Ostracods and rock facies across the Emsian/Eifelian boundary at Couvin (Dinant Synclinorium, Belgium)

A moderately rich ostracod fauna is reported from the upper part of the St. Joseph Formation (Fm), the Eau Noire Fm and the lower part of the Couvin Fm in the Eau Noire section located nearby Couvin. The section that crosses the Emsian/Eifelian boundary belongs entirely to the Couvinian historical stage. The ostracod fauna observed appertains to the Eifelian Mega-Assemblage and is indicative, in the Eau Noire Fm and in the Couvin Fm, of continuous shallow open-marine environments close to the fair-weather wave-base. The sampling and the number of ostracods extracted from the St. Joseph Fm are not sufficient to make environmental inferences and the study does not demonstrate an abnormal change in the ostracod fauna neither in relation with the Eau Noire Fm/Couvin Fm boundary, nor in relation with the Emsian/Eifelian boundary. The ostracods present near the Emsian/Eifelian boundary are mentioned for the first time in the southern border of the Dinant Synclinorium and they display close relations with the Eifel Mountains (Germany) and the Holy Cross Mountains (Poland).