2019年11月11日
Biogenically induced bedded chert formation in the alkaline palaeo-lake of the Green River Formation.
Scientific reports
- ,
- ,
- ,
- ,
- ,
- ,
- 巻
- 9
- 号
- 1
- 開始ページ
- 16448
- 終了ページ
- 16448
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1038/s41598-019-52862-7
- 出版者・発行元
- NATURE PUBLISHING GROUP
Rhythmically bedded cherts are observed in both pelagic marine and lacustrine deposits, but the formation mechanism in the latter remains highly uncertain. Our study of alternating chert-dolomite beds in the Eocene Green River Formation, Utah, USA reveals dense accumulations of organic-matter spheres (30-50 μm diameter) of probable algal cyst origin in the chert layers, and centennial- to millennial-scale periodicities in chert layer deposition. A positive correlation between the degree of degradation of the organic spheres and Si distribution implies decomposition of algal organic matter lead to precipitation of lacustrine chert. As both alkalinity and dissolved silica were likely high in the palaeo-lake waters of the Green River Formation, we hypothesize that decomposition of algal organic matter lowered the pH of sediment pore waters and caused silica precipitation. We propose a formation model in which the initial abundance of algal organic matter in sediment varies with productivity at the lake surface, and the decomposition of this algal matter controls the extent of silica precipitation in sediment. The formation of rhythmically bedded chert-dolomite may be linked to centennial- to millennial-scale climatic/environmental factors that modulate algal productivity, which are possibly tied to solar activity cycles known to have similar periodicities.
- リンク情報
-
- DOI
- https://doi.org/10.1038/s41598-019-52862-7
- PubMed
- https://www.ncbi.nlm.nih.gov/pubmed/31712710
- PubMed Central
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6848130
- Web of Science
- https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000495611100040&DestApp=WOS_CPL
- ID情報
-
- DOI : 10.1038/s41598-019-52862-7
- ISSN : 2045-2322
- PubMed ID : 31712710
- PubMed Central 記事ID : PMC6848130
- Web of Science ID : WOS:000495611100040