The Frasnian-Famennian boundary sections at Hony and Sinsin (Ardenne, Belgium): new interpretation based on quantitative analysis of palynomorphs, sequence stratigraphy and climatic interpretation
Abstract
In the light of recent geochemical and sedimentological investigations, the Frasnian-Famennian Boundary sections at Hony and Sinsin (eastern and central Ardenne, Belgium) are re-evaluated in terms of quantitative analysis of spiny acritarchs and miospores. It is concluded that the shaly interval separating the limestone beds dated Frasnian and Famennian by conodonts corresponds to a transgressive - regressive marine sequence. This interpretation is supported, for the Hony section, by a quantitative analysis of two spiny acritarch groups (Gorgonisphaeridium gr. and Micrhystridium gr.) based on the relationship between their abundance and the depth of the marine environment. It is also corroborated by the frequency distribution of a Prasinophyceae (Maranhites stockmansii) indicative for a maximum flooding surface. A sequence stratigraphic model and the possible causes of the bathymetric changes right at the Frasnian-Famennian Boundary are briefly discussed. It is suggested that these changes are related to a short glacial phase during a "warm mode" period.