Late Eifelian and Early Givetian ostracod assemblages from Wellin, Hotton and On-Jemelle (Ardenne, Dinant Synclinorium, Belgium). Paleoenvironmental implications

The study of 3430 ostracods collected in the Lomme, Hanonet and Trois-Fontaines formations (Late Eifelian/Early Givetian) in four sections of the Dinant Synclinorium (Ardenne) allowed the recognition of more than 75 taxa. Their study displays the progressive evolution from an external mixed siliciclastic-carbonate ramp to a carbonate platform around the Eifelian/Givetian boundary. Ostracods from the Lomme Fm are published here for the first time. The leperditicopid ostracods are probably indicative of brackish water environments during the deposition of the Trois-Fontaines Fm, and consequently point to wet and warm climatic conditions during Early Givetian times in the Dinant Synclinorium. Their absence in widespread lagoonal environments in the upper part of the Givetian may be on the contrary related to very arid climate conditions. That important climatic change is probably in relation with the Taghanic Biocrisis.