13C/12C ratio double cyclicity in a Miocene browncoal: isotopic signals and orbital forcing
✍ Scribed by Timothy P. Jones; Steven M. Fortier; Volker Mosbrugger; Jochen Roessler; Thorsen Utescher; Abdul R. Ashraf
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 156 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0954-4879
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✦ Synopsis
A detailed stable carbon isotopic profile of a late Miocene browncoal seam from the Lower Rhine Embayment, Germany, reveals two clear separate cycles of different frequency: this is the first instance of this type of isotopic signature being recognized within coals. The ratio of the two frequencies suggests this isotopic signal possibly resulted from climatic or vegetational responses to orbital forcing. The cyclicity has been enhanced by the application of conventional filtering methods on the data set. An analysis of the seam’s palynology indicates a correlation between heavier isotopic compositions and the presence of Sequoiapollenites polyformosus, whose parent plant is believed to have favoured moist climates and higher groundwater tables.