progressed from the margin of a concretion. Based on the compositional gradients across the concretions, a diffusion based diagram has been applied to estimate the growth rates of the different size of spherical concretions. The process and rate estimation indicate that even gigantic spherical concretions can form quite rapidly in the muddy matrices under a diffusion-controlled transport regime.

収録刊行物

• ＧＥＯＣＨＥＭＩＣＡＬ　ＪＯＵＲＮＡＬ

  ＧＥＯＣＨＥＭＩＣＡＬ　ＪＯＵＲＮＡＬ 54 (4), 233-242, 2020

  一般社団法人日本地球化学会

キーワード

• spherical carbonate concretion
• diffusion
• muddy sediments

詳細情報

• CRID: 1390003825207960448
• NII論文ID: 130007891323
• NII書誌ID: AA00654975
• DOI: 10.2343/geochemj.2.0593
• ISSN: 18805973
• ISSN: 00167002
• NDL書誌ID: 030640511
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I030640511
• Web Site: https://www.jstage.jst.go.jp/article/geochemj/54/4/54_2.0593/_pdf
• 本文言語コード: en
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可